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

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