These results suggest that factors released by breast cancer cells are able to upregulate Twist, Slug, and Snail expression in EC, which in turn downregulate the activity of the VE-cadherin promoter.
Breast cancer cell-induced tyrosine phosphorylation of VE-cad was mediated by activation of the H-Ras/Raf/MEK/ERK signaling cascade and depended on the phosphorylation of endothelial myosin light chain (MLC).
Experimental expression of fluorescence-tagged VE-cadherin (VE-EGFP) in undifferentiated, fibroblastoid and E-cadherin-negative MDA-231 (MDA-VE-EGFP) as well as in differentiated E-cadherin-positive MCF-7 human breast cancer cell lines (MCF-VE-EGFP), respectively, displayed differentiation-dependent functional differences.
Frozen sections from breast cancer primary tumours (tumour n = 114, background n = 30) were immunostained with VE-cadherin, factor VIII and PECAM-1 antibodies and microvessel number was assessed.