Objective: Ovarian cancer is the leading cause of gynecologic-related mortality worldwide. Despite successful initial treatment, overall survival rates are very low because tumors develop resistance to chemotherapeutic drugs. The PI3K/mTOR pathway is a key signaling pathway involved in drug resistance of ovarian cancer cells. The aim of this study was to examine the effect of a newly developed PI3K/mTOR dual inhibitor, CMG002, on chemoresistant ovarian cancer cells.
Methods: We examined the effects of CMG002, and its synergistic effects when combined with paclitaxel or cisplatin, on cell viability, cell cycle arrest, and apoptosis of PTX-resistant SKpac17 or cisplatin-resistant A2780cis ovarian cancer cells in vitro. Western blot analysis was performed to assess expression of PI3K, p-mTOR, p-Akt, p-S6, Bim, and caspase-3. In vivo studies were carried out in a xenograft mouse model, followed by TUNEL and immunohistochemical staining of excised tumor tissue.
Results: CMG002 showed marked toxicity against chemoresistant ovarian cancer cells and re-sensitized these cells to chemotherapeutic agents by suppressing cell proliferation and inducing G1 cell cycle arrest and apoptosis. In vivo xenograft studies revealed that treatment with CMG002, either alone or in combination with paclitaxel or cisplatin, led to a marked reduction in tumor growth. CMG002 caused marked suppression of mTOR (Ser2448), Akt (Ser473), Akt (Thr308), and S6 (Ser235/236) phosphorylation, both in vitro and in vivo.
Conclusion: Taken together, CMG002, a very potent PI3K/mTOR dual inhibitor, induced cytotoxicity in chemoresistant ovarian cancer cells, suggesting that this novel inhibitor might be a new therapeutic strategy for chemoresistant ovarian cancer.
Keywords: Chemoresistance; Ovarian cancer; PI3K/mTOR dual inhibitor; Small molecule.
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