Analysis of expression patterns of miRNAs in hepatocellular carcinoma

Abstract

Hepatocellular carcinoma (HCC) is the third-leading cause of cancer-related death worldwide. microRNAs (miRNAs) play important roles in gene regulatory networks, and aberrant miRNA expression has been observed in human hepatocarcinogenesis. The current study aims to identify miRNAs highly expressed in HCC tissues and further to anticipate their potential roles played in tumor development. This study compared the expression profiles of miRNAs in surgically resected HCC tissues and surrounding non-tumor tissues from 20 patients with early stage HCC. Also, expression patterns of miRNAs in a late stage of HCC were analyzed using a murine HCC model. miRNAs isolated from liver tissues were used to synthesize cDNA. Primers were designed for 50 miRNAs, which were selected based on published microarray studies. Quantitative RT-PCR (qRT-PCR) assays were performed to compare expression levels of miRNAs between HCC and surrounding non-HCC tissues in humans, and also, in the murine HCC model.Six miRNAs were highly up-regulated in an early stage HCC; miR-17-5p, 24, 25, 107, 221, and 222 were significantly up-regulated in 70, 65, 75, 75, 90 and 85% of the human HCC samples, respectively. In a late stage HCC, miR-17-5p, 25, 29a, 181a-1, 221, and 222 were significantly up-regulated when full-blown tumors were harvested and analyzed from transgenic mice. Taken together, these data indicate that miR-17-5p, 25, 221 and 222 are up-regulated in HCC regardless of tumor stages and species, and thus are presumed to play important roles in tumor progression and maintenance.