title: [Photo-protection of epigallocatechin-3-gallate on aging and gene mutation of human skin fibroblasts caused by ultraviolet radiation: an in vitro experiment].
abstract: OBJECTIVE
  To investigate the effects of epigallocatechin-3-gallate (EGCG) on the cell aging and hypoxanthine-phosphoribosyl-transferase (HPRT) gene mutation frequency induced by long-term ultraviolet (UV) A and UVB irradiation in human skin fibroblasts (HSF).
  
  
  METHODS
  HSF were separated from infant foreskin, cultured, and divided into six groups: control, EGCG group (treated by 25 microg/ml EGCG), UVA group (irradiated by 10 J/cm(2) UVA for 2 weeks), UVB group (irradiated by 30 mJ/cm(2) UVB for 2 weeks), UVA + EGCG group and UVB + EGCG group. beta-galactosidase (beta-GAL), a biological marker associated with senescence, was detected by histochemical staining. The HPRT gene mutation frequency was detected by the HPRT mutagenesis assay.
  
  
  RESULTS
  The HSFs of the control and EGCG groups only showed a few beta-GAL positive cells, and the beta-GAL positive cell ratios of the other 4 groups were higher and could be arranged from low to high according to the sequence: UVB group (43% +/- 4%) < UVA group (54% +/- 4%) < EGCG + UVB group (64% +/- 5%) < EGCG + UVA group (75% +/- 5%). The mutation rates of the control and EGCG groups were very low. The mutation rates of the UVB and UVA groups were 72 and 241 times that of the control group. The mutation rate of the UVB + EGCG and UVA + EGCG groups were significantly lower than those of the UVB and UVA groups by 52.78% and 32.37%, respectively (t = 2.0742, 2.7042, both P < 0.05).
  
  
  CONCLUSIONS
  The photo-protection of EGCG on HSFs from long-term UVA and UVB irradiation may be related to both the direct reduction of HPRT mutation frequency and the indirect induction of aging cells, thus decreasing the mutation frequency.
authors.affiliation: Department of Dermatology, First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhu
authors.forename: Dan
authors.initials: D
authors.lastname: Luo
authors.forename: Chun-hua
authors.initials: CH
authors.lastname: Shen
authors.forename: Jing
authors.initials: J
authors.lastname: Xu
mesh_terms: D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000187:drug effects* / Q000528:radiation effects; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D052816:Foreskin / Q000166:cytology; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics; D007223:Infant; D008297:Male; D009154:Mutation / Q000187:drug effects* / Q000528:radiation effects; D014466:Ultraviolet Rays; D001616:beta-Galactosidase / Q000378:metabolism