HECT-Type E3 Ubiquitin Ligases in Cancer

Ubiquitination, a post-translational modification that involves a covalent attachment of ubiquitin to a protein substrate, is essential for cellular homeostatic maintenance. At the end of a three-enzyme cascade, E3 ubiquitin ligases (E3s) recruit substrates and promote or directly catalyze ubiquitin transfer to targets. These enzymes largely determine the specificity of the ubiquitination reaction. Genetic alteration, abnormal expression, or dysfunction of E3s account for the occurrence and progression of human cancers. Indeed, excessive degradation of relevant tumor-suppressor molecules and impaired disposal of oncogenic proteins have been linked to tumorigenesis. This review focuses on the emerging roles of HECT-type E3s in tumorigenesis, and emphasizes how perturbations of these enzymes contribute to cancer pathogenesis.