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

Tissue inhibitor of metalloproteinase-1 (TIMP-1) as a prognostic biomarker in gastrointestinal cancer: a meta-analysis

Background

Tissue inhibitor of metalloproteinase 1 (TIMP-1) has recently been shown to be dependent on or independent of Matrix metalloproteinases (MMPs) in its roles in tumorigenesis and progression. This appreciation has prompted various studies assessing the prognostic value of TIMP-1 in patients with gastrointestinal cancer, however, the conclusions were still inconsistent. The aim of this study was to assess the prognostic value of TIMP-1-immunohistochemistry (IHC) staining and pretreatment serum/plasma TIMP-1 level in gastrointestinal cancer survival as well as the association between TIMP-1 and clinicopathologic features.

Methods

The meta-analysis was registered in the International Prospective Register of Systematic Reviews (PROSPERO; Registration NO. CRD42020185407) and followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. A highly sensitive literature search was performed in electronic databases including PubMed, EMBASE and the Cochrane Library. Heterogeneity analysis was conducted using both chi-square-based Q statistics and the I² test. The pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated to assess the prognostic value of TIMP-1 using the fixed-effects model. Odds ratios (ORs) with 95% CIs were calculated to evaluate the associations between TIMP-1 and clinicopathological characteristics. The meta-analysis was conducted using STATA 12.0 software.

Results

A total of 3,958 patients from twenty-two studies were included in the meta-analysis. Elevated TIMP-1 levels were significantly associated with poor survival in gastrointestinal cancer (TIMP-1-IHC staining: HR = 2.04, 95% CI [1.59–2.61], I² = 35.7%, P_Q = 0.156; pretreatment serum/plasma TIMP-1 levels: HR = 2.02, 95% CI [1.80–2.28], I² = 0%, P_Q = 0.630). Moreover, clinicopathological parameter data analysis showed that elevated TIMP-1 levels were significantly associated with lymph node metastasis (N1/N2/N3 vs N0: OR = 2.92, 95% CI [1.95–4.38]) and higher TNM stages (III/IV vs I/II: OR = 2.73, 95% CI [1.23–6.04]).

Conclusion

Both TIMP-1-positive IHC staining and high serum/plasma TIMP-1 levels are poor prognostic factors for the survival of gastrointestinal cancer. In addition, TIMP-1 overexpression was correlated with more advanced clinicopathological features.

Functional Relationship and Gene Ontology Classification of Breast Cancer Biomarkers

Breast cancer is a complex disease that still imposes a significant healthcare burden on women worldwide. The etiology of breast cancer is not known but significant advances have been made in the area of early detection and treatment. The advent of advanced molecular biology techniques, mapping of the human genome and availability of high throughput genomic and proteomic strategies opens up new opportunities and will potentially lead to the discovery of novel biomarkers for early detection and prognostication of breast cancer. Currently, many biomarkers, particularly the hormonal and epidermal growth factor receptors, are being utilized for breast cancer prognosis. Unfortunately, none of the biomarkers in use have sufficient diagnostic, prognostic and/or predictive power across all categories and stages of breast cancer. It is recognized that more useful information can be generated if tumors are interrogated with multiple markers. But choosing the right combination of biomarkers is challenging, because 1) multiple pathways are involved, 2) up to 62 genes and their protein products are potentially involved in breast cancer-related mechanisms and 3) the more markers evaluated, the more the time and cost involved. This review summarizes the current literature on selected biomarkers for breast cancer, discusses the functional relationships, and groups the selected genes based on a Gene Ontology™ classification.

Preoperative Plasma Soluble Urokinase Plasminogen Activator Receptor as a Prognostic Marker in Rectal Cancer Patients. An Eortc-Receptor and Biomarker Group Collaboration

Background and aims

Since approximately 30% of patients with Dukes’ stage B colorectal cancer will experience disease recurrence within five years of primary treatment, current staging of patients with early colorectal cancer apparently fails to adequately predict patient outcome. It has previously been shown that the preoperative plasma concentration of soluble urokinase plasminogen activator receptor (suPAR) is associated with the survival of patients with early colorectal cancer. In this study we sought to confirm the independent prognostic value of suPAR in rectal cancer.

Methods

suPAR was retrospectively determined by two different versions of a suPAR ELISA in preoperatively collected plasma samples from a Swedish (n=354) and a Danish (n=255) cohort of rectal cancer patients.

Results

In both cohorts the suPAR concentration was significantly higher in Dukes’ stage D patients than in Dukes’ stage A-C patients (p<0.0001). Among Dukes’ stage A-C patients, no differences in median suPAR values were seen. In univariate analysis, continuous suPAR was found to be associated with survival (p<0.0001 in both cohorts). Of particular interest was that similar results were obtained for Dukes’ stage A and B patients when analyzed separately. In multivariate analysis, continuous suPAR was found in both cohorts to be independent of Dukes’ stage.

Conclusions

This study confirms that the preoperative concentration of plasma suPAR contains independent prognostic information on patients with rectal cancer. This result was independent of the two different versions of an in-house suPAR ELISA used to perform the analyses. The next step in the evaluation of suPAR as a prognostic parameter in rectal cancer will be to launch an appropriately dimensioned prospective study where the benefit of applying preoperative plasma suPAR measurement to clinical decision-making regarding adjuvant therapy is assessed.

Diversity and functional evolution of the plasminogen activator system

The urokinase plasminogen activator system is a family of serine proteases which consists of uPA (urokinase plasminogen activator), uPAR (urokinase type plasminogen activator receptor) and PAI-1 (plasminogen activator inhibitor 1). In addition to their significant roles in activation, these proteases act as key regulators of the tumor microenvironment and are involved in the metastatic process in many cancers. High levels of uPA system proteases in many human cancer predicts poor patient prognosis and strongly indicated a key role of uPA system in cancer metastasis. Individual components of uPA system are found to be differentially expressed in cancer cells compared to normal cells and therefore are potential therapeutic targets. In this review, we present the molecular and cellular mechanisms underlying the role of uPA system in cancer progression. Epithelial to mesenchymal transitions (EMT) is the main cause of the cancer cell metastasis. We have also attempted to relate the role of uPA signaling in EMT of cancer cells.

Plasminogen Activator System and Breast Cancer: Potential Role in Therapy Decision Making and Precision Medicine

Shifting from the historical TNM paradigm to the determination of molecular and genetic subtypes of tumors has been a major improvement to better picture cancerous diseases. The sharper the picture is, the better will be the possibility to develop subsequent strategies, thus achieving higher efficacy and prolonged survival eventually. Recent studies suggest that urokinase-type plasminogen activator (uPA), uPA Receptor (uPAR), and plasmino-gen activator inhibitor-1 (PAI-1) may play a critical role in cancer invasion and metastasis. Consistent with their role in cancer dissemination, high levels of uPA, PAI-1, and uPAR in multiple cancer types correlate with dismal prognosis. In this respect, upfront determination of uPA and PAI-1 as invasion markers has further opened up the possibilities for individualized therapy of breast cancer. Indeed, uPA and PAI-1 could help to classify patients on their risk for metastatic spreading and subsequent relapse, thus helping clinicians in their decision-making process to propose, or not propose, adjuvant therapy. This review covers the implications for cancer diagnosis, prognosis, and therapy of uPA and PAI-1, and therefore how they could be major actors in the development of a precision medicine in breast cancer.

