Effect of tamoxifen, methoxyprogesterone acetate and combined treatment on cellular proliferation and apoptosis in SKOV3/DDP cells via the regulation of vascular endothelial growth factor.

Purpose: The aim of this study was to investigate the effect of tamoxifen (TAM), methoxyprogesterone acetate (MPA) and their combined treatment on cisplatin-resistant ovarian cancer SKOV3/DDP cells, as well as the potential mechanisms.

Methods: MTT assay was used to investigate the effect of different concentrations (0.01, 0.1, 1, 10 and 100 μM) of TAM, MPA and their combined treatment on the proliferation of cisplatin-resistant ovarian cancer SKOV3/DDP cells. Flow cytometry was employed to analyze the cell cycle and apoptosis rate of SKOV3/DDP cells treated with medium concentration (10 μM) of TAM, MPA and their combined treatment. Change in the protein level of vascular endothelial growth factor (VEGF) in response to drug treatments was measured using Western-blot.

Results: The proliferation of SKOV3/DDP cells was inhibited by 1, 10 and 100 μM of TAM or MPA in a dose-dependent manner. Compared to the control group, 10 μM TAM could significantly arrest SKOV3/DDP cells in the G0/G1 stage and induce apoptosis (p < 0.01). However, 10 μM MPA only promoted cell apoptosis, while exhibited little effect on the cell cycle. We further found that 10 μM TAM could remarkably reduce the protein expression of VEGF, while 10 μM MPA only induce a slight reduction. Strikingly, the combined treatment of TAM and MPA exhibited additive effect on the proliferation, cell cycle, apoptosis rate and VEGF expression of SKOV3/DDP cells.

Conclusions: We found that TAM, MPA and their combined treatment exhibited significant inhibitory effect on the cisplatin-resistant ovarian cancer SKOV3/DDP cells. Hence, TAM and MPA could be potential cytotoxic drugs to treat cisplatin-resistant patients with advanced ovarian cancer.