Department of Respiration, First Affiliated Hospital, Bengbu Medical College, Provincial Key Laboratory of Respiratory disease in Anhui, Bengbu, Anhui 233004, P.R. China.
Int J Mol Med. 2013 Aug;32(2):271-80. doi: 10.3892/ijmm.2013.1405. Epub 2013 Jun 4.
The present study examined the downregulation of survivin expression by hypoxia-inducible factor-1α (HIF-1α) miRNA and its effect in the inhibition of A549 cell growth in vitro and in vivo. Survivin expression, apoptosis, proliferation and migration under normoxic and hypoxic conditions were assessed by standard methods. Cotransfection and chromatin immunoprecipitation were used to observe the effects of HIF-1α on survivin transcription. HIF-1α knockdown in A549 cells were injected into nude mice to examine survivin expression and suppression of tumorigenicity. Transfection of A549 cells with HIF-1α miRNA led to decreased expression of HIF-1α and survivin mRNA and protein. Survivin overexpression is mediated by HIF-1α by direct binding to a putative binding site in the survivin core promoter. HIF-1α-miRNA induced apoptosis and inhibited proliferation of A549 cells under hypoxic, but not normoxic, conditions, whereas transfection by survivin expression vectors partly rescued the apoptotic phenotype and revived cell proliferation under hypoxic conditions. However, cell migration was substantially suppressed by HIF-1α silencing under normoxic and hypoxic conditions. After A549 cells were xenografted in nude mice, survivin expression in mice treated with HIF-1α miRNA was downregulated, and tumor growth was significantly inhibited. Silenced HIF-1α gene expression induced apoptosis and suppressed growth of A549 cells by downregulating survivin expression in vitro and in vivo. Our results also provide a basis to target the HIF-1α pathway in lung cancer therapy.
本研究探讨了缺氧诱导因子-1α（HIF-1α）miRNA 下调生存素表达及其对体外和体内 A549 细胞生长抑制的作用。通过标准方法评估了常氧和缺氧条件下生存素表达、凋亡、增殖和迁移。共转染和染色质免疫沉淀用于观察 HIF-1α 对生存素转录的影响。将 A549 细胞中的 HIF-1α 敲低注射到裸鼠中，以检测生存素表达和肿瘤抑制作用。转染 A549 细胞的 HIF-1α miRNA 导致 HIF-1α 和生存素 mRNA 和蛋白表达降低。生存素的过表达是由 HIF-1α 通过直接结合生存素核心启动子中的一个假定结合位点介导的。HIF-1α-miRNA 在缺氧条件下诱导 A549 细胞凋亡并抑制增殖，但在常氧条件下则不然，而过表达生存素载体部分挽救了缺氧条件下的凋亡表型并恢复了细胞增殖。然而，HIF-1α 沉默在常氧和缺氧条件下均显著抑制细胞迁移。在裸鼠中进行 A549 细胞异种移植后，用 HIF-1α miRNA 处理的小鼠中的生存素表达下调，肿瘤生长受到显著抑制。沉默 HIF-1α 基因表达通过下调体外和体内的生存素表达诱导 A549 细胞凋亡并抑制其生长。我们的结果还为肺癌治疗中靶向 HIF-1α 途径提供了依据。
