厄洛替尼联合放疗对MKN45细胞株的影响

目的:观察厄洛替尼联合放疗对人胃癌MKN45细胞周期和凋亡的影响,了解厄洛替尼对放疗增敏的作用机制.方法:通过MTT法和集落形成实验,检测厄洛替尼和放射线对MKN45细胞的生长抑制作用,计算出半数抑制浓度(50%inhibitory concentration,IC50)和放射生物学参数平均致死剂量(mean lethal dose,D0)、准阈剂量(quasi-threshold,Dq)值,得出放射增敏比;流式细胞仪检测MKN45细胞经厄洛替尼及联合放射线处理后细胞的凋亡率及周期分布情况;Westernblot法检测厄洛替尼及联合放射线对MKN45细胞的Bax与Bcl-2蛋白表达的影响.结果:厄洛替尼及放射线均能抑制MKN45细胞的生长,随用药浓度或剂量的增高,抑制作用增强(P<0.01).厄洛替尼与放射线联合对MKN45细胞的抑制作用大于单药和单纯照射(P<0.01);两者联合使S期细胞比率明显降低,放射敏感的G2/M期和G0/G1期细胞比率明显增加(71.87±0.77vs60.72±0.26,P<0.01),细胞凋亡率增加;厄洛替尼联合放射线作用于细胞后,Bcl-2蛋白表达明显减少,Bax蛋白表达则明显增加.结论:厄洛替尼通过增加G2/M和G0/G1期细胞比率,降低Bcl-2、升高Bax蛋白表达,从而降低Bcl-2/Bax比率,增加细胞凋亡,以此提高MKN45细胞的放射敏感性.

Erlotinib increases sensitivity of MKN45 cells to radiotherapy

AIM:To observe the effect of erlotinib combined with radiotherapy on cell cycle progression and apoptosis of human gastric carcinoma MKN45 cells to explore the mechanism by which erlotinib increases the sensitivity of MKN45 cells to radiotherapy.METHODS:The effect of erlotinib and radiotherapy on MKN45 cells was examined by MTT assay and colony formation assay.The median inhibitory concentration(IC50) and radiobiological parameters D0 and Dq were calculated.Cell apoptosis and cell cycle progression were exam-ined by ? ow cytometry.The expression of Bcl-2 and Bax proteins was detected by Western blot.RESULTS:Both erlotinib and radiotherapy could inhibit MKN45 cell growth in a concentration-and dose-dependent manner(both P < 0.01).The inhibitory effect of erlotinib combined with radiotherapy on MKN45 cell growth was better than that of erlotinib or radiation alone.Combination treatment signif icantly decreased the percentages of cells in S phase cells and increased those in G2/M and G0/G1 phases(71.87 ± 0.77 vs 60.72 ± 0.26,P < 0.01) and cell apoptosis.After treatment with erlotinib combined with radiotherapy,Bcl-2 protein expression decreased and Bax protein expression increased.CONCLUSION:Erlotinib increases radiosensitivity of MKN45 cells by increasing the percentages of cells in G2/M and G0/G1 phases and decreasing Bcl-2/Bax ratio to induce apoptosis.