Microvesicle histone h2ax as a biomarker for genotoxic stress

Abstract

The invention described herein relates to methods of monitoring genotoxic stress in a test subject, specifically by detecting the expression level of microvesicle-associated H2AX from a biological sample.

1 . A method of monitoring genotoxic stress in a test subject, comprising:
 detecting the expression level of microvesicle-associated H2AX in a biological sample from the test subject, and   monitoring genotoxic stress in the subject based on the expression level of the microvesicle-associated H2AX.   
     
     
         2 . The method of  claim 1 , wherein the genotoxic stress is due to environmental contamination with genotoxins or radiation exposure. 
     
     
         3 . The method of  claim 1 , wherein the genotoxic stress is due to cancer treatment. 
     
     
         4 . The method of  claim 3 , wherein the cancer treatment comprises exposure to radiation. 
     
     
         5 . The method of  claim 3 , wherein the cancer treatment comprises administration of an anti-cancer agent selected from the group consisting of a platinum analogue, a tetrazine, an anti-metabolite, a plant alkaloid or terpenoid, a cytotoxic antibiotic, a DNA alkylating agent, or a type I topoisomerase inhibitor. 
     
     
         6 - 10 . (canceled) 
     
     
         11 . The method of  claim 3 , further comprising detecting the expression level of microvesicle-associated H2AX in a biological sample from the test subject at a plurality of time points following administration of the cancer treatment. 
     
     
         12 . The method of  claim 3 , wherein monitoring the genotoxic stress comprises comparing the expression level of microvesicle-associated H2AX in the biological sample from the test subject with the expression level of H2AX in a biological sample from a control subject that is not given the cancer treatment. 
     
     
         13 . The method of  claim 12 , wherein a higher level of expression of microvesicle-associated H2AX in the biological sample from the test subject compared to the level of expression of microvesicle-associated H2AX in the biological sample from the control subject indicates that the cancer treatment is inducing genotoxic stress. 
     
     
         14 . The method of  claim 3 , wherein monitoring genotoxic stress comprises evaluating the efficacy of cancer treatment. 
     
     
         15 . The method of  claim 14 , wherein evaluating the efficacy of the cancer treatment in the test subject comprises comparing the expression level of microvesicle-associated H2AX in the biological sample from the test subject with the expression level of microvesicle-associated H2AX in biological samples from a plurality of control subjects. 
     
     
         16 - 17 . (canceled) 
     
     
         18 . The method of  claim 15 , further comprising a step of deriving a score from the comparison of the expression level of microvesicle-associated H2AX in the biological sample from the test subject with the expression level of microvesicle-associated H2AX in the biological samples from the plurality of control subjects, wherein the score indicates a level of similarity between the expression level of microvesicle-associated H2AX in the biological sample from the test subject and the expression level of microvesicle-associated H2AX in the biological samples from the plurality of control subjects. 
     
     
         19 . (canceled) 
     
     
         20 . The method of  claim 18 , wherein the score is a correlation coefficient. 
     
     
         21 . The method of  claim 3 , wherein the cancer comprises a solid tumor. 
     
     
         22 . The method of  claim 3 , wherein the cancer is selected from the group consisting of pancreatic, ovarian, adenocarcinoma, prostate, breast, brain, head, neck, and lymphoma cancers. 
     
     
         23 - 24 . (canceled) 
     
     
         25 . The method of  claim 1 , wherein the biological sample is selected from the group consisting of plasma, serum, cerebrospinal fluid, urine, tears, milk, lymph fluid, synovial fluid, bronchoalveolar lavage, amniotic fluid, saliva, ocular fluid, ascites, and respiratory droplets. 
     
     
         26 . The method of  claim 1 , wherein detecting the expression level of microvesicle-associated H2AX comprises the use of ELISA, flow cytometry, or liquid chromatography-mass spectrometry. 
     
     
         27 . The method of  claim 1 , wherein detecting the expression level of microvesicle-associated H2AX comprises detecting binding of H2AX to an microvesicle-associated H2AX-specific antibody. 
     
     
         28 - 29 . (canceled) 
     
     
         30 . The method of  claim 3 , further comprising a step of isolating cancer-derived microvesicles from the biological sample prior to detecting the expression level of microvesicle-associated H2AX. 
     
     
         31 . The method of  claim 30 , wherein isolating microvesicles from the biological sample prior to detecting the expression level of microvesicle-associated H2AX comprises:
 contacting the biological sample with a cancer-derived microvesicle-specific reagent, wherein the biological sample comprises microvesicles and the reagent binds to microvesicles;   contacting the microvesicles with a tissue-specific reagent; and   isolating the microvesicles derived from the tissue.   
     
     
         32 . The method of  claim 1 , wherein the H2AX is γH2AX.