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Giornale Italiano di Dermatologia e Venereologia 2003 December;138(6):455-64


language: Italian

Sun light and skin cancer risk factors

Santoianni P., Nino M.

Dipartimento di Patologia Sistematica Sezione di Dermatologia Università degli Studi «Federico II», Napoli


UV radiation is absorbed by many endogenous chromophores: especially DNA bases, tryptophan and other aminoacids, enzymes, NADH-NADPH, riboflavines, cytochromes, urocanic acid. Reactive oxygen species represent the most important agents of UV activity by reducing and destroying antioxidant systems, inducing lipids and proteins oxidation and by activating signals for fibroblasts with growth, differentiation, ageing and collagen degeneration. UV can induce immunocompetent cell modifications, and can alterate immunosurveillance against skin cancers. However, immunomodulation effects are regulated by genetic susceptibility. Natural skin protection against radiations is assured: a) by melanin quantity and phototype, and b) by corneum hardening. Great importance has been represented by many protection systems, interesting cytoplasm and cell membranes. The photoprotective weapons are represented by endogenous antioxidants and free radicals scavengers: alpha-tocopherol, ascorbate, carotenoids, oxycarotenoids, Q coenzyme, glutathion, taurine, and many others, superoxidodismutase, catalase, glutathion peroxidase; lipoic acid, NADPH-NADP+ e NADH-NAD+, and “heat shock proteins” (HSP). Antioxidant pool, with HSP, cytochrome P 450, cytokines, and other mediators, represent a natural defense system and efficient cell protection against UV-induced damage and other endogenous and exogenous factors. Skin defense systems are activated by UV radiation, but most of them become not sufficient after prolonged and intense exposition. A very efficient photoprotection could be realized by: a) radiation screen with chemical and physical agents; b) enhancement of natural systems and control of molecular mechanisms induc-ing photodamage with substances enhancing those present in the skin, introduced orally or systemically, c) inducing corneum hardening with selective and progressive irradiation. The topical and not numerous photoprotection studies, conducted principally on animals have proposed results of not easy application to the men; however, those conducted in men seem to be encouraging and with significant application perspectives.

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