A mitochondrial unfolded protein response inhibitor suppresses prostate cancer growth in mice via HSP60
Rahul Kumar, … , Dean G. Tang, Dhyan Chandra
Rahul Kumar, … , Dean G. Tang, Dhyan Chandra
Published June 2, 2022
Citation Information: J Clin Invest. 2022;132(13):e149906. https://doi.org/10.1172/JCI149906.
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Research Article Cell biology Oncology

A mitochondrial unfolded protein response inhibitor suppresses prostate cancer growth in mice via HSP60

Abstract

Mitochondrial proteostasis, regulated by the mitochondrial unfolded protein response (UPRmt), is crucial for maintenance of cellular functions and survival. Elevated oxidative and proteotoxic stress in mitochondria must be attenuated by the activation of a ubiquitous UPRmt to promote prostate cancer (PCa) growth. Here we show that the 2 key components of the UPRmt, heat shock protein 60 (HSP60, a mitochondrial chaperonin) and caseinolytic protease P (ClpP, a mitochondrial protease), were required for the development of advanced PCa. HSP60 regulated ClpP expression via c-Myc and physically interacted with ClpP to restore mitochondrial functions that promote cancer cell survival. HSP60 maintained the ATP-producing functions of mitochondria, which activated the β-catenin pathway and led to the upregulation of c-Myc. We identified a UPRmt inhibitor that blocked HSP60’s interaction with ClpP and abrogated survival signaling without altering HSP60’s chaperonin function. Disruption of HSP60-ClpP interaction with the UPRmt inhibitor triggered metabolic stress and impeded PCa-promoting signaling. Treatment with the UPRmt inhibitor or genetic ablation of Hsp60 inhibited PCa growth and progression. Together, our findings demonstrate that the HSP60-ClpP–mediated UPRmt is essential for prostate tumorigenesis and the HSP60-ClpP interaction represents a therapeutic vulnerability in PCa.

Authors

Rahul Kumar, Ajay K. Chaudhary, Jordan Woytash, Joseph R. Inigo, Abhiram A. Gokhale, Wiam Bshara, Kristopher Attwood, Jianmin Wang, Joseph A. Spernyak, Eva Rath, Neelu Yadav, Dirk Haller, David W. Goodrich, Dean G. Tang, Dhyan Chandra

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Figure 7

DCEM1 induces proteostatic stress and cell death in PCa cells.

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DCEM1 induces proteostatic stress and cell death in PCa cells. (A) LNCaP...
(A) LNCaP and PC-3 cells were treated with DCEM1 for 24 hours, and poly-Ub protein levels were analyzed by Western blotting. (B) LNCaP and PC-3 cells were treated with DCEM1 for 24 hours, and mitoROS levels were analyzed by flow cytometry using mitoSOX dye and are represented as fold change compared to control. (C) LNCaP and PC-3 cells were treated with either DCEM1 or H2O2 (200 μM) for 24 hours, and total DNA was isolated and analyzed for mtDNA damage. (D) LNCaP cells were treated with DCEM1 for 24 and 48 hours, and apoptotic cell populations were analyzed using annexin V–FITC/PI. (E) PC-3 cells were treated with DCEM1 for 24 and 48 hours, and apoptotic cell populations were analyzed using annexin V–FITC/PI. (F) 22RV1 cells were treated with DCEM1 for 24 and 48 hours, and apoptotic cell populations were analyzed using annexin V–FITC/PI. (G) DU145 cells were treated with DCEM1 for 24 and 48 hours, and apoptotic cell populations were analyzed using annexin V–FITC/PI. (H) LNCaP and PC-3 cells were pretreated with SQM1 (750 nM) followed by DCEM1 (10 μM) treatment, and analyzed for cell viability by MTT assay and are represented as fold change compared to control. (I) LNCaP, PC-3, and 22RV1 cells were treated with DCEM1 and analyzed for c-Myc and EZH2 protein expression after 24 hours of treatment. (J) LNCaP, 22RV1, and VCaP cells were treated with DCEM1 and analyzed for AR and PSA protein expression after 24 hours of treatment. Data are mean ± SD (n ≥ 3). *P < 0.05 compared to respective control by 1-way ANOVA followed by Dunnett’s multiple-comparison test (B and D–G) or 1-way ANOVA followed by Tukey’s multiple-comparison test (H). Actin serves as a loading control.