ZBTB46/FOXA2/HIF1A transcription activator complex promotes MCTP1-regulated neuroendocrine differentiation and epithelial-to-mesenchymal transition

Abstract Androgen deprivation therapy (ADT)-induced neuroendocrine differentiation (NED) is a well-known lethal subtype of prostate cancer (PCa) with a median survival rate of less than one year. Despite the increasing research attention on this variant of PCa, the underlying mechanism orchestrating therapy-related neuroendocrine prostate cancer (NEPC) remains elusive. We found that ADT-induced hypoxia-associated ZBTB46/FOXA2/HIF1A signaling enhances the multiple C2 domain transmembrane protein 1 (MCTP1), which promotes NED and epithelial-to-mesenchymal transition (EMT) of PCa. Mechanistically, ZBTB46 physically interacts with the HIF1A/FOXA2 complex, in which ZBTB46 may be a co-activator of the hypoxia-related FOXA2 transcription factor. Interestingly, this ZBTB46/FOXA2/HIF1A complex accumulates after hypoxia and functions as a transcriptional activator of MCTP1. Hypoxia-upregulated MCTP1 subsequently leads to NED and the increase in EMT, whereas the opposite is true for the knockdown of MCTP1 in PCa cells. Consistent with previous results, MCTP1 is highly expressed in high-grade castration-resistance prostate cancer (CRPC) and small-cell PCa (SCPC) tissues and is associated with NE markers and ZBTB46/FOXA2/HIF1A abundance. In this study, we explored the direct interaction of ZBTB46 protein with hypoxia-related FOXA2/HIF1A complex in PCa cells under hypoxic conditions, which promote MCTP1-driven EMT and NED. Our finding suggests that MCTP1 could be used as a biomarker for diagnosing NEPC and as a therapeutic target in clinical applications. Citation Format: Vu Thuy Dung Phan, Yu-Ching Wen, Wei-Yu Chen, Wei-Hao Chen, Kuo-Ching Jiang, Han-Ru Li, Van Thi Ngoc Tram, Zi-Qing Chen, Wan-Hsin Wang, Yen-Nien Liu. ZBTB46/FOXA2/HIF1A transcription activator complex promotes MCTP1-regulated neuroendocrine differentiation and epithelial-to-mesenchymal transition. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3736.