Hypoxic silencing of tumor suppressor RUNX3 by histone modification in gastric cancer cells
Hypoxic silencing of tumor suppressor RUNX3 by histone modification in gastric cancer cells
复制标题
DOI：
10.1038/onc.2008.377
复制
发表时间：
2009-01-01
期刊：
影响因子：
8
通讯作者：
Lee, Y. M.
中科院分区：
文献类型：
--
作者：
Lee, S. H.;Kim, J.;Lee, Y. M.
RUNX 3是一种肿瘤抑制因子，在其启动子超甲基化后在癌症中沉默。缺氧对肿瘤抑制基因（TSG）转录的影响在很大程度上是未知的。在这里，我们研究了缺氧诱导的RUNX 3沉默机制。RUNX 3基因表达在转录水平下调，以响应缺氧在人胃癌细胞。这种下调在用组蛋白去乙酰化酶（HDAC）抑制剂阿司他丁A（TSA）和胞嘧啶甲基化抑制剂5-氮杂-2-脱氧胞苷（5-Aza）处理后被消除，这表明表观遗传调节机制可能参与缺氧引起的RUNX 3沉默。DNA甲基化PCR和亚硫酸氢盐测序结果显示缺氧不影响RUNX 3启动子的甲基化。染色质免疫沉淀（ChIP）试验显示，缺氧后RUNX 3启动子中组蛋白H3-赖氨酸9二甲基化增加，H3乙酰化减少。缺氧导致G9 a组蛋白甲基转移酶（HMT）和HDAC 1的上调;此外，G9 a和HDAC 1的过表达减弱了RUNX 3的表达。G9 a和HDAC 1的过表达抑制了RUNX 3的核定位和表达，但它们的突变体没有抑制。通过siRNA介导的G9 a和HDAC 1的敲低，在缺氧过程中RUNX 3的mRNA表达和核定位减少。这项研究表明，缺氧沉默RUNX 3通过表观遗传组蛋白调节在胃癌的进展。
RUNX3 is a tumor suppressor that is silenced in cancer following hypermethylation of its promoter. The effects of hypoxia in tumor suppressor gene (TSG) transcription are largely unknown. Here, we investigated hypoxia-induced silencing mechanisms of RUNX3. The expression of RUNX3 was downregulated in response to hypoxia in human gastric cancer cells at the transcriptional level. This downregulation was abolished following treatment with the histone deacetylase ( HDAC) inhibitor trichostatin A (TSA) and cytosine methylation inhibitor 5-aza-2-deoxycytidine (5-Aza), suggesting that an epigenetic regulatory mechanism may be involved in RUNX3 silencing by hypoxia. DNA methylation PCR and bisulfite-sequencing data revealed that hypoxia did not affect the methylation of RUNX3 promoter. A chromatin immunoprecipitation (ChIP) assay revealed increased histone H3-lysine 9 dimethylation and decreased H3 acetylation in the RUNX3 promoter following hypoxia. Hypoxia resulted in the upregulation of G9a histone methyltransferase (HMT) and HDAC1; additionally, overexpression of G9a and HDAC1 attenuated RUNX3 expression. The overexpression of G9a and HDAC1, but not their mutants, inhibited the nuclear localization and expression of RUNX3. Diminished mRNA expression and nuclear localization of RUNX3 during hypoxia was abolished by siRNA-mediated knockdown of G9a and HDAC1. This study suggests that hypoxia silences RUNX3 by epigenetic histone regulation during the progression of gastric cancer.