EpCAM1 liver cancer stem-like cells exhibiting autocrine wnt signaling potentially originate in cirrhotic patients

Abstract

Hepatocellular carcinoma (HCC) is believed to originate from cancer stem cells (CSCs). While epithelial cell adhesion molecule (EpCAM) is a marker of normal hepatic stem cells (HSCs), EpCAM1 cells from HCC behave like CSCs. Since HCC mostly develops on a cirrhotic background, we sought to determine whether CSC-like EpCAM1 cells exist in patients with advanced cirrhosis. Both flow cytometry and immunohistochemistry showed that frequency of EpCAM1 cells in advanced cirrhosis was increased as compared to control. To determine whether increased EpCAM population in advanced cirrhosis harbors any CSC-like cells, we compared molecular and functional features of EpCAM1 cells from advanced cirrhosis (Ep1CIR; n520) with EpCAM1 cells from both HCC (Ep1HCC; n520) and noncancerous/noncirrhotic (control) (Ep1NSC; n57) liver tissues. Ep1CIRs displayed similarity with Ep1HCC cells including upregulated expression of stemness and Notch pathway genes, enhanced self-renewal in serial spheroid assay and generation of subcutaneous tumors in nonobese diabetic/severe combined immunodeficiency mice. Moreover, transcriptome and miRNome of Ep1CIRs appeared closer to that of Ep1HCC cells than Ep1NSCs. Interestingly, more than 50% micro RNAs (miRNAs) and transcripts specifically expressed in Ep1HCCs were also expressed in Ep1CIRs. However, none of Ep1NSC specific miRNAs and only 7% Ep1NSC specific transcripts were expressed in Ep1CIRs. Further, according to gene expression and in vitro Wnt inhibition analysis, autocrine Wnt signaling appeared to be a distinct feature of Ep1CIR and Ep1HCC cells, which was absent from Ep1NSCs. EpCAM1 cells in advanced cirrhosis possibly include a population of CSC-like cells which can be explored for early diagnosis of HCC development.