ABSTRACT

Gallbladder carcinoma (GBC) is one of the most common fatal biliary tract tumors in the world. Its 3-year survival rate is 30% and the recurrence rate remains very high. miR-365 was downregulated in numerous tumors and worked as tumor suppressor gene. However, the role of miR-365 in GBC was unclear. In this study, our results found that the expression of miR-365 in GBC tissues was reduced rather than that in non-cancerous tissues. miR-365 overexpression inhibited the proliferation, metastasis and expansion of GBC CSCs. Mechanically, bioinformatic and luciferase reporter analysis identified Ras-related C3 botulinum toxin substrate 1 (RAC1) as a direct target of miR-365. Overexpression of miR-365 in GBC cells reduced the RAC1 mRNA and protein expression. The special RAC1 inhibitor EHop-106 abolished the discrepancy of growth, metastasis and self-renewal ability between miR-365-overexpression GBC cells and their control cells, which further demonstrated that RAC1 was involved in miR-365-disrupted GBC cells growth, metastasis and self-renewal. More importantly, reduced expression of miR-365 was a predictor of poor prognosis of GBC patients. In conclusion, miR-365 inhibited GBC cell growth, metastasis and self-renewal capacity by directly targeting RAC1, and may therefore prove to be a novel prognosis biomarker for GBC patients.

摘要

胆囊癌（GBC）是世界上最常见的致命性胆道肿瘤之一。其3年生存率为30%，复发率仍然很高。miR-365 在许多肿瘤中被下调并作为肿瘤抑制基因。然而，miR-365 在 GBC 中的作用尚不清楚。在这项研究中，我们的结果发现 miR-365 在 GBC 组织中的表达降低，而不是在非癌组织中。miR-365过表达抑制GBC CSCs的增殖、转移和扩张。机械地，生物信息学和荧光素酶报告分析确定 Ras 相关的 C3 肉毒杆菌毒素底物 1 (RAC1) 是 miR-365 的直接靶标。GBC 细胞中 miR-365 的过表达降低了 RAC1 mRNA 和蛋白质的表达。特殊的 RAC1 抑制剂 EHop-106 消除了生长的差异，miR-365过表达的GBC细胞与其对照细胞之间的转移和自我更新能力，这进一步证明RAC1参与了miR-365破坏的GBC细胞的生长、转移和自我更新。更重要的是，miR-365 表达降低是 GBC 患者预后不良的预测因素。总之，miR-365通过直接靶向RAC1抑制GBC细胞生长、转移和自我更新能力，因此可能被证明是GBC患者的一种新的预后生物标志物。