The Effect Of Elongator Complex On Tumor DNA Damage Repair In The Hepatocellular Carcinoma Cells

Objective: To explore the relationship between Elongator complex and DNA damage induced by 60 Co γ ray,and the molecular mechanisms of Elongator with respect to DNA damage and repair in hepatocellular carcinoma cells.Methods:1. After the treatment of LY294002 and the irradiation of 60 Co γ ray,with OTM as an indicator, the change of DNA damage in different groups was determined by comet assay.2. After the treatment of LY294002, cell apoptosis rate in each cell line was measured by flow cytometry.3. After the treatment of LY294002, cell proliferation assay by Cell Counting Kit-8（CCK-8）. Absorbance was measured at a wavelength of 450 nm for each well.4. After the treatment of LY294002, the DNA damage repair protein expression level of RAD50、MRE11、Ku70 was detected by western blot.5. The xenografts of hepatocellular carcinoma in nude mices were applied to observe the effects of Elp3 on xenografts formation.6. Immunohistochemical staining was applied to detect the expression of Elp3、p-AKT、MRE11、p-Bad and Ki67 in the xenografts.Results:1. After the treatment of LY294002, the Elp3 and Elp4 overexpression groups can reduce the extent of DNA damage in Hep G2 cells detected by comet assay, but the depletion groups did not.2. After the treatment of LY294002, the Elp3 and Elp4 overexpression groups can reduce the extent of cell apoptosis rate in HepG2 cells detected by Flow cytometry, but the depletion groups did not.3. After the treatment of LY294002, the Elp3 and Elp4 overexpression groups can promote the poloferation in HepG2 cells detected by CCK-8 assay, but the depletion groups did not.4. After the treatment of LY294002, the Elp3 and Elp4 overexpression groups can promote the expression of Mre11 and Ku70 was related to Elongator in DNA damage and repair, but the depletion groups did not.5. The Elp3 can promote the growth of the xenografts of hepatocellular carcinoma in nude mices, but the depletion groups inhibition of cell proliferation.6. Immunohistochemical staining showed that Elp3 promoted the proliferation of hepatoma cells, p-AKT 、 MRE11 and Ki67 was up-regulated and p-Bad was down-regulated in the xenografts.Conclusion:1. After the irradiation of ⁶⁰Co γ ray, Elongator complex can reduce the extent of DNA damage, decrease cell apoptosis rate, promote the poloferation in HepG2 cells. Elongator can maintain genome stability and play an important role in DNA damage and repair.2. Elp3 and Elp4 can regulate DNA damage repair through PI3K/AKT signal pathway.