miR-155对乳腺癌细胞增殖、凋亡及耐药蛋白表达的调控作用研究

目的 探讨microRNA-155（miR-155）对乳腺癌MCF-7细胞增殖、凋亡及乳腺癌耐药相关蛋白表达的调控作用。方法 采用实时荧光定量PCR（qRT-PCR）法检测MCF-7细胞和人乳腺正常上皮细胞中miR-155的表达水平。将MCF-7细胞分为4组：对照组、空转染组、抑制（转染miR-155 inhibitor）组和过表达（转染miR-155 mimics）组，采用qRT-PCR检测转染24、48、72及96 h后各组的转染效果，噻唑蓝（MTT）法检测各组转染24、48、72及96 h的增殖能力，采用流式细胞仪PI／Annexin V双染色法检测各组转染24、48 h后的凋亡率，Western blotting法检测各组转染48 h后乳腺癌耐药蛋白（BCRP）、P-糖蛋白（P-gp）及多药耐药相关蛋白1（MRP1）的表达水平。结果 乳腺癌MCF-7细胞中的miR 155水平高于人乳腺正常上皮细胞（P＜0.05），且转染miR-155 inhibitor或mimics可呈时间依赖的方式降低或升高MCF-7细胞的miR-155水平（P＜0.05）。与对照组相比，抑制组转染后的细胞增殖率及BCRP、P-gp和MRP1的表达水平均降低，凋亡率升高（P＜0.05）；而过表达组的细胞增殖率及BCRP、P gp和MRP1的表达水平均升高，凋亡率降低（P＜0.05）。结论 MCF-7细胞中miR-155呈高表达，下调miR-155表达可抑制其增殖及耐药相关蛋白的表达，同时诱导凋亡。

Regulatory effect of miR-155 on the proliferation,apoptosis and expression of breast cancer resistance protein

Objective To explore the regulatory effect of microRNA-155 （miR-155） on the proliferation， apoptosis and expression of breast cancer resistance protein. Methods The real-time quantitative PCR （qRT-PCR） was employed to measure the miR-155 level in MCF-7 cells and human normal breast epithelium cells. The MCF-7 cells were randomly assigned into four groups according to the experiment protocol： control group， blank group， inhibition group （transfection with miR-155 inhibitor） and over-expression group （transfection with miR-155 mimics）. The qRT-PCR was used to detect the transfection effect at 24， 48， 72 and 96 h after transfection. Methyl thiazolyl tetrazolium （MTT） assay was used to assess the proliferation ability at 24， 48， 72 and 96 h after transfection. The apoptosis rate was evaluated at 24 and 48 h after transfection by PI／Annexin V double staining with flow cytometry. Western blotting was used to measure the expression levels of breast cancer resistance protein （BRCP）， P-glycoprotein （P-gp） and multidrug resistance associated protein 1 （MRP1） protein. ResultsThere was higher level of miR-155 in MCF-7 cells versus human normal breast epithelium cells （P＜0.05）. Transfection with miR-155 inhibitor or mimics could reduce or increase the level of miR 155 in time dependent manner in MCF-7 cells （P＜0.05）； In comparison with control group， the rates of proliferation and expression levels of BRCP， P-gp and MRP1 decreased in inhibition group but increased in over expression group （P＜0.05）. The apoptosis rate increased in inhibition group but decreased in over expression group（P＜0.05）. Conclusion There is higher level of miR-155 in MCF-7 cells. Down-regulation of miR-155 presents an inhibitory effect on the proliferation and expression of drug resistance related protein along with the induction of apoptosis.