PRODUCTION AND RELEASE OF PROOPIOMELANOCORTIN (POMC) DERIVED PEPTIDESBY HUMAN MELANOCYTES AND KERATINOCYTES IN CULTURE - REGULATION BY ULTRAVIOLET-B

It is demonstrated that ultraviolet B (UVB) radiation stimulates incre ased expression of the proopiomelanocortin (POMC) gene which is accomp anied by production and release of a-melanocyte stimulating hormone (a lpha-MSH) and adrenocorticotropin (ACTH) by both normal and malignant human melanocytes and keratinocytes. The production and release of bot h peptides are also stimulated by dibutyryl cyclic adenosine monophosp hate (dbcAMP) and interleukin 1 alpha (IL-1 alpha) but not by endothel in-1 (ET-1) or tumor necrosis factor-alpha (TNF-alpha). N-acetyl-cyste ine (NAC), a precursor of glutathione (GSH), an intracellular foe radi cal scavenger, abolishes the UVB-stimulated POMC peptide production an d secretion. Conclusions are as follows: (1) Cultured human cells of c utaneous origin, namely keratinocytes and melanocytes, can produce and express POMC; (2) POMC expression is enhanced by exposure to UVB, pos sibly through a cyclic AMP-dependent pathway; and (3) The action of UV B on POMC production may involve a cellular response to oxidative stre ss.