Identification of AKT kinases as unfavorable prognostic factors for hepatocellular carcinoma by a combination of expression profile, interaction network analysis and clinical validation

Abstract

Background & aim: identification of key markers that differentiate occurrence and progression of hepatocellular carcinoma (HCC) is of great significance to develop novel prognostic factors and improve therapeutic strategies. The aim of this study was to screen novel markers for HCC by combining expression profile, interaction network analysis and clinical validation. Methods & results: HCC significant molecules which were differentially expressed in HCC tissues were obtained from five existing HCC related databases (OncoDB.HCC, HCC.net, dbHCCvar, EHCO and Liverome). The protein–protein interaction network of HCC significant proteins was constructed and 331 candidate HCC markers were identified by calculating four topological features of the network (‘Degree’, ‘Betweenness’, ‘Closeness’ and ‘K-coreness’). According to the enrichment analysis on Gene ontology items and KEGG pathways, these candidate HCC markers were more frequently involved in cellular protein metabolic processes, translational elongation and intracellular signaling cascade, which are associated with cancer development and metastasis. Among 331 candidate HCC markers, the three AKT kinase family members (AKT1–AKT3) were selected for clinical validation by immunohistochemistry analysis using 130 HCC specimens and matched adjacent non-neoplastic liver tissues. Interestingly, the upregulation of AKT1, AKT2 and AKT3 proteins were all significantly associated with tumor aggressiveness and poor prognosis in patients with HCC. Conclusion: this study provided an integrated analysis by combining expression profile and interaction network analysis to identify a list of biologically significant HCC related markers and pathways. Further experimental validation also indicated that AKT1, AKT2 and AKT3 proteins may all be novel unfavorable prognostic factors for patients with HCC.