Factor VIII as a potential player in cancer pathophysiology

Factor VIII as a Novel Biomarker for Diagnosis, Prognosis, and Therapy Prediction in Human Cancer and Other Disorders

Coagulation factor VIII (FVIII) is an essential cofactor in the coagulation cascade, encoded by the F8 gene on the long arm of chromosome X (Xq28). FVIII is normally circulated in complex with Von Willebrand factor (VWF) and has relevant emerging extracoagulative functions. Dysregulation of FVIII is associated with tumor progression, and could be used as a novel biomarker for tumor screening and monitoring. In breast cancer, bladder cancer, colorectal carcinoma, esophageal carcinoma, hepatocellular carcinoma and lung cancer, F8 is regarded as an oncogene. In coronary heart disease, hemophilia A and liver disease, F8 dysregulation has been recognized as a potential biomarker for disease diagnosis and prognosis. However, the basis of these differential expression levels remains to be understood. In this review, which is a mixture of literature review and bioinformatics analysis we described the biological functions and characteristics of FVIII, and also its expression level in non-malignant disorders and various cancers.

Heterogeneity and reciprocity of FVIII and VWF expression, and the response to shear stress in cultured human endothelial cells

BACKGROUND

Substantial phenotypic heterogeneity exists in endothelial cells and while much of this heterogeneity results from local microenvironments, epigenetic modifications also contribute.

METHODS

Cultured human umbilical vein endothelial cells, human pulmonary microvascular endothelial cells, human hepatic sinusoidal endothelial cells, human lymphatic endothelial cells (hLECs), and two different isolations of endothelial colony forming cells (ECFCs) were assessed for levels of factor VIII (FVIII) and von Willebrand factor (VWF) RNA and protein. The intracellular location and co-localization of both proteins was evaluated with immunofluorescence microscopy and stimulated release toof FVIII and VWF from Weibel-Palade bodies (WPBs) was evaluated. Changes in expression of FVIII and VWF RNA after hLECs and ECFCs were exposed to 2 or 15 dynes/cm2 of laminar shear stress were also assessed.

RESULTS

We observed considerable heterogeneity in FVIII and VWF expression among the endothelial cells. With the exception of hLECs, FVIII RNA and protein were barely detectable in any of the endothelial cells and a reciprocal relationship between levels of FVIII and VWF appears to exist. When FVIII and VWF are co-expressed, they do not consistently co-localize in the cytoplasm. However, in hLECs where significantly higher levels of FVIII are expressed, FVIII and VWF co-localize in WPBs and are released together when stimulated. Expression of both FVIII and VWF is markedly reduced when hLECs are exposed to higher or lower levels of laminar shear stress, while in ECFCs there is a minimal response for both proteins.

CONCLUSIONS

Variable levels of FVIII and VWF RNA and protein exist in a subset of cultured human endothelial cells. Higher levels of FVIII present in hLECs co-localize with VWF and are released together when exposed to a secretagogue.