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

目的 观察体外缺氧条件下肝癌细胞株HepG2中缺氧诱导因子-1α(HIF-1α)和甲硫氨酸腺苷转移酶2A(MAT2A)的表达,探讨HIF-1α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-1α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-1α后对MAT2A基因表达的影响.结果　缺氧24 h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-1α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-1α在蛋白水平表达升高,缺氧时HIF-1α能上调MAT2A基因的表达水平.

Abstract：

Objective To observe the expression of hypoixa inducible factor-1α (HIF-α) and methionine 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 expression vector was constructed. CoCl2 was used as a chemical hypoxia-inducible reagent to mimic tumor bypoxic microenvironment. MAT2A promoter activity, and mRNA and protein expression of HIF-α were detected 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-1α was downregulated 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 cells, and HIF-1α up-regulates the gene expression of MAT2A.