Combined Proteomics and Transcriptomics Identifies Carboxypeptidase B1 and Nuclear Factor κB (NF-κB) Associated Proteins as Putative Biomarkers of Metastasis in Low Grade Breast Cancer

Current prognostic factors are insufficient for precise risk-discrimination in breast cancer patients with low grade breast tumors, which, in disagreement with theoretical prognosis, occasionally form early lymph node metastasis. To identify markers for this group of patients, we employed iTRAQ-2DLC-MS/MS proteomics to 24 lymph node positive and 24 lymph node negative grade 1 luminal A primary breast tumors. Another group of 48 high-grade tumors (luminal B, triple negative, Her-2 subtypes) was also analyzed to investigate marker specificity for grade 1 luminal A tumors. From the total of 4405 proteins identified (FDR < 5%), the top 65 differentially expressed together with 30 previously identified and control markers were analyzed also at transcript level. Increased levels of carboxypeptidase B1 (CPB1), PDZ and LIM domain protein 2 (PDLIM2), and ring finger protein 25 (RNF25) were associated specifically with lymph node positive grade 1 tumors, whereas stathmin 1 (STMN1) and thymosin beta 10 (TMSB10) associated with aggressive tumor phenotype also in high grade tumors at both protein and transcript level. For CPB1, these differences were also observed by immunohistochemical analysis on tissue microarrays. Up-regulation of putative biomarkers in lymph node positive (versus negative) luminal A tumors was validated by gene expression analysis of an independent published data set (n = 343) for CPB1 (p = 0.00155), PDLIM2 (p = 0.02027) and RELA (p = 0.00015). Moreover, statistically significant connections with patient survival were identified in another public data set (n = 1678). Our findings indicate unique pro-metastatic mechanisms in grade 1 tumors that can include up-regulation of CPB1, activation of NF-κB pathway and changes in cell survival and cytoskeleton. These putative biomarkers have potential to identify the specific minor subpopulation of breast cancer patients with low grade tumors who are at higher than expected risk of recurrence and who would benefit from more intensive follow-up and may require more personalized therapy.

Estrogen receptor alpha mediates epithelial to mesenchymal transition, expression of specific matrix effectors and functional properties of breast cancer cells

The 17β-estradiol (E2)/estrogen receptor alpha (ERα) signaling pathway is one of the most important pathways in hormone-dependent breast cancer. E2 plays pivotal roles in cancer cell growth, survival, and architecture as well as in gene expression regulatory mechanisms. In this study, we established stably transfected MCF-7 cells by knocking down the ERα gene (designated as MCF-7/SP10+ cells), using specific shRNA lentiviral particles, and compared them with the control cells (MCF-7/c). Interestingly, ERα silencing in MCF-7 cells strongly induced cellular phenotypic changes accompanied by significant changes in gene and protein expression of several markers typical of epithelial to mesenchymal transition (EMT). Notably, these cells exhibited enhanced cell proliferation, migration and invasion. Moreover, ERα suppression strongly affected the gene and protein expression of EGFR and HER2 receptor tyrosine kinases, and various extracellular matrix (ECM) effectors, including matrix metalloproteinases and their endogenous inhibitors (MMPs/TIMPs) and components of the plasminogen activation system. The action caused by E2 in MCF-7/c cells in the expression of HER2, MT1-MMP, MMP1, MMP9, uPA, tPA, and PAI-1 was abolished in MCF-7/SP10+ cells lacking ERα. These data suggested a regulatory role for the E2/ERα pathway in respect to the composition and activity of the extracellular proteolytic molecular network. Notably, loss of ERα promoted breast cancer cell migration and invasion by inducing changes in the expression levels of certain matrix macromolecules (especially uPA, tPA, PAI-1) through the EGFR-ERK signaling pathway. In conclusion, loss of ERα in breast cancer cells results in a potent EMT characterized by striking changes in the expression profile of specific matrix macromolecules highlighting the potential nodal role of matrix effectors in breast cancer endocrine resistance.

Molecular diagnostic testing in breast cancer

OBJECTIVES

An overview of molecular tests used in the treatment of breast cancer, organized by stage and clinical condition.

DATA SOURCES

Systematic review of scientific literature, guideline recommendations, and data published by test manufacturers.

CONCLUSION

Several molecular tests that analyze expression of cancer-related genes have been validated in clinical trials and are recommended by clinical practice guidelines to inform diagnosis and treatment decisions for personalized interventions.

IMPLICATIONS FOR NURSING PRACTICE

Molecular testing has become an important part of patient care for those with breast cancer. Oncology nurses must understand this methodology to prescribe tests, interpret the results, and provide guidance to patients.

An ultra-sensitive immunoassay for quantifying biomarkers in breast tumor tissue

Urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor type-1 (PAI-1) have been validated at the highest level of evidence as clinical biomarkers of prognosis in breast cancer. The American Society of Clinical Oncology recommends using uPA and PAI-1 levels in breast tumors for deciding whether patients with newly diagnosed node-negative breast cancer can forgo adjuvant chemotherapy. The sole validated method for quantifying uPA and PAI-1 levels in breast tumor tissue is a colorimetric ELISA assay that takes 3 days to complete and requires 100-300 mg of fresh or frozen tissue. In this study we describe a new assay method for quantifying PAI-1 levels in human breast tumor tissue. This assay combines pressure-cycling technology to extract PAI-1 from breast tumor tissue with a highly sensitive liposome polymerase chain reaction immunoassay for quantification of PAI-1 in the tissue extract. The new PAI-1 assay method reduced the total assay time to one day and improved assay sensitivity and dynamic range by >100, compared to ELISA.

Annexin A2 promotes glioma cell invasion and tumor progression

Gliomas are highly invasive, lethal brain tumors. Tumor-associated proteases play an important role in glioma progression. Annexin A2 is overexpressed in many cancers and correlates with increased plasmin activity on the tumor cell surface, which mediates degradation of extracellular matrix and promotes neoangiogenesis to facilitate tumor growth. In this study, we used two glioma cell lines, mouse GL261-EGFP and rat C6/LacZ, as well as stable clones transfected with an annexin A2 knockdown construct. We find that the annexin A2 knockdown decreased glioma cell migration in vitro and decreased membrane-bound plasmin activity. In vivo, we injected the glioma cells into the rodent brain and followed glioma progression. Knockdown of annexin A2 in glioma cells decreased tumor size and slowed tumor progression, as evidenced by decreased invasion, angiogenesis, and proliferation, as well as increased apoptosis in the tumor tissue of the annexin A2 knockdown group. Moreover, we report that the levels of expression of annexin A2 in human glioma samples correlate with their degree of malignancy. Together, our findings demonstrate that inhibition of annexin A2 expression in glioma cells could become a new target for glioma therapy.

