EGFR和TGF-α在肺癌细胞放疗增敏中的作用

The effect of EGFR and TGF-α in radiosensitization of lung cancer cells

目的研究表皮生长因子受体(EGFR)、转化生长因子-α(TGF-α)与肺癌细胞不同放疗分割剂量的关系及可能作用机制。方法对A549细胞采用常规分割(2 Gy/天)和大分割(4、8 Gy/天)照射,DT=8 Gy,采用实时荧光定量PCR(QPCR)、酶联免疫吸附测定(ELISA)法、Western blotting分别检测A549细胞中EGFR、TGF-α基因和蛋白表达,另采用免疫荧光法测定γ-H2AX表达。结果 4 Gy/天和8 Gy/天分割组A549细胞中EGFR、TGF-αmRNA表达水平均显著低于2 Gy/天组(P<0. 05); 4 Gy/天和8 Gy/天分割组A549细胞中EGFR、TGF-α蛋白表达均显著低于2 Gy/天组(P<0. 05)。免疫荧光法结果显示,4 Gy/天和8 Gy/天分割组A549细胞中γ-H2AX表达明显高于对照组和2 Gy/天分割组。结论大剂量分割放疗后EGFR、TGF-α表达明显下调,增加A549细胞对放射线的敏感性,其机制可能与DNA损伤修复组蛋白γ-H2AX表达上调有关。

Objective To study the relationship between epidermal growth factor receptor(EGFR),transforming growth factor-α(TGF-α)and different fractional doses of radiotherapy in lung cancer cells and its possible mechanism.Methods Lung cancer cell line A549 cells were irradiated with conventional fractionation(2Gy/day)and large fractionation(4,8 Gy/day),DT=8 Gy.Real-time fluorescence quantitative PCR(QPCR),enzyme-linked immunosorbent assay(ELISA)and Western blotting were used to detect EGFR,TGF-αgene and protein expression in A549 cells,respectively.In addition,the expression ofγ-H2AX was determined by immunofluorescence assay.Results The expression levels of EGFR mRNA and TGF-αmRNA in A549 cells of 4 Gy/day and 8 Gy/day fractionation groups were significantly lower than those of 2 Gy/day fractionation group(P<0.05).The expressions of EGFR and TGF-αproteins in A549 cells of 4 Gy/day and 8 Gy/day fractionation groups were significantly lower than those of 2 Gy/day fractionation group(P<0.05).Immunofluorescence assay showed that the expression ofγ-H2AX in A549 cells in 4 Gy/day and 8 Gy/day fractionation groups was significantly higher than that in control group and 2 Gy/day fractionation group.Conclusion The expression of EGFR and TGF-αdecreased significantly after high dose fractionated radiotherapy,which increased the sensitivity of A549 cells to radiation.The mechanism may be related to the up-regulation of the expression of histoneγ-H2AX in DNA damage repair.