A Recombinant Peptide, Hirudin, Potentiates the Inhibitory Effects of Stealthy Liposomal Vinblastine on the Growth and Metastasis of Melanoma

Abstract

The metastasis of tumor cells is one of the major obstacles to successful clinical chemotherapy, surgery, and radiotherapy. Accordingly, new therapeutic strategies are needed for overcoming the occurrence of invasion and metastasis of tumor to improve patients' prognosis and survival.The anticoagulants low-molecular weight heparin (LMWH) and recombinant hirudin have shown anti-invasion and antimetastasis effects in experimental models.1,2) However, recombinant hirudin was found ineffective at preventing metastasis of HT168-M1 human melanoma cells in preclinical study, 1) suggesting that the anti-invasion and anti-metastasis effects of anticoagulants may vary by tumor cells. Most likely, each anticoagulant agent has its own mechanisms for application.The association of thrombosis and cancers as evidenced by platelet and fibrin deposition is well established.3-6) Previous studies indicate that exogenous thrombin (1 U/ml) acting through its protease-activated receptor (PAR-1) is capable of enhancing tumor adhesion to platelets, 7-9) endothelial cells, 10) fibronectin, and von Willebrand factor 8) in vitro. Studies have also revealed that exogenous thrombin promotes tumor growth in vitro 11) and in vivo 7,8,12) as well as metastasis in experimental animals (via tail-vein injection of cancer cells). 9,13) The endogenous generation of host thrombin plays a significant role during tumor growth and spontaneous metastasis.2) Recent investigation demonstrated that advanced cancer is associated with a hypercoagulable state triggered by tissue factor (TF).14) TF-initiated thrombin generation is a critical step for metastasis through fibrin, platelet deposition, and PAR-1 signaling responses. In addition, PAR-2, which was not cleaved by thrombin, appears to be a cosignal with PAR-1 to elicit thrombin effects in metastatic tumor cells. 14)Hirudin is a highly potent and specific inhibitor of thrombin. It has shown an inhibitory effects against tumor growth and metastasis in experimental tumor models. [15][16][17] Hirudin induced a pronounced lag time in the appearance of tumor growth, as compared with phosphate-buffered saline (PBS) as control, but had no effect on existing tumor cells. We postulated that hirudin may have different effects on tumor growth depending on its administrations, because hirudin resulted in central necrosis of the tumor nodule, and inhibited spontaneous metastases from subcutaneously implanted tumor by reducing the number of tumor nodules in the lungs following administration at early stage of tumor cell inoculation in experimental animals. 2)Heparins are negatively charged polysaccharides that are able to bind to a number of proteins and molecules, thus probably influencing their biological activity. LMWH is composed of low-molecular weight fragments of heparin manufactured by controlled enzymatic or chemical depolymerization. LMWH may affect the progression of tumor in many ways. For example, it may potentially inhibit intravascular arrest and metastasis due to its anticoagulant role. [18][19][20] I...

Recombinant hirudin suppresses the viability, adhesion, migration and invasion of Hep-2 human laryngeal cancer cells

“…A previous study suggested that rH had no impact on adhesion to extracellular matrix (ECM) proteins, migration and invasion of in vitro cultured human A375 melanoma cells (10). However, our data clearly showed that rH inhibited Hep-2 cell adhesion to fibronectin, migration and invasion in a dose-dependent manner.…”

“…Thrombin, the key terminal enzyme of coagulation, enhances angiogenesis, stimulates the adhesion of tumor cells to platelet and endothelium, and promotes the growth and metastasis of tumor cells (9). Previous in vitro studies have shown that exogenous thrombin (1 U/ml) acting through its protease-activated receptor (PAR)-1 is capable of enhancing tumor adhesion to platelets, endothelial cells, fibronectin and von Willebrand factor (10). Moreover, exogenous thrombin was shown to promote tumor growth as well as metastasis in experimental animals (11).…”

“…Administration of hirudin at the early stage after tumor cell inoculation in experimental animals led to apparent central necrosis of the tumor nodule and inhibition of spontaneous metastases from the subcutaneously implanted tumors, accompanied by the reduced number of tumor nodules in the lungs (11). Moreover, administration of rH followed by stealthy liposomal vinblastine resulted in enhanced inhibition of the growth and metastasis of melanoma in vivo (10). Thus, targeting thrombin by rH is a promising strategy for the development of anticancer therapeutic modalities, particularly for those tumor cells with PAR-1 on the cell surface.…”

A role for thrombin in the initiation of the immune response to therapeutic factor VIII

“…38 A dose of 200 g/mouse (ϳ 10 mg/kg) was used because it is the minimal dose others have shown to significantly increase activated partial thromboplastin time and thrombin time in the mouse. 39 As shown in Figure 5, the B-and T-cell responses to FVIII are reduced when mice were treated simultaneously with FVIII and hirudin compared with standard treatment with FVIII only. We also could not detect any nonspecific, toxic, suppressive effects of hirudin in terms of inhibition of mitogenic stimulation of T cells (supplemental Figure 2).…”

Thrombin—unique coagulation system protein with multifaceted impacts on cancer and metastasis

“…A prothrombotic state is characteristic for advanced and metastatic cancers [10,11,16,17], and enzymatically active thrombin is reportedly present on surgically excised tumor specimens, including malignant melanoma [reviewed in 3]. Additionally, hirudin, a highly specific thrombin inhibitor, markedly suppresses tumor seeding into the blood, implantation, and spontaneous metastasis in a mouse model, which prolongs survival [13,[18][19][20]. Several decades ago, pioneering work determined that the Gprotein-coupled thrombin receptor was present on the surface of cancer cells in solid tumors [21], where its contribution to experimental lung metastasis was described [4][5][6][7][8].…”