Nitric oxide regulates IL-8 expression in melanoma cells at the transcriptional level.

We investigated the role of nitric oxide (NO) in the expression of interleukin-8 (IL-8) in the human melanoma cell line, G361. Three NO donors, 3-morpholinosydnonimine hydrochloride (SIN-1), S-nitroso-N-acetylpenicillamine (SNAP), and S-nitroso-L-glutathione (SNOG), all caused an increase in both IL-8 protein secretion and promoter activity. Truncation of the promoter showed that 101 bp of the 5' flanking region proximal to the transcription start site are sufficient for the response to NO. Furthermore, mutation of the NF-kappa B and NF-IL-6 binding sites led to a significant decrease in NO-stimulated promoter activity. The nitric oxide synthase inhibitor, NG-amino-L-homoarginine (NAHA), inhibited TNF-alpha-stimulated IL-8 promoter activity by 60%. Addition of excess L- but not D-arginine partially reversed the NAHA-mediated inhibition. These results demonstrate that NO is an endogenous regulator of IL-8 production in G361 melanoma cells.