Effect Of (-)-epigallocatechin-3-gallate On Radiotheraphy In HepG2 Cells In Vitro

Aim: To study effect of (-)-epigallocatechin-3-gallate combined different doses radiotherapy on apoptosis and hTERT in HepG2 cells ,then explore the possibility of EGCG as radiation sensitizers.Methods: To detect the effect of different concentration EGCG (10μmol/L,25μmol/L,50μmol/L,100μmol/L,200μmol/L) on HepG2 cell proliferation by MTT assay, to detect cell apoptosis induced by EGCG in HepG2 by fluorescence microscope and to examine the effect of different concentration EGCG on hTERT gene expression in HepG2 by Real-time fluorescence quantitative PCR. Then to find a right EGCG dose used in the radiation experiments in vitro.To detect HepG2 apoptosis ratio induced by different doses of radiotherapy (0Gy, 2Gy, 4Gy, 6Gy) combined with EGCG or not co-EGCG by FCM, and to examine the effect of different doses of radiotherapy (0Gy, 2Gy, 4Gy, 6Gy) combined with EGCG or not co-EGCG on hTERT gene expression in HepG2 by Real-time fluorescence quantitative PCR. Linear accelerator 6MVX line was used in radiotherapy.Results: MTT results showed that EGCG inhibited the growth of HepG2 in a concentration dependent (R2=0.9558, P<0.05). Fluorescence microscopy results showed that EGCG can induce apoptosis in HepG2 in a concentration dependent. Real-time fluorescence quantitative PCR results showed that there were significant differences between10μmol/L group and 0μmol/L (P<0.01) and 10μmol/L group can raise the level of hTERT, not significant differences between 25μmol/L and 0μmol/L, and there were significant differences between 50μmol/L,100μmol/L,200μmol/L andμmol/L, and these doses EGCG can decline the lever of hTERT.Based on the above results, 25μmol/L EGCG was selected to use in next radiotherapy experiments in vitro. Real-time fluorescence quantitative PCR results showed that alone 25μmol/L didn't obviously impact on the hTERT gene in HepG2, yet 2Gy, 4Gy, 6Gy radiotherapy combined EGCG can decline the level of hTERT. There were significant differences between 2Gy group, 4Gy group, 6Gy group and 0Gy group. There were significant differences between 2Gy group and 4Gy group (P<0.05). There were significant differences between 2Gy group and 6Gy group (P<0.05). There were significant differences between 4Gy group and 6Gy group (P>0.05). Tips: 2Gy group difference may be more significant.FCM results showed that there were significant differences between 2Gy group, 4Gy group, 6Gy group and 0Gy group. There were significant differences between 2Gy group and 4Gy group (P<0.05). There were significant differences between 2Gy group and 6Gy group (P<0.05). There were significant differences between 4Gy group and 6Gy group (P>0.05). Tips: 2Gy group difference may be more significant.Conclusion: Different doses of radiotherapy combined with 25μmol/L EGCG may decline the level of hTERT and raise the apoptosis ratio in HepG2 in vitro. Thus, EGCG may play a role in radiation sensitivity.