Stromal Nox4 -derived ROS signaling in prostate cancer

Background: Prostate cancer is a major cause of male cancer death in Western societies. Activated fibroblasts (termed cancer-associated fibroblasts, CAFs) within the stromal tumor microenvironment play a critical role in tumor development, progression and response to current therapies. The applicant previously showed that inhibiting (via pharmacological/genetic means) reactive oxygen species (ROS) signaling by the enzyme NADPH oxidase 4 (Nox4) in prostate stromal fibroblasts impairs their activation and reduces their pro-proliferative/migratory effects on PCa cells. Similar results were observed in pilot studies on prostate CAFs but not patient-matched benign adjacent fibroblasts, which express much lower levels of Nox4. Since Nox4 is specifically elevated in PCa-adjacent stroma and also higher in PCa patients that relapse following surgical removal of the prostate, these findings suggest the potential therapeutic benefit of Nox4 inhibition as a novel stromal-targeted approach for PCa. Hypothesis: Nox4-derived ROS orchestrate functions in the PCa stroma that are crucially involved in the tumor-promoting role of the PCa microenvironment. Methods: To closely mimic human PCa, human prostate-derived CAFs or patient-matched benign adjacent fibroblasts will be isolated from tissue specimens of consenting PCa patients undergoing surgical removal of the prostate. State of the art bioinformatic analyses, biochemical technologies and protein quantification methods will be employed to comprehensively analyze molecular mechanisms of Nox4-derived ROS signaling in the prostatic stroma. Key regulators of stromal Nox4 action and its downstream effectors identified from these studies will be functionally analyzed using cellissue culture models and immune-deficient mice to discern their downstream effects on processes related to PCa progression. Importantly, these studies will employ a Nox4 inhibitor to evaluate its potential future therapeutic use in PCa. Construction of a stroma-orientated prostate cancer tissue microarray from carefully annotated tissue specimens will permit comparison of protein levels of these key regulators to clinical parameters such as patient outcome. Novelty: Research outlined herein will provide a better understanding of Nox4-ROS signaling in the prostatic stroma as well as the molecular mechanisms by which reactive stroma promotes PCa progression. Specific targeting of dysregulated stromal-epithelial interactions, which play a critical role in many human carcinomas, is a major area for the development of new anti-cancer therapies. Thus, findings from studies outlined herein are expected to be of broad scientific interest to cancer biology researchers and will potentially identify strategies for therapeutic intervention.