Correlation of expression DNA double-strand break repair protein with radiosensitivity of tumor cells / 肿瘤

ABSTRACT

Objective: To explore the correlation between the expressions of DSB (DNA double-strand break) repair protein (including Ku80, DNA-PKcs, and ATM) and radiosensitivity parameters of human tumor cell lines, and to reveal the value of the three proteins for the prognosis of the radiosensitivity of tumor cells. Methods: Eight tumor cell lines were selected including four human cervical carcinoma cell lines (HeLa, SiHa, C33A, and Caski), three human breast carcinoma cell lines (MCF-7, MDA-MB-231, MDA-MB453), and one human lung carcinoma cell line (A549). The expressions of Ku80, DNA-PKcs and ATM protein were measured by Western blotting. The apoptotic ratio of tumor cells was analyzed by flow cytometry after 48 h X-ray irradiation at 10 Gy of 6 MV. SF2 value (survival fraction at 2 Gy) and α and β values were obtained by clone formation assay. The correlation of protein expression with SF2, α/β value or apoptotic ratio was analyzed by Pearson linear correlation analysis. Results: The expression of same protein in different cell lines and the expression of the three proteins in the same cell line had significant difference. There was a positive correlation between the expression of DNA-PKcs and SF2 (r=0.723, P=0.043 0.05). The expression of the three proteins had no correlation with either apoptotic ratio or α/ β value (P>0.05). Conclusions: Tumor cells with higher expression of DNA-PKcs protein will have higher radioresistance. The expression level of DNA-PKcs protein in tumor cells may be an indicator for predicting the radiosensitivity of tumor cells.