Cutaneous melanoma patients have normal repair kinetics of ultraviolet-induced DNA repair in skin in situ

The DNA lesions induced by ultraviolet radiation include cyclobutane pyrimi dine dimers and 6-4 photoproducts. We investigated whether cutaneous melano ma patients have an impaired ability to repair their ultraviolet-induced ph otolesions. Seventeen patients with melanoma and 13 healthy controls took p art in this study. Both groups received a dose of 40 mJ per cm(2) Commissio n Internationale de l'Eclairage of solar simulating radiation on previously unexposed buttock skin. Skin biopsies were taken at 0 h, 24 h, and 48 h af ter ultraviolet exposure. A P-32-postlabeling method was used to measure bo th cyclobutane pyrimidine dimers and 6-4 photoproducts in skin. Cyclobutane pyrimidine dimers and 6-4 photoproduct levels did not differ in the melano ma patients from those in the control group at any time point post-ultravio let radiation. The repair rate of cyclobutane dimer TT=C was faster than th at for TT=T both at 24 h and 48 h postirradiation in both groups, providing evidence of site-specific repair (p < 0.05). We conclude that patients wit h melanoma have a normal ultraviolet-induced DNA repair capacity in skin in situ.