Upregulation of Glycoprotein Nonmetastatic B by Colony-Stimulating Factor-1 and Epithelial Cell Adhesion Molecule in Hepatocellular Carcinoma Cells

Considerable effort has been made in elucidating the appropriate biomarkers and the mechanism and functional significance of these biomarkers in hepatocellular carcinoma (HCC). Glycoprotein nonmetastatic B (GPNMB) overexpression occurs in cutaneous melanomas and breast cancer, and it is an attractive candidate for cancer therapy. However, little is known about the expression and regulation of GPNMB in HCC. In this study, we investigated the expression of GPNMB in HCC histochemically and tested the regulation effects of the epithelial cell adhesion molecule (EpCAM) and colony-stimulating factor (CSF-1) on the expression of GPNMB in HCC cells. Our results demonstrated that GPNMB levels were significantly enhanced in HCC compared with adjacent normal liver tissues. In HCC cells, GPNMB expression was regulated by EpCAM and CSF-1 partly through their common downstream product c-myc. Taken together, these results suggest that GPNMB, the expression of which was regulated in HCC cells by the highly coordinated function of various proteins, may be a potential target for HCC therapy.