Tissue-type plasminogen activator in plasma from breast cancer patients determined by enzyme-linked immunosorbent assay

Tamoxifen-Induced Changes in the Plasma Fibrinolytic Factors in Menopausal Women with Breast Cancer

There is evidence that tissue-type plasminogen activator (tPA), urokinase-type plasminogen activator (uPA), and the plasminogen activator inhibitors 1 and 2 (PAI-1, PAI-2), are involved in the invasion and metastasis of breast tumors. Menopausal controls and menopausal women with breast cancer, who were taking tamoxifen, 10 mg b.i.d., had plasma antigenic levels of tPA, uPA, PAI-1, and PAI-2 determined by enzyme-linked immunosorbent assay (ELISA). In addition, five women being placed on this tamoxifen regimen also had these same determinations made before and after 6 months. Significant increases were observed for tPA, uPA, and PAI-1 in the 26 tamoxifen-treated patients. The percent increase in tPA and uPA combined were greater than that of PAI-1. Nonsignificant increases were also seen in the five women evaluated before and after initiation of treatment. Linear correlations were seen for tPA and PAI-1 over time length of exposure to tamoxifen. Ratios of tPA/PAI- 1 and UPA/PAI-1 were not significantly different, but were correlated and linear. From these data, it appears that tamoxifen increases the fibrinolytic factors in these patients and that this was not proportional as the ratios of the factors were not different after treatment. The increase in activators was greater than inhibitors, which could be detrimental in terms of the potential for invasion and metastasis of the tumor cell. As a negative correlation was seen for tPA over time while PAI- was positively correlated, this may help explain why some patients taking tamoxifen are at risk for thromboembolytic events. Key Words: TPA—uPA—PAI-1—PAI-2—Tamoxifen—Breast cancer.

Long-term efficacy and downstream mechanism of anti-annexinA2 monoclonal antibody (anti-ANX A2 mAb) in a pre-clinical model of aggressive human breast cancer

There is considerable direct evidence that calcium binding protein ANX A2 is a potential target for treating aggressive breast cancer. The most compelling data are based on the finding of ANX A2 overexpression in aggressive triple negative human breast cancer (TNBC) cell lines and in human breast cancer tissues. Previously, we and others reported a unique role of ANX A2 in cancer invasion, including breast cancer. Moreover, we demonstrated that anti-ANX A2 mAb-mediated immunoneutralization of ANX A2 inhibited invasive human breast cancer growth in a xenograft model. We further evaluated the long-term effects of multiple treatments with anti-ANX A2 mAb and its mechanism of inhibition on human breast tumor growth. We now demonstrate that three treatments with anti-ANX A2 mAb led to significant inhibition of breast tumor growth in immunodeficient mice, and that the anti-tumor response was demonstrable from day 94. After treatment, we followed tumor growth for 172 days and demonstrated 67% inhibition of tumor growth without detectable adverse effects. Biochemical analysis demonstrated that anti-ANX A2 mAb treatment caused significant inhibition of conversion of tissue plasminogen activator (tPA) in the tumor microenvironment. This led to disruption of plasmin generation that consequently inhibited activation of MMP-9 and MMP-2. These results suggest that ANX A2 plays an important role in aggressive breast tumor growth by regulating proteolytic pathways in the tumor microenvironment. ANX A2 may represent a new target for the development of therapeutics for treatment of aggressive breast cancer.

Antibody-directed neutralization of annexin II (ANX II) inhibits neoangiogenesis and human breast tumor growth in a xenograft model

Activation of the fibrinolytic pathway has long been associated with human breast cancer. Plasmin is the major end product of the fibrinolytic pathway and is critical for normal physiological functions. The mechanism by which plasmin is generated in breast cancer is not yet fully described. We previously identified annexin II (ANX II), a fibrinolytic receptor, in human breast tumor tissue samples and observed a strong positive correlation with advanced stage cancer (Sharma et al., 2006a). We further demonstrated that tissue plasminogen activator (tPA) binds to ANX II in invasive breast cancer MDA-MB231cells, which leads to plasmin generation (Sharma et al., 2010). We hypothesize that ANX II-dependent plasmin generation in breast tumor is necessary to trigger the switch to neoangiogenesis, thereby stimulating a more aggressive cancer phenotype. Our immunohistochemical studies of human breast tumor tissues provide compelling evidence of a strong positive correlation between ANX II expression and neoangiogenesis, and suggest that ANX II is a potential target to slow or inhibit breast tumor growth by inhibiting neoangiogenesis. We now report that administration of anti-ANX II antibody potently inhibits the growth of human breast tumor in a xenograft model. Inhibition of tumor growth is at least partly due to attenuation of neoangiogenic activity within the tumor. In vitro studies demonstrate that anti-ANX II antibody inhibits angiogenesis on three dimensional matrigel cultures by eliciting endothelial cell (EC) death likely due to apoptosis. Taken together, these data suggest that selective disruption of the fibrinolytic activity of ANX II may provide a novel strategy for specific inhibition of neoangiogenesis in human breast cancer.

