Recent Hints on the Dual Role of Discs Large MAGUK Scaffold Protein 5 in Cancers and in Hepatocellular Carcinoma

Discs large MAGUK scaffold protein 5 (DLG5) is a multi-domain member of membrane-associated guanylate kinase (MAGUK) family, which plays a major role in the maintenance of cell epithelial polarity being part of the SCRIB-LGL-DLG complex. Although polarity proteins have been generally considered tumor suppressors, recent discoveries led to reconsidering their role in cancer. This is also true for DLG5 in different cancer types, including hepatocellular carcinoma (HCC). In this cancer, DLG5 was negatively associated with malignant characteristics, however recent findings associated DLG5 expression with advanced stages of HCC. In vitro studies evidenced its possible role in sustaining cell growth and migration by the interaction with several intracellular pathways, such as Hippo, Hedgehog, and PI3K/AKT signaling pathways. In this review, we summarize the recent finding on the dual role of DLG5 and other polarity proteins in cancers. What emerges is a still undefined role of those proteins in cancers, especially in HCC, one of the most frequent cancers worldwide, where the function of DLG5 and other polarity proteins is still largely unexplored.