Cancer examination method and examination kit

Abstract

An object of the present invention is to elucidate a molecular mechanism of ligand-independent activation of EphA2 in cancer cells, make EphA2 a more useful target in the treatment of cancer, and provide a cancer testing method and the like using the mechanism. The present invention provides, for example, a cancer testing method including a step of measuring an amount of an EphA2 protein fragment having a molecular weight of from 30 kDa to 80 kDa in a sample derived from a subject.

1 . A method of testing cancer, comprising a step of measuring an amount of a fragment of EphA2 protein having a molecular weight of from 30 kDa to 80 kDa in a sample derived from a subject. 
     
     
         2 . The method according to  claim 1 , wherein the fragment of EphA2 protein is a fragment comprising an N terminal of EphA2 protein. 
     
     
         3 . The method according to  claim 1 , wherein the fragment of EphA2 protein is at least one of the following peptides (i) to (iii):
 (i) a peptide having any one of the amino acid sequences set forth in SEQ ID NO: 1 to 4;   (ii) a peptide having an amino acid sequence obtained by adding, substituting, or deleting one or more amino acids from any one of the amino acid sequences set forth in SEQ ID NO: 1 to 4; and   (iii) a peptide having an amino acid sequence having 80% or more sequence identity with any one of the amino acid sequences set forth in SEQ ID NO: 1 to 4.   
     
     
         4 . The method according to  claim 1 , wherein the cancer expresses EphA2. 
     
     
         5 . The method according to  claim 1 , wherein the sample is at least one selected from blood, lymph, urine, and feces. 
     
     
         6 . The method according to  claim 1 , which is performed to estimate an effect or side-effect of an anticancer agent. 
     
     
         7 . The method according to  claim 1 , wherein the amount of a fragment of EphA2 protein is measured using an antibody capable of recognizing the EphA2 fragment. 
     
     
         8 . The method according to  claim 7 , wherein an epitope of the antibody capable of recognizing the EphA2 fragment is located in a cysteine-rich domain of EphA2 protein. 
     
     
         9 . A kit for testing cancer, comprising an antibody capable of detecting a fragment of EphA2 protein having a molecular weight of from 30 kDa to 80 kDa. 
     
     
         10 . The kit according to  claim 9 , wherein the fragment comprises an N terminal of EphA2 protein. 
     
     
         11 . The kit according to  claim 9 , wherein an epitope of the antibody is in a cysteine-rich domain on EphA2 protein. 
     
     
         12 . The kit according to  claim 9 , wherein the antibody is an antibody against at least one of the following peptides (i) to (iii):
 (i) a peptide having any one of the amino acid sequences set forth in SEQ ID NO: 1 to 4;   (ii) a peptide having an amino acid sequence obtained by adding, substituting, or deleting one or more amino acids from any one of the amino acid sequences set forth in SEQ ID NO: 1 to 4; and   (iii) a peptide having an amino acid sequence having 80% or more sequence identity with any one of the amino acid sequences set forth in SEQ ID NO: 1 to 4.   
     
     
         13 . The kit according to  claim 9 , wherein the kit is used for estimating an effect or side-effect of an anticancer agent. 
     
     
         14 . A method of screening an anticancer agent, comprising:
 culturing a cell expressing EphA2 under conditions where MT1-MMP processes EphA2,   adding a test compound to a culture medium of the cell and incubating in the presence of MT1-MMP, and   determining whether EphA2 is processed or not.   
     
     
         15 . The screening method according to  claim 14 , wherein in the step of determining whether EphA2 is processed or not, the test compound which lowers processing compared with processing in the absence of the test compound is selected as the candidate for the anticancer agent. 
     
     
         16 . An anticancer agent comprising a double stranded RNA having any of the following sequences: 
       
         
           
                 
                 
               
                     
                   siRNA #1 
                 
                     
                   S: 
                 
                     
                   (SEQ ID NO: 6) 
                 
                     
                   ggauggacacggagaauuutt 
                 
                     
                     
                 
                     
                   AS: 
                 
                     
                   (SEQ ID NO: 7) 
                 
                     
                   aaauucuccguguccaucctt 
                 
                     
                     
                 
                     
                   siRNA #2 
                 
                     
                   S: 
                 
                     
                   (SEQ ID NO: 8) 
                 
                     
                   gcgaugaagucuucacuuatt, 
                 
                     
                     
                 
                     
                   AS: 
                 
                     
                   (SEQ ID NO: 9) 
                 
                     
                   uaagugaagacuucaucgctt, 
                 
                     
                   and 
                 
                     
                     
                 
                     
                   siRNA #3 
                 
                     
                   S: 
                 
                     
                   (SEQ ID NO: 10) 
                 
                     
                   ggguagagacccugagacatt 
                 
                     
                     
                 
                     
                   AS: 
                 
                     
                   (SEQ ID NO: 11) 
                 
                     
                   ugucucagggucucuaccctt; 
                 
             
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
               
            
           
         
         or a precursor thereof, or a nucleic acid encoding the RNA or precursor. 
       
     
     
         17 . A method of treating cancer, comprising inhibiting expression or function of MT1-MMP.