Hypoxia-mediated up-regulation of MGr1-Ag/37LRP in gastric cancers occurs via hypoxia-inducible-factor 1-dependent mechanism and contributes to drug resistance
Hypoxia-mediated up-regulation of MGr1-Ag/37LRP in gastric cancers occurs via hypoxia-inducible-factor 1-dependent mechanism and contributes to drug resistance
复制标题
胃癌中缺氧介导的 MGr1-Ag/37LRP 上调是通过缺氧诱导因子 1 依赖性机制发生的，并有助于耐药性。
DOI：
10.1002/ijc.24135
复制
发表时间：
2009-04-01
影响因子：
6.4
通讯作者：
Fan, Daiming
中科院分区：
文献类型：
--
作者：
Liu, Lili;Sun, Li;Fan, Daiming
我们前期的研究发现，缺氧诱导因子-1(HIF-1)可诱导多药耐药(MDR)表型，本实验室报道的一种新的耐药蛋白MGr1-Ag/37LRP与胃癌的多药耐药相关。鉴于这种关联，我们假设MGr1-Ag/37LRP参与了HIF-1依赖的低氧诱导的MDR表型。初步实验表明，siRNA阻断MGr1-Ag/37LRP在胃癌细胞中的表达可有效逆转缺氧诱导的多药耐药表型。随后对胃癌细胞MGr1-Ag/37LRP的mRNA和蛋白进行分析，发现随着缺氧时间的延长，MGr1-Ag/37LRP的表达呈时间依赖性增加。用siRNA抑制HIF-1后，MGr1-Ag/37LRP的上调作用被取消。使用荧光素酶启动子构建的研究显示，在低氧条件下，细胞的活性显着增加，而在共转染针对HIF-1的siRNA的细胞中，这种低氧诱导能力消失。对MGr1-Ag/37LRP启动子的分析揭示了HIF-1的几个潜在结合部位。凝胶迁移率改变分析和染色质免疫沉淀表明，在MGr1-Ag/37LRP基因调控序列中存在一个功能性的HIF-1结合位点，位于转录起始点的-16到-11之间。这些观察结果表明，MGr1-Ag/37LRP在低氧条件下活跃，是一个新的高保真靶标。这些结果提示，低氧诱导MGr1-Ag/37LRP的表达是胃癌对化疗药物耐药的一个途径。(C)2008年Wiley-Liss，Inc.
Our previous study demonstrated hypoxia-inducible factor-1(HIF-1) could prompt multidrug resistance (MDR) phenotype and MGr1-Ag/37LRP, a novel drug-resistance protein was reported by our labortary, associated with multidrug resistance in gastric cancer. Given this association, we hypothesized that MGr1-Ag/37LRP contributed to HIF-1-dependent hypoxia-induced MDR phenotype. Initial experiments revealed that blocking MGr1-Ag/37LRP expression by siRNA in gastric cancer cells effectively reversed multidrug resistance phenotype induced by hypoxia. Subsequent analysis of MGr1-Ag/37LRP mRNA and protein in gastric cancer cells revealed a time-de pendent manner increase with hypoxia. While the up-regulation of MGr1-Ag/37LRP was abolished by HIF-1 inhibition with siRNA. Studies using luciferase promoter constructs revealed a significant increase in activity in cells subject to hypoxia and such hypoxia inducibility was lost in cells co-transfected siRNA targeting HIF-1. Analysis of the MGr1-Ag/37LRP promoter revealed several potential binding sites for HIF-1. Electrophoretic mobility shift assay and chromatin immunoprecipitation demonstrated a functional HIF-1 binding site within MGr1-Ag/37LRP gene regulatory sequence located at -16 to -11 relative to the transcriptional initiation point. These observations demonstrate that MGr1-Ag/37LRP is actively engaged by hypoxia and represent a novel HIFI target. Such results suggest hypoxia-elicited MGr1-Ag/37LRP expression as a pathway for resistance of gastric cancer to chemotherapeutics. (C) 2008 Wiley-Liss, Inc.