Cellular differentiation and death in a renaissance castle

Tissue transglutaminase activity protects from cutaneous melanoma metastatic dissemination: an in vivo study

The role of tissue transglutaminase (TG-2, TGase-2) in cancer development is still a fascinating field of research. The available reports do not elucidate fully its mechanism of action, due to the limitations of in vitro approaches. Therefore, to understand TG-2 role in cancer, we carried out an in vivo study with a more direct approach. TG-2 was in vivo overexpressed in a murine model of melanoma (intravenous injection of B16 melanoma cells in C57BL/6N mice) by means of a plasmid carrying the TG-2 cDNA. The evaluation of the frequency and size of the metastases indicated that the number of melanoma lung foci was more markedly reduced by TG-2 overexpression than the metastatic size. Then, TG-2 overexpressing mice showed a prolonged survival with respect to control mice. Further analyses were carried by means of proteomic analysis of melanoma cell lysates and meta-analysis of published transcriptomic datasets. Proteomic analysis of cell lysates from a human melanoma cell line compared to human keratinocytes showed significant differences in the expression of TG-2 substrates known to be involved in proliferation/differentiation and cancer progression. Taken together, these findings indicate a protective role of TG-2 enzymatic activity in melanoma progression in vivo.

Transglutaminases in inflammation and fibrosis of the gastrointestinal tract and the liver

Transglutaminases are a family of eight currently known calcium-dependent enzymes that catalyze the cross-linking or deamidation of proteins. They are involved in important biological processes such as wound healing, tissue repair, fibrogenesis, apoptosis, inflammation and cell-cycle control. Therefore, they play important roles in the pathomechanisms of autoimmune, inflammatory and degenerative diseases, many of which affect the gastrointestinal system. Transglutaminase 2 is prominent, since it is central to the pathogenesis of celiac disease, and modulates inflammation and fibrosis in inflammatory bowel and chronic liver diseases. This review highlights our present understanding of transglutaminase function in gastrointestinal and liver diseases and therapeutic strategies that target transglutaminase activities.