title: Characterization of platelet aggregation induced by human colon adenocarcinoma cells and its inhibition by snake venom peptides, trigramin and rhodostomin.
abstract: SW-480 cells, derived from a primary human colon adenocarcinoma, caused dose-dependent platelet aggregation in heparinized human platelet-rich plasma. SW-480 tumour cell-induced platelet aggregation (TCIPA) was completely inhibited by hirudin (5 U/ml) but unaffected by apyrase (10 U/ml). This TCIPA was also unaffected by cysteine proteinase inhibition with E-64 (10 microM) but was limited by cell pretreatment with phospholipase A2. SW-480 cell suspension caused marked dose-dependent decreases in plasma recalcification times using normal, factor VIII-deficient and factor IX-deficient human plasma. This effect was potentiated with cell lysates but inhibited in intact cells pretreated with sphingosine. SW-480 cell suspension did not affect the recalcification time of factor VII-deficient plasma. Moreover, monoclonal antibody against human tissue factor completely abolished SW-480 TCIPA. Taken together, these data suggest that SW-480 TCIPA arises from SW-480 tissue factor activity expression. Trigramin and rhodostomin, RGD-containing snake venom peptides, which antagonize the binding of fibrinogen to platelet membrane glycogen IIb/IIIa, prevented SW-480 TCIPA. Likewise, synthetic peptide GRGDS as well as monoclonal antibodies against platelet membrane glycoprotein IIb/IIIa and Ib prevent SW-480 TCIPA, which was unaffected by control peptide GRGES. On a molar basis, trigramin (IC50 0.09 microM) and rhodostomin (IC50 0.03 microM) were about 6000 and 18,000 times, respectively, more potent than GRGDS (IC50 0.56 mM).
authors.affiliation: Pharmacological Institute, College of Medicine, National Taiwan University, Taipei.
authors.forename: H S
authors.initials: HS
authors.lastname: Chiang
authors.forename: M W
authors.initials: MW
authors.lastname: Swaim
authors.forename: T F
authors.initials: TF
authors.lastname: Huang
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology*; D001081:Apyrase / Q000494:pharmacology; D002118:Calcium / Q000097:blood; D003110:Colonic Neoplasms / Q000473:pathology*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D005340:Fibrinogen / Q000037:antagonists & inhibitors; D006629:Hirudins / Q000494:pharmacology; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D007700:Kinetics; D010455:Peptides / Q000494:pharmacology*; D010741:Phospholipases A / Q000494:pharmacology; D054467:Phospholipases A2; D010974:Platelet Aggregation / Q000187:drug effects / Q000502:physiology*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D015853:Cysteine Proteinase Inhibitors; D006629:Hirudins; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D010975:Platelet Aggregation Inhibitors; C054194:trigramin; C072026:rhodostomin; D005340:Fibrinogen; D010741:Phospholipases A; D054467:Phospholipases A2; D001081:Apyrase; D002118:Calcium