[Puerarin inhibits DNA damage of HaCaT cells induced by UVB via ceramide pathway].

This study is to investigate the effect and mechanism of puerarin on DNA damage of HaCaT cells induced by UVB. Puerarin pre-treated cells were irradiated with UVB at 30 mJ x cm(-2). Twenty four hours after irradiation, DNA damage was detected by comet assay, ceramide was measured by thin layer chromatography and gas chromatography, intracellular free calcium ion was analyzed by flow cytometry, the phosphorylation level of p38 protein was examined by Western blotting method. Levels of DNA damage, ceramide, free calcium ion and p-p38 protein were elevated in UVB model cells. Contrary to the model group, all indicators above were reduced in all groups pre-treated by puerarin. Puerarin restrains the ceramide accumulation to block downstream p38 MAPK pathway and calcium ion rising, therefore reduces DNA damage in HaCaT cells induced by UVB.

Polypeptide from Chlamys farreri protects HaCaT cells from UVB-induced apoptosis.

A natural polypeptide from marine Chlamys farreri (a kind of scallop) (PCF), has been recently been found to be an effective photoprotective agent against ultraviolet rays B (UVB)-induced mitochondria damage in normal human fibroblasts. To investigate whether PCF has the antiapoptotic effect on human keratinocytes, in the present study, we established an apoptotic model on HaCaT cell line by means of UVB radiance of 30 mJ/cm(2) and compared the effect of different PCF treatments on UVB-radiated cells. Flow cytometry analyses showed that PCF treatment before UVB-irradiation inhibited UVB-induced apoptosis, the loss of mitochondrial membrane potential (Deltapsim) and the increase of free Ca(2+) level in HaCaT cells. In parallel with these results, UVB-irradiation enhanced activities of caspases-3, 8, 9, while this enhancement was inhibited by PCF treatment prior to irradiation. PCF added after irradiation neither reduced UVB-induced activities of the three caspases nor synergized the effect of pre-added PCF. Cellular ultrastructural features obtained from transmission electron microscopy further confirmed the antiapoptotic effect of PCF pre-treatment. It is concluded that the antiapoptotic effect of PCF is not therapeutic but prophylactic. Caspases-3, 8, 9, Deltapsim and calcium are involved in UVB-induced apoptosis, while prophylactic PCF inhibits apoptosis of UVB-irradiated HaCaT cells by blocking the caspases activities, the Deltapsim lost and the elevation of intracellular free Ca(2+) level.