title: Ex vivo Determination of an Estradiol Analogue-Induced Changes on Platelet Morphology and Angiogenic Biomarkers.
abstract: Angiogenesis is a closely controlled biological process that takes place during fetal development of blood vessels and wound healing, and includes the development of new blood vessels from preexisting blood vessels. Tumor angiogenesis is a means by which tumors obtain oxygen, nutrition and promote tumor growth. Angiogenesis-regulating proteins are therefore ideal biomarkers in the study of tumor pathophysiology. In our laboratory, a new in silico-designed analogue of 2-methoxyestradiol has been synthesized with angiogenic properties, namely 2-ethyl-3-O-sulfamoyl-estra-1,3,5(10)16-tetraene (ESE-16). The ex vivo influence of ESE-16 on angiogenesis and morphology in platelets of healthy participants was investigated. Scanning electron microscopy revealed no morphological changes in ESE-16-treated platelets. The possible antiangiogenic effect of ESE-16-exposed platelets was determined by means of flow cytometry measurement of angiogenic protein levels, which were significantly increased after platelets were added to tumorigenic breast epithelial cells. This indicates that binding of platelets to cancer cells causes differential release of platelet constituents. Vascular endothelial growth factor levels were decreased in platelets, whereas platelet-derived growth factor and matrix metallopeptidase-9 levels were not significantly affected in platelets. In light of the above-mentioned data, further investigation of ESE-16's influence on morphology and angiogenic markers in platelets of cancer patients is warranted.
authors.affiliation: Department of Physiology,School of Medicine, Faculty of Health Sciences,University of Pretoria,Pretoria,Gauteng 0001,South Africa.
authors.forename: Lisa
authors.initials: L
authors.lastname: Repsold
authors.affiliation: Department of Physiology,School of Medicine, Faculty of Health Sciences,University of Pretoria,Pretoria,Gauteng 0001,South Africa.
authors.forename: Etheresia
authors.initials: E
authors.lastname: Pretorius
authors.affiliation: Department of Physiology,School of Medicine, Faculty of Health Sciences,University of Pretoria,Pretoria,Gauteng 0001,South Africa.
authors.forename: Annie M
authors.initials: AM
authors.lastname: Joubert
keywords: 
                 ex vivo
              ; ESE-16; angiogenesis-regulating proteins; platelets; tumors