Novel Biomarkers of Hepatocellular Carcinoma

Abstract

The efficacy of current hepatocellular carcinoma (HCC) surveillance has been questioned, with some guidelines removing alpha-fetoprotein (AFP) from screening recommendations and relying on liver ultrasound alone. A prospectively enrolled Australian HCC surveillance cohort showed a combined surveillance method of ultrasound with AFP is more efficacious than ultrasound alone in HCC detection. Survival analyses showed having Asian ethnicity conferred a protective effect on HCC survival. Antiviral therapy improved HCC survival in hepatitis C. Extracellular vesicles (EV) have been shown to be mediators and effectors of cancer gene pathways. In this thesis EV were phenotyped with transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and flow cytometry. TEM qualified the ultrastructure of EV. NTA and flow cytometry demonstrated EV concentration to be increased in hepatitis and HCC. Flow cytometry demonstrated hepatocyte-specific EV concentration to be increased in HCC. EV can carry short segments of RNA including miRNA. In our studies differential expression of plasma EV miRNA was found in HCC compared to cirrhosis and hepatitis. Gene set enrichment analyses of miRNA expression profiles were performed using nCounter and OpenArray, with the finding of more than 80% concordance in cancer gene pathways including p53, epithelial mesenchymal transition, TNF- signalling via NF-, TGF-, kRAS, PI3K/AKT/mTOR, IL-6 JAK/STAT, and Wnt/-catenin. In conclusion, traditional HCC surveillance methods are efficacious. EV and its miRNA profiling may provide a sensitive surveillance, diagnosis and prognostication tool for HCC. nCounter and OpenArray technologies showed differential miRNA expression profiles in HCC plasma EV with enriched gene pathways corresponding to genomic studies in HCC tissue. These findings support future investigations into the utility of plasma EV as a circulating biomarker of HCC.