WO2008060368A2 - Transglutaminase-binding peptides and methods of use - Google Patents

Abstract

The presently disclosed subject matter discloses diagnostic and prognostic techniques and compositions for the detection and evaluation of a pathologic disorder. Particularly, the presently disclosed subject matter relates to compositions and methods for evaluating the presence of transglutaminase expression in a pathologic condition compared to normal, healthy expression to diagnose, treat and effectively monitor the pathologic condition.

Description

DESCRIPTION TRANSGLUTAMINASE-BINDING PEPTIDES AND METHODS OF USE

RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application

Serial No. 60/848,710, filed October 2, 2006, the disclosure of which is incorporated herein by reference in its entirety.

GRANT STATEMENT This work was supported by grant CA42745 from the National Cancer

Institute. Thus, the U.S. government has certain rights in the presently disclosed subject matter.

TECHNICAL FIELD The presently disclosed subject matter relates to methods and compositions for use in detecting transglutaminase activity in pathologic disorders for use in laboratory and clinical applications.

ABBREVIATIONS CT computerized tomography

DNA deoxyribonucleic acid

DTPA diethylenetriaminepentaacetic acid

ID injected dose

IHC immunohistochemical FFDM freedom from distant metastases

FFLR freedom from local recurrence

FFR freedom from recurrence

FIGO International Federation of Gynecology and Obstetrics g gram Gd gadolinium

GDP guanosine diphosphate

GTP guanosine triphosphate

HPLC high performance liquid chromatography id injected dose i.v. intravenous kg kilogram

MBq megabecquerel mCi millicurie mg milligram min minute mm millimeter

MRI magnetic resonance imaging

P probability

PET Positron Emission Tomography

RH radical hysterectomy

SPECT Single Photon Emission Computed Tomography

Tc-99m Technetium-99m

TG transglutaminase tTG tissue transglutaminase

% percent

= equal to

> greater than

< less than

AMINO ACID ABBREVIATIONS, CODES, AND FUNCTIONALLY

EQUIVALENT CODONS

Amino Acid 3-Letter 1 -Letter Codons

Alanine Ala A GCA GCC GCG GCU

Arginine Arg R AGA AGG CGA CGC CGG CGU

Asparagine Asn N AAC AAU

Aspartic Acid Asp D GAC GAU

Cysteine Cys C UGC UGU

Glutamic acid GIu E GAA GAG

Glutamine GIn Q CAA CAG

Glycine GIy G GGA GGC GGG GGU

Histidine His H CAC CAU lsoleucine lie I AUA AUC AUU

Leucine Leu L UUA UUG CUA CUC CUG CUU

Lysine Lys K AAA AAG

Methionine Met M AUG Phenylalanine Phe F UUC UUU

Proline Pro P CCA CCC CCG CCU

Serine Ser S ACG AGU UCA UCC UCG UCU

Threonine Thr T ACA ACC ACG ACU

Tryptophan Trp W UGG Tyrosine Tyr Y UAC UAU

Valine VaI V GUA GUC GUG GUU

BACKGROUND Transglutaminases are a family of protein cross-linking enzymes that polymerize proteins into high molecular weight aggregates via intermolecular q(g glutamyl) lysine bonds (Gaudrv, C.A. et al. (1999) Cell Res 252: 104-113). Thus, transglutaminases are responsible for the introduction of post- translational covalent bonds that confer strength and stability in a variety of pathologic situations. Because transglutaminases are distributed in plasma, tissues, and extracellular fluids, transglutaminase-modified proteins are present throughout the body in locations that include fibrin blood clots, cell membranes, and the extracellular matrix.

Once activated, transglutaminases can catalyze a number of reactions involving peptidyl glutamine residues as acyl donors and a variety of primary amines as acyl acceptors, with the generation of proteinase-resistant isopeptide bonds (Folk. J. E., et al. (1977) Adv Protein Chem 311 -333; Lorand. L., et al. (1984) MoI Cell Biochem 58: 9-35). For example, the plasma transglutaminase Factor XIII assists in the prevention of blood loss through the stabilization of fibrin clots. Tissue transglutaminase, the most abundant transglutaminase, is a

GTP-GDP binding enzyme (Mian. S., et al. (1995) FEBS Lett 370: 27-31 , Achvuthan, K.E.. et al. (1987) J Biol Chem 262: 1901-1906), that can function as a Ga protein in a signal transduction mechanism (Nakoaka, H., etal. (1994) Science 264: 1593-1596). Tissue transglutaminase is expressed by a variety of cell types, including endothelial cells, smooth muscle cells, and macrophages, which are major components of artherosclerotic lesions as well as solid tumors. Moreover, tissue transglutaminase appears to be involved in the regulation of several biological events including cellular proliferation, differentiation, and apoptosis (Aeschlimann. P., etal. (1994) Thromb Haemost 71: 402-415; Griffin. M.. et al. (2002) J Biochem 368: 377-396).

Intracellular activation of tissue transglutaminase can give rise to cross- linked protein envelopes in apoptotic cells, whereas extracellular activation contributes to stabilization of the extracellular matrix and promotes cell- substrate interaction (Schense, J.C.. etal. (1999) Bioconjug Chem 10: 75-81). Thus, although tissue transglutaminase synthesis and activation is normally part of a protective cellular response contributing to tissue homeostasis, the enzyme also has a role in a number of pathologic conditions including fibrosis, atherosclerosis, neurodegenerative diseases, celiac disease, and cancer metastasis (Haroon. ZA. ef al. (1999) Faseb J 13: 1787-1795. Haroon. ZA. et al (1999) Lab Invest 79: 1679-1686).

To improve the diagnosis of cancer and other disorders, researchers have used the systemic administration of imaging agents (e.g., proton relaxation agents and fluorescent chromophores) for contrast enhancement in techniques such as magnetic resonance imaging (MRI) and laser phototherapy.

For example, tumor location using radiolabeled antibodies for intraoperative tumor detection has been attempted (Arnold et al. (1992) Surgery 112:624-

631). In addition, the introduction of fluorescein-conjugated antibodies for endoscopic tumor location in animals and in humans has also been attempted (FoIIi ef al. (1994) Cancer Res. 54:2643-2450; Peleqrin et al. (1994) Cancer 67:2529-2535). While such techniques show promise, use has been limited by a lack of agents or conjugates that show specific localization. For example, the administration of a labeled substrate used by an enzyme present at sites of neoplastic development would aid in tumor diagnosis, localization and excision.

By way of additional example, although cytological screening and treatment protocols have reduced cervical cancer deaths, cervical cancer is still the leading cause of death for women in third world countries. It remains the leading gynecological malignancy in the United States with 14,500 new cases and 4,800 deaths every year (Parker. S. L. et a/.. (1997) CA Cancer J. CHn. 47: 1 -27). Approximately 25% of women with histologically proven high-grade intraepithelial neoplasia are not identified to be at risk during routine gynecological examination (Blomfield, P.I, et al. (1998) CBJ Brit J Obstet Gyn 105:486-492; Genest. D. R. et al. (1998) Arch Pathol Lab Med 122:338-341). Although surgical therapy is successful most of the time, metastasis into other locations is difficult to diagnose until the cancer is well advanced, because the imaging techniques utilized in conjunction with clinical staging fail to reliably identify occult lymphatic spread (Kim. P..Y. et al. (1998) Gyn One 69:243-247). The ability to assess patients at risk for metastasis of an invasive cancer would allow the implementation of more appropriate treatment protocols with possible reduction of morbidity and mortality.

Thus, the ability to target detectable compounds (for example, labeled enzyme substrates) to enzymes localized at the site of a pathologic disorder would enhance a variety of clinical efforts, since such enzymes (transglutaminases, for example) can be associated with a wide spectrum of tumors, as well as other disorders. However, no techniques are currently available for such targeting of such agents. Accordingly, there remains a need in the art for approaches for delivering detectable agents to tumors, particularly delivering detectable agents to enzymes present at the site of a tumor for use in diagnosing, establishing a prognosis, imaging, monitoring progression and facilitating treatment of tumors and other pathologic disorders. The presently disclosed subject matter addresses these and other needs in the art.

SUMMARY

In some embodiments, the presently disclosed subject matter provides methods of determining a diagnosis or prognosis of a pathologic condition in a subject. In some embodiments, the methods comprise: (a) detecting an expression level, an activity level, or a combination thereof of transglutaminase, and (b) determining a diagnosis or prognosis based on the expression level, activity level, or combination thereof of transglutaminase. In some embodiments, the methods comprise administering an effective amount of a detectable reagent to the subject or to a biological sample from a subject.

In some embodiments, the presently disclosed subject matter provides methods of monitoring progression of a pathologic condition in a subject. In some embodiments, the methods comprise: (a) detecting an expression level, an activity level, or a combination thereof, of transglutaminase, and (b) monitoring progression of the pathologic condition based on the expression level, activity level, or combination thereof of transglutaminase. In some embodiments, the methods comprise administering an effective amount of a detectable reagent to the subject or to a biological sample from a subject.

In some embodiments, the presently disclosed subject matter provides methods of facilitating treatment of a pathologic condition in a subject. In some embodiments, the methods comprise: (a) detecting an expression level, an activity level, or a combination thereof of transglutaminase, and (b) selecting a treatment of a pathologic condition based on the expression level, activity level, or combination thereof of transglutaminase. In some embodiments, the methods comprise administering an effective amount of a detectable reagent to the subject.

In some embodiments, the presently disclosed subject matter provides methods of non-invasively generating a visible image of a pathologic condition in a subject. In some embodiments, the methods comprise administering an effective amount of a detectable reagent to a subject wherein the detectable reagent provides an image of transglutaminase expression level and/or activity; and scanning the subject, whereby a visible image of the pathologic condition is non-invasively generated.

In some embodiments, the presently disclosed subject matter provides a contrast enhancement agent useful for providing a visible image of a pathologic condition in a subject or in a biological sample of a subject. In some embodiments, the contrast agent comprises an effective amount of a detectable reagent, wherein the detectable reagent provides for a visible image of transglutaminase expression and/or activity; and at least one paramagnetic metal ion, and at least one chelator. In some embodiments, the presently disclosed subject matter recites a kit for the detection, diagnosis, prognosis, or monitoring of a pathologic condition in a subject. In some embodiments, the kit comprises: (a) an effective amount of at least a first detectable reagent; and (b) a detection reagent for labeling or detecting the first reagent.

