EZH2 Inhibition Sensitizes CARM1-High, Homologous Recombination Proficient Ovarian Cancers to PARP Inhibition

Publication date: Available online 30 January 2020Source: Cancer CellAuthor(s): Sergey Karakashev, Takeshi Fukumoto, Bo Zhao, Jianhuang Lin, Shuai Wu, Nail Fatkhutdinov, Pyoung-Hwa Park, Galina Semenova, Stephanie Jean, Mark G. Cadungog, Mark E. Borowsky, Andrew V. Kossenkov, Qin Liu, Rugang ZhangSummaryIn response to DNA double-strand breaks, MAD2L2-containing shieldin complex plays a critical role in the choice between homologous recombination (HR) and non-homologous end-joining (NHEJ)-mediated repair. Here we show that EZH2 inhibition upregulates MAD2L2 and sensitizes HR-proficient epithelial ovarian cancer (EOC) to poly(adenosine diphosphate-ribose) polymerase (PARP) inhibitor in a CARM1-dependent manner. CARM1 promotes MAD2L2 silencing by driving the switch from the SWI/SNF complex to EZH2 through methylating the BAF155 subunit of the SWI/SNF complex on the MAD2L2 promoter. EZH2 inhibition upregulates MAD2L2 to decrease DNA end resection, which increases NHEJ and chromosomal abnormalities, ultimately causing mitotic catastrophe in PARP inhibitor treated HR-proficient cells. Significantly, EZH2 inhibitor sensitizes CARM1-high, but not CARM-low, EOCs to PARP inhibitors in both orthotopic and patient-derived xenografts.Graphical Abstract
Source: Cancer Cell - Category: Cancer & Oncology Source Type: research