Anti-Tumor and Anti-Invasive Effects of ONC201 on Ovarian Cancer Cells and a Transgenic Mouse Model of Serous Ovarian Cancer

Abstract

\n Background: ONC201 is a promising first-in-class small molecule that has been reported to have anti-neoplastic activity in various types of cancer through activation of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) as well as activation of mitochondrial caseinolytic protease P (ClpP).Methods: Our objective was to evaluate the effect of the ONC201 on (1) proliferation, cellular stress, apoptosis and invasion in human serous ovarian cancer (OC) cell lines, and (2) inhibition of tumor growth in a genetically engineered mouse model of high grade serous OC (K18-gT121+/-;p53fl/fl;Brca1fl/fl; KpB) under obese (high fat diet) and lean (low fat diet) conditions. Results: ONC201 significantly suppressed cell proliferation, induced arrest in G1 phase, and increased cellular stress and apoptosis, accompanied by dual inhibition of the AKT/mTOR/S6 and MAPK pathways in OC cells. ONC201 also resulted in inhibition of adhesion and invasion via epithelial–mesenchymal transition and reduction of VEGF expression. Pre-treatment with the anti-oxidant, N-acetylcysteine (NAC), reversed the ONC201-induced oxidative stress response, and prevented ONC201-reduced VEGF and cell invasion by regulating epithelial–mesenchymal transition protein expression. Knockdown of ClpP in ovarian cancer cells reduced ONC201 mediated the anti-tumor activity and cellular stress. Diet-induced obesity accelerated ovarian tumor growth in the KpB mouse model. ONC201 significantly suppressed tumor growth, and decreased serum VEGF production in obese and lean mice, leading to a decrease in tumoral expression of Ki-67, VEGF and phosphorylation of p42/44 and S6 and an increase in ClpP and DRD5, as assessed by immunohistochemistry. Additionally, ONC201 exhibited greater anti-tumor efficacy in obese (75%) as compared to lean (65%) mice. InterpretationConclusions: These results suggest that ONC206 may be a promising therapeutic agent to be explored in future clinical trials in high grade serous OC.