In some embodiments of any of the presently disclosed methods, the detectable reagent is a transglutaminase substrate.

In some embodiments of any of the presently disclosed methods, the detectable transglutaminase substrate is a peptide. In some embodiments of any of the presently disclosed methods, the peptide comprises SEQ ID NO:1 , or a fragment or variant thereof.

In some embodiments of any of the presently disclosed methods, the peptide is in detectably labeled form.

In some embodiments of any of the presently disclosed methods, the peptide is disposed in a pharmaceutically acceptable diluent.

In some embodiments of any of the presently disclosed methods, the pharmaceutically acceptable diluent is phosphate buffered saline.

In some embodiments of any of the presently disclosed methods, the detectable reagent is labeled with a radioactive isotope. In some embodiments of any of the presently disclosed methods, the radioactive isotope is selected from the group comprising ^99mTc, ¹⁸F, ¹³²1, ¹²⁵I,

131 , 90_γ 211_At 67_Cu 153^ 32_p 186_Re 188_Re 212_pb ^ 212_Bj

In some embodiments of any of the presently disclosed methods, the detectable reagent is administered to the subject intravenously, intraperitoneal^, intramuscularly, intratumorally, or intradermally.

In some embodiments of any of the presently disclosed methods, the detecting comprises a technique selected from the group including but not limited to MRI, CAT scan, CT scan, gamma imaging, intravascular ultrasound, PET imaging, SPECT imaging, and immunohistochemical detection. In some embodiments of any of the presently disclosed methods, the expression level, activity level, or combination thereof, of transglutaminase is compared to the expression level, activity level, or combinations thereof of transglutaminase in a control sample. In some embodiments, the control sample is obtained from one or more subjects known to have a pathologic condition, or known to lack a pathologic condition.

In some embodiments of any of the presently disclosed methods, determining a diagnosis or prognosis is based on detecting an increased expression level, activity level, or combinations thereof of transglutaminase.

In some embodiments of any of the presently disclosed methods, the pathologic condition is selected from the group including but not limited to fibrosis, atherosclerosis, neurodegenerative disease, celiac disease, and cancer metastasis. In some embodiments of any of the presently disclosed methods, the cancer metastasis is cancer metastasis from a cancer that can form a solid tumor. In some embodiments, the cancer metastasis is selected from the group including but not limited to breast cancer, ovarian cancer, colon cancer, lung cancer, cervical cancer, head and neck cancer, neuroblastoma, prostate cancer, soft tissue sarcoma, hepatocellular cancer, gastric cancer, pancreatic cancer, liver cancer, bladder cancer, cancer of the urinary tract, thyroid cancer, renal cancer, carcinoma, melanoma, and brain cancer.

In some embodiments of any of the presently disclosed methods, the detectable transglutaminase substrate comprises a contrast enhancement agent comprising at least one paramagnetic metal ion and at least one chelator.

In some embodiments of any of the presently disclosed methods, the paramagnetic metal ion is selected from the group consisting of transition, lanthanide, and actinide elements. In some embodiments, the paramagnetic metal ion is selected from the group including but not limited to Gd(III), Mn(II), Cu(II), Cr(III), Fe(II), Fe(III), Co(II), Er(II), Ni(II), Eu(III) and Dy(III).

In some embodiments of any of the presently disclosed methods, the chelator is selected from the group including but not limited to DTPA, substituted DTPA, DOTA, substituted DOTA, EDTA, substituted EDTA, CDTA and substituted CDTA. In some embodiments of any of the presently disclosed methods, the detection reagent comprises a reagent selected from the group including but not limited to a contrast enhancing agent, a radioactive isotope, and an antibody. In some embodiments of any of the presently disclosed methods, the presently disclosed subject matter comprises an isolated peptide consisting essentially of SEQ ID NO: 1 , or a fragment or variant thereof, wherein said peptide is a substrate for transglutaminase. Accordingly, it is an object of the presently disclosed subject matter to provide novel methods and compositions for use in detecting transglutaminase expression and/or activity. This and other objects are achieved in whole or in part by the presently disclosed subject matter.

An object of the presently disclosed subject matter having been stated above, other objects and advantages of the presently disclosed subject matter will become apparent to those of ordinary skill in the art after a study of the following Description, Drawings, and non-limiting Examples.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a line graph depicting a Kaplan-Meier analysis of human cervical cancer. Patients were stratified by percent tumor tissue expressing tTG less than versus greater than or equal to 50%. Freedom from recurrence was significantly poorer for specimens with elevated extent of expression

(p=0.020, 5-year FFR 68% versus 38%). The symbols V₁ "- - -", and " " represent censored, extent < 50%, and extent > 50%, respectively.

Figure 2 is a schematic representation of the chemical reaction catalyzed by transglutaminase.

Figures 3A-3D are a series of photomicroscopic images indicating transglutaminase localization in cervical tissue slides. Figures 3A and 3B present degree of transglutaminase expression in cervical cancer tissue.

Figures 3C and 3D present degree of transglutaminase expression in healthy, non-cancerous cervical tissue.

Figures 4A-4D are a series of photomicroscopic images indicating transglutaminase localization in head and neck tissue slides. Figures 4A and 4B present degree of transglutaminase expression in cancerous head and neck tissue. Figures 4C and 4D present degree of transglutaminase expression in healthy, non-cancerous head and neck tissue. Figures 5A-5D are a series of photomicroscopic images indicating transglutaminase localization in brain tissue slides. Figures 5A and 5B present degree of transglutaminase expression in neuroblastoma tissue. Figures 5C and 5D present degree of transglutaminase expression in healthy, non- cancerous brain tissue.

Figures 6A-6D are a series of photomicroscopic images indicating transglutaminase localization in connective tissue slides. Figures 6A and 6B present degree of transglutaminase expression in soft tissue sarcoma tissue.

Figures 6C and 6D present degree of transglutaminase expression in healthy, non-cancerous connective tissue.

Figures 7A-7D are a series of photomicroscopic images indicating transglutaminase localization in prostate tissue slides. Figures 7A and 7B present degree of transglutaminase expression in cancerous prostate tissue.

Figures 7C and 7D present degree of transglutaminase expression in healthy, non-cancerous prostate tissue.

Figures 8A-8E are a series of photomicroscopic images indicating transglutaminase localization in normal tissue adjacent to cancerous tissue. Figure 8A presents degree of transglutaminase expression in healthy, noncancerous tissue adjacent to cancerous head and neck tissue. Figure 8B presents degree of transglutaminase expression in healthy, non-cancerous tissue adjacent to neuroblastoma tissue. Figure 8C presents degree of transglutaminase expression in healthy, non-cancerous tissue adjacent to prostate cancer tissue. Figure 8D presents degree of transglutaminase expression in healthy, non-cancerous tissue adjacent to soft tissue sarcoma tissue. Figure 8E presents degree of transglutaminase expression in healthy, non-cancerous tissue adjacent to cervical cancer tissue.

Figure 9 is a diagram representing the chemical reaction involved in labeling the transglutaminase substrate peptide using N-succinimidyl 4-[¹⁸F] fluorobenzoate.

DETAILED DESCRIPTION

The presently disclosed subject matter pertains in part to the novel observation that the degree of expression and/or activity of transglutaminase is a significant prognostic marker for disease progression in cancers, such as, but not limited to, early stage cervical cancer. The variability of expression and/or activity in several other tumor types has also been shown. See, for example, Figures 3-8. As such, the presently disclosed subject matter provides methods for predicting treatment outcome in a variety of solid cancers. Thus, in some embodiments, the presently disclosed subject matter provides compositions, methods, and kits for using transglutaminase expression and/or activity as a prognostic marker in pathologic disorders.

The presently disclosed subject matter also provides methods, compositions, and kits for monitoring the progression of a pathologic condition in a subject., In some embodiments, the method comprises detecting an expression level and/or activity level of transglutaminase in a subject or in a biological sample from a subject. In some embodiments, the method comprises providing an effective amount of a detectable transglutaminase substrate, administering the substrate to the subject, or to a biological sample from the subject prior to detecting the expression level and/or activity level of transglutaminase. The expression level and/or activity level of transglutaminase is indicative of pathologic disease progression. In some embodiments, the transglutaminase substrate can be a peptide. The quantity of transglutaminase expression can be compared to the quantity of expression in a control sample obtained from one or more individuals known to have a pathologic condition, or known to lack a pathologic condition. In some embodiments, the detection of an increased expression level and/or activity facilitates the monitoring of a pathologic condition in the subject. The presently disclosed subject matter also provides compositions, methods, and kits for diagnosing a pathologic condition in a subject. In some embodiments, the method comprises detecting an expression level and/or activity level of transglutaminase in a subject or in a biological sample from a subject, wherein the expression level and/or activity level of transglutaminase is diagnostic of a pathologic condition. In some embodiments, the method comprises providing an effective amount of a detectable transglutaminase substrate, administering the substrate to the subject, or to a biological sample from the subject prior to detecting the expression level and/or activity level of transglutaminase. The quantity of transglutaminase expression level and/or activity level can be compared to the quantity of expression in a control sample obtained from one or more individuals known to have a pathologic condition, or to lack the pathologic condition. In some embodiments, the transglutaminase substrate can be a peptide. In some embodiments, the detection of an increased expression level and/or activity facilitates the diagnosis of a pathologic condition in the subject.

The presently disclosed subject matter also provides a method of facilitating treatment of a pathologic condition in a subject. In some embodiments, the method comprises detecting an expression level and/or activity of transglutaminase in a subject or in a biological sample from a subject, and choosing a treatment based on the expression level and/or activity of transglutaminase. In some embodiments, the method comprises providing an effective amount of a detectable transglutaminase substrate, administering the substrate to the subject or to a biological sample from the subject prior to detecting the expression level and/or activity of transglutaminase. In some embodiments, the transglutaminase substrate can be a peptide. The quantity of transglutaminase expression can be compared to the quantity of expression in a control sample obtained from one or more individuals known to have a pathologic condition. Alternatively, the quantity of transglutaminase activity can be compared to the quantity of expression in a control sample obtained from one or more individuals known not to have a pathologic condition.

