Relationship between expression of radiation-induced immediate-earlyresponse 5 and Ku70 factor and radiosensitivity in human cervical cancertissues

Objective To investigate the expression of radiation-induced immediate-early response 5(IER5) and Ku70 gene before and after radiotherapy in cervical cancer, as well as the relationship between the two genes and their clinical characteristics. Methods Thirty-five cases patients with stage Ⅱb-Ⅲb cervical cancer who had received cisplatin-based concurrent chemoradiotherapy(DDP-CCRT) were registered.Specimens tissues were obtained from the cervical tumors before and after administration of irradiation dose of 2-6 Gy, 10 Gy, 20 Gyand 30 Gy.Western blotting and quantitative polymerase chain reaction(qPCR) method were performed to detect the expression of proteins and mRNA in IER5 and Ku70, respectively.The relationship between IER5 and Ku70 was analyzed. Results The protein and mRNA expression levels of IER5 in cervical cancer patients treated with radiation doses of 10 Gy(0.818±0.678), 20 Gy(0.981±0.734), 30Gy(1.637±0.817) were significantly higher than those before treatment(0.503±0.188, t=2.626, 3.516, 6.919, P<0.01). The expression of IER5 was positively correlated with the radiation dose(r=0.498, P<0.01), increased with the increase of dose.Ku70 proteins at the dose of 30 Gy was higher than those before treatment((0.494±0.304) vs.(0.318±0.098), t=2.239, P<0.05). There was a certain correlation between IER5 and Ku70 before and after radiotherapy(r=0.558, P<0.05; r=0.344, P<0.01). There was a significant interaction between the expression of IER5 in different irradiation dose and the tumor size(F=2.582, P<0.05). Conclusion IER5 may participate in the regulation of DNA damage repair process by interacting with Ku70, so as to affect the sensitivity of cervical cancer radiotherapy.It is possible to predict the sensitivity of radiotherapy through detecting the combined expression of IER5 and Ku70 in cervical cancer. Key words: Radiation-induced immediate-early response 5; Ku70; Cervical cancer; Radiosensitivity; Nnonhomologous end joining