Examining the Role of von Willebrand Factor on Breast Cancer Metastasis

Significant crosstalk exists between tumour cells and the haemostatic system, as metastatic tumour cells undergo blood-borne migration they are exposed to a milieu of coagulation proteins that can contribute to metastatic advancement. Interestingly, the extra-haemostatic functions of VWF may facilitate tumour development with VWF regarded as a regulator of endothelial angiogenesis, an inflammatory mediator that can mediate vascular permeability, a medium for transmigration that can tether and extravasate immune cells and finally as a coagulopathic agent, where it is an independent risk factor for venous thromboembolism. We sought to characterise how VWF could influence breast cancer advancement. In this project VWF plasma levels were identified as a clinical biomarker in patients with breast cancer, with elevated VWF indicative of disease stage. I found that increased plasmatic VWF levels in a metastatic breast cancer cohort may be associated of increased mortality. Elevated VWF also significantly correlated with higher fibrinogen levels in both early and late stage breast cancer but only in late stage breast cancer for D-dimer levels. Secondly, I assessed the adhesion of VWF to breast cells and revealed that VWF displayed enhanced adhesion to breast cancer cells over non-neoplastic counterparts. I determined that the D’A3 VWF-domain primarily mediated adhesion through breast cancer cell receptors GPIbα and LRP1, VWF adhesion to these receptors occurred both statically and under venous shear flow. Low molecular weight heparin ablates VWF adhesion to tumour cells as well as VWF mediated tumour cell adhesion to the endothelial layer. Finally, the functional roles of VWF in breast cancer were characterised using migration, invasion, proliferation and angiogenic assays. I was able to deduce pro-migratory and invasive properties of VWF on breast cancer cells by inducing chemotactic cell motility. Furthermore, by addressing the angiogenic capabilities of VWF I described that VWF did not directly induce classical angiogenic regulators from breast cancer cells but could induce pseudo-vasculature structures as VWF promoted breast tumour vasculogenic mimicry. An in vivo study targeting VWF revealed a reduction in time to metastasis by reducing pulmonary and liver metastasis. Collectively, these novel findings determine a pro-metastatic role for VWF in breast cancer through enhanced migration, endothelial adhesion and subsequent invasion. Additionally, for the first time VWF has been described as an inducer of vasculogenic mimicry in cancer. Finally, we determined that VWF may be a therapeutic target to reduce blood-borne cancer metastasis. </p

Von Willebrand factor and cancer; metastasis and coagulopathies

Von Willebrand factor (VWF) is a multimeric procoagulant plasma glycoprotein that mediates platelet adhesion along the endothelium. In addition to its role maintaining normal hemostasis, more recently novel biological functions for VWF have been described, including inflammation, angiogenesis, and metastasis. Significantly increased plasma VWF levels have been reported across a variety of cancer patient cohorts. Given that VWF is established as a risk factor for venous thrombosis, this is of direct clinical importance. Moreover, elevated VWF has also been observed localized within the tumor microenvironment, correlating with advanced disease stage and poorer clinical outcome. Critically, evidence suggests that elevated VWF levels in cancer patients may not only contribute to cancer associated coagulopathies but may also mediate cancer progression and metastasis. Studies have shown that VWF can promote pro-inflammatory signaling, regulate angiogenesis and vascular permeability, which may facilitate tumor cell growth and extravasation across the vessel wall. Endothelial secreted VWF multimers contribute to the adhesion and transendothelial migration of tumor cells key for tumor dissemination. In support of this, VWF inhibition attenuated metastasis in vivo. Perhaps most intriguingly, specific tumor cells have been reported to acquire de novo VWF expression which increases tumor-platelet heteroaggregates and confers enhanced metastatic activity. Current knowledge on the roles of VWF in cancer and in particular its contribution to metastasis and cancer associated coagulopathies is summarized in this review

Von Willebrand factor and cancer; metastasis and coagulopathies

Von Willebrand factor (VWF) is a multimeric procoagulant plasma glycoprotein that mediates platelet adhesion along the endothelium. In addition to its role maintaining normal hemostasis, more recently novel biological functions for VWF have been described, including inflammation, angiogenesis, and metastasis. Significantly increased plasma VWF levels have been reported across a variety of cancer patient cohorts. Given that VWF is established as a risk factor for venous thrombosis, this is of direct clinical importance. Moreover, elevated VWF has also been observed localized within the tumor microenvironment, correlating with advanced disease stage and poorer clinical outcome. Critically, evidence suggests that elevated VWF levels in cancer patients may not only contribute to cancer associated coagulopathies but may also mediate cancer progression and metastasis. Studies have shown that VWF can promote pro-inflammatory signaling, regulate angiogenesis and vascular permeability, which may facilitate tumor cell growth and extravasation across the vessel wall. Endothelial secreted VWF multimers contribute to the adhesion and transendothelial migration of tumor cells key for tumor dissemination. In support of this, VWF inhibition attenuated metastasis in vivo. Perhaps most intriguingly, specific tumor cells have been reported to acquire de novo VWF expression which increases tumor-platelet heteroaggregates and confers enhanced metastatic activity. Current knowledge on the roles of VWF in cancer and in particular its contribution to metastasis and cancer associated coagulopathies is summarized in this review

