Epithelial-to-mesenchymal transition as the driver of changing carcinoma and glioblastoma microenvironment.

Epithelial-to-mesenchymal transition (EMT) is an essential molecular and cellular process that is part of normal embryogenesis and wound healing, and also has a ubiquitous role in various types of carcinoma and glioblastoma. EMT is activated and regulated by specific microenvironmental endogenous triggers and a complex network of signalling pathways. These mostly include epigenetic events that affect protein translation-controlling factors and proteases, altogether orchestrated by the switching on and off of oncogenes and tumour-suppressor genes in cancer cells. The hallmark of cancer-linked EMT is that the process is incomplete, as it is opposed by the reverse process of mesenchymal-to-epithelial transition, which results in a hybrid epithelial/mesenchymal phenotype that shows notable cell plasticity. This is a characteristic of cancer stem cells (CSCs), and it is of the utmost importance in their niche microenvironment, where it governs CSC migratory and invasive properties, thereby creating metastatic CSCs. These cells have high resistance to therapeutic treatments, in particular in glioblastoma.