title: Hemostasis and cancer: tumor cells induce the expression of tissue factor-like procoagulant activity on endothelial cells.
abstract: OBJECTIVE
  Clotting activation and thromboembolic manifestations are common features in patients with cancer. The two-way interaction between tumor cells and host cells is of crucial importance in this context. In the present study we investigated the effect of tumor cell-endothelial cell co-culture on the expression of procoagulant activity in the mixed cell populations.
  
  
  METHODS
  Human tumor cell lines (HL60 promyelocytic leukemia and HeLa uterine cervical cancer) and human umbilical vein endothelial cells (HUVEC) were cultured in vitro according to standard procedures. Procoagulant activity was studied in a coagulometer and was found to be tissue factor-like. A calibration curve was obtained with decreasing concentrations of rabbit brain thromboplastin (RBT) and the procoagulant activity of both tumor cells and HUVEC was expressed as RBT U/10(5) cells.
  
  
  RESULTS
  Before incubation procoagulant activity (means S.E.) was found to be 0.18 +/- 0.04 U in HUVEC, 9.8 +/- 1.9 U in HL60 cells, 11.9 +/- 2.2 U in HeLa cells, 7.2 +/- 1.4 U in a mixed HL60 cell-HUVEC population (ratio 2:1) and 8.5 +/- 2.0 in a mixed HeLa cell-HUVEC population (ratio 2:1). Incubation at 37 degrees C for up to 4 hours of tumor cells or HUVEC alone did not produce any change in procoagulant activity. In contrast, co-incubation of tumor cells with HUVEC for 4 hours was followed by a significant increase in procoagulant activity of the mixed cell populations. Addition of supernatants from tumor cells, HUVEC or tumor cell-HUVEC co-cultures to HUVEC or tumor cells showed that the tissue factor-like procoagulant activity generated during coincubation was localized on HUVEC.
  
  
  CONCLUSIONS
  Our results show that the close interaction of tumor cells with endothelial cells may induce surface expression of tissue factor in the latter. This effect could represent an additional mechanism of clotting activation in patients with cancer.
authors.affiliation: Department of Internal Medicine and Medical Therapy, City of Pavia Institute for Medical Care, University of Pavia, viale Parco Vecchio 27, 27100 Pavia, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Maiolo
authors.forename: Aldo
authors.initials: A
authors.lastname: Tua
authors.forename: Guido
authors.initials: G
authors.lastname: Grignani
mesh_terms: D002450:Cell Communication; D018920:Coculture Techniques; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006487:Hemostasis; D006801:Humans; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology; D013925:Thromboplastin / Q000378:metabolism* / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000187:drug effects; D014470:Umbilical Cord
chemical_list: D017077:Culture Media, Conditioned; D013925:Thromboplastin