Internal Medicine-Oncology, The First Affiliated Hospital of Bengbu Medical College, Bengbu, Anhui, China.
Surgical oncology, The First Affiliated Hospital of Bengbu Medical College, Bengbu, Anhui, China.
Cancer Gene Ther. 2015 Apr;22(3):122-9. doi: 10.1038/cgt.2014.75. Epub 2015 Jan 23.
MicroRNAs (miRNAs) are important regulators that play key roles in tumorigenesis and tumor progression. In this study, we investigate whether let-7b acts as a tumor suppressor to inhibit invasion and metastasis in gastric cancers. We analyzed the expression of let-7b in 60 pair-matched gastric neoplastic and adjacent non-neoplastic tissues by quantitative real-time polymerase chain reaction. Functional analysis of let-7b expression was assessed in vitro in gastric cancer cell lines with let-7b precursor and inhibitor. The roles of let-7b in tumorigenesis and tumor metastasis were analyzed using a stable let-7b expression plasmid in nude mice. A luciferase reporter assay was used to assess the effect of let-7b on inhibitor of growth family, member 1 (ING1) expression. Real-time PCR showed decreased levels of let-7b expression in metastatic gastric cancer tissues and cell lines that are potentially highly metastatic. Cell invasion and migration were significantly impaired in GC9811-P and SGC7901-M cell lines after transfection with let-7b mimics. Nude mice with xenograft models of gastric cancer confirmed that let-7b could inhibit gastric cancer metastasis in vivo after transfection by the lentivirus pGCsil-GFP- let-7b. Luciferase reporter assays demonstrated that let-7b directly binds to the 3'-UTR of ING1, and real-time PCR and western blotting further indicated that let-7b downregulated the expression of ING1 at the mRNA and protein levels. Our study demonstrates that overexpression of let-7b in gastric cancer can inhibit invasion and migration of gastric cancer cells through directly targeting the tumor metastasis-associated gene ING1. These findings help clarify the molecular mechanisms involved in gastric cancer metastasis and indicate that let-7b modulation may be a bona fide treatment of gastric cancer.
微小 RNA（miRNAs）是重要的调节因子，在肿瘤发生和肿瘤进展中发挥关键作用。在这项研究中，我们研究了 let-7b 是否作为肿瘤抑制因子抑制胃癌的侵袭和转移。我们通过定量实时聚合酶链反应分析了 60 对配对的胃癌肿瘤和相邻非肿瘤组织中 let-7b 的表达。通过 let-7b 前体和抑制剂在胃癌细胞系中进行体外功能分析评估 let-7b 表达。使用裸鼠中的稳定 let-7b 表达质粒分析 let-7b 在肿瘤发生和肿瘤转移中的作用。荧光素酶报告基因测定用于评估 let-7b 对生长抑制因子家族成员 1（ING1）表达的影响。实时 PCR 显示转移性胃癌组织和潜在高转移性细胞系中 let-7b 表达水平降低。在 GC9811-P 和 SGC7901-M 细胞系中转染 let-7b 模拟物后，细胞侵袭和迁移显著受损。携带胃癌异种移植模型的裸鼠证实，通过慢病毒 pGCsil-GFP-let-7b 转染后，let-7b 可抑制体内胃癌转移。荧光素酶报告基因测定表明 let-7b 可直接结合 ING1 的 3'-UTR，实时 PCR 和 Western blot 进一步表明 let-7b 下调 ING1 的 mRNA 和蛋白水平。我们的研究表明，在胃癌中过表达 let-7b 可通过直接靶向肿瘤转移相关基因 ING1 抑制胃癌细胞的侵袭和迁移。这些发现有助于阐明胃癌转移涉及的分子机制，并表明 let-7b 调节可能是治疗胃癌的有效方法。
