Targeted degradation of BET proteins in triple-negative breast cancer

Longchuan Bai, Bing Zhou, Chao Yie Yang, Jiao Ji, Donna McEachern, Sally Przybranowski, Hui Jiang, Jiantao Hu, Fuming Xu, Yujun Zhao, Liu Liu, Ester Fernandez-Salas, Jing Xu, Yali Dou, Bo Wen, Duxin Sun, Jennifer Meagher, Jeanne Stuckey, Daniel F. Hayes, Shunqiang LiMatthew J. Ellis, Shaomeng Wang

Research output: Contribution to journalArticlepeer-review

115 Scopus citations

Abstract

Triple-negative breast cancers (TNBC) remain clinically challenging with a lack of options for targeted therapy. In this study, we report the development of a second-generation BET protein degrader, BETd-246, which exhibits superior selectivity, potency, and antitumor activity. In human TNBC cells, BETd-246 induced degradation of BET proteins at low nanomolar concentrations within 1 hour of exposure, resulting in robust growth inhibition and apoptosis. BETd-246 was more potent and effective in TNBC cells than its parental BET inhibitor compound BETi-211. RNA-seq analysis revealed predominant downregulation of a large number of genes involved in proliferation and apoptosis in cells treated with BETd-246, as compared with BETi-211 treatment that upregulated and downregulated a similar number of genes. Functional investigations identified the MCL1 gene as a critical downstream effector for BET degraders, which synergized with small-molecule inhibitors of BCL-xL in triggering apoptosis. In multiple murine xenograft models of human breast cancer, BETd-246 and a further optimized analogue BETd-260 effectively depleted BET proteins in tumors and exhibited strong antitumor activities at well-tolerated dosing schedules. Overall, our findings show that targeting BET proteins for degradation represents an effective therapeutic strategy for TNBC treatment.

Original languageEnglish
Pages (from-to)2476-2487
Number of pages12
JournalCancer research
Volume77
Issue number9
DOIs
StatePublished - May 1 2017

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