Prognostic importance of PAI-1 in node negative breast cancer patients--results after 10 years of follow up

The serine protease urokinase-type plasminogen activator (uPA) and its inhibitor (PAI-1) play key roles in the proteolytic cascade involved in physiological and pathological degradation of the extracellular matrix. The aim of this study was to determine the prognostic importance of PAI-1 expression in tumor cells in node-negative breast cancer patients that did not receive adjuvant chemotherapy. We used immunohistochemistry (IHC) as a detection method. The study retrospectively included 133 ductal invasive breast cancer patients from the Clinical Hospital Center Zagreb, Croatia, surgically treated in a two-year interval (1998-1999) with 10 years of follow up. The Cox proportional hazard regression test with stepwise variable selection was used to calculate the relative effect of investigated data on patients' prognosis. Univariate analysis showed that all investigated factors, such as lymph node involvement (p=0.025), tumor grade (p<0.001), estrogen receptor status (p=0.011), vascular invasion (p=0.001), HER2 overexpression (p<0.001), and proliferative index (p<0.001), had a statistically significant influence on patients' OS. Multivariate statistical analysis showed that only HER-2 (p<0.001) can be considered an independent, statistically significant poor prognostic factor. In patients with negative lymph nodes that did not receive adjuvant chemotherapy, we found a significant correlation in overall survival (p=0.009), which is favorable for PAI-1 negative tumors. In conclusion, it seems that PAI-1 in primary breast cancer tissue correlates with disease aggressiveness and has a strong prognostic impact on primary breast cancer, and is a strong prognostic factor for node-negative patients that did not receive chemotherapy.

Forkhead transcription factor foxq1 promotes epithelial-mesenchymal transition and breast cancer metastasis

Epithelial-mesenchymal transition (EMT) promotes cancer invasion and metastasis, but the integrative mechanisms that coordinate these processes are incompletely understood. In this study, we used a cross-species expression profiling strategy in metastatic cell lines of human and mouse origin to identify 22 up-regulated and 12 down-regulated genes that are part of an essential genetic program in metastasis. In particular, we identified a novel function in metastasis that was not previously known for the transcription factor Forkhead Box Q1 (Foxq1). Ectopic expression of Foxq1 increased cell migration and invasion in vitro, enhanced the lung metastatic capabilities of mammary epithelial cells in vivo, and triggered a marked EMT. In contrast, Foxq1 knockdown elicited converse effects on these phenotypes in vitro and in vivo. Neither ectopic expression nor knockdown of Foxq1 significantly affected cell proliferation or colony formation in vitro. Notably, Foxq1 repressed expression of the core EMT regulator E-cadherin by binding to the E-box in its promoter region. Further mechanistic investigation revealed that Foxq1 expression is regulated by TGF-β1, and that Foxq1 knockdown blocked TGF-β1-induced EMT at both morphological and molecular levels. Our findings highlight the feasibility of cross-species expression profiling as a strategy to identify metastasis-related genes, and they reveal that EMT induction is a likely mechanism underlying a novel metastasis-promoting function of Foxq1 defined here in breast cancer.

Optimizing chemotherapy regimens for patients with early-stage breast cancer

While moving toward a personalized treatment approach for early breast cancer, it is clear that treatment must be tailored specifically to the tumor's and patient's characteristics. Understanding the tumor's molecular signature and using validated prognostic and predictive tools can assist the oncologist in providing the optimal therapy. Through a shared decision process, a treatment plan must be formulated based on the tumor's biologic phenotype, taking into consideration the patient's comorbidities and preferences. This review summarizes the available tools that can assist in this process and provides an overview of the chemotherapy regimens approved for the adjuvant treatment of patients with early-stage breast cancer.

Plasminogen activator inhibitor-1 (PAI-1): a key factor linking fibrinolysis and age-related subclinical and clinical conditions

INTRODUCTION

The close relationship existing between aging and thrombosis has growingly been studied in this last decade. The age-related development of a prothrombotic imbalance in the fibrinolysis homeostasis has been hypothesized as the basis of this increased cardiovascular and cerebrovascular risk. Fibrinolysis is the result of the interactions among multiple plasminogen activators and inhibitors constituting the enzymatic cascade, and ultimately leading to the degradation of fibrin. The plasminogen activator system plays a key role in a wide range of physiological and pathological processes.

METHODS

Narrative review.

RESULTS

Plasminogen activator inhibitor-1 (PAI-1) is a member of the superfamily of serine-protease inhibitors (or serpins), and the principal inhibitor of both the tissue-type and the urokinase-type plasminogen activator, the two plasminogen activators able to activate plasminogen. Current evidence describing the central role played by PAI-1 in a number of age-related subclinical (i.e., inflammation, atherosclerosis, insulin resistance) and clinical (i.e., obesity, comorbidities, Werner syndrome) conditions is presented.

CONCLUSIONS

Despite some controversial and unclear issues, PAI-1 represents an extremely promising marker that may become a biological parameter to be progressively considered in the prognostic evaluation, in the disease monitoring, and as treatment target of age-related conditions in the future.

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.

Development of a Mammalian suspension culture for expression of active recombinant human urokinase-type plasminogen activator

The development of specific catalytic inhibitors for the serine protease urokinase-type plasminogen activator (uPA) has been hindered due to difficulties in producing sufficient amounts of active recombinant uPA that is catalytically equivalent to native uPA. The purpose of this study was to develop an efficient system for the expression of recombinant human uPA that exhibits comparable proteolytic activity to that of the native protein. Since post-translational modifications (e.g. glycosylations) of uPA are necessary for efficient proteolytic activity, we have used a mammalian cell line [Chinese hamster ovary (CHO)-S] to express recombinant human uPA. CHO-S cells were selected to stably express full-length recombinant human uPA containing a hexahistidine tag at its C-terminus to permit purification by nickel-based affinity chromatography. Secretion of recombinant uPA into the culture media was confirmed by immunoblotting and the presence of an N-linked glycosylation was confirmed by PNGase sensitivity. Enzymatic activity of purified recombinant uPA was demonstrated using zymography and quantitatively compared to native uPA by kinetic analysis using an uPA-specific substrate. Native uPA and the recombinant uPA demonstrated comparable K(m) values (55.7 and 39 muM, respectively). Furthermore, inhibition studies using benzamidine resulted in a K(i) of 195 muM for native uPA, while recombinant uPA had a K(i) of 112 muM. These data indicate that recombinant human uPA expressed by CHO-S cells is functionally comparable to native uPA.

