Thrombin stimulates tumor-platelet adhesion in vitro and metastasis in vivo.

Abstract

Recent studies have revealed a role for platelets and the platelet-adhesive proteins, fibronectin and von Willebrand factor (vWF) in platelet-tumor cell interaction in vitro and metastasis in vivo. The present report documents the effect of thrombin treatment of platelets on this interaction in vitro and in vivo. In vitro, thrombin at 100-1,000 mU/ml maximally stimulated the adhesion of six different tumor cell lines from three different species two-to fivefold. As little as 1-10 mU/ml was effective. The effect of thrombin was specific (inhibitable by hirudin, dansyl-arginine N43-ethyl-1,5 pentanediyl) amide and unreactive with the inactive thrombin analogue N-P-tosyl-L-phenylchloromethylketone-thrombin and D-phenylalanyl-L-propyl-L-arginine chloromethylketone-thrombin (PPACK-thrombin), and required high-affinity thrombin receptors (competition with PPACK-thrombin but not with N-P-tosyl-L-lysine-chloromethyl-ketone-thrombin). Functionally active thrombin was required on the platelet surface. Binding of tumor cells to thrombin-activated platelets was inhibitable by agents known to interfere with the platelet GPIIb-GPIIIa integrin: monoclonal antibody 10E5, tetrapeptide RGDS and 'y chain fibrinogen decapeptide LGGAKQAGDV, as well as polyclonal antibodies against the platelet adhesive ligands, fibronectin and vWF. In vivo, thrombin at 250-500 mU per animal increased murine pulmonary metastases fourfold with CT26 colon carcinoma cells and 68-413-fold with B16 amelanotic melanoma cells. Thus, thrombin amplifies tumor-platelet adhesion in vitro twoto fivefold via occupancy of high-affinity platelet thrombin receptors, and modulation of GPIIb-GPIIIa adhesion via an RGD-dependent mechanism. In vivo, thrombin enhances tumor metastases 4-413-fold with two different tumor cells lines. (J. Clin. Invest. 1991. 87:229-236.).

Inhibition of angiogenesis, tumour growth and metastasis by the NO‐releasing vasodilators, isosorbide mononitrate and dinitrate

“…It is therefore likely that the effects of NO in angiogenesis and tumour growth and metastasis are at least partly mediated via inhibition of platelet adhesion (a) to the vascular wall and/or (b) to tumour cells creating aggregates which then interact with the vascular wall. The fact that NO-releasing compounds completely reverse the angiogenic effect of thrombin further supports the above hypothesis since thrombin, a major platelet activator, has been shown to enhance platelet-tumour adhesion (Nierodzik et al, 1991; and metastasis in tumour animal models.…”

Differential effects of anticoagulants on tumor development of mouse cancer cell lines B16, K1735 and CT26 in lung

“…Thrombin binds PAR-1 and mediates increased invasiveness and metastatic potential of cancer cells [33][34][35] and enhanced cancer cell adhesion to platelets [36][37][38], endothelial cells [39], fibronectin and Von Willebrand factor [12,37]. Inhibition of thrombin by Hirudin may switch off PAR-1 signalling resulting in decreased tumor growth.…”

von Willebrand factor expression in osteosarcoma metastasis

“…[16][17][18] Pretreatment of either tumor cells or platelets with an antibody or peptide that neutralizes vWF or blocks vWF-capable receptors (eg integrins GPIIb/ IIIa and GPIb-present on numerous tumor cell lines) has been shown to inhibit tumor cell-platelet interaction in vitro for colon carcinoma, Walker 256 carcinosarcoma, melanoma and osteosarcoma cell lines (including SAOS2). 19,[44][45][46][47][48][49][50][51][52] Notably, treatment with monoclonal anti-vWF antibody significantly decreased tumor cell metastases in vivo for colon, Lewis bladder and melanoma carcinoma cell 53 suggested that this tumor cell-platelet mechanism may be partially responsible for the common metastasis of osteosarcoma to the lung. In support of this, the osteosarcoma cell lines MG63, HOS, U2-OS, TE-85 and SAOS2 have been shown to induce platelet aggregation.…”