Structural and Functional Impact of Posttranslational Modification of Glypican-3 on Liver Carcinogenesis

Glypican-3 (GPC3) is a cell-surface glycoprotein that is fre-quently overexpressed in hepatocellular carcinoma (HCC). GPC3 undergoes extensive posttranslational modification (PTM) includ-ing cleavage and glycosylation. This review focuses on the structure and function of GPC3 in liver cancer, highlighting the PTM of the tertiary and quaternary structures of GPC3 as a potential onco-genic regulatory mechanism. We propose that the function of GPC3 in normal development can vary with extensive PTM and that dysregulation of these processes leads to disease. Defining the regulatory impact of these modifications can provide a deeper understanding of the role of GPC3 in oncogenesis, epithelial- mesenchymal transition, and drug development. Through review of current literature, this article provides a unique perspective on the role of GPC3 in liver cancer, focusing on potential regulatory mechanisms of PTM on GPC3 function at the molecular, cellular, and disease level.