Expression of cyclin D1 and c-Ki- ras gene product in human epithelial ovarian tumors

Abstract

The expression of cyclin Dl gene product in human ovarian tumors was studied. We found that cyclin D1 is expressed at high levels in several ovarian cancer cell lines. Immunohistochemical study also showed that a significant proportion of primary ovarian tumor tissues overexpressed cyclin D1 gene product. Clear nuclear staining of cyclin Dl protein was detected in 28% of the cases. We also characterized the expression of c-Ki- ras gene product in ovarian cancer cell lines and tumor tissues. Amplification or overexpression of this protooncogene has been reported in ovarian tumors from Taiwan. These results show that c-Ki- ras is strongly expressed in PA-1 and NIH: OVCAR-3 cells in which cyclin D1 also expressed at high levels. Specific cytoplasmic staining of c-Ki- ras protein was detected in 11 tumors (52%). Statistical analyses show a strong positive correlation between cyclin D1 and c-Ki- ras immunoexpression. Thus, these data support the ideas that cyclin D1 may be involved in the pathogenesis of ovarian cancer, and coactivation of cyclin D1 and c-Ki- ras gene expression may represent one of the major pathways that lead to the development of ovarian cancer in Taiwan.