Radioprotective Effects And Its Mechanism Of Genistein On X- Ray Induced DNA Damage On Human Liver L-02 Cells

There has long been a trick situation facing with the radiotherapy because of lacking of an efficient radioprotector, traditional radioprotectors like cysteamine, cystamine and WR2721 are limited in the use of radiotherapy because of its high toxicity, while the functional components in food which show promising radioprotective effects attract great attention. Soybean isoflavones are polyhydroxybenzene componds which possess lots of biological activities, such as anti-oxidation effect and estrogen-like effect, they could also protect cardiovascular system, prevent osteoporosis and regulate immune system, etc. Recent studies showed soybean isoflavones also has radioprotective effects, which were mainly based on in-vivo studies.Genistein, the largest part of soybean isoflavones, has the most powerful anti-oxidation effect among all the components. Therefore, our research aims to investigate the protective effects and its mechanism of GEN on irradiation-induced DNA damage.We choose L-02 cells as the target cells and X ray as the radio source. Firstly, we use Typan blue and MTT methods to screen out the proper dosage of X-ray and the radioprotective concentration of GEN. Secondly, Single cell gel electrophoresis was used to find out the radioprotective effect of GEN on radiation-induced DNA damage and assessed the DNA damage repair among different time point and different concentration of GEN. At last, we used the real-time PCR method to detect the expression of some Endoplasmic Reticulum Stress related genes(GRP78, HERPUD1 and GADD153) and DNA damage repair related genes(hHR23A, hHR23 Band APE1) to find out the mechanism accounting for the radioprotective effects of GEN on L-02 cells.Our conclusions: Typan blue and MTT results showed that the effective X ray dosage is between 6Gy and 12Gy, and effective radioprotective concentrations of GEN are 1 and 5μM. Single cell gel electrophoresis results showed that low concentration (1, 5μM) GEN could effectively protect the human liver cells L-02 against X-ray induced DNA damage, while high concentration (10, 20μM) GEN turned out to be radiosensitizers on irradiated L-02 cells. Real time PCR results showed, the possible mechanism of this radioprotection concerning with its protective effects on Endoplasmic Reticulum, GEN could keep the expression of GRP78 in normal level and up-regulate the expression of HERPUD1, hHR23A/hHR23B and APE1. The radiosensitizer effects of high concentration of GEN may concern with the down-regulation of HERPUD1 and hHR23B. In general, our research not only enriches the bioactivity of GEN but also provides a solid foundation for GEN to be a promising radioprotector in the future.