中文摘要：

目的：通过建立人胃癌细胞SGC-7901的顺铂耐药细胞株SGC-7901/DDP,探讨miR-497对SGC-7901/DDP耐药性的影响及其机制。方法：体外研究采用顺铂体外逐步加量诱导法建立人胃癌细胞SGC-7901耐药株,并通过检测药物半抑制浓度和耐药基因MDR1、BCRP、MRP1的表达以鉴定耐药细胞株;检测在亲本及耐药细胞中miR-497、MDR1、MRP1、BCRP和凋亡相关基因Bax、Bcl-2的表达水平;miR-497模拟物分别转染SGC-7901/DDP细胞株,利用SRB法和流式细胞术检测转染miR-497模拟物后细胞对顺铂醇的敏感程度和细胞的周期、凋亡的变化,并检测耐药基因和凋亡相关基因的表达。结果：成功建立人胃癌SGC-7901/DDP耐药细胞株,耐药细胞株中耐药基因MDR1、BCRP、MRP1表达均升高,抗凋亡基因Bcl-2升高,凋亡基因Bax下降,miR-497表达下降（P〈0.05）;miR-497模拟物提高耐药细胞株对顺铂的药物敏感性,凋亡水平增加,细胞周期G0/G1期细胞增多（P〈0.05）,并可抑制耐药细胞中耐药基因的表达,降低Bcl-2/Bax比值（P〈0.05）。结论：人胃癌耐药细胞株SGC-7901/DDP的miR-497表达下调;上调miR-497的表达可逆转人胃癌SGC-7901/DDP细胞株对化疗药物顺铂的耐药性。

英文摘要：

OBJECTIVE To investigate effects of miR-497 on drug resistance of SGC-7901/DDP and its mechanism. METHODS SGC-7901 resistant strains of human gastric cancer cell lines were established by method of capsulation in vitro. IC50 was determined, expression levels of BCRP, Bax, MDRI, MRP1 and apoptosis related genes Bcl-2 and miR-497 in the parental and resistant cells were detected. MiR-497 mimics were transfected into SGC-7901/DDP cells, and SRB assay and flow cytome- try were used to detect sensitivity of cells to cisplatin and cell cycle, apoptosis, and expression of resistance and apoptosis relat- ed genes. RESULTS Resistant cell line of human gastric cancer SGC-7901/DDP was successfully established. Drug resistant cell line had increased expression of MRP1, BCRP and MDR1, increased Bcl-2, decreased Bax and miR-497 expression （P〈 0. 05）. The miR-497 mimics improved sensitivity of drug resistant cell line to cisplatin, and increased the level of apoptosis, in- creased ceils in Go/G1 phase （P〈0. 05）, inhibited expression of drug resistant genes, and reduced Bcl-2/Bax ratio （P〈0.05）.CONCLUSION Expression of miR-497 in human cell line SGC-7901/DDP is down regulated. Up regulated miR-497 expression can reverse drug resistance of SGC-7901/DDP cell line to cisplatin in chemotherapy.