Department of Medical Oncology, Fudan University Shanghai Cancer Center, Shanghai 200032, China.
Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China.
Acta Biochim Biophys Sin (Shanghai). 2020 Mar 18;52(3):259-267. doi: 10.1093/abbs/gmz166.
Tumor metastasis is the main cause of treatment failure and death in patients with late stage of gastric cancer (GC). Studies showed that microRNAs (miRNAs) are important regulators in the process of tumor metastasis. In this study, we used miRNA array analysis to search for metastasis-associated miRNAs in primary and matched metastasis tissues of patients with GC and found that miR-345-5p (miR-345) was significantly higher in primary sites. Decreased expression of miR-345 was observed in GC tissues and cell lines, which was correlated with aggressive stage and grade. Patients with a higher level of miR-345 had a better prognosis. miR-345 could inhibit the migration and spheroid formation abilities in GC cell lines in transwell assay and spheroid formation assay. RNA sequencing and bioinformatics analysis revealed that miR-345 downregulated the epidermal growth factor receptor pathway substrate 8 (EPS8) and its downstream Rac1 signaling. Mechanistically, we confirmed that miR-345 could target EPS8 by directly binding to its 3' untranslated region by luciferase reporter assay. Further rescue assay showed that the ability of miR-345 in inhibiting the migration, stem-like cell phenotype, and epithelial-mesenchymal transition (EMT) in GC was partly dependent on targeting EPS8. In conclusion, miR-345 plays an inhibitory role in GC metastasis through inhibiting cell migration, EMT, and cancer stem cell phenotype via inactivation of Rac1 signaling by targeting EPS8, which provides the potential therapeutic and predictive value of miR-345 in GC.
肿瘤转移是导致胃癌（GC）晚期患者治疗失败和死亡的主要原因。研究表明，microRNAs（miRNAs）是肿瘤转移过程中的重要调节因子。在本研究中，我们使用 miRNA 芯片分析在 GC 患者的原发和配对转移组织中寻找与转移相关的 miRNAs，发现 miR-345-5p（miR-345）在原发部位显著升高。miR-345 在 GC 组织和细胞系中的表达降低，与侵袭性分期和分级相关。miR-345 水平较高的患者预后较好。miR-345 可在 Transwell 检测和球体形成检测中抑制 GC 细胞系的迁移和球体形成能力。RNA 测序和生物信息学分析表明，miR-345 下调了表皮生长因子受体途径底物 8（EPS8）及其下游 Rac1 信号。通过荧光素酶报告基因检测，我们证实 miR-345 可以通过直接结合其 3'UTR 来靶向 EPS8。进一步的挽救实验表明，miR-345 抑制 GC 迁移、干细胞样细胞表型和上皮-间充质转化（EMT）的能力部分依赖于靶向 EPS8。总之，miR-345 通过靶向 EPS8 抑制 Rac1 信号通路，从而抑制细胞迁移、EMT 和癌症干细胞表型，在 GC 转移中发挥抑制作用，为 miR-345 在 GC 中的治疗和预测价值提供了依据。
