P21 and p53 expression in patients with epithelial ovarian carcinoma

Kim, Young Jae; Nam, Dong Guk; Lee, Jae Kyu; Cho, Sam Hyun; Kim, Kyung Tai

Abstract

OBJECTIVE
Mutations in p53 are the most common genetic alterations in human malignancies. Expression of its protein product has been linked to decreased survival rate in ovarian carcinoma. P53 is well known as a pro-apoptotic tumor suppressor gene, but less is known about the importance of p21 expression in patients with epithelial ovarian malignancies. The purpose of this study was to investigate the different expression levels of p53 and p21 in various cell type of epithelial ovarian carcinomas and to determine their clinical significances.
METHODS
Fifty eight patients (serous (n=18), mucinous (n=14), clear cell (n=12), endometrioid (n=14) carcinoma) with epithelial ovarian carcinoma were studied using paraffin-embedded tissue specimens. Immunohistochemical staining utilizing monoclonal antibody against p21 and p53 were performed. Amount of their proteins were quantified using western blotting.
RESULTS
Mean age was 49.2 years old and advanced stage (III and IV) of cancer were 26 (44.8%). Recurrence rate and death rate were 20.7%, 22.4% respectively. With immunohistochemical staining for p21 and p53, p53 were significantly strongly stained in almost all epithelial ovarian carcinomas. However, p21 expressions were found in 10% of patients with serous carcinoma, 14% of patients with mucinous carcinoma, 38% of patients with endometrioid carcinoma, but 100% of patients with clear cell carcinoma. Among the patients whose tumors showed p21 staining, over expression were found in all clear cell typein western blot. But positive staining for p21 was below 10% in each slides of serous, mucinous and endometrioid type of ovarian carcinoma except clear cell type. This finding suggest that P21 expression was independent pathway in cell cycle regulation and apoptosis to the expression of p53 in serous, mucinous, and endometrioid type of ovarian carcinoma, but showed strongly positive correlation P21 and p53 expression in clear cell carcinoma.
CONCLUSION
P21 may be used as a marker for confirmation of diagnosis of clear cell carcinoma due to its unique expressions of p21.