EFFECT OF DIETARY OMEGA-3 AND OMEGA-6 FATTY-ACID SOURCES ON PUVA-INDUCED CUTANEOUS TOXICITY AND TUMORIGENESIS IN THE HAIRLESS MOUSE

Because of concern about psoralen-induced phototoxicity and photocarci nogenesis, we investigated the effects of dietary lipids in a mouse mo del in which 8-methoxypsoralen (8-MOP) and UVA (PUVA) therapy has been shown to be carcinogenic. SKH-Hr-1 hairless albino mice were fed diet s containing either omega-3 or omega-6 fatty-acid sources (menhaden oi l and corn oil, respectively). After 2 weeks on the diets, the mice we re treated topically with 8-MOP and then exposed to UVA (5 J/cm2). Mic e receiving the omega-3 fatty-acid source exhibited a marked decrease in inflammatory response and a more rapid repair, as expressed both gr ossly and microscopically. In support of the latter response, i.e. rep air, ornithine decarboxylase activity was about 20% greater in animals receiving the omega-3 fatty-acid source. The effects of the dietary f atty acid sources on PUVA tumorigenesis were examined in long-term stu dies in which animals were treated topically with 0.01% 8-MOP thrice w eekly after which they were exposed to UVA (1 J/cm2). These studies in dicated that a dietary lipid rich in omega-3 fatty acid and known to e xhibit anti-inflammatory properties can markedly ameliorate the course of PUVA toxicity but does not impede the course of PUVA tumorigenesis .