Investigating intra- and extra-cellular functions of Transglutaminase 2 by use of inhibitors with different localization in breast cancer cells

Transglutaminase 2 is involved in breast cancer with several processes, such as epithelial-mesenchymal transition, aggressiveness, and metastatization. This protein displays intracellular and extracellular roles, which we have investigated using membrane-permeable and impermeable inhibitors. The alteration of transcriptome following the treatment of two triple-negative breast cancer cell lines allows us to determine the modulated genes, pathways, and networks. Integrin signaling and p53 were commonly affected by each inhibitor, while other pathways were specific. AA9, entering the cell, induced apoptosis in MDA-MB-436, affecting cadherin, Wnt, gastrin, and cholecystokinin receptors (CCKR) signaling, with RHOB and GNG2 as relevant players, while it decreased glycolytic enzymes by impact on the Warburg effect. In MDA-MB-231 cells, AA9 significantly modulated genes belonging to HIF-mediated hypoxia, AKT, and mTOR pathways. These effects suggest an anti-tumor efficacy exhibited by inhibiting intracellular TG2 functions. Generally, these effects suggest an anti-tumor efficacy exhibited by inhibiting intracellular TG2 functions. In contrast, NCEG2 increased the expression of ATP synthase and DNA replication-related proteins, indicating that inhibition of extracellular functions could encourage cell division as pro-cell replication action. This study underlines opposite effects following the treatment with inhibitors having different cell localization that will need to be considered for the applications of anti-tumor strategies.