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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。
Transforming growth factor-β1 (TGF-β1) is closely related to the carcinogenesis, development and apoptosis of tumor cells. DNA methyltransferases (DNMTs) play an important role in tumorigenesis and drug resistance , SPARC (secreted protein acidic and rich in cysteine) is often downregulated due to abnormal methylation. In order to explore the molecular mechanism of lung cancer resistance to cisplatin, A549 cells were treated with exogenous TGF-β1 and the expression of DNMTs and SPARC m RNA by RT-PCR A549 cell proliferation and sensitivity to cisplatin. The results showed that the expression of DNMT1 m RNA in A549 cells was significantly down-regulated (P <0.01, P <0.001) and the expression of SPARC m RNA was significantly increased after treated with 5 ng / mL and 10 ng / mL TGF- <0.001, P <0.001). The IC50 of A549 cells treated with 5 ng / mL and 10 ng / mL TGF-|Â1 for cisplatin was significantly lower than that of the control group [(12.34 ± 0.36) μmol / L, (P <0.01, P <0.01); A549 cells treated with 5 ng / mL and 10 ng / mL TGF-|Â1 showed no effect on cisplatin , The number of clones in the TGF-β1 group was significantly lower than that of the blank control group. The apoptotic rates of 5ng / m L TGF-β1 group at 15μmol / L cisplatin for 24 h were significantly higher than that of the blank control group (P < 0.05, P <0.01). The results suggest that TGF-β1 can down-regulate the expression of DNMT1 in A549 cells, up-regulates tumor suppressor gene SPARC and increases its sensitivity to cisplatin, reversing the malignant phenotype of lung adenocarcinoma A549 cells. This study provides a new idea for further elucidating the mechanism of lung cancer resistance to cisplatin.