Antithrombin III producing hepatocellular carcinoma

Haemostatic abnormalities in liver disease: could some haemostatic tests be useful as liver function tests?

The liver plays a central role in haemostasis, being the site of synthesis of most of the clotting factors, coagulation inhibitors and fibrinolytic parameters, in addition to its clearance of activated clotting and fibrinolytic factors. Nonetheless, no haemostatic test(s) is included among the routine liver function tests and this study aims to probe this possibility. The liver disease group (n=258) included acute hepatitis (n=25), chronic viral hepatitis (n=128), hepatitis B (HB) carriers (n=25), liver cirrhosis (n=67), and hepatocellular carcinoma (HCC) (n=13). The prothrombin time was significantly prolonged in acute hepatitis, liver cirrhosis and HCC. However, the reptilase time was prolonged in all the groups except in HB carriers, while the thrombin time was prolonged only in the HCC group. Antithrombin III and protein C levels exhibited significant reduction in acute hepatitis, liver cirrhosis and HCC. On the other hand, protein S levels (total and free) were reduced significantly in all the patients groups, including HB carriers when compared with healthy controls. Derangement of haemostatic tests is a common feature in liver disease, being most significant in acute hepatitis, liver cirrhosis and hepatocellular carcinoma. The most sensitive markers of hepatocyte malfunction are protein S (total and free) and the reptilase time as they were abnormal, in the mildest liver affections, when other biochemical tests as well as other haemostatic tests were normal. Further studies are needed to see whether these two tests qualify for inclusion among the routine liver function tests.

Anti-thrombin is expressed in the benign prostatic epithelium and in prostate cancer and is capable of forming complexes with prostate-specific antigen and human glandular kallikrein 2

Anti-thrombin, a member of the serpin family and an inhibitor of thrombin and blood coagulation factor Xa, was recently shown to inhibit angiogenesis and tumor growth. In the present study, we examined the expression of anti-thrombin in benign and malignant prostate gland. Using immunohistochemistry, anti-thrombin was found in prostate epithelium and stroma cells. Tissue microarrays of tumors (n = 112) and three different prostate cancer cell lines (PC-3, LNCaP, and DU-145) were all positive for anti-thrombin. Abundant expression in a population of prostatic tumor cells was further evidenced by in situ hybridization experiments. The immunostaining for anti-thrombin was confined to the cytoplasm, was most intense in Gleason grade 3 tumors, and in part overlapped with that of prostate-specific antigen. Western blotting of benign and malignant tissue homogenates revealed a predominant 58-kd anti-thrombin immunoreactive component. In vitro, anti-thrombin formed complexes more readily with human kallikrein 2, particularly in the presence of heparin, and less efficiently with prostate-specific antigen. Both complexes could be recognized by polyclonal and monoclonal IgGs against anti-thrombin. We conclude that anti-thrombin is widely expressed in prostate cancer but is gradually lost in tumors of high Gleason grade. Anti-thrombin may act as a local anti-angiogenic factor, the effect of which is partially lost in poorly differentiated prostatic tumors.

Hypercoagulable states

The hypercoagulable state has been defined as the potential to develop thrombosis in association with hereditary and noninherited genetic mutations and acquired disorders. It is a condition that places an individual at risk for, but does not in itself inevitably lead to, thrombosis. The focus of this article is understanding mechanisms in the hypercoagulable state that enhance and maintain the production of thrombin in circulating blood while preventing its progression to thrombosis. These mechanisms include reactions that produce thrombin from prothrombin, feedback loop mechanisms that affect the rate of thrombin production from prothrombin and the inactivation of thrombin in blood. The fibrinolytic system is involved in clot lysis but not in thrombin production and inactivation.

Antiangiogenic activity of the cleaved conformation of the serpin antithrombin

Antithrombin, a member of the serpin family, functions as an inhibitor of thrombin and other enzymes. Cleavage of the carboxyl-terminal loop of antithrombin induces a conformational change in the molecule. Here it is shown that the cleaved conformation of antithrombin has potent antiangiogenic and antitumor activity in mouse models. The latent form of intact antithrombin, which is similar in conformation to the cleaved molecule, also inhibited angiogenesis and tumor growth. These data provide further evidence that the clotting and fibrinolytic pathways are directly involved in the regulation of angiogenesis.