Overexpression of p21, cyclin E and decreased expression of p27 in DMBA (7, 12-dimethylbenzanthracene)-induced rat ovarian carcinogenesis

Ovarian cancer is a common gynecological malignancy and a leading cause of death in women. Inactivation of the tumor suppressor gene and deregulation of cyclin E are frequent in human ovarian cancer. The objective of this study was to investigate the expressions and roles of cyclin E, p21 and p27 in 7, 12-dimethylbenzanthracene (DMBA)-induced ovarian tumors in rats. The expressions of cyclin E, p21 and p27 were evaluated by immunohistochemistry and western blot analysis. The expressions of cyclin E and p21 in ovarian tumors was higher than that in normal ovarian surface epithelium. In contrast, the expression of p27 in ovarian tumors was lower than that in normal ovarian surface epithelium. But there were no differences among the cancer types. Positive correlation was present between cyclin E and p21. p27 was negatively correlated with cyclin E and p21. These results suggest that the increased expression of cyclin E and p21, and the decreased expression of p27, occur in DMBA-induced rat ovarian carcinogenesis and result in tumor progression.