PEGylated DX-1000: pharmacokinetics and antineoplastic activity of a specific plasmin inhibitor

Novel inhibitors of the urokinase-mediated plasminogen (plg) activation system are potentially of great clinical benefit as anticancer treatments. Using phage display, we identified DX-1000 a tissue factor pathway inhibitor-derived Kunitz domain protein which is a specific high-affinity inhibitor of plasmin (pln) (K(i) = 99 pM). When tested in vitro, DX-1000 blocks plasmin-mediated pro-matrix metalloproteinase-9 (proMMP-9) activation on cells and dose-dependently inhibits tube formation, while not significantly affecting hemostasis and coagulation. However, this low-molecular weight protein inhibitor ( approximately 7 kDa) exhibits rapid plasma clearance in mice and rabbits, limiting its potential clinical use in chronic diseases. After site-specific PEGylation, DX-1000 retains its activity and exhibits a decreased plasma clearance. This PEGylated derivative is effective in vitro, as well as potent in inhibiting tumor growth of green fluorescent protein (GFP)-labeled MDA-MB-231 cells. 4PEG-DX-1000 treatment causes a significant reduction of urokinase-type plasminogen activator (uPA) and plasminogen expressions, a reduction of tumor proliferation, and vascularization. 4PEG-DX-1000 treatment significantly decreases the level of active mitogen-activated protein kinase (MAPK) in the primary tumors and reduces metastasis incidence. Together, our results demonstrate the potential value of plasmin inhibitors as therapeutic agents for blocking breast cancer growth and metastasis.

American Society of Clinical Oncology 2007 update of recommendations for the use of tumor markers in breast cancer

PURPOSE

To update the recommendations for the use of tumor marker tests in the prevention, screening, treatment, and surveillance of breast cancer.

METHODS

For the 2007 update, an Update Committee composed of members from the full Panel was formed to complete the review and analysis of data published since 1999. Computerized literature searches of MEDLINE and the Cochrane Collaboration Library were performed. The Update Committee's literature review focused attention on available systematic reviews and meta-analyses of published tumor marker studies. In general, significant health outcomes (overall survival, disease-free survival, quality of life, lesser toxicity, and cost-effectiveness) were used for making recommendations. Recommendations and

CONCLUSIONS

Thirteen categories of breast tumor markers were considered, six of which were new for the guideline. The following categories showed evidence of clinical utility and were recommended for use in practice: CA 15-3, CA 27.29, carcinoembryonic antigen, estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2, urokinase plasminogen activator, plasminogen activator inhibitor 1, and certain multiparameter gene expression assays. Not all applications for these markers were supported, however. The following categories demonstrated insufficient evidence to support routine use in clinical practice: DNA/ploidy by flow cytometry, p53, cathepsin D, cyclin E, proteomics, certain multiparameter assays, detection of bone marrow micrometastases, and circulating tumor cells.

Deciphering the molecular basis of breast cancer metastasis with mouse models

Breast cancer begins as a localized disease, but has the potential to spread to distant sites within the body. This process--known as metastasis--is the leading cause of death from breast cancer. Whether the ability of cancer cells to metastasize is an intrinsic or acquired feature is currently a topic of considerable debate. Nevertheless, the key cellular events required for metastasis are generally accepted. These include invasion of the surrounding stromal tissue, intravasation, evasion of programmed cell death, arrest within the vasculature at a distant site, extravasation, and establishment and growth within a new microenvironment. The development of mouse models that faithfully mimic critical aspects of human neoplasia has been instrumental in framing our current understanding of multistage carcinogenesis. This review examines the advantages and limitations of existing murine models for mammary carcinogenesis for probing the molecular mechanisms that contribute to metastasis, as well as non-invasive tumor imaging approaches to facilitate these investigations.

Urokinase-type plasminogen activator and plasminogen activator inhibitor type-1 mRNA assessment in breast cancer by means of NASBA: correlation with protein expression

Urokinase plasminogen activator (uPA) and its main inhibitor, plasminogen activator inhibitor type-1 (PAI-1) determined in tumor tissue by means of enzyme-linked immunosorbent assay (ELISA) can discriminate patients with primary breast cancer at high risk vs low risk for recurrence. The aim of this study was to analyze uPA and PAI-1 messenger RNA (mRNA) expression by means of quantitative nucleic acid sequence-based amplification (NASBA) on 77 primary breast tumor samples and to correlate this expression with the uPA and PAI-1 protein content. We observed that the 2 markers were significantly overexpressed (uPA, P < .0001; PAI-1, P = .0042) in mRNA in the ELISA+ group. The receiver operating characteristic (ROC) curves demonstrated high concordance between NASBA and ELISA (area under the ROC curve of 0.84 and 0.70 for uPA and PAI-1, respectively) and showed that uPA and PAI-1 status could be predicted by using the molecular assay with sensitivity and specificity values of 80.8% and 82.4% and sensitivity and specificity values of 66.7% and 74.0%, respectively.

Effect of reoxygenation on the hypoxia-induced up-regulation of serine protease inhibitor PAI-1 in head and neck cancer cells

In squamous cell carcinoma of the head and neck (SCCHN), hypoxia is considered a crucial physiological modulator for malignant progression, wherebythe plasminogen activation system is involved in overlapping functions such as moulding of the extracellular matrix, cell proliferation and signal transduction. Little is known about the effects of reoxygenation on the plasminogen activation system in SCCHN cells. Three human SCCHN cell lines (BHY, CAL27, FaDu) and a non-transformed human fibroblast cell line (VH7) were exposed to hypoxic (<0.5% O(2)) conditions for up to 72 h and subsequently reoxygenated at normoxic conditions for 24 h. Urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor-1 (PAI-1) protein concentration and former protein activity were determined by ELISA and complex ELISA, respectively. Reoxygenation induced significant changes in cell-associated and secreted PAI-1 protein compared to the normoxic control. Significant increase in cell-associated and secreted uPA protein after reoxygenation was only observed for some of the cell lines. Determination of uPA-PAI-1 complex formation revealed the release of active protein into the cell supernatant. The beneficial role of reoxygenation during radiation therapy is widely accepted. However, reoxygenation does not seem to counteract the effects induced by hypoxia on the plasminogen activation system. Fatally irradiated reoxygenat- ed tumour cells might still produce sufficient amounts of 'harmful' protein and thus initiate a path for invasion and metastasis for surviving tumour cells.

Protease nexin-1 expression is altered in human breast cancer

Background

Urokinase-type Plasminogen Activator (uPA), a serine protease, plays a pivotal role in human breast cancer metastasis by mediating the degradation of extracellular matrix proteins and promoting cell motility. In more advanced breast cancers, uPA activity is significantly up regulated and serves as a prognostic indicator of poor patient outcome. Classically, regulation of uPA activity, especially in breast cancers, is thought to be mediated by Type 1 Plasminogen Activator Inhibitor (PAI-1). However, we have recently found that a lesser known natural inhibitor of uPA, Protease Nexin 1 (PN-1), is expressed in normal human mammary tissue. Based on this observation, we investigated if PN-1 is also expressed in human breast cancers where it may contribute to the regulation of uPA and participate in the development of a metastatic phenotype.

