Amplification of cyp24 and uses thereof

Abstract

This invention pertains to the discovery that an amplification of the CYP24 gene or an increase in CYP24 activity is a marker for the presence of, progression of, or predisposition to, a cancer (e.g., breast cancer). Using this information, this invention provides methods of detecting a predisposition to cancer in an animal. The methods involve (i) providing a biological sample from an animal (e.g. a human patient); (ii) detecting the level of CYP24 within the biological sample; and (iii) comparing the level of CYP24 with a level of CYP24 in a control sample taken from a normal, cancer-free tissue where an increased level of CYP24 in the biological sample compared to the level of CYP24 in the control sample indicates the presence of said cancer in said animal.

What is claimed is: 
     
         1 . A method of screening a test agent for the ability to inhibit proliferation of a CYP24-expressing cell, said method comprising:
 (i) contacting said CYP24-expressing cell with said test agent; and   (ii) detecting the level of CYP24 activity;   
       wherein a decreased level of CYP24 activity as compared to the level of CYP24 activity in a cell not contacted with said agent indicates that said agent inhibits proliferation of said cell. 
     
     
         2 . The method of  claim 1 , wherein said cell is contacted with vitamin D. 
     
     
         3 . The method of  claim 1 , wherein said detecting comprises detecting the level of CYP24 mRNA, wherein a decreased level of CYP24 mRNA in said CYP24-expressing cell as compared to the CYP24 mRNA level in a cell not contacted with said agent sample, at a given level of vitamin D receptor activity indicates that said agent inhibits proliferation of said cell. 
     
     
         4 . The method of  claim 1 , wherein said detecting comprises hybridizing a nucleic acid from said cell to an array of nucleic acid probes. 
     
     
         5 . The method of  claim 1 , wherein said detecting comprises detecting the level of CYP24 protein, wherein a decreased level of CYP24 protein in said CYP24-expressing cell as compared to the CYP24 protein level in a cell not contacted with said agent sample indicates that said agent inhibits proliferation of said cell. 
     
     
         6 . The method of  claim 5 , wherein said level of CYP24 protein in said contacted cell and said cell not contacted with said agent is measured at the same vitamin D receptor activity or the CYP24 protein levels are normalized to the level of vitamin D receptor activity in the sample and control. 
     
     
         7 . The method of  claim 1 , wherein said detecting comprises detecting the level of 25-hydroxyvitamin D3 24-hydroxylase enzyme activity in said cell, wherein an decreased level of 25-hydroxyvitamin D3 24-hydroxylase enzyme activity in said CYP24-expressing cell as compared to the 25-hydroxyvitamin D3 24-hydroxylase enzyme activity level in a cell not contacted with said agent sample, at a given level of vitamin D receptor activity indicates that said agent inhibits proliferation of said cell. 
     
     
         8 . The method of  claim 7 , wherein said level of 25-hydroxyvitamin D3 24-hydroxylase enzyme activity in said contacted cell and said cell not contacted with said agent is measured at the same vitamin D receptor activity or the activity protein levels are normalized to the level of vitamin D receptor activity in the sample and control. 
     
     
         9 . The method of  claim 1 , wherein said CYP24-expressing cell is a tumor cell. 
     
     
         10 . The method of  claim 1 , wherein said CYP24-expressing cell is a hyperproliferative cell. 
     
     
         11 . The method of  claim 1 , wherein the difference between said decreased level of CYP24 activity and the level of CYP24 activity in a cell not contacted with said agent is a statistically significant difference. 
     
     
         12 . The method of  claim 1 , wherein said decreased level of CYP24 activity is at least about 2-fold lower than the level of CYP24 activity in a cell not contacted with said agent. 
     
     
         13 . The method of  claim 1 , wherein said decreased level of CYP24 activity is at least about 4-fold lower than the level of CYP24 activity in a cell not contacted with said agent. 
     
     
         14 . A method of decreasing the proliferation of a cell with an elevated level of CYP24, said method comprising reducing the level of CYP24 activity in said cell using an inhibitor of CYP24. 
     
     
         15 . The method of  claim 14 , wherein said method further comprises contacting the cell with vitamin D. 
     
     
         16 . The method of  claim 14 , wherein said cell is a tumor cell. 
     
     
         17 . The method of  claim 16 , wherein said tumor cell is selected from the group consisting of breast cancer cells, prostate cancer cells, colorectal cancer cells, leukemia cells, lymphomas, lung cancer cells, brain cancer cells, pancreatic cancer cells, and ovarian cancer cells. 
     
     
         18 . The method of  claim 14 , wherein said cell is a hyperproliferative cell. 
     
     
         19 . The method of  claim 14 , wherein said cell is a metastatic cell. 
     
     
         20 . The method of  claim 14 , wherein said inhibitor is selected from the group consisting of antisense oligonucleotides, ribozymes, repressors of CYP24 gene expression, competitive inhibitors of 25-hydroxyvitamin D3 24-hydroxylase activity, and non-competitive inhibitors of 25-hydroxyvitamin D3 24-hydroxylase activity.