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 4

BMX blockade and inhibition of 3βHSD1 phosphorylation inhibit expression of androgen-regulated genes and prostate cancer proliferation.

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BMX blockade and inhibition of 3βHSD1 phosphorylation inhibit expression...
(A) C4-2 cells with stable shRNA-mediated knockdown of 3βHSD1 were stably infected with lentivirus expressing either WT 3βHSD1 or 3βHSD1-Y344F and subsequently treated with [3H]-DHEA for 5 hours, followed by steroid extraction from media and steroid separation and quantitation with HPLC. (B) As in A, but cells were deprived of serum overnight, followed by treatment with DHEA for the indicated days; cell proliferation was assessed with the WST-1 assay and growth for each cell line was normalized to WT control for each designated day. (C) As in A, but cells were deprived of serum overnight and treated with DHEA for 48 hours, followed by RNA extraction and qPCR. Expression is normalized to control and RPLP0 expression. (D) Cells stably expressing shNT or 1 of 2 shRNA sequences against BMX were deprived of serum overnight, followed by treatment with DHEA and cell proliferation assessment as in B. (E) As in C, except that RNA extraction and qPCR was done on shBMX or control cells treated with DHEA for 48 hours. (F) LNCaP or C4-2 cells were deprived of serum overnight, treated with zanubrutinib or DHEA for the indicated times, and cell proliferation assessed as in B. (G) LNCaP or C4-2 cells were deprived of serum overnight and treated with zanubrutinib or DHEA for 48 hours, followed by RNA extraction and qPCR. Expression is normalized to control and RPLP0 expression. For A and C, mean ± SEM represents combined data from 3 biological independent replicates performed in technical triplicate (unpaired 2-tailed t test). For B, D, and F, mean ± SEM represents 3 replicates in 1 experiment. Three independent experiments were performed (2-way ANOVA with Bonferroni’s multiple comparisons test). For E, mean ± SEM represents combined data from 3 biological independent replicates performed in technical triplicates (1-way ANOVA with Bonferroni’s multiple comparisons test). For G, mean ± SEM represents 4 replicates in 1 experiment. Three independent experiments were performed (1-way ANOVA with Bonferroni’s multiple comparisons test). *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.