Comparison of Ku protein Expression in CNE1 and CNE2 nasopharyngeal carcinoma cell lines / 中华放射肿瘤学杂志

ABSTRACT

Objective Radiosensitivity is highly correlated with DNA doub le stra nd breaks(DSBs). The repair of human DSB is possible mainly through nonhomologou s DNA end joining(NHEJ)pathway. This study was designed to determine the relat ionship between expression of 70Ku/ 80Ku prot ein (a modulating subunit of DNA-PK, which is an important component in NHEJ pathway) and radiosensitivity of nasoph aryngeal carcinoma cell lines. Methods Radiosensitivity parameters of the nasoph aryngeal carcinoma cell lines were obtained by the colony forming assay and radi ation dose-survival curve was done by linear quadratic model. Western blot was p erformed to determine the expression of 70Ku and 80 Ku in total extract of CNE1 a nd CNE2 at baseline level、different time after 4?Gy irradiation、12 h after di ff erent doses of irradiation. To perform a semi-quantitated assay of protein expr e ssion, the optic density (OD) value of each band was estimated by automatic imag e analysis system. Results Surviving fraction of CNE1 was higher than those of CNE2 at each dose point. Mean inactivation dose was higher in the CNE1(2.35)t han that in the CNE2(1.11), but the quantity of 70Ku/ 80Ku in either cell line was similar at both baseline and postirradiation levels. Conclusions CNE2 is mo re radiaosensitive than CNE1; as there was no marked correlation observed betwee n the quantity of Ku protein and radiosensitivity of the nasopharyngeal carcinom a cell lines. X-irradiation cannot result in any change in total quantity of Ku protein.