Modulazione del signaling purinergico in cellule vascolari endoteliali dal microambiente tumorale

The study of tumor microenvironment and its interactions with surrounding cells has gained much interest in recent years. A key feature of the tumor microenvironment is represented by vascular component, which is responsible of tumor growth and spreading. Tumoral endothelium highly differs from normal one from morphological and functional point of view reflecting the presence of tortuous, highly permeable and aberrant vessels. Tumor microenvironment is characterized by peculiar chemical and mechanical components such as hypoxia, altered extracellular matrix composition, acidosis and high ATP levels. Indeed, extracellular ATP reaches much higher concentrations than healthy tissues (tens of nanomolar vs. hundreds of micromolar or millimolar). Purinergic receptors are a class of plasma membrane receptors whose natural agonists include ATP and its catabolites. Purinergic signalling and its downstream pathways have been deeply investigated in cancer cells but its role in vascular component is still unclear. Among the different metabotropic and ionotropic purine receptors, P2X7 represents one of the most relevant mediators of purinergic signalling in tumors since it is activated by high ATP concentration. Previous studies have shown that breast tumor-derived endothelial cells (BTEC) display an altered profile in purinergic receptors. In addition, P2X7 activation through ATP and its synthetic analogue BzATP, inhibits BTEC migration but not of normal endothelial cells (EC). In this study we focused on normal endothelium investigating the modulation of purinergic signalling in EC when conditioned by different cancer cells (MCF-7 and PANC-1). We observed an overexpression of P2X7 in conditioned EC and therefore we studied the biological effects in terms of cell migration. In particular, we performed random migration and wound healing assays, showing that BzATP unveils the effects mediated by cancer cells conditioning. In the end, we analysed the effects on tubulogenesis assay, demonstrating that both cancer cells conditioning and BzATP treatment influences capillary-like structures formation. Overall, these findings support the hypothesis that cancer cells influence EC behaviour altering purinergic signalling that might be involved in endothelial sensing of tumor microenvironment.