Results

Using quantitative real-time PCR analysis, we measured PN-1 mRNA expression in tissues obtained from 26 human breast tumor biopsies and compared these values with those obtained from 10 normal breast tissue samples. Since both PAI-1 and uPA expression levels are known to be elevated in metastatic breast cancer, we also measured their levels in our 26 tumor samples for direct comparison with PN-1 expression. We found that PN-1 expression was elevated over that found in normal mammary tissue; an increase of 1.5- to 3.5-fold in 21 of 26 human breast tumors examined. As anticipated, both PAI-1 and uPA mRNA levels were significantly higher in the majority of breast tumors; 19 of 26 tumors for PAI-1 and 22 of 26 tumors for uPA. A quantile box plot of these data demonstrates that the elevated PN-1 expression in breast tumor tissues directly correlates with the increased expression levels found for PAI-1 and uPA.

Conclusion

The fact that PN-1 expression is elevated in human breast cancer, and that its increased expression is directly correlated with increases measured for PAI-1 and uPA, suggests that PN-1 may contribute to the regulation of uPA-mediate tumor cell motility and metastatic spread.

Study of the topographic distribution of ets-1 protein expression in invasive breast carcinomas in relation to tumor phenotype

BACKGROUND

Ets-1 is a transcription factor, implicated in the regulation of expression of various genes'. The aim of the present study was to investigate the expression of ets-1 protein in invasive breast carcinomas and its correlation with classic clinicopathological parameters, patients' survival and various biological markers.

METHODS

Immunohistochemistry was performed in paraffin-embedded tissue specimens from 149 invasive breast carcinomas to detect the proteins ets-1, p53, topoisomerase IIalpha, matrix metalloproteinase-7 (MMP-7) and urokinase-type plasminogen activator receptor (uPAR). Results were subjected to univariate and multivariate statistic analysis.

RESULTS

Ets-1 protein was detected in the 77.9% of the cases in the cytoplasm, in the 46.3% in the nucleus of the malignant cells, and in stromal fibroblasts as well. Cytoplasmic ets-1 was inversely correlated with nuclear and histologic grade of the tumor (p=0.004 and 0.033, respectively) and topoisomerase IIotaalpha (p=0.057), while nuclear ets-1 showed a positive association with p53 (p=0.002). Stromal ets-1 revealed a negative correlation with estrogen receptors (ER) (p=0.003) and a positive one with stromal uPAR and MMP-7 as well (p=0.048 and 0.066, respectively). The univariate statistic analysis showed nuclear ets-1 to be related to a shortened overall survival of the postmenopausal patients (p=0.032).

CONCLUSIONS

Ets-1 seems to be related to a different tumor phenotype according to its topographic distribution, with nuclear localization being associated with decreased apoptotic potential of the malignant cells through its relation to the mutant p53 protein, cytoplasmic being related to a favorable tumor phenotype and stromal ets-1 being related to tumor invasion.

Angiogenesis-associated protein annexin II in breast cancer: selective expression in invasive breast cancer and contribution to tumor invasion and progression

Many advanced human tumors including breast cancer overproduce plasmin that is known to promote angiogenesis and metastasis. The mechanism of this effect is poorly understood. Here we report that annexin II, an endothelial co-receptor for tPA (tissue-type plasminogen activator) and plasminogen, was undetectable in normal and hyperplastic ductal epithelial cells and ductal complexes. By contrast, it was consistently expressed in invasive breast cancer and ductal carcinoma in situ (DCIS) indicating its involvement in breast cancer. Using the well established invasive/metastatic MDA-MB231 cell line and the noninvasive/nonmetastatic MCF-7 human breast cancer cell line, we investigated the mechanism by which annexin II regulates breast cancer progression and metastasis. Western and Northern blot analyses demonstrate selective expression of annexin II in MDA-MB231 cells but not in poorly invasive MCF-7 cells suggesting its participation in invasive breast cancer. Since annexin II is a receptor for plasminogen, we tested whether MDA-MB231 cells are capable of producing plasmin in vitro. MDA-MB231 cell membranes induced plasmin generation in a time-dependent manner while those from MCF-7 cells failed to convert plasminogen to plasmin. The generated plasmin is capable of degrading ECM consequently facilitating cell invasion and migration, biological functions required for angiogenesis and metastasis. Plasmin generation and its dependent invasion and migration can be blocked by a monoclonal antibody to annexin II or angiostatin, potent inhibitors of angiogenesis, breast cancer, and metastasis. Our findings indicate that annexin II-dependent localized plasmin generation by human breast cancer cells could contribute to angiogenesis and metastasis. These results suggest that annexin II may be an attractive target for new anti-angiogenic and anti-breast cancer therapies.

Host-derived plasminogen activator inhibitor-1 (PAI-1) concentration is critical for in vivo tumoral angiogenesis and growth

Plasminogen activator inhibitor type 1 (PAI-1) plays a key role in tumor progression and is believed to control proteolytic activity and cell migration during angiogenesis. We report here that host PAI-1, at physiological concentration, promotes in vivo tumor invasion and angiogenesis. In sharp contrast, inhibition of tumor vascularization was observed when PAI-1 was produced at supraphysiologic levels, either by host cells (transgenic mice overexpressing PAI-1) or by tumor cells (after transfection with murine PAI-1 cDNA). This study provides for the first time in vivo evidence for a dose-dependent effect of PAI-1 on tumor angiogenesis. Of great interest is the finding that PAI-1 produced by tumor cells, even at high concentration, did not overcome the absence of PAI-1 in the host, emphasizing the importance of the cellular source of PAI-1.

Stromal cell involvement in cancer

Solid tumors co-opt the body's endogenous extracellular proteolytic machinery for their invasion and metastasis. This is supported by a large number of independent observations ranging from histochemical and prognostic studies of cancer patient material to animal experiments. There are several extracellular proteolytic systems that are relevant in the context of cancer, but the plasminogen activation (PA) system and the matrix metalloproteases (MMPs) remain the most thoroughly investigated. Localization studies by immunohistochemistry and in situ mRNA hybridization in tumors of common human cancers have repeatedly identified members of the PA and MMP systems in stromal cells. The cancer cells, of epithelial origin, contribute PA and MMP components in some cases, but their contribution fades in comparison with the overwhelming expression of proteolytic components by fibroblasts, macrophages, endothelial cells, and other stromal cells. Ideal animal models of human cancers should recapitulate this fundamental proteolytic aspect of tumor biology. However, in the transplantable tumor models where PA or MMP components have been studied at the cellular level in vivo, this is most often not the case. Transgenic cancer models may provide a closer parallel to the human situation, in that PA and MMP components are synthesized by the tumor stroma. The pivotal role of stromal cells has been confirmed experimentally in mouse models in which the expression pattern of proteolytic components is strongly reminiscent of human tumors. In these models it is possible to reconstitute the wild-type tumor characteristics of proteolytically deficient tumor-bearing mice by transplantation with wild-type fibroblasts or hemapoietic cells. These studies collectively show that cancer-associated proteolysis is a collaborative effort of malignant cancer cells and various stromal cells--a collaboration in which stromal cells contribute the majority of the active proteolytic components that are necessary for the invasive behavior of the tumors. This cellular division of labor positions the stromal cells as prime targets for future research and possibly therapy. Vascular endothelial cells are already the focus of intense therapeutically relevant research, but tumor-associated fibroblasts, macrophages, neutrophils, lymphendothelial cells, etc. provide additional largely unexplored territory in the ongoing search for efficient countermeasures against invasive cancer.

