Dual target PARP1/EZH2 inhibitors inducing excessive autophagy and producing synthetic lethality for triple-negative breast cancer therapy

Abstract

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 (IC₅₀ = 6.89 nM) and EZH2 (IC₅₀ = 27.34 nM). Meanwhile, KWLX-12e showed an optimal cytotoxicity against MDA-MB-231 cells (IC₅₀ = 2.84 μM) and BT-549 cells (IC₅₀ = 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.

Keywords: EZH2; PARP; Synthetic lethality; Triple-negative breast cancer.