过表达miR-134b抑制CD133^+ U87胶质瘤干细胞增殖及侵袭

Overexpressed miRNA-134b inhibits proliferation and invasion of CD133^+ U87glioma stem cells

目的探讨微小RNA-134b(miR-134b)在胶质瘤干细胞(GSC)中的作用及相关机制。方法实时定量PCR检测U87胶质瘤细胞系分离出的CD133^+ GSC和CD133^- GSC中miR-134b的表达量;包装慢病毒,构建过表达miR-134b的GSC,实时定量PCR检测其miR-134b、CD133、神经干细胞蛋白(nestin)、基质金属蛋白酶2(MMP-2)、MMP-9和MMP-12 mRNA表达水平;Western blot法检测过表达miR-134b的GSC中Notch2、MMP-2、MMP-9和MMP-12蛋白表达;Transwell^(TM)侵袭实验检测过表达miR-134b对GSC侵袭能力的影响;建立U87细胞裸鼠成瘤模型,皮下注射过表达miR-134b(实验组)及空载体(对照组)的CD133^+ GSC,定期测量肿瘤大小,70 d后处死裸鼠,测定肿瘤质量,以探讨过表达miR-134b对在体肿瘤生长的影响。结果实时定量PCR检测结果表明,与CD133^- GSC相比,CD133^+ GSC中miR-134b表达显著下调;通过慢病毒包装的方法成功构建过表达miR-134b的GSC,其miR-134b的表达显著高于空载体对照细胞,而MMP-2、MMP-9 mRNA及蛋白表达无显著变化,而MMP-12的mRNA及蛋白表达均显著下降;Transwell^(TM)侵袭实验结果表明,与对照组相比,过表达miR-134b抑制CD133^+ GSC的侵袭能力;实验组裸鼠体内肿瘤体积显著低于对照组,与对照组相比,过表达miR-134b的实验组肿瘤质量也降低了42%。结论过表达miR-134b抑制CD133^+ GSC的生长和侵袭。

Objective To investigate the role of microRNA-134b （miR-134b） in the tumorigenesis of glioma stem cells （GSCs） and the possible molecular mechanism. Methods Real-time quantitative PCR （qRT-PCR） was used to evalate the expression of miR-134b in CD133^＋ and CD133^- U87 GSCs. A lentiviral vector overexpressing miR-134b in U87 GSCs was constructed, and the effect of miR-134b overexpression on matrix metalloproteinase-2 （MMP-2）, MMP-9 and MMP-12 expressions at both mRNA and protein levels were detected by qRT-PCR and Western blotting, respectively. TranswellTM assay was performed to determine the effect of miR-134b overexpression on GSCs invasion ability. Tumor xenograft models in nude mice were established to evaluate the effect of miR-134b overexpression on tumorgenesis in vivo. Results The qRT-PCR showed that, compared with CD133- cells, miR-134b was significantly down-regulated in CD133^＋ cells. Cell line over-expressing miR-134b was successfully established, and miR-134b was up-regulated significantly compared with empty vector control. Overexpression of miR-134b remarkably inhibited the invasion of U87 GSCs and the expression of MMP-12. However, overexpression of miR-134b did not affect MMP-2 and MMP-9 expressions, rniR-134b also suppressed U87 GSCs xenograft growth in vivo. Tumor volume in tumor xenograft model group was significantly lower than that in control group, and tumor weight decreased by 42% in the former group. Conclusion Overexpression of miR-134b inhibits the growth and invasion of CD133^＋ GSCs.