The presently disclosed subject matter comprises methods, compositions, and kits for imaging a pathologic condition in a subject. In some embodiments, the method comprises providing an effective amount of a transglutaminase substrate, administering the substrate to the subject, or to a biological sample from the subject, and imaging transglutaminase expression and/or activity. The imaging of expression and/or activity of transglutaminase can be indicative of a pathologic condition. In some embodiments, the transglutaminase substrate can be a peptide. In some embodiments, the kits of the presently disclosed subject matter can employ methods to image a pathologic condition in a subject, without employing a transglutaminase substrate, such as but not limited to immunohistochemical methods. The quantity of transglutaminase expression can be compared to the quantity of expression in a control sample obtained from one or more individuals known to have a pathologic condition. Alternatively, the quantity of transglutaminase activity can be compared to the quantity of expression in a control sample obtained from one or more individuals known not to have a pathologic condition.

The presently disclosed subject matter is based, in some embodiments, on knowledge of specific peptide sequences that are substrates for the crosslinking activity of the transglutaminase enzyme. Figure 2 illustrates the crosslinking reaction catalyzed by transglutaminase. Transglutaminase substrate peptides can be labeled with an appropriate detectable moiety. Upon administration, the labeled peptide is retained in areas of transglutaminase activity, since the primary function of the enzyme is to suture proteins together via the isopeptide bond formation. Once the peptide is retained, activity of transglutaminase can be detected, thereby determining the relative expression level and activity within a region of a pathology, such as a tumor region.

In some embodiments, the presently disclosed subject matter comprises an isolated peptide YQSIYVPDIK (SEQ ID NO: 1), or fragment or variant thereof, wherein the peptide is a substrate for transglutaminase. In some embodiments, the presently disclosed subject matter comprises an isolated peptide consisting essentially of SEQ ID NO: 1 , or fragment or variant thereof, wherein the peptide is a substrate for transglutaminase.

In some embodiments, the presently disclosed subject matter comprises an isolated peptide consisting of SEQ ID NO: 1 , or fragment or variant thereof, wherein the peptide is a substrate for transglutaminase.

I Definitions

All technical and scientific terms used herein, unless otherwise defined below, are intended to have the same meaning as commonly understood by one of ordinary skill in the art. References to techniques employed herein are intended to refer to the techniques as commonly understood in the art, including variations on those techniques or substitutions of equivalent techniques that would be apparent to one of skill in the art. While the following terms are believed to be well understood by one of ordinary skill in the art, the following definitions are set forth to facilitate explanation of the presently disclosed subject matter.

Following long-standing patent law tradition, the terms "a", "an", and "the" are meant to refer to one or more as used herein, including the claims. For example, the phrase "a tumor cell" can refer to one or more tumor cells.

As used herein, the term "detecting" can refer to confirming the presence of a target entity by observing the occurrence of a detectable signal, such as but not limited to a radiologic or spectroscopic signal that can appear exclusively in the presence of the target entity.

As used herein, the terms "metal chelator" and "chelator" are used interchangeably and mean a molecule that forms a stable complex with a traceable metal atom under physiological conditions such that the metal remains bound to the conjugate in vivo. As used herein, the term "activity" can refer to the involvement of transglutaminase in wound healing, tissue remodeling and extracellular matrix stabilization. The term "activity" can also refer to the ability of transglutaminase to catalyze ε-(γ-glutamyl) lysine isopeptide bond formation.

As used herein, the term "expression" can refer to the transcription and stable accumulation of sense (mRNA) or antisense RNA derived from the nucleic acid fragment of the presently disclosed subject matter. Expression can also refer to translation of mRNA into a polypeptide.

As used herein, the term "biological sample" can encompass a variety of sample types obtained from a subject and can be used in a wide variety of diagnostic and monitoring assays. The definition can encompass blood and other liquid samples of biological origin, solid tissue samples such as a biopsy specimen, tissue cultures or cells derived therefrom, and the progeny thereof. The definition can also include samples that have been manipulated in anyway after their procurement, such as by treatment with reagents, solubilization, or enrichment for certain components, such as proteins or polynucleotides. Thus, the term "biological sample" can encompass a clinical sample, and can also include cells in culture, cell supematants, cell lysates, serum, plasma, biological fluid, and tissue samples. With respect to proteins or peptides, the term "isolated protein (or peptide)" or "isolated and purified protein (or peptide)" is used herein. This term can refer to a protein produced by expression of an isolated nucleic acid molecule of the presently disclosed subject matter. Alternatively, this term can refer to a protein that has been sufficiently separated from other proteins with which it would naturally be associated, so as to exist in "substantially pure" form. For example, a naturally-occurring polynucleotide or polypeptide present in a living animal is not isolated, but the same polynucleotide or polypeptide, separated from some or all of the coexisting materials in the natural system, is isolated. Such polynucleotides could be part of a vector and/or such polynucleotides or polypeptides could be part of a composition, and still be isolated in that such vector or composition is not part of its natural environment.

The terms "label" or "labeled" refers to incorporation of a detectable marker, e.g., by the incorporation of a radiolabeled amino acid or attachment to a polypeptide of biotinyl moieties that can be detected by marked avidin (e.g., streptavidin containing a fluorescent marker or enzymatic activity that can be detected by optical, or colorimetric methods). Various methods of labeling polypeptides and glycoproteins are known in the art and can be used. Examples of labels for polypeptides include, but are not limited to, the following: radioisotopes (e.g., ^99mTc, ¹⁸F, ¹³²1, ¹²⁵1, ¹³¹I₁ ⁹⁰Y, ²¹¹At, ⁶⁷Cu, ¹⁵³Sm, ³²P, ¹⁸⁶Re, ¹⁸⁸Re, ²¹²Pb, and ²¹²Bi), fluorescent labels (e.g., FITC, rhodamine, and lanthanide phosphors), enzymatic labels or reporter genes (e.g., horseradish peroxidase, β-galactosidase, β-latamase, luciferase, alkaline phosphatase), chemiluminescent groups, biotinyl groups, predetermined polypeptide epitopes recognized by a secondary reporter (e.g., leucine zipper pair sequences, binding sites for secondary antibodies, metal binding domains, epitope tags). In some embodiments, labels are attached by spacer arms of various lengths to reduce potential steric hindrance.

As used herein, the term "diagnosis" generally refers to the determination of a subject's susceptibility to a pathologic condition. For example, a diagnosis can comprise a determination as to whether a subject is unaffected, susceptible to, or presently affected by a pathologic condition. Particularly, diagnosis can include the identification of a pathologic condition at any stage of development, i.e., the cancer state of the cell, and also includes the determination of a predisposition of a subject to develop the disease.

The term "prognosis" as used herein is generally defined as a determination of the severity of a pathologic condition (e.g., identification of cancerous stages), which can be correlated with potential outcome, response to therapy, etc. Thus, as used herein, the term "prognosis" can refer to predicting the outcome or course of a pathologic disorder.

The term "peptide" as used herein is defined as a chain of polymerized amino acids or amino acid mimetics. The term "binding" refers to the determination by standard assays, including those described herein, that a binding moiety recognizes and binds reversibly to a given target. Such standard assays include equilibrium dialysis, gel filtration, and the monitoring of spectroscopic changes that result from binding. In some embodiments the term "binding" can refer to the binding of one material preferentially to another, i.e., selective binding. Selective binding can be assessed by an approach as would be apparent to one of ordinary skill in the art upon a review of the present disclosure. For example, selective binding can be assessed using enzyme activity assays.

The term "transglutaminase" as used herein is defined as an enzyme capable of catalyzing an acyl transfer reaction in which a γ-carboxyamide group of a peptide-bound glutamine residue is the acyl donor. In some embodiments, the term "transglutaminase" refers to tissue transglutaminase, a GTP-GDP binding enzyme that can function as a Ga protein in a signal transduction mechanism, and is involved in the regulation of several biological events including cellular proliferation, differentiation, and apoptosis.

The term "cross-linking" as used herein can refer to the formation of a chemical bond within a molecule or between two molecules, for example macromolecules. Thus, the term "cross-linking" can refer to the formation of a bond between two functionalities present on a macromolecule or macromolecules, such as photoaffinity ligands or chemical cross-linking agents. Cross-linking moieties can include covalent binding species that covalently link two molecules either spontaneously or via an activation step, such as but not limited to photoactivation and the like. The phrase "pharmaceutically or pharmacologically acceptable" refers to molecular entities and compositions that do not produce adverse, allergic, or other untoward reactions when administered to an animal or a human. As used herein, "pharmaceutically acceptable carrier" includes any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents and the like. The use of such media and agents for pharmaceutically active substances is well known in the art. Supplementary active ingredients also can be incorporated into the compositions.

The term "tumor," as used herein, refers to all neoplastic cell growth and proliferation, whether malignant or benign, and all pre-cancerous and cancerous cells and tissues.

The terms "cancer" and "cancerous" refer to or describe the physiological condition in mammals that is typically characterized by unregulated cell growth, including but not limited to tumors. Examples of cancer include, but are not limited to, breast cancer, ovarian cancer, colon cancer, lung cancer, cervical cancer, head and neck cancer, neuroblastoma, prostate cancer, soft tissue sarcoma, hepatocellular cancer, gastric cancer, pancreatic cancer, liver cancer, bladder cancer, cancer of the urinary tract, thyroid cancer, renal cancer, carcinoma, melanoma, and brain cancer. The term "pathologic disorder" can include pathologies and deleterious conditions, such as, but not limited to, inflammatory responses, cancer, autoimmune disorders, and genetic disorders.

The "pathology" of cancer includes all phenomena that compromise the well-being of the subject. This includes, without limitation, abnormal or uncontrollable cell growth, metastasis, tumors, interference with the normal functioning of neighboring cells, release of cytokines or other secretory products at abnormal levels, suppression or aggravation of inflammatory or immunological response, neoplasia, premalignancy, malignancy, invasion of surrounding or distant tissues or organs, such as lymph nodes, etc.

