Differentially expressed miRNAs in hepatocellular carcinoma cells under hypoxic conditions are associated with transcription and phosphorylation

Abstract

Hypoxia is a critical aspect of tumor biology and has been associated with poor prognosis and resistance to traditional therapy. In the present study, differentially expressed genes and microRNAs (miRNAs/miRs) were screened for in the hepatocellular carcinoma (HCC) cell line Huh7 under hypoxic conditions. On the basis of microarray data, 11,508 mRNAs and 58 miRNAs exhibiting ≥1.5-fold change in expression under hypoxic conditions were identified. Gene Ontology (GO) and Kyoto Encyclopedia or Genes and Genomes pathway analysis revealed that the differentially expressed genes were primarily involved in cell cycle regulation, cell division, transcription and G-protein-coupled receptor signaling pathways. Using the TargetScan and miRanda software packages with the miRNA-mRNA negative expression network, differentially expressed miRNA targets were predicted. GO analysis revealed that the primary function of these miRNAs was to regulate transcription and phosphorylation. The miRNA-mRNA networks for transcription and phosphorylation were analyzed. Network analysis revealed that the key miRNAs in these networks were miR-19a, miR-34a, miR-29a, mir-196a, miR-25 and miR-1207, whose potential gene targets include DNA-binding proteins, zinc-finger proteins and transcription factors. Certain protein kinases, includingmitogen-activated protein kinase (MAPK) 1, MAPK kinase kinase4 and cyclin-dependent kinase 18, were also revealed to be present in the network. In hypoxic HCC tissue, levels of several key miRNAs implicated in the network analyses (miR-19a, miR-34a, miR-25 and miR-1207) were revealed to exhibit increased expression levels compared with the surrounding tissue. The results of the present study provide evidence that miRNAs serve an important function in transcription and phosphorylation in the hypoxic response of HCC cells.