[Photosensitized DNA damage: mechanisms and clinical use]

On the basis of our recent investigations by a DNA sequencing technique, mechanisms of photoinduced DNA damage in the presence of various endogenous molecules are summarized with special reference to UV carcinogenesis. In particular, riboflavin and pterin derivatives have been shown to induce DNA damage, mainly 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-oxodG) formation, specifically at the 5' site of 5'-GG-3' sequences through electron transfer reaction. The involvement of 8-oxodG formation in ras mutation is discussed. In addition, recent works concerning the mechanism of photodynamic therapy and the properties of photoactivatable DNA-cleaving molecules are described.