Cell proliferative activity and mutation of P53 suppressor gene in human gestational trophoblastic disease

Cell proliferative activity and the overaccumulation of P53 suppressor gene were evaluated in 26 cases of gestational trophoblastic disease and five cases with normal placentae. Formalin-fixed, paraffin-embedded histological sections were used for immunohistochemistry, utilizing the avidin-biotin-peroxidase technique and antibodies to PCNA (proliferative cell nuclear antigen) and to P53 (product of suppressor gene). Positive reactions for PCNA were graded from 1+ to 3+ (1(+)-less than 10% of cells; 2(+)-10-50%; 3(+)-more than 50%). Eight of 10 cases of choriocarcinoma (80%) showed moderate to strong reactivity for PCNA (2+ and 3+). All 9 cases with hydatidiform mole and 6 of 7 cases with partial mole also demonstrated 2+ and 3+ reactions for PCNA. There was minimal or no PCNA staining in the trophoblastic cells of normal placentae. Five of 10 cases with choriocarcinoma (50%) exhibited P53 overaccumulation as did 7 of 9 cases with hydatidiform mole (78%). In hydatidiform moles, P53 staining was limited to the areas of trophoblastic proliferation separate from chorionic villi. None of the partial moles or normal placentae showed P53 overaccumulation. It is concluded that the cell proliferative activity of choriocarcinomas as well as complete and partial hydatidiform moles are comparable. On the other hand, the mutation of P53 suppressor gene, as demonstrated by the overaccumulation of P53 protein, is seen only in true trophoblastic neoplasms, namely, choriocarcinomas and hydatidiform moles.