IL Peptide Substrates

MA Peptide Substrate Synthesis

In some embodiments of the presently disclosed subject matter, a transglutaminase substrate peptide comprises the sequence YQSIYVPDIK (Tyr-Gln-Ser-lle-Tyr-Val-Pro-Asp-lle-Lys)(SEQ ID NO:1). In some embodiments, the peptide can consist essentially of SEQ ID NO:1. In some embodiments, the peptide can consist of SEQ ID NO:1. In some embodiments, a transglutaminase substrate peptide of the presently disclosed subject matter, or a fragment or variant thereof, selectively binds transglutaminase. As described herein, a competing enzyme activity assay can be used to indicate the affinity between the transglutaminase substrate and transglutaminase. The presently disclosed peptide substrates, fragments, and variants thereof, can be chemically synthesized in whole or part using techniques that are known in the art (See, e.g., Creiqhton, T. E. Proteins: Structure and Molecular Properties, W.H. Freeman & Co., San Francisco, pp. 79-86 (1983), incorporated herein by reference in its entirety). Alternatively, those skilled in the art can use in vitro recombinant DNA techniques, synthetic techniques and in vivo recombination/genetic recombination to synthesize the disclosed peptide substrates. See, e.g., the techniques described in Sambrook et al. (2001) Molecular Cloning: A Laboratory Manual, 3rd ed. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. and Ausubel ef a/. (1989) Current Protocols in Molecular Biology, Greene Publishing Associates and Wiley Interscience, N.Y., both incorporated herein by reference in their entireties.

Because of their relatively small size, the peptide substrates of the presently disclosed subject matter can be synthesized in solution or on a solid support in accordance with conventional techniques. Various automatic synthesizers are commercially available and can be used in accordance with known protocols. See, for example, Stewart and Young. (1984) Solid Phase Peptide Synthesis, (2d ed.), Pierce Chemical Co., Rockford, III.; Tarn et al. (1983) J. Am. Chem. Soc, 105:6442; Merrifield (1986) Science 232: 341-347; and Barany and Merrifield (1979) The Peptides, Gross and Meienhofer, eds., Academic Press, New York, pp. 1 -284, each incorporated herein by reference.

Thus, the peptide substrates can be chemically synthesized and purified using well-known techniques, or by using recombinant DNA techniques, i.e., where the nucleotide sequence encoding the peptide is inserted in an appropriate expression vector, e.g., an E. coli or yeast expression vector, expressed in the respective host cell, and purified therefrom using well-known techniques.

II. B. Peptide Substrate Variants Amino acid sequence fragments and variants of the disclosed peptide substrates are also encompassed by the presently disclosed subject matter. For example, amino acid sequence variants of the disclosed peptide substrates can be substitutional variants or insertional variants.

Substitutional variants involve the exchange of one amino acid for another at one or more sites within the peptide substrate, and can be designed to modulate one or more properties of the peptide, such as stability against proteolytic cleavage, without the loss of other functions or properties, such as but not limited to transglutaminase substrate functionality. Substitutions of this kind in some embodiments are conservative. That is, one amino acid can replaced with another amino acid of similar shape and charge.

Insertional mutants involve the addition of material at a non-terminal point in the peptide substrate. For example, one or more amino acid residues or an immunoreactive epitope can be inserted within the peptide. In some embodiments, the added material is modified, such as by methylation, acetylation, and the like. Alternatively, additional residues can be added to the N-terminal or C-terminal ends of the peptide substrate.

In making such changes, the hydropathic index of amino acids can be considered. The importance of the hydropathic amino acid index in conferring interactive biologic function on a peptide/protein is generally understood in the art (Kvte & Doolittle (1982) J. MoI. Biol. 157:105-132, incorporated herein by reference). It is accepted that the relative hydropathic character of an amino acid contributes to the secondary structure of the resultant peptide, which in turn defines the interaction of the peptide with other molecules, for example, enzymes, substrates, receptors, DNA, antibodies, antigens, and the like. It is also understood in the art that the substitution of like amino acids can be made effectively on the basis of hydrophilicity. U.S. Patent No. 4,554,101 , incorporated herein by reference, discloses that the greatest local average hydrophilicity of a protein, as governed by the hydrophilicity of its adjacent amino acids, correlates with a biological property of the protein. It is understood that an amino acid can be substituted for another having a similar hydrophilicity value and still obtain a biologically equivalent and immunologically equivalent protein. As outlined above, amino acid substitutions are generally based on the relative similarity of the amino acid side-chain substituents, for example, their hydrophobicity, hydrophilicity, charge, size, and the like. Exemplary substitutions that take various of the foregoing characteristics into consideration are well known to those of skill in the art and include: arginine and lysine; glutamate and aspartate; serine and threonine; glutamine and asparagine; and valine, leucine and isoleucine. However, alterations to the amino acids of the presently disclosed subject matter can be other than conservative and still within the scope of the disclosure so long as the peptides still retain substrate function to transglutaminase. In some embodiments, the peptide substrates can comprise peptide mimetics. As would be understood by one of ordinary skill in the art, mimetics are peptide-containing molecules that mimic elements of protein secondary structure. A peptide mimetic is expected to permit molecular interactions similar to the natural molecule. These principles can be used, in conjunction with the principles outline above, to engineer second generation molecules having many of the natural properties of the disclosed peptide substrates, but with altered and even improved characteristics.

The methods of the presently disclosed subject matter can also employ peptide fragments and functional variants of a peptide. Such peptide fragments and functional variants need not comprise all or substantially all of the amino acid sequence of the disclosed peptide substrates. The term "functional" includes any biological activity or feature of the peptide.

The presently disclosed subject matter can further include amino acids in addition to the disclosed peptide substrate. For example, one or more amino acids can be added to the N-terminus or C-terminus of the peptide. II. C. Labeling Peptide Substrates

In some embodiments, the peptide substrates can be coupled to auxiliary substances that enhance or complement the function of the peptide substrates. Such auxiliary substances include, for example, labels such as radioisotopes, fluorescent labels, enzyme labels and the like. For example, in some embodiments, the substrate peptides can be labeled with radioactive isotopes selected from the group consisting of, but not limited to, ^99mTc, ¹⁸F, ¹³²I, ¹²⁵I, ¹³¹I₁ ⁹⁰Y, ²¹¹At, ⁶⁷Cu, ¹⁵³Sm, ³²P, ¹⁸⁶Re, ¹⁸⁸Re, ²¹²Pb, and ²¹²Bi.

As would be readily apparent to one of skill in the art, one factor to consider in selecting a radionuclide for in vivo prognosis and/or diagnosis is that the half-life of a nuclide be long enough so that it is still detectable at the time of maximum uptake by the target, but short enough so that deleterious radiation upon the host, as well as background, is minimized.

A label can be bound to the peptide substrate, fragment, or variant thereof either directly or indirectly by using an intermediary functional group. Intermediary functional groups that are commonly used to bind labels (e.g., radioisotopes) that are diethylenetriaminepentaacetic acid (DTPA) and ethylene diaminetetracetic acid (EDTA).

Suitable techniques for coupling of peptide substrates to desired auxiliary substances are generally known for a variety of such auxiliary substances, and the specific nature of the coupling procedure will depend on the nature of the auxiliary substance chosen. Coupling can be direct covalent coupling or can involve the use of synthetic linkers such as those marketed by Pierce Chemical Co., Rockford, Illinois, United States of America. In some embodiments, the peptide substrate can be radiolabeled to allow non-invasive visualization of the transglutaminase distribution within a host tissue. Accordingly, in some embodiments, a radiolabeled transglutaminase substrate peptide is used as an imaging agent in non-invasive imaging detection of a pathologic disorder (e.g., tumors and tumor edges).

IiL Prognostic and Diagnostic Methods

The compositions, methods and kits of the presently disclosed subject matter can be useful in the diagnosis or prognosis of a pathologic condition. In some embodiments, an effective amount of a detectable transglutaminase substrate is administered to a subject or a biological sample from a subject. In some embodiments, the detectable transglutaminase substrate is a peptide. The transglutaminase expression level, activity, or a combination thereof can be detected, wherein a diagnosis or prognosis can be determined based on the expression level, activity, or combination thereof of transglutaminase. In some embodiments, the transglutaminase expression level, activity, or combination thereof can be detected such as, but not limited to, by using immunohistochemical methods without the administration of a detectable transglutaminase substrate. The quantity of transglutaminase expression can be compared to the quantity of expression in a control sample obtained from one or more individuals known to have a pathologic condition, or known to lack a pathologic condition.

The progression of a pathologic condition can be monitored using the presently disclosed subject matter. In some embodiments, an effective amount of a detectable transglutaminase substrate is administered to a subject or to a biological sample from a subject. In some embodiments, the detectable transglutaminase substrate can be a peptide. The transglutaminase expression level, activity, or a combination thereof can be detected and the progression of the pathologic condition monitored based on the expression level, activity, or combination thereof of transglutaminase. In some embodiments, the transglutaminase expression level, activity, or combination thereof can be detected such as, but not limited to, by using histochemical methods without the administration of a detectable transglutaminase substrate.

The quantity of transglutaminase expression can be compared to the quantity of expression in a control sample obtained from one or more individuals known to have a pathologic condition, or known to lack a pathologic condition. In some embodiments, the presently disclosed subject matter comprises methods, compositions, and kits for use in facilitating treatment of a pathologic condition in a subject. Particularly, in some embodiments, an effective amount of a detectable transglutaminase substrate can be administered to a biological sample from a subject or to a subject. In some embodiments, the detectable transglutaminase substrate can comprise a peptide. The transglutaminase expression level, activity, or a combination thereof can be detected such that a treatment of the pathologic condition can be selected based on the expression level, activity, or combination thereof of transglutaminase. In some embodiments, the transglutaminase expression level, activity, or combination thereof can be detected without the administration of a detectable transglutaminase substrate, such as but not limited to using immunohistochemical methods. The quantity of transglutaminase expression can be compared to the quantity of expression in a control sample obtained from one or more individuals known not to have a pathologic condition such that a suitable treatment method can be selected. Suitable treatment methods include, but are not limited to, radiation therapy, surgery, administration of biological response modifiers, chemotherapy, targeted therapeutics (such as but not limited to tyrosine kinase inhibitors), and administration of anti- angiogenic agents.

In some embodiments, the substrate becomes detectable upon exposure to transglutaminase activity, such as but not limited to, by a non- fluorescent to fluorescent change. In some embodiments, the transglutaminase substrate is detectably labeled in accordance with techniques disclosed herein.

