ras oncogene product p21 expression and prognosis of human ovarian tumors.

Monoclonal antibody rp-28 directed against the ras gene product p21 has been studied to evaluate ras p21 expression in malignant and benign ovarian tissues. Some ovarian carcinomas of serous and mucinous cystadenocarcinomas, undifferentiated adenocarcinomas, and clear cell carcinomas demonstrated intense staining of ras p21. The frequency and intensity of ras p21 staining were observed to increase with the degree of malignancy. There was no significant difference in ras p21 expression between early and late stages in ovarian tumors arising from the coelomic epithelium. With respect to prognosis, no differences between the ras p21-positive and -negative cases in ovarian tumors arising from the coelomic epithelium were observed. It is, therefore, possible to say that ras p21 expression was not related to clinical staging and prognosis. Expression of ras p21 in malignant lesions was higher than that in benign lesions of the ovary, and the expression is associated with the degree of malignancy in some types of ovarian tumors. Overexpression of ras p21 was observed in epithelial tumors; however, increased expression was not observed in germ cell and sex-cord stromal tumors. This differential expression of ras p21 is due to the different histogenesis of ovarian tumors. This fact may reflect a different carcinogenic mechanism for different types of malignancy.