Breast cancer cell surface annexin II induces cell migration and neoangiogenesis via tPA dependent plasmin generation

Annexin II, an abundant phospholipids binding cell surface protein, binds tPA and functions as a regulator of fibrinolysis. Annexin II also mediates angiogenesis and enhances tumor growth and metastasis. However, the mechanism supporting this role is not known. Using human breast cancer model we show that invasive human breast cancer cells (MDA-MB231) synthesize annexin II and tissue plasminogen activator (tPA). In vitro both annexin II and tPA interacts which in turn convert zymogen plasminogen to reactive enzyme plasmin. Cell surface produced plasmin inhibited the migration of MDA-MB231 cells. Silencing of annexin II gene in MDA-MB231 cells abolished tPA binding therefore inhibited tPA dependent plasmin generation. These annexin II suppressed MDA-MB231 cells showed reduced motility. Immunohistochemical analysis of prediagnosed clinical specimens showed abundant secretion of tPA and expression of annexin II on the surface of invasive human breast cancer cells which correlates with neovascularization of the tumor. Taken together, these data indicate that annexin II may regulate localized plasmin generation in breast cancer. This may be an early event switching breast cancer from the prevascular phase to the vascular phase and thus contributing to aggressive cancer with the possibility of metastasis. The data provide a mechanism explaining the role of annexin II in breast cancer progression and suggest that annexin II may be an attractive target for therapeutic strategies aimed to inhibit angiogenesis and breast cancer.

Prognostic value of tissue-type plasminogen activator (tPA) and its complex with the type-1 inhibitor (PAI-1) in breast cancer

The prognostic value of tissue-type plasminogen activator (tPA) measured in samples derived from 865 patients with primary breast cancer using a recently developed enzyme-linked immunosorbent assay (ELISA) was evaluated. Since the assay could easily be adapted to the assessment of the complex of tPA with its type-1 inhibitor (PAI-1), it was investigated whether the tPA:PAI-1 complex also provides prognostic information. To this end, cytosolic extracts and corresponding detergent extracts of 100,000 g pellets obtained after ultracentrifugation when preparing the cytosolic fractions for routine steroid hormone receptor determination were assayed. Statistically significant correlations were found between the cytosolic levels and those determined in the pellet extracts (Spearman correlation coefficient r(s) = 0.75, P < 0.001 for tPA and r = 0.50, P < 0.001 for tPA:PAI-1 complex). In both Cox univariate and multivariate analysis elevated levels of (total) tPA determined in the pellet extracts, but not in cytosols, were associated with prolonged relapse-free (RFS) and overall survival (OS). In contrast, high levels of the tPA:PAI-1 complex measured in cytosols, but not in the pellet extracts, were associated with a poor RFS and OS. The prognostic information provided by the cytosolic tPA:PAI-1 complex was comparable to that provided by cytosolic (total) PAI-1. Furthermore, the estimated levels of free, uncomplexed tPA and PAI-1, in cytosols and in pellet extracts, were related to patient prognosis in a similar way as the (total) levels of tPA and PAI-1 respectively. Determination of specific forms of components of the plasminogen activation system, i.e. tPA:PAI-1 complex and free, uncomplexed tPA and/or PAI-1, may be considered a useful adjunct to the analyses of the separate components (tPA and/or PAI-1) and provide valuable additional prognostic information with respect to survival of breast cancer patients.

Plasminogen activators and plasminogen activator inhibitor in portal blood from patients with and without gastric malignancy

BACKGROUND

Plasminogen activators (PA) may be released by the gut and eliminated by the liver. Patients with liver disorders or malignancy often have abnormal plasma levels of PAs. Some tumours may produce PAs.

METHODS

In patients undergoing gastric surgery for malignant (n = 18) or benign (n = 21) disorders., blood drawn from the portal vein and a peripheral vein was analysed for tissue-type plasminogen activator antigen and activity (tPA: Ag, tPA: Act), single-chain urokinase-type plasminogen activator activity (scuPA: Act), and plasminogen activator inhibitor antigen and activity (PAI: Ag, PAI: Act).

RESULTS AND CONCLUSIONS

In both groups tPA: Act and scuPA: Act levels were significantly higher in portal blood than in peripheral blood, but tPA: Ag and PAI: Act levels did not differ. PAI: Act levels were significantly lower in patients with malignant disease, but levels of the other markers did not differ in the two groups.

Plasminogen activators and plasminogen activator inhibitors in human colorectal carcinoma tissues are not expressed by the tumour cells

Plasminogen activators (PA) have been implicated with the degradation of extracellular matrix during the invasive growth of metastasising tumour cells. The significance of PA expression in tumour cells for the in vivo growth of malignant tumours is still a matter of debate. We, therefore, performed immunohistological studies on human colon tumours using monoclonal antibodies against urokinase- (u-PA) and tissue-type plasminogen activator (t-PA) as well as against plasminogen activator inhibitors 1 and 2 (PAI-1, PAI-2). Normal colorectal mucosa of seven samples was negative for all four constituents of the PA system. Tumour epithelium of 64 colorectal carcinomas and 10 liver metastases was consistently negative for both, PA and their inhibitors. However, two of four human colon carcinoma cell lines weakly expressed u-PA, PAI-1 and PAI-2. Intestinal dendritic or fibroblast-like cells within the tumour tissue strongly expressed u-PA and, at a lower level, also t-PA, PAI-1 and PAI-2. Vascular endothelial cells were weakly positive for all components of the PA system in colon carcinoma. Our findings indicate that colon carcinoma cells in their natural environment do not express constituents of the PA system. PA activity, previously found in colon carcinoma tissue, is most likely derived from interstitial cells.