Production and removal of photoproducts induced by UVB irradiation and intervention effect of epigallocatechingallate in HaCaT cells

Objective Cyclobutane pyrimidine dimers(CPDs) are characteristic photoproducts in cells after ultraviolet irradiation.The study investigated the production and removal of photoproducts induced by UVB irradiation and intervention effect by epigallocatechingallate(EGCG) in human eternal keratinocyte line-HaCaT cells.Methods HaCaT cells were irradiated only by UVB or cultured with 200 μg/ml EGCG right after UVB irradiation.The production and removal of CPDs at different time intervals were examined by immunohistochemical method.Results The damage of HaCaT cells was increased in the dosage of UVB irradiation.CPDs appeared in HaCaT cells and reached the peak at 0.5h and removed rapidly during the first 4h and then removed slowly or almost cleared out up to 24h after UVB irradiation.The quantity of CPDs was decreased when irradiated HaCaT cells were incubated with EGCG(P0.05).Conclusions The photodamage of HaCaT cells was UVB dose dependent.There seems to be two phases in the removal of CPDs: a rapid phase and a slower phase after UVB irradiation.EGCG can decrease the level of CPDs.