Guo Bo, Zhang Jing, Li Qian, Zhao Zhenghao, Wang Wenjing, Zhou Kaiyue, Wang Xiaofei, Tong Dongdong, Zhao Lingyu, Yang Juan, Huang Chen
Department of Cell Biology and Genetics, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi An, China.
Department of Clinical Medicine, Medical College of Yan'an University, Yan'an, China.
Cell Physiol Biochem. 2018;50(2):411-425. doi: 10.1159/000494153. Epub 2018 Oct 11.
BACKGROUND/AIMS: MicroRNAs (miRNAs) have been well studied in human carcinogenesis and cancer progression. Our previous study showed the down-regulation of miR-338-3p expression in human gastric cancer (GC). However, the reasons of this dysregulation remain largely unclear.
Bisulfite sequence analysis was performed to explore the methylation status of the promoter region of miR-338-3p. Cell wound-healing and transwell assays were performed to examine the capacity of cell migration and cell interaction. A dual-luciferase reporter was used to validate the bioinformatics-predicted target gene of miR-338-3p. Western blotting, RNA interference, and immunofluorescence (IF) were used to evaluate the expression of MMPs and the location of N-cadherin to determine the mechanism underlying miR-338-3p-induced anti-tumor effects.
miR-338-3p was epigenetically silenced, and this loss of expression was significantly correlated with the Borrmann Stage in GC. Restoring miR-338-3p expression in BGC-823 cells inhibited cell migration and invasion. Moreover, Ras-related protein (Rab-14) and Hedgehog acyltransferase (Hhat) were identified as direct targets of miR-338-3p. Both enforced expression of miR-338-3p and small interfering RNA induced Rab14-mediated accumulation of N-cadherin in the cell -cell junctions or Hhat-associated matrix metalloproteinase (MMP) degradation, which may underline the metastasis defects caused by loss of miR-338-3p in GC.
These data indicate that miR-338-3p functions as a tumor suppressor in GC, and that the hypermethylation status of its CpG island might be a novel potential strategy for treating GC.
背景/目的：微小RNA（miRNA）在人类致癌作用和癌症进展方面已得到充分研究。我们之前的研究表明，miR-338-3p在人类胃癌（GC）中表达下调。然而，这种失调的原因在很大程度上仍不清楚。
进行亚硫酸氢盐测序分析以探究miR-338-3p启动子区域的甲基化状态。进行细胞划痕愈合和Transwell实验以检测细胞迁移和细胞相互作用能力。使用双荧光素酶报告基因验证miR-338-3p的生物信息学预测靶基因。采用蛋白质免疫印迹法、RNA干扰和免疫荧光法（IF）评估基质金属蛋白酶（MMP）的表达及N-钙黏蛋白的定位，以确定miR-338-3p诱导抗肿瘤作用的机制。
miR-338-3p在表观遗传上沉默，且这种表达缺失与GC中的Borrmann分期显著相关。在BGC-823细胞中恢复miR-338-3p表达可抑制细胞迁移和侵袭。此外，Ras相关蛋白（Rab-14）和刺猬酰基转移酶（Hhat）被鉴定为miR-338-3p的直接靶标。miR-338-3p的过表达和小干扰RNA均诱导Rab14介导的N-钙黏蛋白在细胞间连接处的积累或Hhat相关的基质金属蛋白酶（MMP）降解，这可能是GC中miR-338-3p缺失导致转移缺陷的原因。
这些数据表明miR-338-3p在GC中起肿瘤抑制作用，其CpG岛的高甲基化状态可能是治疗GC的一种新的潜在策略。
