ENDOTHELIAL NOS, ESTROGEN RECEPTOR BETA, AND HIFS COOPERATIVELY ACTIVATE A PROGNOSTIC TRANSCRIPTIONAL PROGRAM IN AGGRESSIVE HUMAN PROSTATE CANCER

In the clinical management of prostate cancer (PCa) the ability to distinguish between aggressive and indolent forms of the disease is critical. Therefore identification of biomarkers that are capable to anticipate the clinical outcome is crucial for diagnosis and treatment. In this study, we used epithelial cell strains (n=50) of prostate tissue freshly explanted from patients with PCa to define a molecular mechanism underlying PCa progression that involves the functional activation of endothelial NOS (eNOS) and HIFs in association with estrogen receptor beta (ER?). Cells from patients with poor prognosis exhibited a constitutively hypoxic phenotype and increased NO production. Upon estrogen treatment, formation of ER?/eNOS, ER?/HIF-1?, or ER?/HIF-2? combinatorial complexes led to chromatin remodeling and transcriptional induction of prognostic genes. Tissue microarray analysis, using an independent cohort of patients (n= 100), established a hierarchical predictive power for these proteins, with expression of eNOS plus ER? and nuclear eNOS plus HIF-2? being the most relevant indicators of adverse clinical outcome. Genetic or pharmacological modulation of eNOS expression and activity resulted in reciprocal conversion of the transcriptional signature in cells from patients with opposite outcome. Altogether these data led us to postulate that activation of eNOS is a crucial requirement toward acquisition of androgen-independence and tumor progression in the prostate microenviroment highly sensitive to abnormal estrogen level and hypoxia. ERs and HIFs are already exploited in clinical oncology as therapeutic targets in endocrine cancers. We contribute to this approach by adding a key molecule, eNOS, which together with abnormal ER and Hypoxia-response signaling, drives PCa towards a more aggressive phenotype. Our work has considerable clinical relevance since it may enable the earlier diagnosis of poor prognosis PCa through routine biopsy assessment of eNOS, ER?, and HIF-2? expression. Furthermore, proposing eNOS as a therapeutic target fosters innovative therapies for PCa with NO inhibitors, which are employed in pre-clinical trials in non-oncological diseases.