Abstract：In this study, SMMC-7721, BEL-7402 and HepG2 hepatoma cells were irradiated by Xrays, and the survival fraction was detected by colony formation assay; PER1 expression was detected by western blot and RTqPCR; Flow cytometry was used to detect apoptosis. The results showed that the survival fraction of SMMC7721, BEL7402 and HepG2 cells decreased gradually under Xray irradiation of 0, 2, 4, 6, 8, 10 Gy, among which SMMC-7721 was the most sensitive one to radiation, while the radioresistance of BEL-7402 was the highest. Western blot analysis showed that the expression level of PER1 in SMMC7721 was significantly higher than that of BEL-7402 and HepG2 (P<0.05). After overexpression of PER1 protein, apoptosis rate of BEL7402 cells exposed to 5 Gy Xray irradiation was significantly increased. At the same time, western blot and RT-qPCR showed that expression of antiapoptotic protein Bcl2 was significantly decreased, and the cleavage of apoptosisexecuting protein caspase-3 was significantly increased in BEL7402 cells overexpressing PER1. The results showed that high level expression of PER1 protein can promote X-ray induced apoptosis and enhance the radiosensitivity of liver cancer cells.
