Metastatic castration-resistant prostate cancers (mCRPCs) are treated with therapies that antagonize the androgen receptor (AR). Nearly all patients develop resistance to AR-targeted therapies (ARTs). Our previous work identified CREB5 as an upregulated target gene in human mCRPC that promoted resistance to all clinically approved ART. The mechanisms by which CREB5 promotes progression of mCRPC or other cancers remains elusive. Integrating ChIP-seq and rapid immunoprecipitation and mass spectroscopy of endogenous proteins, we report that cells overexpressing CREB5 demonstrate extensive reprogramming of nuclear protein–protein interactions in response to the ART agent enzalutamide. Specifically, CREB5 physically interacts with AR, the pioneering actor FOXA1, and other known co-factors of AR and FOXA1 at transcription regulatory elements recently found to be active in mCRPC patients. We identified a subset of CREB5/FOXA1 co-interacting nuclear factors that have critical functions for AR transcription (GRHL2, HOXB13) while others (TBX3, NFIC) regulated cell viability and ART resistance and were amplified or overexpressed in mCRPC. Upon examining the nuclear protein interactions and the impact of CREB5 expression on the mCRPC patient transcriptome, we found that CREB5 was associated with Wnt signaling and epithelial to mesenchymal transitions, implicating these pathways in CREB5/FOXA1-mediated ART resistance. Overall, these observations define the molecular interactions among CREB5, FOXA1, and pathways that promote ART resistance.
Bibliographical noteFunding Information:
This work was supported in part by the Weizmann Institute of Science – National Postdoctoral Award Program for Advancing Women in Science (to RA), Targets of Cancer Training program grant T32 CA009138 (to ML), Ray of Light Foundation (to HEB), NIH/NCI (K00 CA212221) (to JPR), American Cancer Society-AstraZeneca (PF-16-142-01-TBE) (to JH), Young Investigator Award from the American Society of Clinical Oncologists (ASCO) and by the PhRMA Foundation and Kure It Cancer Research Foundation (to SCB), U01 CA233100 (EMV), Mark Foundation Emerging Leader Award (EMV), U.S. National Institutes of Health/National Cancer Institute: U01 CA176058 (to WCH). We acknowledge Joshua Pan from Dana Farber Institute and Broad Institute of MIT and Harvard for designing approaches for co-dependency analysis.
© 2022, Hwang, Arafeh, Seo et al.