Advances in the management of cancer-associated thrombosis

The association between cancer and venous thromboembolism (VTE) has been established for more than 150 years. Nevertheless, cancer-associated thrombosis still remains a major clinical challenge and is associated with significant morbidity and mortality for patients with cancer. The clinical presentation of cancer-associated thrombosis can be distinct from that of a patient without an underlying malignancy. Moreover, specific cancer types, including pancreatic cancer and hematological malignancies, as well as advanced stage disease can confer a significant thrombotic risk. This risk is further augmented by specific anticancer treatment modalities. The pathophysiology of cancer-associated thrombosis is complex and multifactorial. However, understanding the biological mechanisms underpinning VTE risk may provide insight into novel targeted prophylaxis in cancer patients. Over the last decade, low-molecular-weight heparin has been the preferred anticoagulant agent for patients with cancer-associated thrombosis due to improved efficacy compared with Vitamin K antagonists. However, the advent of direct oral anticoagulants (DOACs) has added to the repertoire of ammunition now at the disposal of clinicians to aid in the management of cancer-associated thrombosis. Several randomized controlled trials have now been published, demonstrating DOAC as a noninferior alternative for both the treatment and prevention of cancer-associated thrombosis. Notwithstanding this, limitations for their widespread use remain, with the potential for increased bleeding risk, drug interactions, and poor DOAC metabolism. This review discusses the evidence base for the incidence and risk factors associated with VTE in cancer, development, and refinement of risk prediction models and novel advances in the therapeutic management of cancer-associated thrombosis

The role of von Willebrand factor in breast cancer metastasis

Breast cancer is the most common female cancer globally, with approximately 12% of patients eventually developing metastatic disease. Critically, limited effective treatment options exist for metastatic breast cancer. Recently, von Willebrand factor (VWF), a haemostatic plasma glycoprotein, has been shown to play an important role in tumour progression and metastasis. In breast cancer, a significant rise in the plasma levels of VWF has been reported in patients with malignant disease compared to benign conditions and healthy controls, with an even greater increase seen in patients with disseminated disease. Direct interactions between VWF, tumour cells, platelets and endothelial cells may promote haematogenous dissemination and thus the formation of metastatic foci. Intriguingly, patients with metastatic disease have unusually large VWF multimers. This observation has been proposed to be a result of a dysfunctional or deficiency of VWF-cleaving protease activity, ADAMTS-13 activity, which may then regulate the platelet-tumour adhesive interactions in the metastatic process. In this review, we provide an overview of VWF in orchestrating the pathological process of breast cancer dissemination, and provide supporting evidence of the role of VWF in mediating metastatic breast cancer

Breast cancer cells mediate endothelial cell activation, promoting von Willebrand Factor release, tumour adhesion and transendothelial migration.

Background: Breast cancer results in a three- to four-fold increased risk of venous thromboembolism (VTE), which is associated with reduced patient survival. Despite this, the mechanisms underpinning breast cancer-associated thrombosis remain poorly defined. Tumor cells can trigger endothelial cell (EC) activation resulting in increased von Willebrand factor (VWF) secretion. Importantly, elevated plasma VWF levels constitute an independent biomarker for VTE risk. Moreover, in a model of melanoma, treatment with low molecular weight heparin (LMWH) negatively regulated VWF secretion and attenuated tumor metastasis. Objective: To investigate the role of VWF in breast cancer metastasis and examine the effect of LMWH in modulating EC activation and breast tumor transmigration. Methods: von Willebrand factor levels were measured by ELISA. Primary ECs were used to assess tumor-induced activation, angiogenesis, tumor adhesion, and transendothelial migration. Results and conclusion: Patients with metastatic breast cancer have markedly elevated plasma VWF:Ag levels that also correlate with poorer survival. MDA-MB-231 and MCF-7 breast cancer cells induce secretion of VWF, angiopoietin-2, and osteoprotegerin from ECs, which is further enhanced by the presence of platelets. Vascular endothelial growth factor-A (VEGF-A) plays an important role in modulating breast cancer-induced VWF release. Moreover, VEGF-A from breast tumor cells also contributes to a pro-angiogenic effect on ECs. VWF multimers secreted from ECs, in response to tumor-VEGF-A, mediate adhesion of breast tumor cells along the endothelium. LMWH inhibits VWF-breast tumor adhesion and transendothelial migration. Our findings highlight the significant crosstalk between tumor cells and the endothelium including increased VWF secretion which may contribute to tumor metastasis.</p

