BMX controls 3βHSD1 and sex steroid biosynthesis in cancer
Xiuxiu Li, … , Eric Klein, Nima Sharifi
Xiuxiu Li, … , Eric Klein, Nima Sharifi
Published January 17, 2023
Citation Information: J Clin Invest. 2023;133(2):e163498. https://doi.org/10.1172/JCI163498.
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Research Article Oncology

BMX controls 3βHSD1 and sex steroid biosynthesis in cancer

Abstract

Prostate cancer is highly dependent on androgens and the androgen receptor (AR). Hormonal therapies inhibit gonadal testosterone production, block extragonadal androgen biosynthesis, or directly antagonize AR. Resistance to medical castration occurs as castration-resistant prostate cancer (CRPC) and is driven by reactivation of the androgen-AR axis. 3β-hydroxysteroid dehydrogenase-1 (3βHSD1) serves as the rate-limiting step for potent androgen synthesis from extragonadal precursors, thereby stimulating CRPC. Genetic evidence in men demonstrates the role of 3βHSD1 in driving CRPC. In postmenopausal women, 3βHSD1 is required for synthesis of aromatase substrates and plays an essential role in breast cancer. Therefore, 3βHSD1 lies at a critical junction for the synthesis of androgens and estrogens, and this metabolic flux is regulated through germline-inherited mechanisms. We show that phosphorylation of tyrosine 344 (Y344) occurs and is required for 3βHSD1 cellular activity and generation of Δ4, 3-keto-substrates of 5α-reductase and aromatase, including in patient tissues. BMX directly interacts with 3βHSD1 and is necessary for enzyme phosphorylation and androgen biosynthesis. In vivo blockade of 3βHSD1 Y344 phosphorylation inhibits CRPC. These findings identify what we believe to be new hormonal therapy pharmacologic vulnerabilities for sex-steroid dependent cancers.

Authors

Xiuxiu Li, Michael Berk, Christopher Goins, Mohammad Alyamani, Yoon-Mi Chung, Chenyao Wang, Monaben Patel, Nityam Rathi, Ziqi Zhu, Belinda Willard, Shaun Stauffer, Eric Klein, Nima Sharifi

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Figure 1

3β-hydroxysteroid dehydrogenase pY344 is required for DHEA metabolism.

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3β-hydroxysteroid dehydrogenase pY344 is required for DHEA metabolism. (...
(A) C4-2 cells overexpressing HA-3β-hydroxysteroid dehydrogenase (HA-3βHSD1) were treated with or without DHEA for 1 hour. Pan-phospho-tyrosine (pTyr) was detected by IP and Western blot. Control lysate without DHEA treatment was used for the IgG control. (B) 3βHSD1-GST was transfected, and cells were treated with DHEA for 1 hour. GST pull-down complexes were immunoblotted, and the indicated phosphopeptides on human 3βHSD1 were identified by LC-MS/MS. A doubly charged peptide with a mass of 896.91 Da was identified in the survey analysis of GST-HSD3B1. The CID spectra for this peptide are dominated by singly charged C-terminal y ions. The mass difference between y7 and y6 is consistent with modification at Y344. (C) Cells were transfected with HA-3βHSD1 mutants and treated as in (A). Lysate from WT-expressing cells was used for the IgG control. (D) 3βHSD1 enzyme activity was assessed by analyzing DHEA metabolism by HPLC. Cells were transfected with Flag-3βHSD1 mutants and subsequently treated with [3H]-DHEA for 4 hours, followed by steroid extraction from media, steroid separation, and quantitation with HPLC. The experiment was done in triplicate and repeated in independent experiments. Shown are the steroid sites of 3βHSD1 biochemical modification. Mean ± SEM represents 3 replicates in 1 experiment. Three independent experiments were performed. ***P < 0.001 (unpaired 2-tailed t test). (E) C4-2 cells overexpressing 3βHSD1-GST were treated with ethanol or DHEA, pregnenolone, or androstenediol for 1 hour. GST pull-down complexes were immunoblotted with a phospho-3βHSD1-Y344 antibody.