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 int erleukin-8 (IL-8) in the human melanoma cell line, G361. Three NO dono rs. 3-morpholinosydnonimine hydrochloride (SIN-1), S-nitroso-N-acetylp enicillamine (SNAP). and S-nitroso-L-glutathione (SNOG), all caused an increase in both IL-8 protein secretion and promoter activity. Trunca tion of the promoter showed that 101 bp of the 5' flanking region prox imal to the transcription start site are sufficient for the response t o NO. Furthermore, mutation of the NF-kappa B and NF-IL-6 binding site s led to a significant decrease in NO-stimulated promoter activity. Th e nitric oxide synthase c inhibitor, N-G-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 regulat or of IL-8 production in G361 melanoma cells. (C) 1995 Academic Press, inc.