三氧化二砷下调MG-63骨肉瘤细胞IEX-1基因表达的转录调控机制研究

Study on The Mechanism of Transcriptional Regulation of IEX-1 Gene Induced By As_2O3 in Human Osteosarcoma MG-63

三氧化二砷(arsenic trioxide,As2O3)是中国传统中药砒霜的主要有效成分,最早应用于血液系统肿瘤的治疗,随后研究表明其对实体瘤也具有抑制细胞增殖并诱导凋亡的作用.早期研究发现,1.0!mol/L的As2O3可以体外诱导骨肉瘤细胞系MG-63细胞凋亡,进一步的cDNA芯片分析、RT-PCR、RNA印迹证实细胞凋亡与As2O3干预后IEX-1基因表达下调有关.IEX-1为早期诱导应答基因,调节细胞生长和凋亡.通过荧光素酶分析,EMSA、蛋白质印迹等实验,发现As2O3干预骨肉瘤细胞系MG-63后能诱导p53蛋白表达上调,增加的p53蛋白通过与IEX-1的启动子结合,转录抑制IEX-1的转录,导致IEX-1基因表达下调.进一步证实了IEX-1与骨肉瘤的重要关系,同时也阐明As2O3诱导IEX-1基因表达下调的转录调控机制.

As2O3 is a Chinese traditional medicine. In previous study, 1.0 μmol/L As2O3 have been found that could induce MG-63 cell apoptosis in vitro. And then it was identified that IEX-1 gene expression was down regulated after the addition of 1.0 μmol/L As2O3 using eDNA Array, RT-PCR, Northern blot. IEX-1, a recently discovered early response gene, regulates cell growth and apoptosis. The exact transcriptional mechanism of IEX-1 was found using Dual-luciferase assay, EMSA, Western blot. Transcriptional factor p53 was up-regulated after the addition of 1.0 μmol/L As2O3, and the increased p53 protein bind the promoter region of IEX-1 gene, which repress the transcription and result in down-regulation of IEX-1 gene expression. It is further confirmed that IEX-1 gene is associated with osteosarcoma and the exact transcriptional mechanism of IEX- 1 after the addition of As2O3 was found.