Tissue factor-positive tumor microvesicles activate platelets and enhance thrombosis in mice

Area of Science:

• Oncology
• Hematology
• Thrombosis Research

Background:

• Cancer patients exhibit a 4-fold higher risk of venous thromboembolism (VTE), with poorer survival rates.
• Tumor cells release microvesicles (MVs) that may drive thrombosis in cancer patients.
• Elevated levels of circulating tumor-derived, tissue factor-positive (TF(+) ) MVs are linked to VTE in pancreatic cancer patients.

Purpose of the Study:

• To investigate the hypothesis that TF(+) tumor-derived MVs (TMVs) activate platelets.
• To assess the role of TF(+) TMVs in platelet activation both in vitro and in vivo.
• To determine if TF(+) TMVs contribute to venous thrombosis (VT) in mouse models.

Main Methods:

• Utilized human pancreatic adenocarcinoma cell lines (BxPc-3 and L3.6pl) with varying TF expression.
• Studied the impact of TF(+) TMVs on human platelet activation and aggregation in vitro.
• Administered TF(+) TMVs to mouse models to evaluate in vivo platelet activation and thrombosis enhancement.

Main Results:

• TF(+) TMVs from both cell lines induced platelet activation and aggregation in vitro, dependent on tissue factor (TF) and thrombin.
• In vivo, BxPc-3 TF(+) TMVs triggered platelet activation and augmented thrombosis in mouse models, in a TF-dependent manner.
• Reduced thrombosis was observed in Par4-deficient mice and clopidogrel-treated mice, indicating platelet activation is crucial.

Conclusions:

• TF(+) tumor-derived microvesicles activate platelets, contributing to thrombosis in cancer patients.
• Platelet activation is a key mechanism linking cancer and venous thrombosis.
• Targeting platelet activation with antiplatelet drugs may offer a strategy to prevent VT in cancer patients.