缺氧应激对HepG2细胞中甲硫氨酸腺苷转移酶2A基因表达的影响

Effect of hypoxia inducible factor-1α on methionine adenosyltransferase-2A gene expression in HepG2 cells under Hypoxia

目的观察体外缺氧条件下肝癌细胞株HepG2中缺氧诱导因子-α（HIF-α）和甲硫氨酸腺苷转移酶2A（MAT2A）的表达，探讨HIF-α在低氧条件下对MAT2A基因表达的调控作用。方法构建人MAT2A启动子真核表达载体质粒，CoCl2化学模拟肿瘤缺氧环境，检测缺氧条件下MAT2A启动子活性，HIF-α和MAT2A在HepG细胞中的共定位、mRNA和蛋白水平的表达。以及小干扰RNA（siRNA）沉默HIF-α后对MAT2A基因表达的影响。结果缺氧24h能使HepG2细胞活性增加到高峰（41．26±2．34），同时MAT2A基因的表达也较常氧时显著升高（P〈0．01），siRNA转染HepG2细胞后能显著下调HIF-α蛋白表达（抑制率90％），并导致MAT2A基因的表达也受到明显抑制。结论缺氧促使HepG2细胞中HIF-α在蛋白水平表达升高，缺氧时HIF-α能上调MAT2A基因的表达水平。

Objective To observe the expression of hypoixa inducible factor-1α （HIF-α） and me- thionine adenosyltransferase-2A （MAT2A） gene in HepG2 cells under hypoxia in vitro, and explore the regulation of MAT2A gene expression by HIF-1α. Methods Human MAT2A promoter eukaryotic expres- sion vector was constructed. CoC12 was used as a chemical hypoxia-inducible reagent to mimic tumor hy- poxic microenvironment. MAT2A promoter activity, and mRNA and protein expression of HIF-αwere de- tected in the HepG2 cells transfected with RNA interference （RNAi） originated by small interfering RNA （siRNA）. The change of MAT2A gene expression was observed after HIF-1α gene silencing. Results Under hypoxia for 24 h, HepG2 cell activity was increased to （41.26 ± 2. 34） , and the mRNA and protein expression levels of MAT2A were up-regulated （P 〈 0. 01 ）. After siRNA targeting, the HIF-1 α was down- regulated efficiently in HepG2 cells （ inhibition ratio： 90% ）, and MAT2A gene was down-regulated as well. Conclusion Hypoxia can increase protein level of HIF-1α in HepG2 ceils, and HIF-1α up-regu- lates the gene expression of MAT2A.