Prognostic value of maspin mRNA expression in ER alpha-positive postmenopausal breast carcinomas

Maspin, a member of the serpin family, has a role in cell migration, angiogenesis and apoptosis. Little is known of the clinical significance of maspin gene expression in human cancers. We developed a real-time quantitative RT-PCR assay to quantify the full range of maspin mRNA copy numbers in a series of 10 ER alpha-positive and 10 ER alpha-negative breast tumours. We observed a statistical link between low maspin mRNA levels and positive oestrogen status (P=0.0012). In consequence, to better assess the prognostic value of maspin gene expression in breast cancer, we then quantified maspin mRNA content in an additional independent well-defined cohort of 105 ER alpha-positive postmenopausal breast cancer patients treated with primary surgery followed by adjuvant tamoxifen alone. Maspin expression varied widely in tumour tissues (by nearly four orders of magnitude), being underexpressed in 33 out of 105 tumours (31.4%) and overexpressed in 24 out of 105 tumours (22.9%) relative to normal breast tissues. Immunohistochemical studies demonstrated that maspin protein was strictly expressed in myoepithelial cells of normal breast tissue and in tumour epithelial cells, exclusively in maspin-overexpressing tumours. Patients with tumours overexpressing the maspin gene had significantly shorter relapse-free survival after surgery than patients whose tumours normally expressed or underexpressed maspin (P=0.0011). The prognostic significance of maspin overexpression persisted in Cox multivariate regression analysis (P=0.0024). These findings show that the maspin mRNA level can have important prognostic significance in human breast cancer, and point to the maspin gene as a putative molecular predictor of hormone responsiveness in breast cancer.

T1 breast cancer: identification of patients at low risk of axillary lymph node metastases

OBJECTIVE

The status of the axillary lymph nodes is one of the most important prognostic factors in patients with breast cancer. A panel of molecular markers of tumor aggressiveness in addition to conventional clinical and histopathologic features were analyzed in an attempt to identify a subgroup of patients with a low risk of axillary lymph node metastases.

MATERIAL AND METHODS

Data from 358 patients with T1 breast cancer who underwent level I/II axillary lymph node dissection (ALND) were investigated. Hormone receptor status, Ki-67, S-phase fraction, DNA ploidy, HER-2/neu, p53, epidermal growth factor receptor, urokinase type plasminogen activator, plasminogen activator inhibitor-1, bone marrow micrometastases as well as patient age, menopausal status, tumor site, tumor size, histologic type, tumor grade, carcinoma in situ, multifocality, and lymph vascular invasion (LVI) were studied to predict axillary lymph node status.

RESULTS

In a multivariate logistic regression analysis LVI (present v.s. not present), Ki-67 (> or = 18% v.s. < 18%), tumor size (1.1-2 cm v.s. < or = 1 cm), and histologic grade (G3 v.s. G1/2) were identified as independent predictive factors of axillary lymph node metastases. Approximately 13% of patients (n = 47) with well or moderately differentiated tumors less than or equal to 1 cm, no lymph vascular invasion, and a low Ki-67 staining were identified as having a low risk of axillary lymph node metastases of 4.3%. However, 20 patients with all four unfavorable predictive factors had a 75% incidence of axillary lymph node involvement.

CONCLUSION

Primary tumor characteristics can be used to identify a subgroup of patients with a low risk of axillary lymph node metastases in T1 breast cancer. Preoperative risk assessment might be used to omit routine ALND in those patients at low risk of axillary lymph node metastases.

Measurement of the Noncomplexed Free Fraction of Tissue Inhibitor of Metalloproteinases 1 in Plasma by Immunoassay

Background: We previously found differences in total concentrations of tissue inhibitor of metalloproteinases 1 (TIMP-1) in plasma from donors and cancer patients. Because TIMP-1 can exist in more than one molecular form, a new immunoassay to specifically detect free TIMP-1 was developed and concentrations were determined in plasma from healthy donors and colorectal cancer (CRC) patients.

Methods: We established and validated an immunoassay for the specific measurement of free TIMP-1 that uses a polyclonal anti-TIMP-1 antibody for capture and a monoclonal anti-TIMP-1 antibody that binds only free TIMP-1 for detection of antigen. Plasma samples from healthy donors and CRC patients were assayed for free TIMP-1. Total TIMP-1 was measured by our previously published assay.

Results: The mean (SD) concentrations of free TIMP-1 were similar in citrate [55.5 (11.5) μg/L] and EDTA plasma [58.9 (13.3) μg/L] from 76 donors (r2 = 0.82). In 154 donors, the ratio of free TIMP-1 [mean (SD), 64.5 (18.0) μg/L] to total TIMP-1 [83.8 (19.8) μg/L] in EDTA plasma was 0.77. Plasma concentrations of free and total TIMP-1 correlated significantly to age (free, r2 = 0.19; total, r2 = 0.27; P &lt;0.0001), increasing 50% over an age span of 45 years. Free and total TIMP-1 were significantly increased in CRC patients (P &lt;0.0001), whereas the ratio of free to total TIMP-1 (mean, 0.58) was significantly lower than in donors.

Conclusions: Most of the TIMP-1 in donor plasma is present in its free form, and free TIMP-1 increases with age. Free and total TIMP-1 are increased in CRC patient plasma, but the ratio of free to total TIMP-1 is significantly lower in these patients than in donors.

Quantitative Real-Time Reverse Transcription-PCR Assay for Urokinase Plasminogen Activator, Plasminogen Activator Inhibitor Type 1, and Tissue Metalloproteinase Inhibitor Type 1 Gene Expressions in Primary Breast Cancer

Background: The plasminogen activation system and matrix metalloproteinases (MMPs) play a key role in the degradation of basement membrane and extracellular matrix in tissue remodeling, cancer cell invasion, and metastasis.

Methods: Quantitative real-time reverse-transcription-PCR (RT-PCR) assays were developed to quantify urokinase-type plasminogen activator (uPA), plasminogen activator inhibitor type 1 (PAI-1), and tissue metalloproteinase inhibitor type 1 (TIMP-1) mRNA in 54 breast cancer tissues. Gene fragments were amplified in a LightCycler real-time PCR system using gene-specific primers and SYBR Green I. The results were normalized to β-actin mRNA. We also quantified antigen and functional concentrations of these components.

