Alteration of G1/S Cell Cycle Regulatory Proteins in Ovarian Epithelial Tumors

ABSTRACT

BACKGROUND: Disturbances of the cell cycle regulatory proteins are key events underlying the development and/or progression of human malignancies. The aim of this study was to evaluate the expression of G1/S cell cycle regulatory proteins in ovarian epithelial tumor. METHODS: We simultaneously evaluated the expression of cyclin D1, cyclin E, CDK4, CDK2, p16, Rb, E2F1, p53 and the Ki67 labelling index (LI) by immunohistochemical methods in 148 cases of ovarian epithelial tumor of the benign (n=47), borderline (n=29), and malignant type (n=72). RESULTS: The expression of cyclin E, CDK2, p16, Rb, E2F1, p53 and the Ki67 LI gradually increased from the benign type, through the borderline type, to the malignant tumors. Between the borderline and malignant tumors, the increased expression of cyclin E, E2F1, and p53, and the decreased expression of Rb were significantly associated with malignancy. The reduced Rb expression and the increased E2F1 expression were correlated with the FIGO stage and the histologic grade in the malignant ovarian epithelial tumors. CONCLUSIONS: Cyclin E, E2F1, and p53 overexpressions and the loss of Rb are the important components during carcinogenesis of ovarian epithelial tumors. Our results suggest that in- creased expression of E2F1 should be considered as a new parameter for the prognosis of patients with malignant ovarian epithelial tumors.