Analysis of cyclin E and CDK2 in ovarian cancer: gene amplification and RNA overexpression

Cyclins and their associated kinases (cdks) play a key role in controlling the cell cycle, a process whose disregulation can potentially lead to uncontrolled cell growth and hence to cancer. We have studied the role of both cyclin E and its associated kinase cdk2 in ovarian cancer. Primary, metastatic, recurrent and benign ovarian tumors were screened for cyclin E and cdk2 gene amplification. Cyclin E was shown to be amplified in 21% and cdk2 in 6.4% of the cases analyzed. Cyclin E and cdk2 RNA expression levels were determined by semi-quantitative RT-PCR analysis in a partially overlapping series of samples and compared to the expression levels of normal ovarian surface epithelial cells. Cyclin E RNA was overexpressed in 29.5% and cdk2 in 6.5% of ovarian tumors tested. We determined that in most cases gene amplification leads to higher RNA levels for cyclin E and that the overall levels of cyclin E and cdk2 RNA were correlated. We hypothesize that cyclin E and cdk2 are, in part co-regulated and that they may concur to ovarian tumor development.