A Novel Small-molecule WNT Inhibitor, IC-2, Has the Potential to Suppress Liver Cancer Stem Cells.

Abstract

The presence of cancer stem cells (CSCs) contributes to metastasis, recurrence, and resistance to chemo/radiotherapy in hepatocellular carcinoma (HCC). The WNT signaling pathway is reportedly linked to the maintenance of stemness of CSCs. In the present study, in order to eliminate liver CSCs and improve the prognosis of patients with HCC, we explored whether small-molecule compounds targeting WNT signaling pathway suppress liver CSCs. The screening was performed using cell proliferation assay and reporter assay. We next investigated whether these compounds suppress liver CSC properties by using flow cytometric analysis and sphere-formation assays. A mouse xenograft model transplanted with CD44-positive HuH7 cells was used to examine the in vivo antitumor effect of IC-2. In HuH7 human HCC cells, 10 small-molecule compounds including novel derivatives, IC-2 and PN-3-13, suppressed cell viability and WNT signaling activity. Among them, IC-2 significantly reduced the CD44-positive population, also known as liver CSCs, and dramatically reduced the sphere-forming ability of both CD44-positive and CD44-negative HuH7 cells. Moreover, CSC marker-positive populations, namely CD90-positive HLF cells, CD133-positive HepG2 cells, and epithelial cell adhesion molecule-positive cells, were also reduced by IC-2 treatment. Finally, suppressive effects of IC-2 on liver CSCs were also observed in a xenograft model using CD44-positive HuH7 cells. The novel derivative of small-molecule WNT inhibitor, IC-2, has the potential to suppress liver CSCs and can serve as a promising therapeutic agent to improve the prognosis of patients with HCC.