Plasminogen activator system localization in 60 cases of ductal carcinoma in situ

Expression of urokinase-type plasminogen activator (uPA), its receptor (uPAR), and inhibitor (PAI-1) in human breast carcinomas and their clinical relevance

Serine proteases convert plasminogen to plasmin which is involved in tissue remodeling under physiologic and pathophysiologic conditions, including breast carcinoma invasion and progression. Both urokinase-type plasminogen activator (uPA) and pro-uPA associate with uPA receptor (uPAR) on target cells, where plasminogen activator inhibitors (e.g., PAI-1) may modulate their activities. Expression levels of these factors were compared in breast carcinomas relative to patient characteristics, carcinoma features, and clinical outcome. uPA, uPAR, and PAI-1 were quantified by enzyme-linked immunosorbent assay (ELISA) in extracts of 226 biopsies while estrogen receptor (ER) and progestin receptor (PR) were determined by enzyme immunoassay (EIA) or radio-ligand binding. Each set of assays contained a novel reference specimen with known quantities of each of these five analytes. Levels in ng/mg protein of these biomarkers exhibited ranges: uPA (0-12.3); uPAR (0-19.5); PAI-1 (0-91.2). When considered independently, expression of uPA, uPAR, or PAI-1 was unrelated to patient age or menopausal status. Although no correlation was observed between each analyte with stage, grade, or ER/PR status, levels appeared to differ with pathology and nodal status. A dendrogram from hierarchical clustering of uPA, uPAR, and PAI-1 levels in 106 specimens revealed three clusters of breast cancer patients. Kaplan-Meier analyses of uPA, uPAR, and PAI-1 indicated a correlation with overall survival (OS), suggesting collective examination of these biomarkers is useful in predicting clinical outcome of breast cancer.

High level of urokinase plasminogen activator contributes to cholangiocarcinoma invasion and metastasis

AIM

To investigate the role of urokinase plasminogen activator (uPA) in cholangiocarcinoma (CCA) invasion and its correlation with clinicopathological parameters.

METHODS

uPA expression in CCA tissue was determined by immunohistochemistry. The level of uPA from two CCA cell lines (HuCCA-1 and KKU-M213) and a non-cancer immortalized cholangiocyte cell line (H69) was monitored by plasminogen-gelatin zymography and western blotting, whereas that of plasminogen activator inhibitor type 1 (PAI-1) protein and uPA receptor (uPAR) mRNA was monitored by western blotting and quantitative real-time reverse transcriptase polymerase chain reaction, respectively. Two independent methods were employed to suppress uPA function: a synthetic uPA inhibitor (B428) and silencing of uPA gene expression using siRNA. In vitro invasion of the uPA-disrupted cells was assessed by Matrigel-coated Transwell assay.

RESULTS

The immunohistochemical study showed that 75.3% (131/174) of CCA tissues expressed uPA. High uPA expression was correlated with lymphatic invasion and metastasis of CCA patients. Plasminogen-gelatin zymography of the conditioned media and cell-surface eluates showed that both CCA cell lines, but not H69, expressed both secreted and membrane-bound forms of uPA. Although the two CCA cell lines, HuCCA-1 and KKU-M213, expressed a relatively high level of uPA and uPAR, the latter exhibited a much lower degree of in vitro invasiveness, correlating with a high expression of PAI-1 in the latter, but not in the former. Suppressing uPA function with a specific uPA inhibitor, B428, or with siRNA against uPA reduced in vitro invasiveness of KKU-M213 cells, demonstrating the requirement for uPA in the invasiveness of CCA cells. Therefore, our in vivo and in vitro studies suggest that uPA is an important requirement for the invasion process of CCA.

CONCLUSION

uPA expression correlates with lymphatic invasion and metastasis in vivo and is required for CCA cell invasion in vitro, suggesting its potential as a therapeutic target.

Prognostic relevance of tumour cell-associated uPAR expression in invasive ductal breast carcinoma

AIMS

The urokinase-type plasminogen activator receptor (uPAR) is a key molecule for pericellular proteolysis in tumour cell invasion and metastasis. The aim was to evaluate the prognostic impact of uPAR in invasive breast cancer dependent on which cell types within the tumour express uPAR.

METHODS AND RESULTS

uPAR expression was analysed by immunohistochemistry in 270 tumour tissue specimens of invasive ductal breast carcinomas using tissue microarrays. For evaluation of uPAR immunoexpression we used the epitope-mapped, uPAR domain II-specific monoclonal antibody IID7. High uPAR score values in both tumour cells (uPAR-Tc) and stromal cells were significantly related to high tumour grade (G3), and inversely correlated with oestrogen receptor status. On multivariate analysis, high uPAR-Tc values contributed independent prognostic information for disease-free survival (hazard ratio 1.93, P = 0.007) when adjusted for prognostically relevant clinicopathological parameters, whereas uPAR expression in stromal cells was not related to prognosis. In addition, elevated uPAR-Tc values were found to be prognostic indicators in clinically relevant subgroups of patients with invasive breast cancer.

CONCLUSIONS

In invasive breast cancer uPAR expression in invasive carcinoma cells, but not in stromal cells, has a significant impact on patients' prognosis, and contributes to a more aggressive tumour phenotype.

IGF binding proteins (IGFBPs) and regulation of breast cancer biology

The IGFBP family comprises six proteins with high affinity for the IGFs. Changes in the balance of the components of the IGF system may contribute to the progression of breast cancer. In tumours the abundance of IGFBPs relates to the estrogen receptor status and their production in the breast is controlled by hormones, principally estrogen and progesterone. Important interactions occur between IGFBPs and key growth regulators such as TGF-beta, PTEN and EGF which are reviewed. The conflicting observations between the effects of IGFBPs on the risk of breast cancer, in particular IGFBP-3, obtained from epidemiology studies in comparison to in vivo observations are highlighted and potential explanations provided. The functional activity of IGFBPs can also be affected by proteolysis, phosphorylation and glycosylation and the implications of these are described. The IGFs are generally present at levels far in excess of that required for maximal receptor stimulation, and the IGFBPs are critical regulators of their cellular actions. IGFBPs can affect cell function in an IGF-dependent or independent manner. The key mechanisms underlying the intrinsic actions of the IGFBPs are still in debate. IGF bioactivity locally in the breast is influenced not only by local tissue expression and regulation of IGFs, IGFBPs and IGFBP proteases, but also by these factors delivered from the circulation. Finally, the therapeutic potential of IGFBPs-2 and -3 are considered together with key questions that still need to be addressed.