Cellular arrangement of human breast cancer cell lines determines hemostatic parameters.

Two in vitro models are compared to investigate whether cellular configuration or composition of the matrix in which the cells are cultured influences growth and/or prognostic parameters. T47D, MCF-7 and Hs578T breast cancer cell lines were cultured on two different matrices (agarose and collagen). Growth curves, biological markers (Ki-67, p53 and bcl-2) and the expression of hemostatic parameters were studied. The tested hemostatic parameters were urokinase-type plasminogen activator, tissue-type plasminogen activator and plasminogen activator inhibitor as fibrinolytic parameters and von Willbrand factor, tissue factor, antithrombin III, factor X and factor Xa as coagulation parameters. We found that T47D and MCF-7 formed spheroids in both matrices. Hs578T did not form spheroids; instead, the cells remained single cells in the agarose matrix and grew invasively through the collagen matrix. Expression of the biological markers was similar for spheroids and monolayers. In contrast, a clear difference in expression of hemostatic factors by spheroids and monolayers was found.

Tumour angiogenesis: pathophysiology and clinical significance.

In the 1970s it was first proposed that tumours depended on the establishment of a microcirculation in order to grow beyond a few millimetres. Thereafter, the search to prove this hypothesis increased strongly and by the end of the 1980s, evidence was given that tumours were angiogenesis-dependent and metastatic cells were only shed after the tumour had established its microcirculation. The process of neovascularization is regulated by numerous growth factors, vascular endothelial cells, and matrix proteins released from host stromal cells such as macrophages and mast cells. The process of tumour growth and metastasis involves tumour cell-host cell and cell-matrix interactions and many of the underlying mechanisms of these interactions still remain to be elucidated. Although in a minority of cases treatment of solid tumours has been effectively improved, for the majority of cases more adequate treatment is still required to reduce the mortality rate. It has been proposed only recently that specific targeting of the angiogenic process might inhibit tumour growth and metastasis. This promising field of research is now exponentially growing. It is the purpose of this review to summarize current knowledge on the pathophysiology and clinical significance of tumour angiogenesis.

Tumor spheroid-induced vesicle formation on endothelial cells is associated with procoagulant properties.

Fibrin deposits in tumor beds are an intriguing phenomenon. It has been suggested that fibrin plays a role as a provisional matrix in which the tumor grows and induces development of a vascular network. On the other hand fibrin possibly protects the tumor nodule from host defense mechanisms. We therefore investigate whether tumor cells can induce a procoagulant response in endothelial cells leading to fibrin formation. For our studies we employed a modification of the matrix model of Montesano in which sprouting of endothelial cell aggregates can be followed. This system allows us to study in vitro the involvement of coagulation in tumor growth and angiogenesis. Cocultures of endothelial cell aggregates and avascular tumor spheroids in collagen type I gels results in the appearance of extracellular vesicle-like structures on the endothelial sprouts. The vesicles formed on endothelial cell sprouts upon coculturing with tumor cells exhibit an increased amidolytic activity, suggestive of factor X/Xa activity, not dependent on tissue factor exposure. Experiments using HgCl2 and Iodoacetamide point to the importance of SH groups in the factor X/Xa activity on endothelial cell sprouts.