MiR-145对人结肠癌细胞株HCT-116奥沙利铂耐药机制探讨

Role of miR-145 in the acquired resistance to Oxaliplatin of human colon cancer cell line HCT-116

目的探讨microRNA 145(miR-145)对人结肠癌细胞株HCT-116奥沙利铂(L-OHP)耐药作用及其机制。方法采用逐步增加药物浓度的方法,建立人结肠癌耐奥沙利铂细胞株HCT-116/L-OHP。脂质体转染法将miR-145转入建立好的耐药细胞株中,并设立阴性miRNA对照组、miR-145siRNA处理组(miR-145组)、空脂质体组和空白对照组(control组)。MTT法测定转染48h后细胞增殖能力和对L-OHP的敏感性;实时定量PCR检测转染后HCT-116/L-OHP细胞中多药耐药基因MDR1和抑癌基因PTEN的表达;蛋白质印迹法检测P-糖蛋白(P-gp)和PTEN蛋白表达。结果成功建立耐药倍数为母本细胞7倍的HCT-116/L-OHP细胞株。检测HCT-116母本与HCT-116/L-OHP细胞MDR1、PTEN基因表达结果显示,HCT-116/L-OHP细胞MDR1基因水平为0.86±0.05,较母本细胞的0.39±0.03显著升高;HCT-116/L-OHP细胞PTEN基因水平为0.41±0.04,较母本细胞的0.89±0.02显著下调。应用miR-145转染母本及耐药细胞发现,miR-145可明显抑制HCT-116母本及HCT-116/L-OHP细胞的增殖,生长抑制率分别为57%和38%,进而提高细胞对L-OHP的药物敏感性。进一步研究发现,miR-145过表达处理后,抑癌基因PTEN表达水平为0.78±0.03,较control组的0.42±0.01显著上调;而MDR1基因表达水平为0.47±0.01,较control组的0.87±0.02显著下调。经miR-145siRNA预处理后,HCT-116/L-OHP细胞抑癌基因PTEN表达水平为0.35±0.02,较miR-145组显著下降;而MDR1基因表达水平为0.94±0.04,较miR-145组显著上调;PTEN蛋白及MDR1目的蛋白P-gp的变化呈现相同趋势,P值均<0.05。结论 miR-145可降低人结肠癌HCT-116细胞株奥沙利铂耐药性,其作用机制可能是通过影响MDR1和PTEN基因及蛋白表达水平来实现的。

OBJECTIVE To investigate the possible mechanism of miR-145 in the drug resistance to Oxaliplatin （L-OHP） of human colon cancer cell line HCT-116. METHODS L-OHP-resistant human colon cancer cell line （HCT-116/L OHP） was established in vitro by exposuring to increased concentrations of L-OHP in cell culture medium, and miR 145 transfection was made by liposome. MTT（3-（4,5-Dimethyl-2-thiazolyl）-2,5-diphenyl-2H-tetrazolium bro- mide） assay was used to assess the proliferation and sensitivity to L-OHP of HCT ll6/L-OHP cells. The expression lev- els of MDR1 and PTEN gene and protein were detected by PCR and western blotting after pretreatment with the chemi- cally synthesized miR-145 siRNA. RESULTS Successful established a HCT-116 / L-OHP cell line as 7 times drug-resist- ant to the HCT 116 cell line. The MDR1, PTEN gene expression in both cell line showed that MDR1 gene level of HCT-116/L-OHP cells （0.86±0.05） was significantly higher than that of parental cells （0. 39± 0.03）, while PTEN gene level （0.41＋0.04） was significantly lower than that of the parent cell （0. 89 ± 0.02）; miR-145 transfection de creased the proliferation and increased sensitivity to L OHP of both HCT-116 and HCT-116/L OHP cells, the growth in hibition rate was 57 %0 and 38 G respectively. Further mechanism analysis showed that after miR 145 transfection,the mR NA expression of PTEN （0.78±0.03） was significantly increased compared with the control group （0.42±0.01）, while the expression of MDR1 （0.47±0.01） was decreased compared with the control group （0.87±0.02）. Further analysis confirmed that pretreatment with miR-145 siRNA showed a decrease of PTEN （0. 35 ± 0. 02） and increase of MDR1 （0.94±0.04） ,the protein expression changes of both PTEN and P-gp showed a same trend （both P〈0.05）. CONCLU- SIONS miR-145 decreased the proliferation and increased sensitivity to L-OHP of HCT-116/L OHP cells probably by regulating the gene and protein expression of MDR1 and PTEN. Consequently, our findings may provide a potential target for treatment of colon cancer platinum drug resistance.