MTSS1, a novel target of DNA methyltransferase 3B, functions as a tumor suppressor in hepatocellular carcinoma
MTSS1, a novel target of DNA methyltransferase 3B, functions as a tumor suppressor in hepatocellular carcinoma
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MTSS1 是 DNA 甲基转移酶 3B 的新靶点，在肝细胞癌中发挥肿瘤抑制因子的作用
DOI：
10.1038/onc.2011.411
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发表时间：
2012-05-01
期刊：
影响因子：
8
通讯作者：
Guan, X-Y
中科院分区：
文献类型：
--
作者：
Fan, H.;Chen, L.;Guan, X-Y
DNA甲基转移酶3B（DNMT 3B）通过表观遗传机制介导肝细胞癌（HCC）进展过程中的基因沉默。我们的目的是确定DNMT 3B的新靶点及其在HCC中的潜在调控机制。转移抑制因子1（MTSS 1）是DNMT 3B靶点之一，并被选择用于进一步研究。DNMT 3B在81.25%的临床HCC标本中过表达，并且与HCC细胞和临床标本中的MTSS 1呈负相关。使用甲基化特异性聚合酶链反应（PCR）和亚硫酸氢盐基因组测序，染色质免疫沉淀-PCR和荧光素酶报告基因测定的组合，DNMT 3B沉默MTSS 1的潜在机制进行了研究。我们发现MTSS 1启动子区域被稀疏甲基化，甲基化抑制剂未能消除DNMT 3B介导的MTSS 1沉默。DNMT 3B蛋白直接与MTSS 1基因的5′-侧翼区（− 865/− 645）结合以抑制其转录。MTSS 1的功能作用进行了研究，在体外和体内致瘤性测定。因此，MTSS 1发挥肿瘤抑制作用，并将细胞阻滞在G2/M期，但当其在HCC细胞中耗尽或过表达时，则不阻滞在细胞周期的G1/S期。总之，MTSS 1，DNMT 3B的一个新的目标，是通过DNA甲基化非依赖性机制被DNMT 3B抑制。MTSS 1是一个新的肝癌抑癌基因。这些发现强调了DNMT 3B如何调节MTSS 1，这些数据可能有助于开发肝癌的新治疗方案。
DNA methyltransferase 3B (DNMT3B) mediates gene silencing via epigenetic mechanisms during hepatocellular carcinoma (HCC) progression. We aimed to identify novel targets of DNMT3B and their potential regulatory mechanisms in HCC. Metastasis suppressor 1 (MTSS1) was one of the DNMT3B targets and selected for further study. DNMT3B overexpression was detected in 81.25% of clinical HCC specimens and was negatively associated with MTSS1 in HCC cells and clinical samples. The underlying mechanism by which DNMT3B silences MTSS1 was studied using a combination of methylation-specific polymerase chain reaction (PCR) and bisulfite genome sequencing, chromatin immunoprecipitation-PCR and luciferase reporter assays. We found that the MTSS1 promoter region was sparsely methylated, and the methylation inhibitors failed to abolish DNMT3B-mediated MTSS1 silencing. DNMT3B protein bound directly to the 5′-flanking region (− 865/− 645) of the MTSS1 gene to inhibit its transcription. The functional role of MTSS1 was investigated using in vitro and in vivo tumorigenicity assays. As a result, MTSS1 exerted tumor suppressor effects and arrested cells in the G2/M phase, but not the G1/S phase of the cell cycle when it was depleted or overexpressed in HCC cells. Taken together, MTSS1, a novel target of DNMT3B, is repressed by DNMT3B via a DNA methylation-independent mechanism. MTSS1 was further characterized as a novel tumor suppressor gene in HCC. These findings highlight how DNMT3B regulates MTSS1, and such data may be useful for the development of new treatment options for HCC.