UVB-induced decrease of p16/CDKN2A expression in skin cancer patients

The lack of p16 expression has been shown in cultured melanoma cells, howev er contradictory evidence for p16 expression in melanoma tissues exist. Ult raviolet (UV) C and UVB have been shown to affect p16 expression, which imp airs cell cycle regulation in vitro and in vivo, In this study, p16/CDKN2A gene expression was determined by reverse transcription polymerase chain re action in seven skin cancer patients, in one dysplastic nevus patient and i n seven healthy individuals, prior to UVB exposure and at various times aft er application of one minimal erythema dose (MED). Five of the seven skin c ancer patients showed a down-regulation of p16/ CDKN2A expression after UVB exposure, while controls remained unaltered. The UVB-induced decline of p1 6/ CDKN2A in skin cancer patients might offer new insights into photocarcin ogenesis. The putative sequence of events could start with a down-regulatio n of p16/CDKN2A expression, which would lead to impaired cell cycle regulat ion. Altered expression patterns of p16/CDKN2A following UVB exposure could be of value for identifying people with an increased risk of UV-induced sk in cancer.