Currently available PARP inhibitors are mainly used for the treatment of BRCA-mutated triple-negative breast cancer (TNBC), with a narrow application range of approximately 15% of patients. Recent studies have shown that EZH2 inhibitors have an obvious effect on breast cancer xenograft models and can promote the sensitivity of ovarian cancer cells to PARP inhibitors. Here, a series of new dual-target PARP1/EZH2 inhibitors for wild-BRCA type TNBC were designed and synthesized. SAR studies helped us identify compound 12e , encoded KWLX-12e , with good inhibitory activity against PARP1 (IC 50 = 6.89 nM) and EZH2 (IC 50 = 27.34 nM). Meanwhile, KWLX-12e showed an optimal cytotoxicity against MDA-MB-231 cells (IC 50 = 2.84 μM) and BT-549 cells (IC 50 = 0.91 μM), with no toxicity on normal breast cell lines. KWLX-12e also exhibited good antitumor activity with the TGI value of 75.94%, more effective than Niraparib plus GSK126 (TGI = 57.24%). Mechanistic studies showed that KWLX-12e achieved synthetic lethality indirectly by inhibiting EZH2 to increase the sensitivity to PARP1, and induced cell death by regulating excessive autophagy. KWLX-12e is expected to be a potential candidate for the treatment of TNBC.
Xiaohong Xu,Vinothakumar Rajamanicham,Sujing Xu,Zhoudi Liu,Tao Yan,Guang Liang,Guilong Guo,Huiping Zhou,Yi Wang
Triple-negative breast cancer (TNBC) is a subtype of breast cancer lacking prognostic and effective therapeutic targets currently. In this study, we evaluated the toxic potential of schisandrin A (SchA), a bioactive phytochemical found in Schisandra chinensis in TNBC. The anti-cancer effect and underlying mechanism of SchA on MDA-MB-231 and BT-549 cells were determined in vitro and in xenograft mouse model. Our data show that SchA markedly inhibited the growth of TNBC cells via induction of cell cycle arrest and cell apoptosis. Moreover, over activation of Wnt signaling was observed in TNBC cells, which was significantly suppressed by the treatment of SchA. Also, SchA treatment activated ER stress in TNBC cells. Finally, we verified these inhibitory effects of SchA in the MDA-MB-231 xenograft mouse model. In conclusion, SchA effectively inhibited TNBC in preclinical models by inducing cell cycle arrest and apoptosis via regulating Wnt/ER stress signaling pathway. All of these data indicate that SchA could be a potential candidate for the treatment of TNBC.
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