Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai 200032, P.R. China.
Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, P.R. China.
Int J Mol Med. 2020 Jun;45(6):1753-1770. doi: 10.3892/ijmm.2020.4540. Epub 2020 Mar 16.
Promoter methylation‑associated silencing of cancer‑associated microRNAs (miRNAs) is a common epigenetic mechanism during tumorigenesis in various types of human cancer. However, this has not been comprehensively examined in endometrial carcinoma (EC). In the present study, an miRNA microarray consisting of 1,347 common human miRNAs was used to select potential tumor suppressive miRNAs that were hyper‑methylated in EC. This led to the identification of miR‑638, miR‑210 and miR‑3665. The methylation status of miR‑638 was examined by bisulfite sequencing polymerase chain reaction and miR‑638 expression was measured by TaqMan miRNA assays. EC cell lines transfected with vectors overexpressing miR‑638, its target gene myocyte enhancer factor 2C (MEF2C) or both, were constructed. Dual‑luciferase reporter assays, a xenograft mouse model and rescue experiments were designed to study miR‑638 and its target gene MEF2C. The results indicated that the promoter region of miR‑638 was highly methylated and the expression of miR‑638 was significantly downregulated in cancerous tissues from 42 patients with EC who underwent surgical resection. Additionally, a low expression of miR‑638 was significantly associated with advanced Federation of Gynecology and Obstetrics stage and was demonstrated to indicate shorter disease‑free survival. Functional studies indicated that the overexpression of miR‑638 in EC cell lines inhibited in vitro tumor progression and in vivo tumorigenicity. MEF2C was verified as a direct target of miR‑638 and was demonstrated to mediate the tumor‑suppressive function of miR‑638 in EC.
启动子甲基化相关的抑癌微小 RNA（miRNA）沉默是各种类型人类癌症肿瘤发生过程中的一种常见表观遗传机制。然而，在子宫内膜癌（EC）中尚未进行全面的研究。在本研究中，使用包含 1347 种常见人类 miRNA 的 miRNA 微阵列来选择在 EC 中高度甲基化的潜在肿瘤抑制性 miRNA。这导致了 miR-638、miR-210 和 miR-3665 的鉴定。通过亚硫酸氢盐测序聚合酶链反应检测 miR-638 的甲基化状态，并通过 TaqMan miRNA 检测试剂盒测量 miR-638 的表达。构建了过表达 miR-638、其靶基因肌细胞增强因子 2C（MEF2C）或两者的 EC 细胞系转染载体。设计了双荧光素酶报告基因检测、异种移植小鼠模型和挽救实验来研究 miR-638 及其靶基因 MEF2C。结果表明，miR-638 的启动子区域高度甲基化，42 例接受手术切除的 EC 患者的癌组织中 miR-638 的表达显著下调。此外，miR-638 表达水平较低与晚期妇科肿瘤分期显著相关，并表明无病生存率较短。功能研究表明，在 EC 细胞系中过表达 miR-638 可抑制体外肿瘤进展和体内致瘤性。MEF2C 被验证为 miR-638 的直接靶基因，并证明介导了 miR-638 在 EC 中的肿瘤抑制功能。
