MicroRNA-101 Regulates Expression of the v-fos FBJ Murine Osteosarcoma Viral Oncogene Homolog (FOS) Oncogene in Human Hepatocellular Carcinoma

MicroRNAs (miRNAs) have recently been proposed as a versatile class of molecules involved in regulation of various biological processes. Although there is emerging evidence that some microRNAs can function as oncogenes or tumor suppressors, the specific role of miRNA in human hepatocellular carcinoma (HCC) is unclear at this point. In this study, we examined the microRNA expression profiles in a set of 20 human HCC specimens by miRNA microarray and quantitative real-time polymerase chain reaction. The results showed that among the 20 HCC samples analyzed, microRNA-101 was significantly down-regulated twofold or more (twofold to 20-fold) in 16 samples compared with the matching nontumoral liver tissues. Using both a luciferase reporter assay and Western blot analysis, we showed that microRNA-101 repressed the expression of v-fos FBJ murine osteosarcoma viral oncogene homolog (FOS) oncogene, a key component of the activator protein-1 (AP-1) transcription factor. Moreover, using a luciferase expression vector (pAP-1-Luc) driven by seven copies of an AP-1 cis-element, we observed that microRNA-101 expression inhibited phorbol 12-myristate 13-acetate (PMA)-induced AP-1 activity. In in vitro Matrigel invasion and Transwell migration assays, enhanced microRNA-101 expression inhibited the invasion and migration of cultured HCC cells, respectively. These findings suggest that microRNA-101 may play an important role in HCC. Conclusion: MicroRNA-101, which is aberrantly expressed in HCC, could repress the expression of the FOS oncogene. (HEPATOLOGY 2009;49:1194-1202.)

微小RNA（miRNAs）近期被认为是一类参与多种生物过程调控的多功能分子。尽管有新出现的证据表明一些微小RNA可作为癌基因或肿瘤抑制因子发挥作用，但目前微小RNA在人类肝细胞癌（HCC）中的具体作用尚不清楚。在本研究中，我们通过微小RNA微阵列和实时定量聚合酶链反应检测了20例人类肝细胞癌标本中的微小RNA表达谱。结果显示，在分析的20例肝细胞癌样本中，与匹配的非肿瘤肝组织相比，微小RNA - 101在16例样本中显著下调两倍或更多（两倍至20倍）。通过荧光素酶报告基因检测和蛋白质印迹分析，我们发现微小RNA - 101抑制了v - fos FBJ鼠骨肉瘤病毒癌基因同源物（FOS）癌基因的表达，FOS是激活蛋白 - 1（AP - 1）转录因子的关键组成部分。此外，利用由7个AP - 1顺式元件驱动的荧光素酶表达载体（pAP - 1 - Luc），我们观察到微小RNA - 101的表达抑制了佛波醇12 - 肉豆蔻酸13 - 乙酸酯（PMA）诱导的AP - 1活性。在体外基质胶侵袭和Transwell迁移实验中，微小RNA - 101表达增强分别抑制了培养的肝细胞癌细胞的侵袭和迁移。这些发现表明微小RNA - 101可能在肝细胞癌中起重要作用。结论：在肝细胞癌中异常表达的微小RNA - 101能够抑制FOS癌基因的表达。（《肝脏病学》2009年；49卷：1194 - 1202页）