title: Ex vivo apoptotic and autophagic influence of an estradiol analogue on platelets.
abstract: BACKGROUND
  Platelets are known contributors to the vascularization, metastasis and growth of tumors. Upon their interaction with cancer cells they are activated resulting in degranulation and release of constituents. Since the apoptotic- and autophagic effects of 2-ethyl-3-O-sulphamoyl-estra-1,3,5(10)16-tetraene (ESE-16) has been shown to occur in vitro and this compound was designed to bind to carbonic anhydrase II (CAII), the possible occurrence of these cell death mechanisms in platelets as circulatory components, is of importance.
  
  
  METHODS
  Scanning electron microscopy was used to assess morphological changes in platelets after exposure to ESE-16. The possible apoptotic- and autophagic effect of ESE-16 in platelets was also determined by means of flow cytometry through measurement of Annexin V-FITC, caspase 3 activity, autophagy related protein 5 levels and light chain 3-I to light chain 3-II conversion.
  
  
  RESULTS
  Scanning electron microscopy revealed no changes in ESE-16-treated platelets when compared to vehicle-treated samples. Apoptosis detection by Annexin V-FITC and measurement of caspase 3 activity indicated that there was no increase in apoptosis when platelets were exposed to ESE-16. The incidence of autophagy by measurement of autophagy related protein 5 levels and light chain 3-I to light chain 3-II conversion showed that exposure to ESE-16 did not cause the incidence of autophagy in platelets.
  
  
  CONCLUSIONS
  This is the first ex vivo study reporting on involvement of apoptosis- and autophagy-related targets in platelets after exposure to ESE-16, warranting further investigation in platelets of cancer patients.
authors.affiliation: Department of Physiology, Faculty of Health Sciences, School of Medicine, University of Pretoria, Pretoria, South Africa.
authors.forename: Lisa
authors.initials: L
authors.lastname: Repsold
authors.affiliation: Department of Physiology, Faculty of Health Sciences, School of Medicine, University of Pretoria, Pretoria, South Africa.
authors.forename: Etheresia
authors.initials: E
authors.lastname: Pretorius
authors.affiliation: Department of Physiology, Faculty of Health Sciences, School of Medicine, University of Pretoria, Pretoria, South Africa.
authors.forename: Annie Margaretha
authors.initials: AM
authors.lastname: Joubert
keywords: 2-ethyl-3-O-sulphamoyl-estra-1,3,5(10)16-tetraene; Apoptosis; Autophagy; Ex vivo; Platelets