Chiang H S, Swaim M W, Huang T F
Pharmacological Institute, College of Medicine, National Taiwan University, Taipei.
Breast Cancer Res Treat. 1995 Mar;33(3):225-35. doi: 10.1007/BF00665947.
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).
MCF-7细胞是一种转移性人乳腺癌细胞系，在肝素化的富含人血小板的血浆（PRP）中可引起剂量依赖性血小板聚集。MCF-7肿瘤细胞诱导的血小板聚集（TCIPA）几乎被腺苷三磷酸双磷酸酶（0.5 U/ml）阻断，并被水蛭素（5 U/ml）完全抑制。这种TCIPA不受E-64（10 microM）对半胱氨酸蛋白酶的抑制作用影响，但受到磷脂酶A2对细胞的预处理的限制。MCF-7细胞悬液使用正常、缺乏因子VIII和缺乏因子IX的人血浆可导致血浆复钙时间显著的剂量依赖性缩短。这种效应在细胞裂解物中增强，但在用鞘氨醇预孵育的完整细胞中受到抑制。MCF-7细胞悬液不影响缺乏因子VII的血浆的复钙时间。综上所述，这些数据表明MCF-7的TCIPA源于MCF-7组织因子活性的表达。凝血酶样酶和罗豆素是含RGD的蛇毒肽，可拮抗纤维蛋白原与血小板膜糖蛋白IIb/IIIa的结合，可阻止MCF-7的TCIPA。同样，合成肽GRGDS以及抗人组织因子、血小板膜糖蛋白IIb/IIIa和Ib的单克隆抗体也可阻止MCF-7的TCIPA，而对照肽GRGES对其无影响。以摩尔为基础，凝血酶样酶（IC50，0.1 microM）和罗豆素（IC50，0.03 microM）分别比GRGDS（IC50，0.54 mM）强约5000倍和18000倍。