Elevated von Willebrand factor levels in multiple myeloma: dysregulated mechanisms of both secretion and clearance

We read with great interest the recent publication by Ghansah et al whose work demonstrating increased thrombin generation and differential sensitivity to activated protein C (APC) in samples from patients with monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM) is an important addition to our growing understanding of the critical factors behind the high rate of thrombosis in MM.1 In particular, we noted that these authors also found raised von Willebrand Factor (VWF) antigen and Factor VIII (FVIII) levels in patients with newly diagnosed MM and, to a lesser extent in patients with MGUS. However, they concluded that the biological mechanisms underpinning raised VWF:Ag levels in MM and MGUS remain unresolved with the authors suggesting endothelial damage may be a key contributing factor. In fact, following on from the work of Ghansah et al, here, we show for the first time that not only is VWF synthesis increased in MM but that VWF circulatory clearance is also reduced in this disease. Furthermore, we also report the novel finding of raised VWF propeptide in precursor MM disease, incorporating both MGUS and smouldering MM (SM), which strengthens the evidence of a hypercoagulable profile in these premalignant conditions.</div

Breast cancer cells mediate endothelial cell activation, promoting von Willebrand Factor release, tumour adhesion and transendothelial migration.

Background: Breast cancer results in a three- to four-fold increased risk of venous thromboembolism (VTE), which is associated with reduced patient survival. Despite this, the mechanisms underpinning breast cancer-associated thrombosis remain poorly defined. Tumor cells can trigger endothelial cell (EC) activation resulting in increased von Willebrand factor (VWF) secretion. Importantly, elevated plasma VWF levels constitute an independent biomarker for VTE risk. Moreover, in a model of melanoma, treatment with low molecular weight heparin (LMWH) negatively regulated VWF secretion and attenuated tumor metastasis. Objective: To investigate the role of VWF in breast cancer metastasis and examine the effect of LMWH in modulating EC activation and breast tumor transmigration. Methods: von Willebrand factor levels were measured by ELISA. Primary ECs were used to assess tumor-induced activation, angiogenesis, tumor adhesion, and transendothelial migration. Results and conclusion: Patients with metastatic breast cancer have markedly elevated plasma VWF:Ag levels that also correlate with poorer survival. MDA-MB-231 and MCF-7 breast cancer cells induce secretion of VWF, angiopoietin-2, and osteoprotegerin from ECs, which is further enhanced by the presence of platelets. Vascular endothelial growth factor-A (VEGF-A) plays an important role in modulating breast cancer-induced VWF release. Moreover, VEGF-A from breast tumor cells also contributes to a pro-angiogenic effect on ECs. VWF multimers secreted from ECs, in response to tumor-VEGF-A, mediate adhesion of breast tumor cells along the endothelium. LMWH inhibits VWF-breast tumor adhesion and transendothelial migration. Our findings highlight the significant crosstalk between tumor cells and the endothelium including increased VWF secretion which may contribute to tumor metastasis.</p

Elevated von Willebrand factor levels in multiple myeloma: dysregulated mechanisms of both secretion and clearance

We read with great interest the recent publication by Ghansah et al whose work demonstrating increased thrombin generation and differential sensitivity to activated protein C (APC) in samples from patients with monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM) is an important addition to our growing understanding of the critical factors behind the high rate of thrombosis in MM.1 In particular, we noted that these authors also found raised von Willebrand Factor (VWF) antigen and Factor VIII (FVIII) levels in patients with newly diagnosed MM and, to a lesser extent in patients with MGUS. However, they concluded that the biological mechanisms underpinning raised VWF:Ag levels in MM and MGUS remain unresolved with the authors suggesting endothelial damage may be a key contributing factor. In fact, following on from the work of Ghansah et al, here, we show for the first time that not only is VWF synthesis increased in MM but that VWF circulatory clearance is also reduced in this disease. Furthermore, we also report the novel finding of raised VWF propeptide in precursor MM disease, incorporating both MGUS and smouldering MM (SM), which strengthens the evidence of a hypercoagulable profile in these premalignant conditions.</div