1. Inhibition of Nox4-dependent ROS signaling attenuates prostate fibroblast activation and abrogates stromal-mediated protumorigenic interactions.
- Author
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Sampson N, Brunner E, Weber A, Puhr M, Schäfer G, Szyndralewiez C, and Klocker H
- Subjects
- Cancer-Associated Fibroblasts cytology, Cancer-Associated Fibroblasts metabolism, Cell Line, Tumor, Cell Movement drug effects, Culture Media, Conditioned pharmacology, Humans, Male, Oxidative Stress drug effects, Prostatic Neoplasms drug therapy, Prostatic Neoplasms genetics, Pyrazolones, Pyridones, Sequence Analysis, RNA, Signal Transduction drug effects, Stromal Cells cytology, Stromal Cells metabolism, Transforming Growth Factor beta1 metabolism, Cancer-Associated Fibroblasts drug effects, NADPH Oxidase 4 genetics, NADPH Oxidase 4 metabolism, Prostatic Neoplasms metabolism, Pyrazoles pharmacology, Pyridines pharmacology, Reactive Oxygen Species metabolism
- Abstract
Carcinoma-associated fibroblasts (CAFs) play a key onco-supportive role during prostate cancer (PCa) development and progression. We previously reported that the reactive oxygen species (ROS)-producing enzyme NADPH oxidase 4 (Nox4) is essential for TGFβ1-mediated activation of primary prostate human fibroblasts to a CAF-like phenotype. This study aimed to further investigate the functional relevance of prostatic Nox4 and determine whether pharmacological inhibition of stromal Nox4 abrogates paracrine-mediated PCa-relevant processes. RNA in situ hybridization revealed significantly elevated Nox4 mRNA levels predominantly in the peri-tumoral stroma of clinical PCa with intense stromal Nox4 staining adjacent to tumor foci expressing abundant TGFβ protein levels. At pharmacologically relevant concentrations, the Nox1/Nox4 inhibitor GKT137831 attenuated ROS production, CAF-associated marker expression and migration of TGFβ1-activated but not nonactivated primary human prostate fibroblasts. Similar effects were obtained upon shRNA-mediated silencing of Nox4 but not Nox1 indicating that GKT137831 primarily abrogates TGFβ1-driven fibroblast activation via Nox4 inhibition. Moreover, inhibiting stromal Nox4 abrogated the enhanced proliferation and migration of PCa cell lines induced by TGFβ1-activated prostate fibroblast conditioned media. These effects were not restricted to recombinant TGFβ1 as conditioned media from PCa cell lines endogenously secreting high TGFβ1 levels induced fibroblast activation in a stromal Nox4- and TGFβ receptor-dependent manner. Importantly, GKT137831 also attenuated PCa cell-driven fibroblast activation. Collectively, these findings suggest the TGFβ-Nox4 signaling axis is a key interface to dysregulated reciprocal stromal-epithelial interactions in PCa pathophysiology and provide a strong rationale for further investigating the applicability of Nox4 inhibition as a stromal-targeted approach to complement current PCa treatment modalities., (© 2018 The Authors International Journal of Cancer published by John Wiley & Sons Ltd on behalf of UICC.)
- Published
- 2018
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