Suppression of apoptosis in UV-damaged human melanoma cells by a fermented milk, kefir

摘要

Accumulation of DNA damage caused by UV irradiation which could not be excluded by DNA repair or apoptosis mechan isms may cause skin cancer. We studied DNA repair enhancing factors in Kefir, a fermented milk by detecting thymine dimer formed by UV irradi ation with FITC labeledanti-thymine dimer antibody. The aqueous extract of Kefir remarkably enhanced the repair of thymine dimer and the cells treated with Kefir enhanced unscheduled DNA synthesis in the process of DNA repair of LtV-dam aged cells. The Kefir extract exhibi ted potent anti-o xidative activity and shifted the redox state of HMV- 1 cells irradiated with UV from oxidative to more reduced state. The cells treated with Kefir exhibited high colony forming ability than control. Since apoptosis of HMV-l cells caused by UV irradiation was also suppressed by the Kefir extract, suggesting that DNA repair enhancing factors in the Kefir extract coulddecrease DNA damage by UV irradiation and suppress apoptosis.