Li Zhengrong, Zhang Guoyang, Li Daojiang, Jie Zhigang, Chen Heping, Xiong Jianbo, Liu Yi, Cao Yi, Jiang Mengmeng, Le Zhibiao, Tan Shengxing
Department of Gastrointestinal Surgery, First Affiliated Hospital, Nanchang University, Nanchang, Jiangxi Province 330000, China.
Department of Gastrointestinal Surgery, First Affiliated Hospital, Nanchang University, Nanchang, Jiangxi Province 330000, China.
Biochem Biophys Res Commun. 2015 Jan 2;456(1):344-50. doi: 10.1016/j.bbrc.2014.11.083. Epub 2014 Dec 2.
Phosphatase of regenerating liver-3 (PRL-3) is believed to be associated with cell motility, invasion, and metastasis. Our previous work found that PRL-3 is highly overexpressed in gastric cancer (GC) tissue with peritoneal metastasis and directly involved in the pathogenesis of GC peritoneal metastasis. Moreover, we further found that the down-regulation of endogenous miR-495 expression plays a causative role in over expression of PRL-3 in GC peritoneal metastasis. However, the molecular regulation mechanisms by which endogenous miR-495 expression is down-regulated and PRL-3 promotes GC peritoneal metastasis remain to be clearly elucidated. Some studies have shown that the promoter methylation is closely related to the miRNA gene expression. Therefore, in present study, based on our previous findings, we will analysis whether DNA methylation is a major cause of the down-expression of endogenous miR-495, which results in PRL-3 overexpression in GC peritoneal metastasis. Methylation specific PCR (MSP) and sodium bisulfite sequencing method (BSP) detected miR-495 gene promoter methylation status. We treated GC cell lines with 5-Aza-2'-deoxycytidine (5-Aza-dC) to make the gene promoter methylation inactivation. By treating with 5-Aza-dC the migration and invasion of GC cells were significantly inhibited. And the miR-495 was overexpressing, corresponds to the mRNA and protein levels of PRL-3 were reduced, the ability of invasion and metastasis was inhibited. This study suggest that miR-495 have tumor suppressor properties and are partially silenced by DNA hypermethylation in GC, will provide new strategies for prevention and treatment of GC peritoneal metastasis.
再生肝脏磷酸酶-3（PRL-3）被认为与细胞运动、侵袭和转移有关。我们之前的研究发现，PRL-3在伴有腹膜转移的胃癌（GC）组织中高度过表达，并直接参与GC腹膜转移的发病机制。此外，我们进一步发现内源性miR-495表达的下调在GC腹膜转移中PRL-3的过表达中起因果作用。然而，内源性miR-495表达下调以及PRL-3促进GC腹膜转移的分子调控机制仍有待明确阐明。一些研究表明，启动子甲基化与miRNA基因表达密切相关。因此，在本研究中，基于我们之前的发现，我们将分析DNA甲基化是否是内源性miR-495表达下调的主要原因，而这种下调导致了GC腹膜转移中PRL-3的过表达。采用甲基化特异性PCR（MSP）和亚硫酸氢钠测序法（BSP）检测miR-495基因启动子的甲基化状态。我们用5-氮杂-2'-脱氧胞苷（5-Aza-dC）处理GC细胞系以使基因启动子甲基化失活。通过用5-Aza-dC处理，GC细胞的迁移和侵袭受到显著抑制。并且miR-495过表达，相应地PRL-3的mRNA和蛋白水平降低，侵袭和转移能力受到抑制。本研究表明，miR-495具有肿瘤抑制特性，在GC中因DNA高甲基化而部分沉默，这将为GC腹膜转移的防治提供新策略。
