Abstract
The sunlight can induce a variety of acute and chronic skin reactions, including sunburn, suntanning, immunosuppression, photoaging, pre-malignant conditions, and cancer development. These changes occur as a sequence of events, but not independently. Any photobiologic reaction must be preceded by a photochemical reaction, which initiates after a certain chromophore absorbs light energy. It is well known that nuclear DNA is an important chromophore for ultraviolet carcinogenesis, and that UVB radiation induces DNA damage such as pyrimidine dimer formation. Recently we have demonstrated, using model mice of xeroderma pigmentosum, that DNA damage is an initial event to develop sunburn, immunosuppression, photoaging, and then to malignant changes. It is important to protect acute sunburn reaction for the inhibition of skin cancers. [Skin Cancer (Japan) 2003; 18: 101-105]
