Profiling of differentially expressed microRNAs (miRNAs) during differentiation of rat hepatic oval cells (HOCs) into hepatocellular carcinoma (HCC) cells.

OBJECTIVE: To explore the expression profile of miRNAs during differentiation of rat hepatic oval cells (HOCs) into hepatocellular carcinoma cells (HCC). METHODS: Proliferation of rat HOCs was induced by chemical carcinogen, 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB) in male rats. By using Percoll density gradient centrifugation method, HOCs were isolated, followed by continuous cultivation in vitro. The isolated HOCs were identified via Thy-1 and C-kit detection under laser scanning confocal microscope. Total miRNA was then extracted from HOCs during cell differentiation for microarray hybridization. Differentially expressed miRNAs among the indicated time points were identified. The target genes of identified miRNAs were predicted using PicTar, Target-Scan, and miRanda; then the functions and pathways of the genes were enriched. Y chromosome-specific polymerase chain reaction (PCR) technique was utilized to trace the differentiation of the male HOCs in carcinogen-induced HCC of female rats. RESULTS: It was shown that isolated HOCs expressed stem cells markers of Thy-1 and C-kit in cytoplasm and membrane. Among 1,210 miRNAs identified, 22 were differentially expressed (P < 0.05, fold change ≥2), including 19 up-regulated and 3 down-regulated ones. The predicted target genes of these miRNAs were enriched in several functions, including axon guidance, angiogenesis, post-transcriptional protein modification, and small molecular metabolism. For PCR-based SRY detection, HCC genomic DNA of female rats from the experimental group displayed the same PCR product as that from normal male rat. CONCLUSION: Differentially expressed miRNAs exerted important roles during the differentiation process of HOCs to HCC.