Plasmatic Plasminogen Activator Inhibitor Activity in Patients with Primary Breast Cancer

The active fraction of plasmatic plasminogen activator inhibitor type 1 as a possible indicator of increased risk for metastatic melanoma

Plasminogen activator inhibitor type 1 (PAI1) is considered to be the main regulator of fibrinolytic activity in blood and has been identified as a key-enzyme in the metastasis and vascularization of solid tumors. The aim of this study was to determine whether high or low plasma levels and/or activity of PAI1 correlate with the presence of metastatic disease for patients with melanoma. We hypothesized that the presence of metastases could result in a disturbance of the fibrinolytic balance of the blood. To test our hypothesis, we have developed a unique enzyme-linked immunosorbent assay (ELISA) that can measure both the total amount as well as the active fraction of PAI1 in the plasma. We then used this novel assay to analyze the plasmatic PAI1 levels and activity of patients with advanced melanoma (AM, n = 18) and primary melanoma (PM, n = 21) and compare it to a control population (n = 38). We found no statistically significant difference in the total plasmatic PAI1 levels between the controls and patients with PM or AM (P = 0.6199). In contrast, there was a significant difference in the active fraction of PAI1 between the controls and patients with PM or AM (P = 0.0076). The difference between the control and AM groups was highly significant (P = 0.0042). A value of less than 44% active PAI1 was shown to be clinically meaningful by linear discriminant analysis. Surprisingly, the difference between the control and PM groups was also significant--although borderline (P = 0.0488). Of the patients with PM, 19% had PAI1 activity values less than 44%, which strongly supports further investigations to determine whether plasmatic PAI1 activity might be a biological marker of increased metastatic risk.

Determination of the Complex between Urokinase and Its Type-1 Inhibitor in Plasma from Healthy Donors and Breast Cancer Patients

Background: The complex between urokinase (uPA) and its type-1 inhibitor (PAI-1) is formed exclusively from the active forms of these components; thus, the complex concentration in a biological sample may reflect the ongoing degree of plasminogen activation. Our aim was to establish an ELISA for specific quantification of the uPA:PAI-1 complex in plasma of healthy donors and breast cancer patients.

Methods: A kinetic sandwich format immunoassay was developed, validated, and applied to plasma from 19 advanced-stage breast cancer patients, 39 age-matched healthy women, and 31 men.

Results: The assay detection limit was <2 ng/L, and the detection of complex in plasma was validated using immunoabsorption, competition, and recovery tests. Eighteen cancer patients had a measurable complex concentration (median, 68 ng/L; range, <16 to 8700 ng/L), whereas for healthy females and males the median signal values were below the detection limit (median, <16 ng/L; range, <16 to 200 ng/L; P <0.0001). For patient plasma, a comparison with total uPA and PAI-1 showed that the complex represented a variable, minor fraction of the uPA and PAI-1 concentrations of each sample.

Conclusion: The reported ELISA enables detection of the uPA:PAI-1 complex in blood and, therefore, the evaluation of the complex as a prognostic marker in cancer.

Chemotherapy and thrombosis in gynecologic malignancy

Thromboembolism is a severe and frequent problem in gynecologic malignancy. The average DVT incidence during chemotherapy of 5% might represent the lower range of incidence because < 55% of thrombotic complication manifest clinical signs. However, it seems likely that in addition to chemotherapy other risk factors such as menopausal status, BMI of patients, or type of preceding surgery must coincide before thrombosis manifests. While monitoring of patients using sophisticated coagulation tests did not identify patients' risk for DVT during chemotherapy, an evaluation of the coagulation status before initiating chemotherapy is recommended. Patients with a venous access device (e.g., indwelling central venous catheter or with port cart) are at a particularly high risk for DVT. This has to be considered when cytoreductive therapy is given. Thrombosis prophylaxis, orally or subcutaneously, should only be considered in a subpopulation of patients who offer a combination of the aforementioned risk factors. Thrombosis prevention trials during chemotherapy found a significant reduction of DVT in patients treated with anticoagulants.

The urokinase plasminogen activator system as a target for prognostic studies in breast cancer

The identification of patients at high risk of relapse is currently one of the most important issues in breast cancer research. However, the selection of high-risk patients continues to be difficult due to the unpredictable course of this disease. Axillary lymph node status is currently recognized as the best clinical discriminant between good and poor prognosis, yet almost 30% of node-negative patients and 65% of node-positive patients will experience a relapse. Additional prognostic markers are therefore urgently needed. Since metastatic disease is the main cause of cancer patient morbidity and mortality, the measurement of molecules functionally involved in the regulation of tumor invasion and metastasis is attractive as a means to predict prognosis. Cancer invasion is a complex process in which degradation of the extracellular matrix plays a crucial role. This degradation is accomplished by the concerted action of several proteolytic enzyme systems, including generation of plasmin by the urokinase pathway of plasminogen activation, matrix metalloproteases, and other extracellular proteases. Increased expression and secretion of urokinase plasminogen activator (uPA) strongly correlates with the malignant phenotype of many types of cells, and the central role of uPA in tumor invasion is now well established. This review will focus on the prognostic impact of components of the urokinase plasminogen activation system in breast cancer with emphasize on methodological issues.