Calcium entry in tumour endothelial cells

Colorectal cancer liver metastases (CRLM) remain a significant cause of cancer-related mortality. There is an urgent need for novel oncological treatments to support continuing surgical advances. Tumour endothelial cells are emerging as important and unique cells that may be powerful therapeutic targets. Endothelial cell store-operated Ca2+ entry (SOCE) via Ca2+-release activated calcium (CRAC) channels underlies key angiogenic and tumourigenic processes and is the focus of this study. Normal (NEC) and tumour (TEC) endothelial cells were for the first time successfully isolated and characterised from patients with CRLM. Ca2+ entry events were stimulated by agonists, store-depletion and shear stress. TEC express the molecular components of calcium-release activated calcium (CRAC) channels and display SOCE. Novel SOCE inhibitors were developed to potently inhibit SOCE and subsequent angiogenic processes in endothelial cells. A structure-activity drug design strategy allowed key pharmacokinetic and physio-chemical properties to be optimised. Molecular modelling predicted a potential binding site and mechanism of action for SOCE inhibitors. A system for in vivo delivery and plasma measurement of these compounds was established. Drebrin is an actin-binding protein important for cytoskeletal dynamics that has been proposed as a protein target for SOCE inhibitors. Drebrin was significantly up-regulated in CRLM TEC and plays a role in endothelial cell SOCE and cellular migration. However, disruption of the proposed target binding region in drebrin had no influence on pharmacological SOCE inhibition in this study. Novel synthesised SOCE inhibitors have been characterised in vitro, their mechanism of action interrogated and their properties optimised for the next stages of in vivo testing in an animal disease model of CRLM.