目的：探究miR-125a-5p 靶向STAT3 对肾癌细胞增殖和侵袭的影响，并初步分析其作用机制。方法：选取2017 年3月至2018 年2 月于北部战区空军医院泌尿外科接受肾癌手术治疗的癌组织及配对的癌旁组织灶边缘（距癌缘>3 cm）标本各48例，体外培养正常肾细胞HK-2、和肾癌细胞A498、GRC-1、786-O及ACHN，采用qPCR 检测组织和细胞中miR-125a-5p 的表达。分别将miR-125a-5p-NC、miR-125a-5p-mimics、pLV-STAT3 及pLV-STAT3+miR-125a-5p mimics 转染A498 细胞作为NC组（阴性对照组）、miR-125a-5p-mimics 组、pLV-STAT3 组及pLV-STAT3+mimics 组，另外以正常培养A498 细胞作为空白对照组（Control，Ctrl），采用qPCR检测各组细胞中miR-125a-5p、信号转导和转录激活因子3（STAT3）mRNA的表达。应用生物信息学预测软件和双荧光素酶法分析miR-125a-5p 与STAT3 的靶向关系；采用CCK-8 检测各组细胞增殖活性，流式细胞术检测细胞凋亡，Transwell小室法检测细胞侵袭能力；WB检测细胞中STAT3、B 细胞淋巴瘤/白血病-2 蛋白(Bcl-2)、B 细胞淋巴瘤/白血病-2 相关X 蛋白(BAX)、活化半胱氨酸天冬氨酸特异性蛋白酶-3 蛋白（cl-caspase-3）、抑癌基因p21、神经钙黏素（N-cadherin）、钙黏蛋白（E-cadherin）、血管内皮生长因子（VEGF）及缺氧诱导因子-1（HIF-1）的表达。结果：miR-125a-5p 在肾癌组织和细胞中表达显著低于癌旁组织和正常肾细胞（均P<0.05）；相较于NC组，转染miR-125a-5p-mimics 后A498 细胞中miR-125a-5p 的表达显著上升、STAT3mRNA的表达显著下降（均P<0.01）。实验证实STAT3 为miR-125a-5p 的靶基因。与NC组相比，miR-125a-5pmimics 组细胞增殖活性、侵袭细胞数及Bcl-2、N-cadherin、VEGF、HIF-1、STAT3 及其磷酸化水平均显著下降（均P<0.05），凋亡率及BAX、p21、cl-caspase-3 及E-cadherin 表达显著上升（均P<0.05）；pLV-STAT3 组细胞增殖活性、侵袭细胞数及Bcl-2、N-cadherin、VEGF、HIF-1、STAT3 及其磷酸化水平显著上升（均P<0.05），凋亡率及BAX、p21、cl-caspase-3、E-cadherin 表达显著下降（均P<0.05）。与pLVSTAT3组相比，pLV-STAT3 mimics 组细胞增殖活性、侵袭细胞数、Bcl-2、N-cadherin、VEGF、HIF-1、STAT3 及其磷酸化水平显著下降（均P<0.05），凋亡率、BAX、p21、cl-caspase-3 及E-cadherin 表达显著上升（均P<0.05）。结论：miR-125a-5p 在肾癌组织和细胞中呈低表达，可通过下调其靶基因STAT3 抑制A498 细胞的增殖和侵袭，并促进其凋亡。

Objective: To investigate the effects of miR-125a-5p targeting signal transducer and activator of transcription-3 (STAT3)on proliferation and invasion of renal cancer cells, and to preliminarily analyze the action mechanism. Methods: During the period from March 2017 to February 2018, 48 pairs of cancer tissues and corresponding normal adjacent tissues (more than 3 cm away from the tumor margin) resected from patients underwent renal cancer surgery at the Department of Urology, the Air Force Hospital of the Northern War Zone were collected for this study. Normal renal HK-2 cells and renal cancer cells (A498, GRC-1, 786-O and ACHN)were cultured in vitro. The expression of miR-125a-5p in above mentioned tissues and cells was detected by qPCR. miR-125a-5p-NC,miR-125a-5p-mimics, pLV-STAT3 and pLV-STAT3 with miR-125a-5p mimics were transfected into A498 cells, namely NC group (negative control group), miR-125a-5p-mimics group, pLV-STAT3 group and pLV-STAT3+mimics group. The normally cultured A498 cells were used as blank control (Ctrl group). qPCR was performed to detect them RNA expressions of miR-125a-5p and STAT3 in cells of all groups. The bioinformatics prediction software and Dual luciferase assay were performed to analyze the targeting relationship between miR-125a-5p and STAT3. CCK-8, Flow cytometry, Transwell chamber assay were performed to detect cell proliferation activity,apoptosisand invasion, respectively. The expressions of STAT3, Bcl-2, BAX, cleaved cysteinyl aspartate specific proteinase 3 (cl-caspase-3), tumor suppressor gene p21, N-cadherin, E-cadherin, VEGF and HIF-1 in the cells were detected by WB. Results: The expression of miR-125a-5p in renal cancer tissues and cells was significantly lower than that in adjacent normal tissues and normal renal cells (all P<0.05). Compared with NC group, expression of miR-125a-5p in A498 cells transfected with miR-125a-5p-mimics was significantly increased, while expression of STAT3 mRNA was significantly decreased (all P<0.05). STAT3 was the target gene of miR-125a-5p. Compared with NC group, cell viability, number of invasive cells, expressions of Bcl-2, N-cadherin, VEGF, HIF-1, and STAT3 as well as its phosphorylation level in miR-125a-5p mimics group were significantly decreased (all P<0.05), while cell apoptosis and expressions of BAX, p21, cl-caspase-3 and E-cadherin were significantly increased (all P<0.05); the cell viability, number of invasive cells, expressions of Bcl-2, N-cadherin, VEGF, HIF-1 and STAT3 as well as its phosphorylation level in pLV-STAT3 group were significantly increased (all P<0.05), while cell apoptosis and expressions of BAX, p21, cl-caspase-3 and E-cadherin were significantly decreased (all P<0.05). Compared with pLV-STAT3 group, cell viability, number of invasive cells, expressions of Bcl-2, N-cadherin,VEGF, HIF-1, and STAT3 as well asits phosphorylation level were significantly decreased in pLV-STAT3 mimics group (all P<0.05),while cell apoptosis, expressions of BAX, p21, cl-caspase-3 and E-cadherin were significantly increased (all P<0.05). Conclusion: miR-125a-5p shows low expression in renal cancer tissues and cells, which can inhibit proliferation and invasion of A498 cells and promote cell apoptosis by down-regulating its target gene STAT3.

辽宁省科学技术计划资助项目（No. 20170540922）