Results: The intra- and interassay variabilities for mRNA quantification showed mean SDs for the crossing point of 0.12 and 0.15 cycles, respectively. PAI-1, uPA, and TIMP-1 mRNA and antigen concentrations and PAI-1 and uPA functional concentrations increased with tumor severity; the increase was statistically significant for PAI-1, uPA, and TIMP-1 mRNA and antigen concentrations and for uPA functional concentrations. Node-positive patients showed significantly higher PAI-1, uPA, and TIMP-1 mRNA and antigen concentrations than those who were node negative.

Conclusions: Quantitative real-time RT-PCR is a highly sensitive, reproducible, and fast method for measuring gene expression of PAI-1, uPA, and TIMP-1 in breast cancer. These components may be involved in breast cancer development, and increased mRNA expression may be associated with a worse prognosis.

High tumor tissue concentration of plasminogen activator inhibitor 2 (PAI-2) is an independent marker for shorter progression-free survival in patients with early stage endometrial cancer

Previous studies including various tumor types have shown different associations between tumor tissue levels of plasminogen activator inhibitor 2 (PAI-2) and patient survival. High tumor tissue concentrations of PAI-2 have been associated with good prognosis in patients with breast cancer, small cell lung cancer and ovarian cancer, but with poor histologic differentiation and poor prognosis in patients with colorectal cancer. On the other hand, high tumor tissue concentrations of urokinase plasminogen activator (uPA), uPA receptor (R) and PAI-1 have more consistently been associated with poor histologic differentiation and poor prognosis. Our study quantified PAI-2 and uPAR using specific enzyme-linked immunosorbent assays in homogenates of 274 samples of endometrial cancer tissue. The prognostic power of each factor was analyzed in the subgroup of patients with early stage disease, i.e., International Federation of Gynecology and Oncology (FIGO) surgical stage I-II (n = 188). This group had a median follow-up time of 6.8 years (range 0.7-9.9), and 23 progressions were observed. The 80(th) percentile for PAI-2 and uPAR was used to dichotomize the material, and the results were analyzed for associations with clinical data including progression-free survival. The results were also compared with DNA ploidy status, S-phase fraction, uPA and PAI-1, which we reported in a previous study (Fredstorp Lidebring et al., Eur J Cancer 2001; in press). A high PAI-2 level was associated with shorter progression-free survival in univariate analysis and was an independent prognostic factor in bivariate analyses, which included PAI-1, uPA and DNA ploidy status. In contrast, a high level of uPAR had no association with prognosis in early stage endometrial cancer. The combination of high PAI-2 and PAI-1 levels in tumors revealed a small group of stage I-II patients with an accumulative progression rate of 50%.

Prognostic factors in breast cancer: current and new predictors of metastasis

Decisions regarding the use of adjuvant therapy for breast cancer are strongly influenced by the risk of disease recurrence and death. These risks are now determined by examining the currently recognized breast cancer prognostic factors, including clinical stage, axillary nodal status, tumor size and grade, hormone receptor status, and presence of lymphovascular involvement. Newer factors are being evaluated in an attempt to more precisely define disease-related prognosis. This paper provides an overview of issues that need to be considered when analyzing studies of prognostic factors as well as a review of the currently recognized and the newer candidate prognostic factors.

Increased stromal expression of murine urokinase plasminogen activator in a human breast cancer xenograft model following treatment with the matrix metalloprotease inhibitor, batimastat

The matrix metalloprotease (MMP) family of enzymes and the urokinase plasminogen activator (uPA) pathway have both been implicated in tumor invasion and metastasis and in poor prognosis of cancer. We have previously shown that treatment with batimastat, a synthetic MMP inhibitor, leads to significant retardation but not regression of tumor growth in a human breast cancer xenograft model. In addition, batimastat treatment did not inhibit local tumor invasion, nor did it encourage stromal encapsulation of the tumor, suggesting the additional involvement of non-MMP proteolytic mechanisms. To investigate the presence of an alternative extracellular matrix protease whose activity is known to be important in breast cancer, but which is not inhibited by batimastat, expression of murine and human uPA were examined by in situ hybridization and ELISA. No differences were observed between untreated and batimastat-treated tumors regarding human uPA mRNA and protein. In contrast, murine uPA mRNA expression was increased at the tumor-stromal junction in batimastat-treated tumors in comparison with the control tumors. In agreement with these results, batimastat treatment was shown to significantly induce murine uPA protein content in the tumors. Inoculating MDA435/LCC-6 cells into immunodeficient, uPA-deficient mice resulted in tumor growth retardation as compared to tumor growth in littermate wild-type controls, while addition of batimastat treatment to uPA-/- mice did not result in further growth inhibition. The increased expression of stromal uPA may represent a cellular response to MMP inhibition and may demonstrate a new level of plasticity in the malignant progression of the disease. These results may have important implications for the clinical applications of MMP inhibitors, as well as for development of other anti-invasion drugs.

Randomized adjuvant chemotherapy trial in high-risk, lymph node-negative breast cancer patients identified by urokinase-type plasminogen activator and plasminogen activator inhibitor type 1

BACKGROUND

Most patients with lymph node-negative breast cancer are cured by locoregional treatment; however, about 30% relapse. Because traditional histomorphologic and clinical factors fail to identify the high-risk patients who may benefit from adjuvant chemotherapy, other prognostic factors are needed. In a unicenter study, we have found that levels of urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor type 1 (PAI-1) in the primary tumor are predictive of disease recurrence. Thus, we designed the Chemo N(0) prospective randomized multicenter therapy trial to investigate further whether uPA and PAI-1 are such prognostic factors and whether high-risk patients identified by these factors benefit from adjuvant chemotherapy. After 4.5 years, we present results of the first interim analysis.

METHODS

We studied 556 patients with lymph node-negative breast cancer. The median follow-up was 32 months. All patients with low tumor levels of uPA (< or = 3 ng/mg of protein) and of PAI-1 (< or = 14 ng/mg of protein) were observed. Patients with high tumor levels of uPA (> 3 ng/mg of protein) and/or of PAI-1 (> 14 ng/mg of protein) were randomly assigned to combination chemotherapy or subjected to observation only. All statistical tests were two-sided.

RESULTS

A total of 241 patients had low levels of uPA and PAI-1, and 315 had elevated levels of uPA and/or PAI-1. The estimated 3-year recurrence rate for patients with low tumor levels of uPA and PAI-1 (low-risk group) was 6.7% (95% confidence interval [CI] = 2.5% to 10.8%). This rate for patients with high tumor levels of uPA and/or PAI-1 (high-risk group) was 14.7% (95% CI = 8.5% to 20.9%) (P = 0.006). First interim analysis suggests that high-risk patients in the chemotherapy group benefit, with a 43.8% lower estimated probability of disease recurrence at 3 years than high-risk patients in the observation group (intention-to-treat analysis: relative risk = 0.56; 95% CI = 0.25 to 1.28), but further follow-up is needed for confirmation.

