J Biol Chem 2011 Oct;286 (42): 36677-85. [IF:5.328]
MicroRNA-99a inhibits hepatocellular carcinoma growth and correlates with prognosis of patients with hepatocellular carcinoma.
Li D , Liu X , Lin L , Hou J , Li N , Wang C , Wang P , Zhang Q , Zhang P , Zhou W , Wang Z , Ding G , Zhuang SM , Zheng L , Tao W , Cao X .
Institute of Immunology, Zhejiang University School of Medicine, Hangzhou 310058, China.
杭州浙江大学医学院，免疫学研究所
Abstract
In our in-depth analysis carried out by the Illumina Solexa massive parallel signature sequencing, microRNA-99a (miR-99a) was found to be the sixth abundant microRNA in the miRNome of normal human liver but was markedly down-regulated in hepatocellular carcinoma (HCC). Compelling evidence has suggested the important roles of microRNAs in HCC development. However, the biological function of miR-99a deregulation in HCC remains unknown. In this study, we found that miR-99a was remarkably decreased in HCC tissues and cell lines. Importantly, lower miR-99a expression in HCC tissues significantly correlated with shorter survival of HCC patients, and miR-99a was identified to be an independent predictor for the prognosis of HCC patients. Furthermore, restoration of miR-99a dramatically suppressed HCC cell growth in vitro by inducing the G(1) phase cell cycle arrest. Intratumoral injection of cholesterol-conjugated miR-99a mimics significantly inhibited tumor growth and reduced the α-fetoprotein level in HCC-bearing nude mice. Insulin-like growth factor 1 receptor (IGF-1R) and mammalian target of rapamycin (mTOR) were further characterized as the direct targets of miR-99a. Furthermore, protein levels of IGF-1R and mTOR were found to be inversely correlated with miR-99a expression in HCC tissues. miR-99a mimics inhibited IGF-1R and mTOR pathways and subsequently suppressed expression of cell cycle-related proteins, including cyclin D1 in HCC cells. Conclusively, miR-99a expression was frequently down-regulated in HCC tissues and correlates with the prognosis of HCC patients, thus proposing miR-99a as a prospective prognosis predictor of HCC. miR-99a suppresses HCC growth by inducing cell cycle arrest, suggesting miR-99a as potential tumor suppressor for HCC therapeutics.
摘要
我们采用Illumina/Solexa公司的大规模平行测序技术（MPSS）进行深入分析发现：作为正常人体肝脏microRNA组中第六丰富的microRNA，microRNA-99a(miR-99a)在肝癌中表达显著的下调。令人信服的证据表明microRNA在肝癌发生发展中起着至关重要作用，但是，miR-99a在肝癌中表达下调的生物学功能尚不清楚。我们的研究发现miR-99a在肝癌组织和细胞株中的表达显著的降低。重要的是，miR-99a在肝癌组织中的低表达与肝癌患者不良预后密切相关，并成为肝癌患者预后的独立预测因素。此外，miR-99a的补偿疗法在体外可以通过阻滞细胞周期G(1) 期，从而显著的抑制肝癌细胞的生长。瘤内注射胆固醇包裹的miR-99a的类似物可以明显抑制荷人肝癌裸鼠的肿瘤生长，并减少其α-甲胎蛋白的水平。胰岛素样生长因1受体 (IGF-1R)和哺乳动物雷帕霉素靶蛋白(mTOR)是miR-99a下游直接的靶点蛋白。此外，在肝癌组织中，胰岛素样生长因1受体和哺乳动物雷帕霉素靶蛋白的蛋白水平与miR-99a的表达呈负相关。miR-99a类似物通过抑制胰岛素样生长因1受体和哺乳动物雷帕霉素靶蛋白通路，下调细胞周期相关蛋白（包括cyclin D1细胞周期素D1）在肝癌细胞系中的表达。我们的研究结果表明：miR-99a在大多肝癌组织中表达下调并与肝癌患者的预后息息相关。因此，miR-99a可以作为未来评价肝癌患者预后一个潜在的靶标，预示着miR-99a可以作为一个潜在的抑瘤因子用于肝癌治疗。