The visible image of a pathologic condition in a subject can be non- invasively generated using the methods, compositions, and kits of the presently disclosed subject matter. In some embodiments, the visible image of a pathologic condition in a subject can be non-invasively generated without the administration of a detectable transglutaminase substrate such as, but not limited to, by using immunohistochemical methods. In some embodiments, an effective amount of a detectable transglutaminase substrate or a fragment or variant thereof is administered to a subject, wherein the detectable transglutaminase substrate selectively binds transglutaminase. A competing enzyme activity assay can be used to indicate the affinity between the transglutaminase substrate and transglutaminase. Such enzyme activity assays are available in the art. See, for example, Slaughter. T. F. et al. (1992) Anal Biochem 205: 166-171 ; Mazooz G. et al. ( Feb 2005) Cancer Res 65(4): 1369-1375. The subject can then be scanned using magnetic resonance imaging (MRI), or other techniques as disclosed herein whereby a visible image of the pathologic condition can be non-invasively generated. In some embodiments, the detectable transglutaminase substrate is a peptide comprising, consisting essentially of, or consisting of SEQ ID NO:1. The quantity of transglutaminase expression can be compared to the quantity of expression in a control sample obtained from one or more individuals known not to have a pathologic condition. In some embodiments, the quantity of transglutaminase expression can be compared to the quantity of expression in a control sample obtained from one or more individuals known to have a pathologic condition.

In some embodiments of the presently disclosed subject matter, a transglutaminase substrate can be used for screening biological samples for transglutaminase expression and/or activity. Accordingly, the presently disclosed subject matter can comprise the analysis of biological samples from a subject to determine the expression and/or activity levels of transglutaminase.

Further, in some embodiments, biological samples from a subject can be assayed such as, but not limited to, by using immunohistochemical methods to determine transglutaminase expression and/or activity levels present in the sample. Immunohistochemical methods can be used to assay biological samples from a subject without the use of a transglutaminase substrate. Multiple tissue samples can be taken from desired areas in a subject for histological examination to seek evidence of transglutaminase expression and/or activity levels.

IV. Imaging

The presently disclosed subject matter provides in vivo methods of imaging pathologic disorders. In some embodiments, the methods comprise using transglutaminase substrates, such as but not limited to transglutaminase substrate peptides. The term "in vivo imaging" can refer to any non-invasive method that permits the detection of a substrate for transglutaminase located in the body of an animal or human subject. In some embodiments of the presently disclosed subject matter, employing a peptide, fragment, or variant thereof as a substrate for transglutaminase, the uptake of the peptide is imaged by conjugating the peptide, or fragment or variant thereof, to a suitable detectable agent. In some embodiments, methods, such as but not limited to immunohistochemical methods, can be can be employed without the use of transglutaminase substrates to image pathologic disorders in vivo. Accordingly, in some embodiments, the term "in vivo imaging" can refer to any non-invasive method that permits detection of transglutaminase (e.g., employing a labeled antibody, etc.).

In accordance with detection of pathologic disorders by the presently disclosed methods, a tumor cell can be imaged. Although the Examples are directed to cervical cancer cells, any suitable cancerous tissue type can be utilized by the same methods to identify the location of transglutaminase. In accordance with these embodiments, one of ordinary skill in the art can use the methods described herein to identify transglutaminase internalized at the site of other tumors, cancerous tissue, or pathologic disorders including, but not limited to, fibrosis, atherosclerosis, neurodegenerative disease, celiac disease, cervical cancer, head and neck cancer, neuroblastoma, prostate cancer, soft tissue sarcoma and the like.

In some embodiments, the imaging methods can involve administering to a subject an imaging-effective amount of a detectable label conjugated to the peptide substrate, and detecting the uptake of the labeled peptide-labeled substrate by the transglutaminase located within a target tissue. In some embodiments, the detectable label is a spin-labeled molecule or a radioactive isotope that is detectable by non-invasive methods.

Thus, the distribution of the bound radioactive isotope and its increase or decrease with time can be monitored and recorded. The presence, extent, and/or prognosis of the pathologic disorder can be determined in some cases by comparing the results with data obtained from studies of clinically normal (healthy, non-cancerous) subjects.

In some embodiments, a contrast enhancement agent useful for providing a visual image of a pathological condition in a subject or in a biological sample is provided. The contrast agent can comprise at least one paramagnetic metal ion, and at least one chelator. In some embodiments, the contrast agent can further comprise a transglutaminase substrate. The transglutaminase substrate can comprise a peptide comprising the amino acid sequence comprising, consisting essentially of, or consisting of SEQ ID NO: 1 , or a fragment or variant thereof. In some embodiments, the paramagnetic metal ion can be selected from the group including but not limited to transition and inner transition elements. Particularly, the paramagnetic metal ion can be selected from the group including but not limited to Gd(III), Mn(II), Cu(II), Cr(III), Fe(II), Fe(III), Co(II), Er(II), Ni(II), Eu(III) and Dy(III). In some embodiments, the chelator can be selected from the group including but not limited to DTPA, substituted DTPA, DOTA, substituted DOTA, EDTA, substituted EDTA, CDTA and substituted CDTA. As would be readily apparent to one of skill in the art, the exact imaging protocol will necessarily vary depending upon factors specific to the subject, and can also depend upon the body site under examination, method of administration, type of label used and the like. The determination of specific procedures is, however, routine to one of ordinary skill in the art, particularly after a review of the instant disclosure.

V₁ Kjts

In some embodiments, the presently disclosed subject matter provides kits for use in detecting, diagnosing, monitoring, and/or imaging cells and tissues of a tissue pathology, both in vivo, e.g., in a subject, and in vitro, e.g., in biological samples. Such kits can generally comprise a pharmaceutically acceptable composition comprising a detectable transglutaminase substrate (e.g., a peptide fragment or variant thereof) that selectively binds transglutaminase. In some embodiments, an effective amount of a detectable transglutaminase substrate peptide, or a fragment or variant thereof, is provided, wherein the detectable transglutaminase substrate selectively binds transglutaminase. A competing enzyme activity assay can be used to indicate the affinity between the transglutaminase substrate and transglutaminase. In some embodiments, the detectable transglutaminase substrate can be a peptide comprising, consisting essentially of, or consisting of SEQ ID NO:1. The detectable label can be such that it is identifiable by a non-invasive approach for in vivo applications. In some embodiments, the kits of the presently disclosed subject matter can comprise compositions comprising materials suitable for detection, such as but not limited to immunohistochemical detection, of transglutaminase (e.g., an antibody), such that no detectable transglutaminase substrate is required. The kits of the presently disclosed subject matter can also include a container for containing reagents, additional labels and any other reagent containers in close confinement for commercial sale. Such containers can include injection or blow-molded plastic containers into which the desired vials are retained. As the transglutaminase substrate can comprise a peptide substrate, or a fragment, or variant thereof, in some embodiments, these peptides can be provided in the kit. The kits can further comprise a suitably aliquoted amount of the peptide that can target the desired tissue, and for a standard curve to be prepared for a detection assay. The kits of the presently disclosed subject matter can generally comprise one or more containers into which the biological agents are placed and, preferably, suitably aliquoted. The components of the kits can be packaged either in aqueous media or in lyophilized form. Thus, the containers of the kits can generally include at least one vial, test tube, flask, bottle, or even syringe or other container, into which the substrate can be placed, and preferably, suitably aliquoted. Where a detectable label, binding ligand or additional component is provided, the kit can also generally contain a second, third or other additional container into which this label, ligand or component can be placed. The presently disclosed kits can also include instructions for use of any and all reagents provided therein.

VL Subjects

The subjects treated in the presently disclosed subject matter are in some embodiments human subjects, although it is to be understood that the presently disclosed subject matter is effective with respect to all vertebrate animals, including mammals, which are intended to be included in the term

"subject". Moreover, a mammal is understood to include any mammalian species in which treatment or prevention of a disease is desirable, particularly agricultural and domestic mammalian species.

More particularly provided is the treatment of mammals such as humans, as well as those mammals of importance due to being endangered (such as Siberian tigers), of economic importance (animals raised on farms for consumption by humans) and/or social importance (animals kept as pets or in zoos) to humans, for instance, carnivores other than humans (such as cats and dogs), swine (pigs, hogs, and wild boars), ruminants (such as cattle, oxen, sheep, giraffes, deer, goats, bison, and camels), and horses. Also provided is the treatment of birds, including the treatment of those kinds of birds that are endangered, kept in zoos, as well as fowl, and more particularly domesticated fowl, for example, poultry, such as turkeys, chickens, ducks, geese, guinea fowl, and the like, as they are also of economic importance to humans. Thus, provided is the treatment of livestock, including, but not limited to, domesticated swine (pigs and hogs), ruminants, horses, poultry, and the like.

VII. Administration Approaches

For analysis and/or administration into a subject, the presently disclosed compositions can be administered via oral or parenteral routes. As used herein, parenteral dosing can be the administration through a route other than oral, which includes rectal, intravenous, intraperitoneal and intramuscular, intraarterial, transdermal, nasal, inhalation, ocular, and subcutaneous introduction. In some embodiments, suitable methods for administration of the presently disclosed subject matter include, but are not limited to injection or other administration into the target tissue or target site.

Thus, administration of a detectable reagent can be local or systemic and accomplished intravenously, intra-arterially, via the spinal fluid or the like, depending upon the body site under examination. After a sufficient time has lapsed for the labeled reagent to target the pathologic tissue, the area of the subject under investigation is then examined by an imaging technique. MRI, CAT scan, CT scan, gamma imaging, intravascular ultrasound, PET, SPECT, planar scintillation imaging and other emerging imaging techniques can all be used. Multiple imaging techniques can be utilized to clarify or confirm detection, including but not limited to immunohistochemical techniques.

As would be readily apparent to one of skill in the art, the particular mode of administering a composition of the presently disclosed subject matter depends on various factors, including the distribution and abundance of cells to be treated, etc. For example, relatively superficial tumors can be injected intratumorally. By contrast, internal tumors can be treated by intravenous injection.

