Abstract B09: Nitric oxide stimulates PI3K-AKT pathway activation by S-nitrosylation of PTEN in human melanoma cells

Based on our previous finding that inflammation associated nitric oxide synthase (NOS) expression in melanoma and its association with poor prognosis in melanoma patients, we investigated the role of nitric oxide (NO) on the PI3K-Akt pathway. Human melanoma cell lines were exposed in vitro to the NO donor (DETA NONOate), and increased Akt Serine 473 phosphorylation (pAkt S473) was detected after addition of 50-500μM DETA NONOate at as early as 2 hours. Significant increases of pAkt S473 were observed mostly in cell lines with wild-type PTEN, such as A375 and MeWo, which under our conditions do not have elevated basal Akt phosphorylation. A375 cells were further examined for DETA NONOate-induced functional consequences of Akt phosphorylation and activation; enhanced kinase activity was found to increase phosphorylation of 12 of 16 AKT signaling proteins, which include GSK, MAPK, Bad, and others. By analyzing melanoma data in The Cancer Genome Atlas (TCGA), we found a similar result that patients with positive iNOS mRNA expression have higher pAkt S473 levels compared with those without iNOS. When both PTEN and iNOS expression status were analyzed, pAkt S473 is only significantly (P