HCC Gene Expression Profile

The variability in the prognosis of hepatocellular carcinoma (HCC) patients suggests that HCC may comprise several distinctive biological phenotypes. These phenotypes may result from different neoplastic pathways during the tumorigenesis and/or from a different cell of origin. Here we address if the transcriptional characteristics of the HCC would provide insight into the cellular origin of the tumors. We integrated gene expression data from rat fetal hepatoblasts and adult hepatocytes, HCC from mouse models, and human HCC. The HCC patients who shared gene expression patterns with fetal hepatoblasts showed extremely poor prognosis when compared with those lacking the hepatoblast signature. The gene expression program that distinguishes this novel subtype from the rest of HCC includes well known markers of hepatic oval cells, suggesting that HCC in this subtype may arise from hepatic progenitor cells. Two independent gene network analyses of the gene expression signature characteristic for the tumors sharing the hepatoblast expression patterns revealed that activation of AP-1 transcription factors might play key roles in tumor development in the newly identified HCC subtype. In addition, by applying hepatoblast-specific and genome-wide global signatures, HCC patients were further stratified into three distinct subgroups with a significant association with overall survival and recurrence. Total RNAs from 19 normal livers were pooled and used as the reference for all microarray experiments. To obtain gene expression profile data from 49 human HCC, 20 µg of total RNAs from tissues were used to drive fluorescently (Cy-5 or Cy-3) labeled cDNA. At least two hybridizations were carried out for each tissue using a dye-swap strategy to eliminate dye labeling bias.