In some embodiments, a biological sample can be analyzed by contacting the biological sample with a detectable reagent in any suitable manner as would be apparent to one of ordinary skill in the art upon a review of the present disclosure. The biological sample can be analyzed to detect a desired component in vitro as well as in vivo. In vitro and in vivo techniques for the detection of a desired component in a biological sample can include, but are not limited to, immunohistochemical analysis, enzyme linked immunosorbent assays (ELISAs), immunoprecipitations, immunofluorescence, enzyme immunoassay (EIA), radioimmunoassay (RIA), the introduction of a labeled antibody into a subject and Western blot analysis.

VML Formulation

The substrates of the presently disclosed subject matter comprise in some embodiments a composition that includes a carrier, particularly a pharmaceutically acceptable carrier. Any suitable pharmaceutical formulation can be used to prepare the compositions for administration to a subject. In addition, the composition comprising a reagent can optionally include one or more kinds of pharmaceutically acceptable diluents, selected from the group consisting of, but not limited to, saline, buffered saline, dextrose, water, glycerol, and ethanol.

As used herein, the terms "pharmaceutically acceptable", "physiologically tolerable" and grammatical variations thereof, as they refer to compositions, carriers, diluents and reagents, are used interchangeably and represent that the materials are capable of administration to or upon a subject without the production of undesirable physiological effects such as nausea, dizziness, gastric upset and the like.

For example, suitable formulations can include aqueous and nonaqueous sterile injection solutions that can contain anti-oxidants, buffers, bacteriostatics, bactericidal antibiotics and solutes which render the formulation isotonic with the bodily fluids of the intended recipient; and aqueous and nonaqueous sterile suspensions which can include suspending agents and thickening agents. The formulations can be presented in unit-dose or multi- dose containers, for example sealed ampoules and vials, and can be stored in a frozen or freeze-dried (lyophilized) condition requiring only the addition of sterile liquid carrier, for example water for injections, immediately prior to use.

It should be understood that in addition to the ingredients particularly mentioned above the formulations of the presently disclosed subject matter can include other agents conventional in the art with regard to the type of formulation in question. For example, sterile pyrogen-free aqueous and nonaqueous solutions can be used.

JX. Dosage

An effective dose of a composition of the presently disclosed subject matter is administered to a subject in need thereof. An "effective amount" is an amount of a composition sufficient to provide for appropriate detection in a subject or sample being treated. For example, the actual amount of a reagent in the compositions of the presently disclosed subject matter can be varied so as to administer an amount effective to achieve the desired response for a particular subject or sample.

As would be readily apparent to one of skill in the art, the dosage regimen of the presently disclosed subject matter can be selected in accordance with a variety of factors including type, species, age, weight, sex and medical condition of the subject; the severity of the condition to be treated; the route of administration; the renal and hepatic function of the subject; and the particular substrate employed. Upon a review of the present disclosure, a physician of ordinary skill can determine and prescribe an effective amount of the substrate. It is within the skill of the art to start doses of the compound at levels lower than required to achieve the desired effect and to gradually increase the dosage until the desired effect is achieved.

Thus, after review of the disclosure herein, one of ordinary skill in the art can tailor the dosages to an individual subject, taking into account the particular formulation, method of administration to be used with the composition, and factors to be associated with tissues to be imaged (e.g., tumor size, location, etc.). Further calculations of dose can consider subject height and weight, severity and stage of symptoms, and the presence of additional deleterious physical conditions. Such adjustments or variations, as well as evaluation of when and how to make such adjustments or variations, are known to those of ordinary skill in the art of medicine.

In some embodiments, a composition of the presently disclosed subject matter can be administered in a single dose, or the dosage can be administered in several divided doses. For combination treatment with more than one active agent, where the active agents are in separate dosage formulations, the active agents can be administered concurrently, or they each can be administered at separately staggered times.

Peptide substrates synthesized or identified according to the methods disclosed herein can be used alone at appropriate dosages defined by routine testing in order to obtain optimal activity while minimizing any potential toxicity.

In addition, co-administration or sequential administration of other agents can be desirable, in some embodiments.

EXAMPLES The following Examples have been included to illustrate modes of the presently disclosed subject matter. In light of the present disclosure and the general level of skill in the art, those of skill will appreciate that the following Examples are intended to be exemplary only and that numerous changes, modifications, and alterations can be employed without departing from the scope of the presently disclosed subject matter. EXAMPLE 1

Tissue Transglutaminase (tTG) Expression in Cancer Tissues The expression of tTG and its role in the carcinogenesis of operable cervical tumors were investigated. The charts of women who underwent a radical hysterectomy (RH) at Duke University Medical Center, Durham, North Carolina, United States of America between 1986 and 2001 as definitive treatment for early-stage cervical cancer were reviewed. A total of 315 patients, predominantly FIGO (International Federation of Gynecology and Obstetrics) stage 1 B, were identified. Pathologic specimens from any patient that recurred or had a follow-up of at least three years and remained disease-free were examined. Blocks from patients with adequate tumor specimens were cut and the slides stained for tTG. The extent and intensity of staining in the tumor specimen were measured in cancer tissues, and an immunohistochemical (IHC) score determined from the product of the extent (0-100%) and intensity (0-3). All reading pathologists were blinded to clinical outcome. Survival curves were generated and the outcome compared by the log-rank method.

Forty-two relapsing patients and 76 non-relapsing patients with a minimum of 3 years follow-up were included in the analysis provided in Figure 1. In the overall group, the median follow-up was 59.6 months (range 4-195 months), the median age 44.9 years (range 19.4-79.8 years), and 27 patients were found to have positive lymph nodes at the time of surgery. The histology was squamous cell, adencarcinoma, adenosquamous and other in 84, 22, 7 and 5 patients, respectively. FIGO stage was IA, IB and MA in 3, 105, and 5 patients; it could not be determined from the clinical data.

Stratifying patients by extent of cancer tissues expressing tTG less than versus greater than or equal to 50%, freedom from recurrence was significantly poorer for specimens with elevated extent of expression (p =0.020, 5-year FFR 68% versus 38%). For the same stratification, freedom from distant metastases approached but did not reach statistical significance (p=0.066, 5- year FFDM 84 versus 58%), while freedom from local recurrence (FFLR) was not different (p=0.18). Intensity of staining and IHC score, in either the tumor or stroma did not predict for FFR, FFDM or FFLR. Thus, elevated tTG expression in cancer tissues is a statistically significant prognostic factor of freedom from recurrence in early-stage cervical cancer. As in other organ sites, the data also suggest that tTG is associated with increased metastatic potential. Accordingly, tTG expression in tumor specimens obtained at RH is believed to be an indication for more aggressive adjuvant therapy.

EXAMPLE 2

Transglutaminase Substrate Peptide Synthesis The transglutaminase substrate peptide sequence YQSIYVPDIK (Tyr-

Gln-Ser-lle-Tyr-Val-Pro-Asp-lle-Lys)(SEQ ID NO:1) is synthesized. A customized order is placed with Bio-Synthesis, Inc. (Lewisville, Texas, United States of America) for transglutaminase 20 mg of specific peptide (Fmoc- YQSIYVPDIK-OH)(SEQ ID NO:2) and 10 mg of control (Fmoc-YASIYVPDIK- OH)(SEQ ID NO:3).

EXAMPLE 3

¹⁸F Labeling of Transglutaminase Substrate Peptide A diagram of the reaction used to label the transglutaminase substrate

18 1ft peptide with F is illustrated in Figure 9. Particularly, N-succinimidyl 4-[ F] fluorobenzoate was combined with substrate peptide to produce ¹⁸F labeled transglutaminase substrate peptide.

EXAMPLE 4 Fischer 344 Biodistribution for ¹⁸F Labeled Transglutaminase Peptide

To ensure consistency of labeling, etc., baseline Fischer 344 biodistribution data for ¹⁸F- transglutaminase peptide is obtained. 50 MBq of ¹⁸F- transglutaminase peptide per animal is injected. Time points are 5, 20, 40, 60, and 90 minutes with n=3 per time point. Blood, muscle, kidneys, bladder and urine, lung, liver, heart, small intestine, large intestine, thyroid, and skin tissues are collected using 3 x injection standards. For blood, muscle, lung, liver and heart tissues, individual body weight and organ weights are recorded and data expressed as % id (injected dose) and % id/g (injected dose per gram).

EXAMPLE 5 Tumor Model Biodistribution for ¹⁸F Labeled Transglutaminase Peptide

Tumor model biodistribution is generated for both ¹⁸F- transglutaminase peptides and ¹⁸F-control peptide using the R3230Ac rat tumor model with Fischer 344 rats in order to determine the optimum tumor update/ratio using non-anesthetized animals. 50 MBq of ¹⁸F- transglutaminase peptide per animal were injected. Time points are 5, 20, 40, 60, and 90 minutes with n=3 per time point.

Blood, muscle, kidneys, bladder and urine, lung, liver, heart, small intestine, large intestine, thyroid, and skin tissues are collected using 3 x injection standards. For blood, muscle, lung, liver and heart tissues, individual body weight and organ weights are recorded and data expressed as % ID

(percent injected dose) and % ID/g (percent injected dose per gram).

EXAMPLE 6 PET Imaging Technique To establish the PET imaging procedure and determine the proper radioisotope dosage for rats and mice to get quality images with reasonable signal/noise levels and conserve peptide stocks, an optimal PET imaging technique is used.

Tumor R3230Ac is transplanted into 3 Fischer 344 rats and 3 NCr athymic nude mice and allowed to grow to approximately 15 mm diameter in rats and approximately 10 mm in mice. The rats and mice are anesthetized using Nembutal (70 mg/kg, Lp.). A catheter is placed in the tail vein for isotope injection. The corresponding dose of ¹⁸F labeled peptides (1 mCi) are injected into the rats/mice intravenously. The rats/mice are micro-SPECT scanned for 1 hour. The animals are euthanized and the tumor collected in liquid nitrogen. The tissue is cryosectioned and immunostained using transglutaminase antibody and image analysis is used to compare image qualities from different doses. EXAMPLE 7

Evaluating Specificity and Sensitivity of Transglutaminase Substrate Peptide

The uptake and retention of a transglutaminase specific peptide is compared to a control, non- transglutaminase substrate peptide in order to evaluate specificity of a transglutaminase substrate peptide in vivo. The uptake of transglutaminase substrate peptide in animals treated with a drug that inhibits transglutaminase expression is compared with a non-treated control animal to characterize the ability of the transglutaminase substrate peptide to respond to the change of transglutaminase level.

