Chemotherapy-induced apoptosis in epithelial ovarian cancers

Abstract

OBJECTIVE: To determine whether chemotherapy drugs elicit programmed cell death (apoptosis) in ovarian cancer cells. METHODS: Monolayers of immortalized ovarian cancer cell lines and primary ovarian cancer cells obtained from ascites were grown in the presence of cisplatin, 4-hydroxyperoxy-cyclophosphamide (the active metabolite of cyclophosphamide) or paclitaxel. Next, DNA was extracted from the cells and subjected to electrophoresis to determine if DNA laddering characteristic of apoptosis was present. RESULTS: In three of six immortalized cell lines (OVCA 420, 429, and 433), apoptosis was not seen in response to any of the three drugs. In contrast, in OVCAR-3 and OVCA 432, DNA laddering consistent with apoptosis was observed in response to all three drugs. In the DOV 13 cell line, apoptosis was seen only with 4-hydroxyperoxycyclophosphamide. Among three primary ovarian cancers, cisplatin elicited apoptosis in one case. Both cell lines with mutant p53 genes (OVCAR-3 and OVCA 432) underwent apoptosis in response to all three drugs, whereas among three cell lines known to have normal p53 genes, one underwent apoptosis in response to 4-hydroxyperoxycyclophosphamide and two were unaffected. CONCLUSION: Ovarian cancer cell death in response to commonly used chemotherapeutic drugs involves the induction of a genetically programmed sequence of events (apoptosis) rather than simply necrosis.