The Role of Transglutaminase 2 (TG2) in Definition of Cancer Hallmarks

Over the past three decades, TGM2, a stress-responsive gene encoding transglutaminase 2 (TG2) has been identified as one of the several genes that may be involved in carcinogenesis and cancer physiology. TG2 is a pleiotropic calcium-dependent enzyme belonging to the transglutaminase family of enzymes, which post-translationally modify glutaminyl and lysyl side chains on the surface of both in vivo and in vitro substrate proteins. Unlike other members of the transglutaminase family, TG2 has additional Ca2+-independent enzymatic and non-enzymatic activities, which have been directly or indirectly implicated in diverse cellular physiological events, including cell growth and differentiation, cell adhesion and morphology, extracellular matrix stabilization, wound healing, cellular development, receptor-mediated endocytosis, apoptosis, and disease pathology. TG2 has specialized biochemical, structural and functional elements, wide tissue distribution and sub-cellular localisation, as well as broad substrate specificity. These specialised features of TG2 account for its multiple patho-physiological functionalities. Considering the multiplicity of TG2 functions and its importance in disease pathology, including cancer; we have reviewed herein, the importance of TG2 in the definition of the hallmark capabilities of cancer cells. This was done with the view to deepen our understanding of the role of TG2 in carcinogenesis and recapitulating its potential as a therapeutic target for cancer treatment.