Cystamine is used as transglutaminase inhibitor. Cystamine has been widely used to inhibit transglutaminase in several transglutaminase-induced diseases (Dedeoglu. A. et al. (2002) J Neurosci 22:9842-8950). Animals are given cystamine intraperitoneally (22.5 mg/kg, dissolved in saline, Sigma (St. Louis, Missouri, United States of America)), according to prior studies (Karpui, M .V. et al. (2002) Nat Med 8:143-149). After 30 minutes of cystamine administrate, transglutaminase peptide imaging is performed to measure the level of transglutaminase expression.

R3230Ac is transplanted in rats and the tumor allowed to grow to approximately 15 mm in diameter. The animal is then anesthetized using Nembutal, (70 mg/kg, i.p.) and a catheter placed in the tail vein for isotope injection.

Animals are divided into 3 groups, as follows. Group 1 contains normal rats injected with transglutaminase specific peptides (n=10). Group 2 contains normal rats injected with non- transglutaminase -specific control peptides (n=10). Group 3 contains transglutaminase inhibitor (cystamine, 22.5 mg/kg, i.p.) treated rats injected with transglutaminase specific peptides (n=10) after 30 minutes.

The animals are imaged dynamically over time with microSPECT up to 90 minutes p.i. The animals are euthanized and tissues collected in liguid nitrogen to determine uptake. Particularly, blood, muscle, kidneys, bladder and urine, lung, liver, heart, small intestine, large intestine, thyroid, and skin tissues are collected using 3 x injection standards. For blood, muscle, lung, liver and heart tissues, individual body weight and organ weights are recorded and data expressed as % id and % id/g. The tissues are cryosectioned and immunostained using transglutaminase antibody. Image analysis is used to compare the uptake and retention of transglutaminase peptide in different groups.

EXAMPLE 8

Immunohistochemistrv and Autoradiography lmmunohistochemistry studies are used to demonstrate the localization of transglutaminase at R3230Ac tumor borders. Particularly, in some embodiments, immunohistochemical methods can be used to detect transglutaminase without requiring the addition of a substrate.

Using the generated tumors, ¹⁸F-autoradiography and immunohistochemistry studies are performed to test whether ¹⁸F- transglutaminase peptide is localized to transglutaminase expression at the tumor border.

After pre-treatment with transglutaminase inhibitor, ¹⁸F-autoradiography and immunohistochemistry studies are also performed to determine whether localization of ¹⁸F- transglutaminase peptide to transglutaminase expression at the tumor border is significantly reduced.

¹⁸F-autoradiography and immunohistochemistry studies are further conducted to verify that the negative control peptide is not localized to transglutaminase expression at the tumor border.

REFERENCES

The references listed below as well as all references cited in the specification are incorporated herein by reference to the extent that they supplement, explain, provide a background for, or teach methodology, techniques, and/or compositions employed herein. Achvuthan. K.E., ef a/. (1987) J Biol Chem 262: 1901-1906. Aeschlimann. P.. et al. (1994) Thromb Haemost lΛ: 402-415. Ausubel et al. (1989) Current Protocols in Molecular Biology, Greene Publishing Associates and Wiley Interscience, N.Y. Baranv and Merrifield (1979) The Peptides, Gross and Meienhofer, eds., Academic Press, New York, pp. 1-284.

Blomfield, P. \. et al. (1998) CBJ Brit J Obstet Gyn 105:486-492.

Creiqhton. T. E. Proteins: Structure and Molecular Properties, W. H. Freeman & Co., San Francisco, pp. 79-86 (1983).

Dedeoglu. A. et al. (2002) J Neurosci 22:9842-8950.

Folk, J.E.. et al. (1977) Adv Protein Chem 311-333.

Gaudrv, CA. et al. (1999) Cell Res 252: 104-113.

Genest. D.R. ef a/. (1998) Arch Pathol Lab Med 122:338-341. Griffin, M., et al. (2002) J Biochem 368: 377-396.

Haroon, ZA., et al. (1999) Faseb J 13: 1787-1795.

Haroon, ZA. ef a/. (1999) Lab Invest 79: 1679-1686.

Hettasch. J.M. ef a/. (1996) Lab Invest 75(5):637-645.

Karpui, M.V. ef a/. (2002) Nat Med 8:143-149. Kim, P.Y. et al. (1998) Gyn One 69:243-247.

Kvte & Doolittle (1982) J. MoI. Biol. 157:105-132.

Lorand. L., et al. (1984) MoI Cell Biochem 58: 9-35.

Mazooz G- ef a/. ( Feb 2005) Cancer Res 65(4): 1369-1375.

Mehta. K. et al. (2004) CHn Cancer Res. 10(23):8068-8076. Merrifield (1986) Science 232: 341-347.

Mian. S.. et al. (1995) FEBS Lett 370: 27-31.

Nakoaka. H., ef a/. (1994) Science 264: 1593-1596.

Parker. S. L et al.. (1997) CA Cancer J. CHn. 47:1-27.

Sambrook et al. (2001) Molecular Cloning: A Laboratory Manual, 3rd ed. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y.

Schense. J.C., et al. (1999) Bioconjug Chem 10: 75-81.

Slaughter. T. F. et al. (1992) Anal Biochem 205: 166-171.

Stewart and Young, (1984) Solid Phase Peptide Synthesis, (2d ed.), Pierce

Chemical Co., Rockford, III. Sugimura, Y. et al. (2006; J Biol Chem 281 (26): 17699-17706.

Tarn et al. (1983) J. Am. Chem. Soc, 105:6442.

U.S. Patent No. 4,554,101 It will be understood that various details of the presently disclosed subject matter can be changed without departing from the scope of the presently disclosed subject matter. Furthermore, the foregoing description is for the purpose of illustration only, and not for the purpose of limitation.

Claims

CLAIMS What is claimed is:

1. A method of determining a diagnosis or prognosis of a pathologic condition in a subject, the method comprising: (a) detecting an expression level, an activity level, or a combination thereof of transglutaminase in a subject or in a biological sample from a subject; and

(b) determining a diagnosis or prognosis based on the expression level, activity level, or combination thereof of transglutaminase.

2. The method of claim 1 , comprising administering an effective amount of a detectable reagent to the subject or to the biological sample from a subject.

3. The method of claim 2, wherein the detectable reagent is a transglutaminase substrate.

4. The method of claim 3, wherein the transglutaminase substrate is a peptide.

5. The method of claim 4, wherein the peptide comprises SEQ ID NO: 1 , or a fragment or variant thereof.

6. The method of claim 2, wherein the detectable reagent is labeled with a radioactive isotope.

7. The method of claim 6, wherein the radioactive isotope is selected from the group comprising ^99mTc, ¹⁸F, ¹³²I, ¹²⁵I, ¹³¹1, ⁹⁰Y, ²¹¹At, ⁶⁷Cu, ¹⁵³Sm₁ ³²P, ¹⁸⁶Re, ¹⁸⁸Re, ²¹²Pb, and ²¹²Bi.

8. The method of claim 2, wherein the detectable reagent is administered to the subject intravenously, intraperitoneally, intramuscularly, intratumorally, or intradermally.

9. The method of claim 1 , wherein the detecting comprises a technique selected from the group consisting of MRI, CAT scan, CT scan, gamma imaging, intravascular ultrasound, PET imaging, SPECT imaging, and immunohistochemical detection.

10. The method of claim 1 , wherein the expression level, activity level, or combination thereof, of transglutaminase is compared to the expression level, activity level, or combinations thereof of transglutaminase in a control sample.

11. The method of claim 10, wherein the control sample is obtained from one or more subjects known to have a pathologic condition, or known to lack a pathologic condition.

12. The method of claim 1 , wherein determining a diagnosis or prognosis is based on detecting an increased expression level, activity level, or combinations thereof of transglutaminase.

13. The method of claim 1 , wherein the pathologic condition is selected from the group consisting of fibrosis, atherosclerosis, neurodegenerative disease, celiac disease, and cancer metastasis.

14. The method of claim 13, wherein the cancer metastasis is cancer metastasis from a cancer that can form a solid tumor.

15. The method of claim 14, wherein the cancer metastasis is selected from the group consisting of breast cancer, ovarian cancer, colon cancer, lung cancer, cervical cancer, head and neck cancer, neuroblastoma, prostate cancer, soft tissue sarcoma, hepatocellular cancer, gastric cancer, pancreatic cancer, liver cancer, bladder cancer, cancer of the urinary tract, thyroid cancer, renal cancer, carcinoma, melanoma, and brain cancer.

16. A method of monitoring progression of a pathologic condition in a subject, the method comprising:

(a) detecting an expression level, an activity level, or a combination thereof, of transglutaminase in a subject or in a biological sample from a subject; and

(b) monitoring progression of the pathologic condition based on the expression level, activity level, or combination thereof of transglutaminase.

17. The method of claim 16, comprising administering an effective amount of a detectable reagent to the subject or to the biological sample from a subject.

18. The method of claim 17, wherein the detectable reagent is a transglutaminase substrate.

19. The method of claim 18, wherein the transglutaminase substrate is a peptide.

20. The method of claim 19, wherein the peptide comprises SEQ ID

NO: 1 , or a fragment or variant thereof.

21. The method of claim 17, wherein the detectable reagent is labeled with a radioactive isotope.

22. The method of claim 21 , wherein the radioactive isotope is selected from the group comprising ^99mTc, ¹⁸F, ¹³²I, ¹²⁵I, ¹³¹1, ⁹⁰Y, ²¹¹At, ⁶⁷Cu, ¹⁵³Sm, ³²P, ¹⁸⁶Re, ¹⁸⁸Re, ²¹²Pb, and ²¹²Bi.

23. The method of claim 17, wherein the detectable reagent is administered to the subject intravenously, intraperitoneally, intramuscularly, intratumorally, or intradermally.

24. The method of claim 16, wherein the detecting comprises a technique selected from the group consisting of MRI₁ CAT scan, CT scan, gamma imaging, intravascular ultrasound, PET imaging, SPECT imaging, and immunohistochemical detection.

