title: Characterization of platelet aggregation induced by human breast carcinoma and its inhibition by snake venom peptides, trigramin and rhodostomin.
abstract: MCF-7 cells, a metastatic human breast carcinoma line, caused dose-dependent platelet aggregation in heparinized human platelet-rich plasma (PRP). MCF-7 tumor cell-induced platelet aggregation (TCIPA) was almost blocked by apyrase (0.5 U/ml) and completely inhibited by hirudin (5 U/ml). This TCIPA was unaffected by cysteine proteinase inhibition with E-64 (10 microM), but was limited by cell pretreatment with phospholipase A2. MCF-7 cell suspension caused marked, dose-dependent decrease in plasma recalcification times using normal, Factor VIII-deficient, and Factor IX-deficient human plasma. This effect was potentiated in cell lysates but was inhibited in intact cells preincubated with sphingosine. MCF-7 cell suspension did not affect the recalcification time of Factor VII-deficient plasma. Taken together, these data suggest that MCF-7 TCIPA arises from MCF-7 tissue factor activity expression. Trigramim and rhodostomin, RGD-containing snake venom peptides which antagonized the binding of fibrinogen to platelet membrane glycoprotein IIb/IIIa, prevented MCF-7 TCIPA. Likewise, synthetic peptide GRGDS as well as monoclonal antibodies against human tissue factor, platelet membrane glycoprotein IIb/IIIa and Ib prevented MCF-7 TCIPA, which was unaffected by control peptide GRGES. On a molar basis, trigramin (IC50, 0.1 microM) and rhodostomin (IC50, 0.03 microM), were about 5,000 and 18,000 times, respectively, more potent than GRGDS (IC50, 0.54 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 / Q000097:blood* / Q000188:drug therapy; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001081:Apyrase / Q000494:pharmacology; D001943:Breast Neoplasms / Q000097:blood* / Q000188:drug therapy; D003435:Crotalid Venoms / Q000494:pharmacology*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D005260:Female; D006629:Hirudins / Q000494:pharmacology; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D009842:Oligopeptides / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology*; D010741:Phospholipases A / Q000494:pharmacology; D054467:Phospholipases A2; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D013110:Sphingosine / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D000911:Antibodies, Monoclonal; D003435:Crotalid Venoms; D015853:Cysteine Proteinase Inhibitors; D006629:Hirudins; D036341:Intercellular Signaling Peptides and Proteins; D009842:Oligopeptides; D010455:Peptides; D010975:Platelet Aggregation Inhibitors; C092614:glycyl-arginyl-glycyl-glutamyl-serine; C054194:trigramin; C072026:rhodostomin; C049554:glycyl-arginyl-glycyl-aspartyl-serine; D010741:Phospholipases A; D054467:Phospholipases A2; D001081:Apyrase; D013110:Sphingosine