TGF-β1经DNMT1调控肺癌A549细胞对顺铂的敏感性

TGF-β1 Regulated the A549 Cells Sensitivity to Cisplatin through DNMT1

转化生长因子-β1(transforming growth factor-beta 1,TGF-β1)与肿瘤的发生、发展以及凋亡关系密切,DNA甲基化关键酶DNMTs(DNA methyltransferases)在肿瘤发生及耐药中发挥重要作用,SPARC(secreted protein acidic and rich in cysteine)常因异常甲基化而表达下调。为探究肺癌对顺铂耐受的分子机制,该研究以肺腺癌A549细胞为研究对象,通过外源TGF-β1作用A549细胞,利用RT-PCR检测TGF-β1作用后DNMTs和SPARC m RNA水平的变化以及A549细胞增殖能力和对顺铂敏感性的影响。结果显示:5 ng/m L、10 ng/m L TGF-β1作用24 h后,A549细胞DNMT1 m RNA表达均显著下调(P<0.01、P<0.001),SPARC m RNA表达均显著上调(P<0.001、P<0.001);5 ng/m L、10 ng/m L TGF-β1作用后的A549细胞对顺铂的IC50均显著低于对照组[(12.34±0.36)μmol/L、(10.93±0.69)μmol/L,对照组为(21.54±1.21)μmol/L;P<0.01、P<0.01];5 ng/m L、10 ng/m L TGF-β1作用后的A549细胞在顺铂环境中,其克隆数显著低于空白对照;15μmol/L顺铂作用24 h时,5 ng/m L、10 ng/m L TGF-β1组细胞凋亡分数均显著高于空白对照(P<0.05、P<0.01)。结果提示:TGF-β1可下调A549细胞DNMT1的表达,进而上调抑癌基因SPARC并增加其对顺铂的敏感性,成功逆转肺腺癌A549细胞的恶性表型。该研究为进一步阐明肺癌对顺铂的耐受机制提供了新的思路。

TGF-β1 is closely associated with the occurrence,development and apoptosis of carcinogenesis.As the key regulative enzyme of DNA methylation,DNMTs play an important role in the occurrence of tumor and drug-resistance.The expression of SPARC in tumor is always reduced for aberrantly methylation.In order to demonstrate the resistive mechanism of cisplatin,human lung adenocarcinoma A549 cells were cultured.After treated with TGF-β1,the changes of DNMTs and SPARC m RNA levels were detected by RT-PCR,and the effect of TGF-β1 on A549 cell＇s viability and sensitivity to cisplatin were evaluated too.Results showed that after treated with 5 ng/m L and 10 ng/m L TGF-β1 for 24 h,m RNA expressions of DNMT1 were reduced greatly（P〈0.01,P〈0.001）,and SPARC were increased greatly（P〈0.001,P〈0.001）;After exposed to different concentrations of cisplatin for 24 h,the IC50 of 5 ng/m L and 10 ng/m L TGF-β1 groups [（12.34±0.36） μmol/L,（10.93±0.69） μmol/L] were decreased greatly than that of negative control [（21.54±1.21） μmol/L]（P〈0.01,P〈0.01）.The clone formation number of 5 ng/m L and 10 ng/m L TGF-β1 groups were decreased greatly than that of negative control with different concentrations of cisplatin;The apoptosis fractions of 5 ng/m L and 10 ng/m L TGF-β1 groups were obviously higher than that of negative control（P〈0.05,P〈0.01） with 15 μmol/L cisplatin for 24 h.The present study indicated that TGF-β1 could decrease the expression of DNMT1 in A549 cells,then increase its sensitivity to cisplatin with the higher expression of SPARC,and finally,reverse the malignant phenotype of A549 cells successfully.These findings provide a new idea for further study on the cisplatin-resistance mechanism of lung cancer.