25. The method of claim 16, wherein the expression level, activity level, or combination thereof, of transglutaminase is compared to the expression level, activity level, or combinations thereof of transglutaminase in a control sample.

26. The method of claim 25, wherein the control sample is obtained from one or more subjects known to have a pathologic condition, or known to lack a pathologic condition.

27. The method of claim 16, wherein the monitoring prognosis is based on detecting an increased expression level, activity level, or combinations thereof, of transglutaminase.

28. The method of claim 16, wherein the pathologic condition is selected from the group consisting of fibrosis, atherosclerosis, neurodegenerative disease, celiac disease, and cancer metastasis.

29. The method of claim 28, wherein the cancer metastasis is cancer metastasis from a cancer that can form a solid tumor.

30. The method of claim 29, wherein the cancer metastasis is selected from the group consisting of breast cancer, ovarian cancer, colon cancer, lung cancer, cervical cancer, head and neck cancer, neuroblastoma, prostate cancer, soft tissue sarcoma, hepatocellular cancer, gastric cancer, pancreatic cancer, liver cancer, bladder cancer, cancer of the urinary tract, thyroid cancer, renal cancer, carcinoma, melanoma, and brain cancer.

31. A method of facilitating treatment of a pathologic condition in a subject, the method comprising:

(a) detecting an expression level, an activity level, or a combination thereof of transglutaminase in a subject or in a biological sample from a subject; and

(b) selecting a treatment of a pathologic condition based on the expression level, activity level, or combination thereof of transglutaminase.

32. The method of claim 31 , comprising administering an effective amount of a detectable reagent to a subject or to a biological sample from a subject.

33. The method of claim 32, wherein the detectable reagent is a transglutaminase substrate.

34. The method of claim 33, wherein the transglutaminase substrate is a peptide.

35. The method of claim 34, wherein the peptide comprises SEQ ID

NO: 1 , or a fragment or variant thereof.

36. The method of claim 32, wherein the detectable reagent is labeled with a radioactive isotope.

37. The method of claim 36, wherein the radioactive isotope is selected from the group comprising ^99mTc, ¹⁸F, ¹³²I, ¹²⁵I, ¹³¹1, ⁹⁰Y₁ ²¹¹At, ⁶⁷Cu, ¹⁵³Sm, ³²P, ¹⁸⁶Re, ¹⁸⁸Re, ²¹²Pb, and ²¹²Bi.

38. The method of claim 32, wherein the detectable reagent is administered to the subject intravenously, intraperitoneally, intramuscularly, intratumorally, or intradermally.

39. The method of claim 31 , wherein the detecting comprises a technique selected from the group consisting of MRI, CAT scan, CT scan, gamma imaging, intravascular ultrasound, PET imaging, SPECT imaging, and immunohistochemical detection.

40. The method of claim 31 , wherein the expression level, activity level, or combination thereof, of transglutaminase is compared to the expression level, activity level, or combinations thereof of transglutaminase in a control sample.

41. The method of claim 40, wherein the control sample is obtained from one or more subjects known to have a pathologic condition, or known to lack a pathologic condition.

42. The method of claim 31 , wherein selecting a treatment of a pathologic condition is based on detecting an increased expression level, activity level, or combinations thereof of transglutaminase.

43. The method of claim 31 , wherein the pathologic condition is selected from the group consisting of fibrosis, atherosclerosis, neurodegenerative disease, celiac disease, and cancer metastasis.

44. The method of claim 43, wherein cancer metastasis is cancer metastasis from a cancer that can form a solid tumor.

45. The method of claim 44, wherein the cancer metastasis is selected from the group consisting of breast cancer, ovarian cancer, colon cancer, lung cancer, cervical cancer, head and neck cancer, neuroblastoma, prostate cancer, soft tissue sarcoma, hepatocellular cancer, gastric cancer, pancreatic cancer, liver cancer, bladder cancer, cancer of the urinary tract, thyroid cancer, renal cancer, carcinoma, melanoma, and brain cancer.

46. A method of non-invasively generating a visible image of a pathologic condition in a subject, the method comprising administering an effective amount of a detectable reagent to a subject wherein the detectable reagent provides an image of transglutaminase expression level and/or activity level; and scanning the subject, whereby a visible image of the pathologic condition is non-invasively generated.

47. The method of claim 46, wherein the detectable reagent is a transglutaminase substrate.

48. The method of claim 47, wherein the transglutaminase substrate is a peptide.

49. The method of claim 48, wherein the peptide comprises SEQ ID NO: 1 , or a fragment or variant thereof.

50. The method of claim 46, wherein the detectable reagent comprises a contrast enhancement agent comprising at least one paramagnetic metal ion and at least one chelator.

51. The method of claim 50, wherein the paramagnetic metal ion is selected from the group consisting of transition, lanthanide, and actinide elements.

52. The method of claim 51 , wherein the paramagnetic metal ion is selected from the group consisting of Gd(III), Mn(II), Cu(II), Cr(III)₁ Fe(II), Fe(III), Co(II), Er(II), Ni(II), Eu(III) and Dy(III).

53. The method of claim 50, wherein the chelator is selected from the group consisting of DTPA, substituted DTPA, DOTA, substituted DOTA, EDTA, substituted EDTA, CDTA and substituted CDTA.

54. The method of claim 46, wherein the detectable reagent is labeled with a radioactive isotope.

55. The method of claim 54, wherein the radioactive isotope is selected from the group comprising ^99mTc, ¹⁸F, ¹³²I, ¹²⁵I, ¹³¹I₁ ⁹⁰Y, ²¹¹At, ⁶⁷Cu,

¹⁵³Sm, ³²P, ¹⁸⁶Re, ¹⁸⁸Re, ²¹²Pb, and ²¹²Bi.

56. The method of claim 46, wherein the detectable reagent is administered to the subject intravenously, intraperitoneal^, intramuscularly, intratumorally, or intradermally.

57. The method of claim 46, wherein the scanning comprises MRI, CAT scan, CT scan, gamma imaging, intravascular ultrasound, PET imaging, and SPECT imaging.

58. The method of claim 46, wherein the pathologic condition is selected from the group consisting of fibrosis, atherosclerosis, neurodegenerative disease, celiac disease, and cancer metastasis.

59. The method of claim 58, wherein the cancer metastasis is cancer metastasis from a cancer that can form a solid tumor.

60. The method of claim 59, wherein the cancer metastasis is selected from the group consisting of breast cancer, ovarian cancer, colon cancer, lung cancer, cervical cancer, head and neck cancer, neuroblastoma, prostate cancer, soft tissue sarcoma, hepatocellular cancer, gastric cancer, pancreatic cancer, liver cancer, bladder cancer, cancer of the urinary tract, thyroid cancer, renal cancer, carcinoma, melanoma, and brain cancer.

61. A contrast enhancement agent useful for providing a visible image of a pathologic condition in a subject or in a biological sample of a subject, the contrast agent comprising an effective amount of a detectable reagent, wherein the detectable reagent provides for a visible image of transglutaminase expression level and/or activity; and at least one paramagnetic metal ion and at least one chelator.

62. The contrast agent of claim 61 , wherein the detectable reagent is a transglutaminase substrate.

63. The contrast enhancement agent of claim 62, wherein the transglutaminase substrate comprises a peptide comprising SEQ ID NO:1 , or a fragment or variant thereof.

64. The contrast agent of claim 61 , wherein the paramagnetic metal ion is selected from the group consisting of transition, lanthanide and actinide elements.

65. The contrast enhancement agent of claim 64, wherein the paramagnetic metal ion is selected from the group consisting of Gd(III), Mn(II), Cu(II), Cr(III), Fe(II), Fe(III), Co(II), Er(II), Ni(II), Eu(III) and Dy(III).

66. The contrast enhancement agent of claim 61 , wherein the chelator is selected from the group consisting of DTPA, substituted DTPA,

DOTA, substituted DOTA, EDTA, substituted EDTA, CDTA and substituted CDTA.

67. A kit for the detection, diagnosis, prognosis, or monitoring of a pathologic condition in a subject, the kit comprising:

(a) an effective amount of at least a first reagent for detecting transglutaminase expression level and/or activity; and

(b) a detection reagent for labeling or detecting the first reagent.

68. The kit of claim 67, wherein the detectable reagent is a selectively binding transglutaminase substrate.

69. The kit of claim 68, wherein the first detectable transglutaminase substrate comprises a peptide comprising SEQ ID NO:1 , or a fragment or variant thereof.

70. The kit of claim 67, wherein the detection reagent comprises a reagent selected from the group consisting of a contrast enhancing agent, a radioactive isotope, and an antibody.

71. The kit of claim 70, wherein the radioactive isotope is selected from the group comprising ^99mTc, ¹⁸F, ¹³²1, ¹²⁵1, ¹³¹I₁ ⁹⁰Y, ²¹¹At, ⁶⁷Cu, ¹⁵³Sm, ³²P,

¹⁸⁶Re, ¹⁸⁸Re, ²¹²Pb, and ²¹²Bi.

72. The kit of claim 67, wherein the pathologic condition is selected from the group consisting of fibrosis, atherosclerosis, neurodegenerative disease, celiac disease, and cancer metastasis.

73. The kit of claim 72, wherein the cancer metastasis is cancer metastasis from a cancer that can form a solid tumor.

74. The kit of claim 73, wherein the cancer metastasis is selected from the group consisting of breast cancer, ovarian cancer, colon cancer, lung cancer, cervical cancer, head and neck cancer, neuroblastoma, prostate cancer, soft tissue sarcoma, hepatocellular cancer, gastric cancer, pancreatic cancer, liver cancer, bladder cancer, cancer of the urinary tract, thyroid cancer, renal cancer, carcinoma, melanoma, and brain cancer.

75. An isolated peptide consisting essentially of SEQ ID NO: 1 , or a fragment or variant thereof, wherein said peptide is a substrate for transglutaminase.

76. The isolated peptide of claim 75, wherein the peptide is disposed in a pharmaceutically acceptable diluent.

77. The isolated peptide of claim 76, wherein the pharmaceutically acceptable diluent is phosphate buffered saline.

78. The isolated peptide of claim 75, wherein the peptide is in detectably labeled form.