Post-transcriptional control of Amblyomin-X on secretion of vascular endothelial growth factor and expression of adhesion molecules in endothelial cells

Angiogenesis is a pivotal process of homeostasis and tissue repair, but it also favours neovascularisation syndromes and cancer nutrition. The chemical mediation of angiogenesis is complex, involving a balance between serine proteases and their inhibitors. We addressed the mechanisms of action of a Kunitz serine protease inhibitor (KPI) on spontaneous angiogenesis, using Amblyomin-X, a KPI designed from the cDNA library of the Amblyomma cajennense tick. Amblyomin-X treatment (10-1000 ng/10 μL; each 48 h; 3 times) reduced the number of vessels in the subcutaneous dorsal tissue of male Swiss mice, as measured by intravital microscopy, haematoxylin-eosin staining, and PECAM-1 immunofluorescence labeling. Incubation of Amblyomin-X with t-End endothelial cells, a murine endothelial microvascular lineage, did not alter cell proliferation, cell-cycle phases, necrosis and apoptosis, and the production of nitric oxide and prostaglandin E2. Nevertheless, Amblyomin-X treatment reduced t-End migration and adhesion to Matrigel®, and inhibited the VEGF-A secretion and VCAM-1 and β3 integrin expressions by posttranscriptional pathways. Together, data herein outline novel posttranscriptional mechanisms of KPIs on endothelial cells during angiogenesis and point out the possible application of Amblyomin-X as a local inhibitor to undesired neovascularisation process.