title: Analysis of the potential of cancer cell lines to release tissue factor-containing microvesicles: correlation with tissue factor and PAR2 expression.
abstract: BACKGROUND
  Despite the association of cancer-derived circulating tissue factor (TF)-containing microvesicles and hypercoagulable state, correlations with the incidence of thrombosis remain unclear.
  
  
  METHODS
  In this study the upregulation of TF release upon activation of various cancer cell lines, and the correlation with TF and PAR2 expression and/or activity was examined. Microvesicle release was induced by PAR2 activation in seventeen cell lines and released microvesicle density, microvesicle-associated TF activity, and phoshpatidylserine-mediated activity were measured. The time-course for TF release was monitored over 90 min in each cell line. In addition, TF mRNA expression, cellular TF protein and cell-surface TF activities were quantified. Moreover, the relative expression of PAR2 mRNA and cellular protein were analysed. Any correlations between the above parameters were examined by determining the Pearson's correlation coefficients.
  
  
  RESULTS
  TF release as microvesicles peaked between 30-60 min post-activation in the majority of cell lines tested. The magnitude of the maximal TF release positively correlated with TF mRNA (c = 0.717; p < 0.001) and PAR2 mRNA (c = 0.770; p < 0.001) expressions while the percentage increase correlated with PAR2 mRNA (c = 0.601; p = 0.011) and protein (c = 0.714; p < 0.001). There was only a weak correlation between resting TF release, and microvesicle release. However, TF release in resting cells did not significantly correlate with any of the parameters examined. Furthermore, TF mRNA expression correlated with PAR2 mRNA expression (c = 0.745; p < 0.001).
  
  
  CONCLUSIONS
  In conclusion, our data suggest that TF and PAR2 mRNA, and PAR2 protein are better indicators of the ability of cancer cells to release TF and may constitute more accurate predictors of risk of thrombosis.
authors.affiliation: Biomedical Section, Department of Biological Sciences, University of Hull, Cottingham Road, Hull, HU6 7RX UK.
authors.forename: Camille
authors.identifier: 0000-0002-6121-5262
authors.initials: C
authors.lastname: Ettelaie
authors.affiliation: Biomedical Section, Department of Biological Sciences, University of Hull, Cottingham Road, Hull, HU6 7RX UK ; Department of Cardiovascular Sciences, University of Leicester, Clinical Sciences Wing, Glenfield General Hospital, Leicester, LE3 9QP UK.
authors.forename: Mary Ew
authors.initials: ME
authors.lastname: Collier
authors.affiliation: Biomedical Section, Department of Biological Sciences, University of Hull, Cottingham Road, Hull, HU6 7RX UK.
authors.forename: Sophie
authors.initials: S
authors.lastname: Featherby
authors.affiliation: Biomedical Section, Department of Biological Sciences, University of Hull, Cottingham Road, Hull, HU6 7RX UK ; Division of Cancer-Hull York Medical School, University of Hull, Cottingham Road, Hull, HU6 7RX UK.
authors.forename: Naima E
authors.initials: NE
authors.lastname: Benelhaj
authors.affiliation: Biomedical Section, Department of Biological Sciences, University of Hull, Cottingham Road, Hull, HU6 7RX UK.
authors.forename: John
authors.initials: J
authors.lastname: Greenman
authors.affiliation: Division of Cancer-Hull York Medical School, University of Hull, Cottingham Road, Hull, HU6 7RX UK.
authors.forename: Anthony
authors.initials: A
authors.lastname: Maraveyas
keywords: Blood coagulation; Cell line; Microvesicles; PAR 2; Tissue factor