A prospective study on the prognostic significance of urokinase-type plasminogen activator levels in breast cancer tissue

uPA and PAI-1 as biomarkers in breast cancer: validated for clinical use in level-of-evidence-1 studies

Urokinase plasminogen activator (uPA) is an extracellular matrix-degrading protease involved in cancer invasion and metastasis, interacting with plasminogen activator inhibitor-1 (PAI-1), which was originally identified as a blood-derived endogenous fast-acting inhibitor of uPA. At concentrations found in tumor tissue, however, both PAI-1 and uPA promote tumor progression and metastasis. Consistent with the causative role of uPA and PAI-1 in cancer dissemination, several retrospective and prospective studies have shown that elevated levels of uPA and PAI-1 in breast tumor tissue are statistically independent and potent predictors of poor patient outcome, including adverse outcome in the subset of breast cancer patients with lymph node-negative disease. In addition to being prognostic, high levels of uPA and PAI-1 have been shown to predict benefit from adjuvant chemotherapy in patients with early breast cancer. The unique clinical utility of uPA/PAI-1 as prognostic biomarkers in lymph node-negative breast cancer has been confirmed in two independent level-of-evidence-1 studies (that is, in a randomized prospective clinical trial in which the biomarker evaluation was the primary purpose of the trial and in a pooled analysis of individual data from retrospective and prospective studies). Thus, uPA and PAI-1 are among the best validated prognostic biomarkers currently available for lymph node-negative breast cancer, their main utility being the identification of lymph node-negative patients who have HER-2-negative tumors and who can be safely spared the toxicity and costs of adjuvant chemotherapy. Recently, a phase II clinical trial using the low-molecular-weight uPA inhibitor WX-671 reported activity in metastatic breast cancer.

Exposure of MCF-7 Breast Cancer Cells to Electromagnetic Fields Up-Regulates the Plasminogen Activator System

Effects of electromagnetic fields (EMFs) on the incidence of breast cancer (BC) have been proposed by a number of epidemiological studies. The molecular mechanism of the impact of EMFs on cells is not yet clear, although changes in gene expression have been reported in various cellular systems. In this investigation, the interference of low-frequency EMFs with the plasminogen activator system was examined in BC cells.

MCF-7 BC cells from 2 different sources were exposed to highly homogeneous 50-Hz EMFs. Changes in gene expression were analyzed by reverse transcriptase-polymerase chain reaction.

In MCF-7 cells exposed to 1.2 μT EMF expression of the urokinase plasminogen activator gene and of plasminogen-activator inhibitor-1 was markedly increased. The expression of the receptor for urokinase plasminogen activator was only marginally increased in 1 of the 2 tested cell lines and expression of the tissue plasminogen activator was at least slightly down-regulated in BC cells exposed to EMFs.

EMFs may be able to increase the metastatic potential of breast tumors. The use of our newly established exposure system for EMFs may allow us to study the signaling processes involved in the induction of a metastatic phenotype of breast cancer cells.

[A 65-year-old female patient with breast cancer accompanied by thrombocytopenia and hyperfibrinolysis]

Tumor diseases can be accompanied by paraneoplastic syndromes. Low platelet counts and hyperfibrinolysis led to the diagnosis of recurrent breast cancer in this case. A tumour disease with disturbed hemostasis caused by both plasmatic coagulation and thrombocytopenia has not yet been reported.

Time-dependent relevance of steroid receptors in breast cancer

PURPOSE

To analyze the time-dependent prognostic role of the investigated variables, considered, when appropriate, on a continuous scale, for the purpose of evaluating and describing the interrelationships between clinically relevant patient and tumor characteristics (age, size and histology, and estrogen receptor [ER] and progesterone receptor content) and the risk of new disease manifestation.

PATIENTS AND METHODS

We applied a flexible statistical model to a case series of 1,793 patients with axillary lymph node-negative breast cancer with a minimal potential follow-up of 10 years. To avoid a potential confounding effect of adjuvant treatment, only patients given local-regional therapy until relapse were considered.

RESULTS

ER content and tumor size (adjusted for all the other covariates) showed a time-dependent relationship with the risk of new disease manifestations. In particular, ER content failed to show a prognostic effect within the first years of follow-up; thereafter, a positive association with risk of relapse was observed. For tumor size, within the first years of follow-up, the risk of relapse was directly related to size for only tumors up to 2.5 cm in diameter; thereafter, the impact on prognosis progressively decreased.

CONCLUSION

The availability of a long follow-up on a large breast cancer series, as well as the use of innovative statistical approaches, allowed us to explore the functional relation between steroid receptors and clinical outcome and to generate a hypothesis on the involvement of ER in favoring long-term metastasis development.

Urokinase plasminogen activator: a prognostic marker in multiple types of cancer

Urokinase plasminogen activator (uPA) is a serine protease causally involved in cancer invasion and metastasis. Consistent with its role in cancer spread, uPA has been shown to be a prognostic marker in a variety of malignancies, especially breast cancer. Approximately 20 different groups have shown that high levels of uPA in breast tumor tissue predict poor outcome. As a prognostic marker in breast cancer, uPA provides information that is independent of traditionally used factors such as tumor size, tumor grade, axillary node status and estrogen receptor status. Furthermore, uPA is prognostic in node-negative patients, and a clinical trial is currently under way to assess whether uPA and its inhibitor, plasminogen activator inhibitor-1, can differentiate between the majority of node-negative breast cancer patients who are cured by surgery from the minority who might benefit from adjuvant therapy. uPA is also prognostic in other malignancies, such as gastric, colorectal, esophageal, renal, endometrial, and ovarian cancers. uPA may thus be a prognostic indicator for multiple types of adenocarcinoma.

Clinical relevance of the urokinase plasminogen activator system in breast cancer

Until recently clinical features and the hormone-receptor status were the only factors used to select systemic (adjuvant) treatment for breast cancer patients. Other biological factors are needed as well to predict the probability of relapse and response with more certainty. The uPA-system is such a prognostic and predictive factor in breast cancer. In this review, the results of research groups that have related relapse-free survival to the quantitative levels of uPA-system proteins and/or activities are discussed. Only studies that described the results from assays on cytosols or triton extracts of breast tumours were included. The levels of uPA-system proteins help to predict the probability of relapse and response, and knowledge of the expression levels of the various components of the uPA-system may lead to new treatment modalities targeted on specific properties of the uPA-system.

Cancer metastasis: an update

OBJECTIVES

To highlight recent research, focusing on inhibiting or blocking the metastatic process, that can be expected to be introduced to the clinical settings in the near future.

DATA SOURCES

Published scientific papers and review articles relating to research involving the metastatic process.

CONCLUSIONS

An explosion of research findings is being incorporated into plausible strategies that will allow cancer treatment options to be tailored to an individual patient's disease status.

IMPLICATIONS FOR NURSING PRACTICE

With new information about the metastatic process becoming available at a rapid pace, it is imperative that nurses continue to be well-informed and prepared to provide safe quality care to people facing cancer while implementing the new treatment strategies.