KEY ROLE OF e NOS IN ASSOCIATION WITH ERB AND HIFS IN THE ACTIVATION OF A TRANSCRIPTIONAL PROGRAM SPECIFIC FOR AGGRESSIVE HUMAN PROSTATE CANCER

We define a molecular mechanism underlying the most aggressive form of prostate cancer and involving functional activation of endothelial nitric oxide synthase (eNOS) and Hypoxia-inducible factors (HIFs) in association with ER? retained expression or abnormal signaling. Cultured cells from patients with worse prognosis exhibit constitutively hypoxic phenotype and increased NO production. Upon estrogen treatment, formation of ER??eNOS, ER??HIF-1? or ER?/HIF-2??combinatorial complexes leads to chromatin remodelling paralleled by induction of genes from a prognostic transcriptional signature. This mechanism was validated in vivo on Tissue Microarrays from an independent cohort of patients with very long follow up by striking correlations between: i. increased eNOS and ER? expression and decreased disease-specific survival; ii. increased HIF-2? expression, unexpected nuclear localization of eNOS and worse outcome for all clinical endpoints. Genetic or pharmacologcal modulation of eNOS expression and activity resulted in reciprocal conversion of the transcriptional signature in cells from patients with opposite outcome, confirming eNOS relevance to tumor progression. These findings facilitate optimization of patient stratification for predicting clinical outcome and foster innovative therapies targeting the combined NO, estrogen and Hypoxia responses.