Summary
Neoplastic diseases are often associated with thromboembolic events,however the precise
mechanism underlying this observation is a matter of ongoing investigation. It is
known that matrixmetalloproteinase- 1 (MMP-1) canonically activates the thrombin receptor
(PAR-1) and we recently reported that highly metastatic tumor cells of melanoma and
colon cancer are secreting matrixmetalloproteinase-1. This tumor-derived MMP1 was
shown to be a major activator of endothelial PAR-1, thus leading to endothelial cell
activation. As tumor-induced thrombosis is a characteristic of metastazing tumors,
we investigated whether tumor-derived supernatant (TUSN) from melanoma and colon cancer
may induce adhesion of circulating platelets,an initial step in thrombus formation.A
time-course study revealed that TU-SN induces a rapid secretion of von Willebrand
factor (VWF) within minutes. Using a novel microfluidic device we analyzed platelet-endothelial
interactions in a closed circuit. Immunofluorescence imaging showed that TU-SN rapidly
induces platelet- string formation via secreted VWF. We demonstrated that tumor-derived
supernatant is a potent agonist inducing platelet adhesion under flow conditions.
Keywords
von Willebrand factor - platelet physiology - cancer - imaging