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背景与目的吲哚-3-甲醇(indole-3-carbinol,I3C)是十字花科蔬菜中一种主要的有效植物化学物质,且具有防癌和抗癌作用。本研究旨在观察I3C是否影响表皮生长因子受体(epidermal growth factor receptor,EGFR)表达水平不同的肺癌细胞放射敏感性。方法采用MTT和克隆形成实验方法分别检测肺癌细胞的生长和存活率;siRNA转染方法降低细胞中EGFR蛋白表达水平;Western blot和RT-PCR法分别测定EGFR蛋白和mRNA的表达。结果采用无明显毒副作用的5mol/L剂量的I3C预处理明显降低了EGFR表达阳性的人肺腺癌H1975和人肺鳞癌H226细胞对γ-射线照射的放射敏感性,而I3C对EGFR表达阴性的人肺鳞癌NIH-H520细胞的放射敏感性则影响非常小。Western blot结果显示I3C可以增加H1975和H226细胞中EGFR蛋白的表达水平和Y845位点磷酸化水平。EGFR siRNA降低了NIH-H1975细胞中EGFR蛋白的表达,增加了细胞的放射敏感性,并有效地降低和抑制了I3C导致的细胞耐辐射效应。结论我们的研究结果首次证实I3C可以通过调节EGFR表达和磷酸化水平从而影响肺癌细胞的放射治疗敏感性,提示EGFR可能是I3C影响肺癌放射治疗敏感性的重要靶蛋白.
Background and objective Indole-3-carbinol (I3C) is a major active phytochemical in cruciferous vegetables and has anti-cancer and anti-cancer effects. This study aimed to investigate whether I3C affects the radiosensitivity of lung cancer cells with different expression levels of epidermal growth factor receptor (EGFR). Methods MTT and clonogenic assay were used to detect the growth and survival rate of lung cancer cells respectively. The siRNA transfection method was used to decrease the expression of EGFR protein. The expression of EGFR protein and mRNA was detected by Western blot and RT-PCR respectively. Results Pretreatment with 5 mol / L I3C at a dose of 5 mol / L significantly reduced the radiosensitivity to γ-ray irradiation in human lung adenocarcinoma H1975 and human lung squamous cell carcinoma H226 cells with EGFR expression, whereas I3C negatively expressed EGFR The radiosensitivity of human lung squamous cell carcinoma NIH-H520 cells is very small. Western blot results showed that I3C increased the expression of EGFR protein and Y845 phosphorylation level in H1975 and H226 cells. EGFR siRNA reduced the expression of EGFR protein in NIH-H1975 cells, increased the radiosensitivity of cells, and effectively reduced and inhibited the radiation-tolerant effect of I3C cells. Conclusions Our results confirm for the first time that I3C can affect the radiosensitivity of lung cancer cells by regulating EGFR expression and phosphorylation, suggesting that EGFR may be an important target protein for I3C affecting the sensitivity of radiotherapy for lung cancer.