SMAC mimetic BV6 acts in synergy with mTOR inhibitor to increase cisplatin sensitivity in ovarian cancer.

The objective of this study is to observe the antitumor efficacy of the second mitochondria-derived activator of caspases (SMAC) mimetic bivalent smac mimetic (BV6) in combination with target of rapamycin (mTOR) inhibitor on DDP (cisplatin) sensitivity. Ovarian cancer cells were exposed to cisplatin, BV6, DDP + BV6, and DDP + BV6 + mTOR inhibitor Rapamycin. Using proteomics and bioinformatics, protein expression profiles in ovarian cancer were determined. Bagg Albino color nude mice were treated with DDP or BV6 alone or in combination, or BV6 + DDP + Rapamycin. The effects of different treatments on ovarian cancer cells and tumor growth were evaluated in vivo and in vitro. Proteomics and bioinformatics analysis revealed significant changes of protein kinase (AKT)/mTOR pathway. Consistently, western blot data indicated that AKT/mTOR axis was gradually activated in BV6-treated ovarian cancer cells and attenuated the cytotoxic effect of BV6. Functional assays showed that DDP or BV6 treatment alone significantly enhanced the sensitivity and inhibited the migration of ovarian cancer cells, but without any synergistic effects. In addition, combination with BV6 and mTOR inhibitor Rapamycin significantly decreased cell viability and inhibited migration of ovarian cancer cells exposed to DDP. Consistently, the xenograft model showed that co-treatment with Rapamycin with BV6 had significantly suppressed tumor growth and metastasis. Our study demonstrated that SMAC analogue BV6 exhibits a strong anticancer effect on ovarian cancer in vitro and in vivo. Combination with Rapamycin overcomes the activation of mTOR pathway by BV6 and increases the chemosensitivity to DDP. These data suggest a potential application of triple combination with DDP + BV6 + Rapamycin in clinical management of ovarian cancer.