A Computational Framework to Identify Transcriptional and Network Differences between Hepatocellular Carcinoma and Normal Liver Tissue and Their Applications in Repositioning Drugs.

Hepatocellular carcinoma (HCC) is one of the most common and lethal malignancies worldwide. Although there have been extensive studies on the molecular mechanisms of its carcinogenesis, FDA-approved drugs for HCC are rare. Side effects, development time, and cost of these drugs are the major bottlenecks, which can be partially overcome by drug repositioning. In this study, we developed a computational framework to study the mechanisms of HCC carcinogenesis, in which drug perturbation-induced gene expression signatures were utilized for repositioning of potential drugs. Specifically, we first performed differential expression analysis and coexpression network module analysis on the HCC dataset from The Cancer Genome Atlas database. Differential gene expression analysis identified 1,337 differentially expressed genes between HCC and adjacent normal tissues, which were significantly enriched in functions related to various pathways, including α-adrenergic receptor activity pathway and epinephrine binding pathway. Weighted gene correlation network analysis (WGCNA) suggested that the number of coexpression modules was higher in HCC tissues than in normal tissues. Finally, by correlating differentially expressed genes with drug perturbation-related signatures, we prioritized a few potential drugs, including nutlin and eribulin, for the treatment of hepatocellular carcinoma. The drugs have been reported by a few experimental studies to be effective in killing cancer cells.

14-3-3ζ up-regulates hypoxia-inducible factor-1α in hepatocellular carcinoma via activation of PI3K/Akt/NF-кB signal transduction pathway.

14-3-3ζ protein, a member of 14-3-3 family, plays important roles in multiple cellular processes. Our previous study showed that 14-3-3ζ could bind to regulate the expression of hypoxia-inducible factor-1α (HIF-1α), which is induced by hypoxia and a crucial factor for induction of tumor metastasis. Moreover, we also have confirmed the response of 14-3-3ζ to hypoxia in our unpublished data as well. Thus, in the present study, we attempted to reveal that whether the regulation effect of 14-3-3ζ on HIF-1α functioned in a similar pattern as hypoxia. Stable regulation of 14-3-3ζ in human HCC cell line SMMC-772 and HCC-LM3 was achieved. The regulation of 14-3-3ζ on HIF-1α mRNA transcription was evaluated by luciferase activity assay and quantitative real-time PCR (qPCR). The effect of 14-3-3ζ on the production of HIF-1α and pathways determining HIF-1α's response to hypoxia was assessed using western blotting assay. Our results showed that regulation of 14-3-3ζ expression influenced the activity of HIF-1α, phosphatidyl inositol 3-kinase (PI3K), Akt, extracellular signal-regulated kinase 1/2 (ERK1/2), and nuclear factor kappa B (NF-кB). Blocking of these pathways using indicated inhibitors revealed that 14-3-3ζ enhanced the production of HIF-1α via the activation of PI3K/Akt/NF-кB pathway, which was identical to hypoxia induced HIF-1α expression. For the first time, our study described the key role of 14-3-3ζ in the HIF-1α production in HCC cells. And the molecule exerted its function on HIF-1α both by directly binding to it and via PI3K/Akt/NF-кB signal transduction pathway.