Effects of quercetin on ionizing radiation-induced cellular responses in HepG2 cells

Quercen has been reported to modulate cell proliferaon and apoptosis. The present study aimed at idenfying whether treatment of ionizing radiaon (IR) combined with quercen induces apoptosis in HepG2 cells.
HepG2 cells were plated at an appropriate density according to each experimental scale and irradiated with 1, 5 and 10 Gy gamma-rays from a 60Co source at room temperature. Cell viability, SOD and CAT were assessed by using commercial assay kits. Western blot analyses were done on apoptosis related proteins. The cells were treated with various concentraons of quercen alone or in combinaon with IR.
The cell viability was decreased in a concentraon-dependent manner 24 h a3er treatment of quercen. It was significantly lowered a3er the combined treatment of quercen with IR than that of the cells treated with quercen alone. Moreover, quercen increased the expression of p53 levels in a dosedependent manner. Combined treatment of quercen with IR significantly increased the levels of pro-apoptoc proteins, cleaved caspase-3 and caspase -7, and Bax. Cell cycle analyses indicated a drasc increase in the Sub G1 populaon a3er quercen treatment combined with IR. The acvity of caspase-3 increased coincidently with apoptosis. The combined treatment of quercen with IR decreased catalase and superoxide dismutase acvies, as well.
Quercen made the radio-resistant HepG2 cells undergo apoptosis by acvang p53. These results suggest that the combined treatment of quercen with IR may provide an effecve therapeuc strategy to improve the radiotherapy efficacy.