The thrombin inhibitor Argatroban reduces breast cancer malignancy and metastasis via osteopontin-dependent and osteopontin-independent mechanisms

Abstract

Osteopontin (OPN) has been clinically and experimentally associated with breast cancer metastasis. Proteolytic cleavage of OPN by thrombin has been reported to increase its biologic activity. The purpose of this study was to determine if inhibition of thrombin could reduce the malignancy-promoting effects of OPN on breast cancer cell behavior in vitro and in vivo. MDA-MB-468 human breast cancer cells were stably transfected to overexpress OPN (468-OPN) or a control vector (468-CON) and compared for functional differences in malignant/metastatic behavior in response to treatment with the thrombin-specific inhibitor Argatroban. Western blot analysis revealed that both 468-CON and 468-OPN cells produce thrombin and the thrombin-related protein tissue factor, and express very low levels of thrombin receptor (PAR-1). In vitro assays demonstrated that Argatroban treatment (25 microg/ml) of 468-OPN cells resulted in decreased cell growth, colony-forming ability, adhesion, and migration relative to untreated controls (P < 0.05), but did not have a significant effect on 468-CON cells. Following mammary fat pad injection, treatment with Argatroban (9 mg/kg/day) increased the in vivo tumor latency of both 468-CON and 468-OPN cells, and reduced primary tumor growth of 468-OPN cells (relative to untreated controls; P < 0.05). Furthermore, Argatroban treatment significantly decreased lymphatic metastasis of both 468-CON (P < 0.04) and 468-OPN (P < 0.01) cells relative to untreated controls. These novel findings indicate that inhibition of thrombin can reduce malignant and metastatic behavior of MDA-MB-468 breast cancer cells using both OPN-dependent and OPN-independent mechanisms, and suggest that thrombin inhibitors such as Argatroban may hold potential as therapeutic agents to combat breast cancer progression.

Thrombin is a therapeutic target for metastatic osteopontin-positive hepatocellular carcinoma

“…Some of these agents have been demonstrated to have an inhibitory effect on metastatic behavior in experimental studies 34 ; however, the main clinical applications of these agents thus far are for the treatment of disorders and complications, rather than for control of tumor metastasis. 35 Despite these desired results, a number of unique challenges still exist for the treatment of cancer patients with antithrombotic agents, including suboptimal efficacy and high risk of bleeding using broad-spectrum agents, particularly for HCC patients, who often have a chronic hepatitis background. 36 The use of more specific anticoagulants such as Argatroban, therefore, holds promise in terms of improved safety and efficacy.…”

Characterization of tumor cell dissemination patterns in preclinical models of cancer metastasis using flow cytometry and laser scanning cytometry

“…1 HLA 2 , and events which fell within region R3 were counted as meeting the criteria for human tumor cells if they were HLA We first used our FCM and LSC assays to assess tumor cell dissemination patterns and kinetics in an in vivo model of spontaneous metastasis (29,(31)(32)(33)(34) (Fig. 3) 3C, dashed lines).…”

Oncogenes and the coagulation system – forces that modulate dormant and aggressive states in cancer

“…Thus, while under normal circumstances several components of the coagulation cascade are produced exclusively in the liver, and under control of vitamin K-regulated mechanisms [71], this requirement can be circumvented by cellular transformation. Indeed, production of coagulation factors VII and II has been reported to occur in hepatocyte-unrelated cancer cells [72,73]. This is important as vitamin K antagonists are often used in thromboprophylaxis, including in cancer, and it remains uncertain whether they are effective in suppressing coagulation factor production by cells harboring mutant oncogenes.…”