Stromal epigenetic alterations drive metabolic and neuroendocrine prostate cancer reprogramming
Rajeev Mishra, … , Edwin M. Posadas, Neil A. Bhowmick
Rajeev Mishra, … , Edwin M. Posadas, Neil A. Bhowmick
Published October 1, 2018; First published July 26, 2018
Citation Information: J Clin Invest. 2018;128(10):4472-4484. https://doi.org/10.1172/JCI99397.
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Research Article Cell biology Metabolism

Stromal epigenetic alterations drive metabolic and neuroendocrine prostate cancer reprogramming

Abstract

Prostate cancer is an androgen-dependent disease subject to interactions between the tumor epithelium and its microenvironment. Here, we found that epigenetic changes in prostatic cancer-associated fibroblasts (CAF) initiated a cascade of stromal-epithelial interactions. This facilitated lethal prostate cancer growth and development of resistance to androgen signaling deprivation therapy (ADT). We identified a Ras inhibitor, RASAL3, as epigenetically silenced in human prostatic CAF, leading to oncogenic Ras activity driving macropinocytosis-mediated glutamine synthesis. Interestingly, ADT further promoted RASAL3 epigenetic silencing and glutamine secretion by prostatic fibroblasts. In an orthotopic xenograft model, subsequent inhibition of macropinocytosis and glutamine transport resulted in antitumor effects. Stromal glutamine served as a source of energy through anaplerosis and as a mediator of neuroendocrine differentiation for prostate adenocarcinoma. Antagonizing the uptake of glutamine restored sensitivity to ADT in a castration-resistant xenograft model. In validating these findings, we found that prostate cancer patients on ADT with therapeutic resistance had elevated blood glutamine levels compared with those with therapeutically responsive disease (odds ratio = 7.451, P = 0.02). Identification of epigenetic regulation of Ras activity in prostatic CAF revealed RASAL3 as a sensor for metabolic and neuroendocrine reprogramming in prostate cancer patients failing ADT.

Authors

Rajeev Mishra, Subhash Haldar, Veronica Placencio, Anisha Madhav, Krizia Rohena-Rivera, Priyanka Agarwal, Frank Duong, Bryan Angara, Manisha Tripathi, Zhenqiu Liu, Roberta A. Gottlieb, Shawn Wagner, Edwin M. Posadas, Neil A. Bhowmick

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Figure 5

Androgen-mediated epigenetic regulation of RASAL3 expression in CAF determines PCa neuroendocrine differentiation and tumor growth in castrate-resistant xenograft models.

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Androgen-mediated epigenetic regulation of RASAL3 expression in CAF dete...
(A) RT-PCR analysis of RASAL3 mRNA expression in NAF and CAF was performed following 5-day treatment with bicalutamide (Bic) (10-5 M), enzalutamide (Enza) (10-5 M), R1881 (10-9 M), or 5-azacytadine (5-Aza) (5 mmol/l). β-Actin was used as a loading control. Representative image of 3 independent experiments is shown. (B) Bisulfide sequencing of the RASAL3 exon 2 was performed on CAF following treatment with vehicle or R1881 for 5 days. The methylation status of the individual CpG dinucleotides is shown by unmethylated (white) or methylated (black) circles (n = 5). (C) 3D cocultures of human CWR22Rv1 with CAF were treated with vehicle, enzalutamide, BPTES, or GPNA for 3 days in glutamine-free media and subjected to quantitative RT-PCR for the expression of a neuroendocrine PCa gene panel (n = 3, see Supplemental Table 4). Heatmap generated relative to vehicle treatment. (D) Schematic diagram of the experimental design of castration, enzalutamide, and GPNA treatment of a castrate-resistant xenograft model. Subrenal capsule xenografts contained tissue recombinants of CWR22Rv1 and CAF. (E) Gross images of representative tumors (dashed circles) as shown on host kidneys. (F) Quantitated tumor volumes are represented as the mean ± SD, analyzed by 2-tailed Student’s t test (n ≥ 8). ****P < 0.0001.