Tissue factor/factor VIIa inhibitors block angiogenesis and tumor growth through a nonhemostatic mechanism

Area of Science:

• Oncology
• Hematology
• Molecular Biology

Background:

• The link between cancer and thrombosis is long-established, yet the precise mechanisms by which coagulation influences tumor progression in vivo are not fully understood.
• Investigating the role of coagulation in regulating tumor growth is crucial for developing novel cancer therapies.

Purpose of the Study:

• To determine the role of coagulation in tumor growth and angiogenesis by evaluating the antitumor activity of specific coagulation inhibitors.
• To elucidate whether the pro-tumorigenic effects of tissue factor (TF)/factor VIIa (fVIIa) are linked to its procoagulant or other proteolytic activities.

Main Methods:

• Utilized specific inhibitors of tissue factor (TF)/factor VIIa (fVIIa) complexes and factor Xa (fXa) in mouse models to assess antitumor effects.
• Administered TF pathway inhibitor (TFPI) and nematode anticoagulant protein rNAPc2 (TF/fVIIa inhibitors), and rNAP5 (fXa inhibitor) to mice bearing tumors.
• Evaluated the impact of these inhibitors on primary tumor growth, metastatic tumor spread, and angiogenesis.

Main Results:

• TF/fVIIa inhibitors, TFPI and rNAPc2, significantly inhibited both primary and metastatic tumor growth in vivo.
• The TF/fVIIa inhibitor rNAPc2 demonstrated potent inhibition of angiogenesis.
• The fXa inhibitor rNAP5 did not exhibit any antitumor activity, despite fXa being downstream of TF/fVIIa activation.

Conclusions:

• The proteolytic activity of TF/fVIIa, rather than its role in hemostasis, promotes tumor growth and angiogenesis through a novel proangiogenic pathway.
• Targeting TF/fVIIa offers a potential therapeutic strategy for cancer treatment by inhibiting tumor progression and angiogenesis.
• These findings suggest that the pro-tumorigenic effects of TF/fVIIa are independent of its hemostatic function.