A pharmacological, biochemical and cellular analysis of the endothelial response to the human VEGF-A cytokine

Vascular endothelial growth factor A (VEGF-A) is an essential cytokine that regulates endothelial function and angiogenesis. VEGF-A binds endothelial receptor tyrosine kinases VEGF receptor I and 2 (VEGFRI; VEGFR2), regulating cell proliferation, migration, survival and blood vessel formation. VEGFR2 is an attractive therapeutic target for the treatment of diseases such as cancer. The molecular and cellular mechanisms linking VEGF-A-mediated intracellular signalling and angiogenesis are largely unknown. Here, whole genome transcriptional profiling and analysis is used to identiry the transcription factor ATF- 2 as a key node in the control1ed expression of a subset of VEGF-A-regulated genes in endothelial cells, namely VCAMI, CXCL2 and MAP3K8. Silencing of ATF-2 abrogates VEGF-A-induced cell proliferation, migration and tubulogenesis. Drug discovery efforts within this thesis combine in silico molecular modelling with studies in primary human umbilical vein endothelial cells (HUVECs) and angiogenesis assays to identify structurally novel small molecule VEGFR2 inhibitors. Novel properties of existing inhibitors are also elucidated, including inhibition of fibroblast growth factor (FGF)-mediated endothelial responses and perturbation ofVEGFR2 expression and trafficking. The effects of disease-induced microenvironmental stress on the VEGF-VEGFR axis are unclear. Here, an endothelial stress-survival mechanism is elucidated in response to serum deprivation, comprising two characteristic adaptive phases. Alterations in stress-activated signalling cascades modulate VEGFR expression and consequently the endothelial response VEGF-A. Taken together these findings enhance our knowledge of how endothelial cells mount a pro-angiogenic response to VEGF-A and how this response can be modulated. both by envirorunental str,e ss in a pathological state and by pharmacological intervention. These results thus provide a foundation for the development of new therapies for diseases linked to aberrant angiogenesis.EThOS - Electronic Theses Online ServiceGBUnited Kingdo