Diffusible thromboplastins of human cancer and chorion tissue

Isolation and characterization of cancer procoagulant: a cysteine proteinase from malignant tissue

Cancer procoagulant, a proteolytic procoagulant enzyme, has been purified from rabbit V2 carcinoma extracts by two procedures. In the first, the protein was purified by benzamidine--Sepharose affinity chromatography, gel filtration chromatography, and phenyl-Sepharose hydrophobic chromatography. Antiserum was raised against the purified protein and was used to prepare an immunoadsorbent column. In the second, tumor extracts were purified by immunoaffinity chromatography followed by p-(chloromercuri)benzoate affinity chromatography. The second procedure was substantially quicker and easier. The final product of both procedures was homogeneous on the basis of analytical sodium dodecyl sulfate--polyacrylamide gel electrophoresis and isoelectric focusing. The molecular weight was 68 000 and the isoelectric point 4.8. The proteinase activity of cancer procoagulant directly activated factor X, in the absence of factor VII, and was inhibited by 1 mM iodoacetamide and 0.1 mM mercury which are classic cysteine proteinase inhibitors. A carbohydrate analysis showed less than 1 mol of hexose or sialic acid/mol of protein. The amino acid analysis showed that serine (19.1%), glycine (18.77%), and glutamic acid (12.5%) were the prevalent amino acids. The amino acid composition of cancer procoagulant was substantially different than other known factor X activating proteinases or other cysteine proteinases including cathepsin B.

Comparison of properties of cancer procoagulant and human amnion-chorion procoagulant

Cysteine proteinases that initiate coagulation in the absence of factor VII have been isolated from rabbit V2 carcinoma and from human amnion-chorion. Many of their biochemical properties, including a molecular weight of 68 000 and inhibition by iodoacetamide and mercury, are the same. In the paper we compare the isoelectric point, the amino acid composition and the carbohydrate content of human amnion-chorion procoagulant and cancer procoagulant. With the exception of minor differences in the amino acid composition, attributable in part to differences in species, the two proteins are closely homologous.

Fibrin as a component of the tumor stroma: origins and biological significance

An association between cancer and the coagulation system was suggested by Trousseau more than a century ago and initial reports of fibrin deposition in the stroma of solid tumors date back some 25 years. However, the validity and generality of these observations have only quite recently been established, and their implications for an understanding of tumor biology, metastasis, and therapy are only now coming to be appreciated by investigators in the mainstream of cancer research. This article reviews the current status of fibrin's role in the biology of tumor growth, considering in turn: (1) the evidence that fibrin is present in tumors, the nature of such fibrin, and its relation to plasma fibronectin; (2) the mechanisms by which fibrin may come to be deposited in tumors; and (3) the potential biological and medical significance of tumor-associated fibrin deposition and degradation. Among the last are such important possibilities as a barrier function to the immune response and possible roles in angiogenesis, desmoplasia, and metastasis.

Heparin treatment of microangiopathic haemolytic anaemia associated with an experimental tumour

In rats bearing the solid Walker 256 carcinosarcoma microangiopathic haemolytic anaemia (MHA) developed during the course of tumour growth. A phase of hypercoagulability was followed by a significant decrease in plasma fibrinogen, platelet count and antithrombin III. A diminished haematocrit and a rise in plasma haemoglobin and schistocyte count were accompanied by fibrin deposits in the tumour vessels. When the rats were treated with heparin during the growth of the Walker tumour, both DIC and MHA were prevented except of the last period of the experiment. The tumour sizes, however, did not differ in the controls and the heparinized animals. There is a fair amount of evidence to suggest that the MHA was induced by a tumour-dependent DIC which was blocked by heparin over a certain time period. In contrast, the tumour growth was not modified by effective suppression of DIC and MHA.