American Association for Cancer Research
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Supporting Information: Methods from Targeted Degradation of BET Proteins in Triple-Negative Breast Cancer

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posted on 2023-03-31, 01:07 authored by 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 Li, Matthew J. Ellis, Shaomeng Wang

This file contains supporting information of methods including compound syntheses, molecular modeling, reagents, proteomic & transcriptome profiling and QPCR primers.

Funding

Breast Cancer Research Foundation

National Cancer Institute

History

ARTICLE 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. Cancer Res; 77(9); 2476–87. ©2017 AACR.