CONCLUSIONS

Using uPA and PAI-1, we have been able to classify about half of the patients with lymph node-negative breast cancer as low risk, for whom adjuvant chemotherapy may be avoided, and half as high risk, who appear to benefit from adjuvant chemotherapy.

The Ets-1 transcription factor is up-regulated together with MMP 1 and MMP 9 in the stroma of pre-invasive breast cancer

The first steps of stroma generation are of pivotal importance for carcinogenesis because at this stage are initiated both angiogenesis, the prerequisite for continuous tumour growth, and the proliferation of stromal fibroblasts. These developments contribute to the onset of tumour invasion by secreting several matrix-degrading proteases. Both angiogenesis and the production of proteases are tightly controlled at several levels; of significant importance is transcription. The Ets-1 transcription factor transactivates several genes encoding matrix-degrading proteases and is thought to be involved in both tumour vascularization and invasion. This study therefore investigated, by in situ hybridization and immunohistochemistry, the expression of Ets-1 and of two of its target genes, encoding matrix metalloproteinase (MMP) 1 and MMP 9, in order to demonstrate a topographical in vivo correlation between the expression of these three genes during breast cancer formation. All three genes were first expressed within both endothelial cells and stromal fibroblasts during the onset of stroma generation around intraductal and intralobular in situ carcinomas and they were significantly up-regulated in the stroma of invasive ductal and lobular cancers. The results of this study further support the suggested in vivo role of Ets-1 for both angiogenesis and tumour invasion, via matrix-degrading proteases which are already expressed during the early stages of breast carcinogenesis.

S-phase fraction and urokinase plasminogen activator are better markers for distant recurrences than Nottingham Prognostic Index and histologic grade in a prospective study of premenopausal lymph node-negative breast cancer

PURPOSE

Histologic grade, Nottingham Prognostic Index (NPI), estrogen receptor (ER) and progesterone receptor (PgR) status, and tumor size have previously been shown to be important prognostic indicators for distant recurrence of breast cancer. The purpose of this study was to compare the prognostic value of these factors with flow cytometric S-phase fraction (SPF), urokinase plasminogen activator (uPA), and plasminogen activator inhibitor type 1 (PAI-1) in premenopausal patients with lymph node-negative breast cancer.

PATIENTS AND METHODS

In 237 consecutive premenopausal patients with lymph node-negative breast cancer and freshly frozen tumor material available, SPF, ER and PgR status, uPA and its inhibitor PAI-1, histologic grade, and NPI were evaluated.

RESULTS

SPF was univariately the most powerful prognostic factor for distant recurrence, followed by uPA, histologic grade, PgR, age, ER, NPI, and PAI-1, the latter being nonsignificant. Multivariate analysis revealed that neither NPI nor histologic grade was significant after adjustment for SPF, a fact that may be explained by the strong association between these factors. uPA was, however, an independent prognostic factor in addition to SPF, NPI, or histologic grade.

CONCLUSION

In this prospective study, SPF and uPA were found to be independent prognostic factors in premenopausal women with lymph node-negative breast cancer. We suggest that SPF, if performed under standardized conditions, can replace histologic grade as a selection instrument for adjuvant medical treatment. The value of the combination of SPF and uPA needs to be confirmed in an independent prospective trial.

Heterotypic signaling between epithelial tumor cells and fibroblasts in carcinoma formation

Tumors arise from cells that have sustained genetic mutations resulting in deregulation of several of their normal growth-controlling mechanisms. Much of the research concerning the origins of cancer has focused on the genetic mutations within tumor cells, treating tumorigenesis as a cell-autonomous process governed by the genes carried by the tumor cells themselves. However, it is increasingly apparent that the stromal microenvironment in which the tumor cells develop profoundly influences many steps of tumor progression. In various experimental tumor models, the microenvironment affects the efficiency of tumor formation, the rate of tumor growth, the extent of invasiveness, and the ability of tumor cells to metastasize. In carcinomas, the influences of the microenvironment are mediated, in large part, by paracrine signaling between epithelial tumor cells and neighboring stromal fibroblasts. In this review, we summarize recent advances in understanding the paracrine signaling interactions between epithelial cancer cells and associated fibroblasts and examine the effects of these bidirectional interactions on various aspects of carcinoma formation. We note, however, that paracrine signaling between other cell types within the carcinomas, such as endothelial cells and inflammatory cells, may play equally important roles in tumor formation and we will refer to these heterotypic interactions where relevant.

Immunohistochemical expression of uPA, uPAR, and PAI-1 in breast carcinoma. Fibroblastic expression has strong associations with tumor pathology

The urokinase-type plasminogen activator (uPA) system has been implicated in tumor spread. We have used immunohistochemistry to examine three components of this system, ie, uPA, uPA receptor (uPAR), and plasminogen activator inhibitor-1 (PAI-1), in a pilot study on 142 cases of breast carcinoma. We wished to determine whether there were any relationships between expression of the proteins in either tumor cells or fibroblasts and clinical and pathological features. Strong uPA expression in each cell type was significantly related to high tumor grade (P = 0.013 and 0.008, respectively), and was more common in invasive than in in situ carcinomas (P < 0.0001). Fibroblastic expression of uPAR was only related to the presence of invasion (P < 0.0001). Strong PAI-1 expression in both cell types was seen in high-grade tumors (tumor cells, P = 0.012; fibroblasts, P < 0.001), but only fibroblastic expression was related to the presence of invasion (P = 0.042). Fibroblastic expression of both uPA and uPAR were positively correlated with tumor size. Although patients with strong fibroblastic expression of uPA showed a tendency toward a shorter time to relapse, none of the plasminogen activator proteins were significantly associated with relapse-free survival. These results suggest that strong expression of uPA, uPAR, and PAI-1 in fibroblasts rather than in tumor cells have the most impact on the clinical behavior of breast cancer. Larger prospective studies are needed to confirm these findings.

Prognostic significance of biologic markers in node-negative breast cancer patients: a prospective study

It is generally thought that future advances in the treatment and cure of breast cancer patients will be made possible through a deeper understanding of tumor biology and an improved capability to define the prognosis of each single patient. This will lead to the formulation of new, more selective, and patient-tailored therapies. It is therefore important, when studying potential prognostic factors, to follow methodologic requirements and guidelines which involve the carrying out of prospective studies as confirmatory steps. Repeatedly or recently investigated prognostic markers (tumor size, menopausal status, ER, PgR, 3H thymidine labeling index, c-erbB-2 and p27 expression) were evaluated on a series of 286 prospectively recruited node negative breast cancer patients who underwent loco-regional treatment alone and were closely followed. The individual and relative prognostic contribution of each variable with respect to other factors, as well as their ability to identify node negative patients at risk, were assessed by univariate and multivariate analysis. At a five-year follow-up, only tumor size (p = 0.021) and TLI (p = 0.016) individually proved to be significant prognostic indicators of relapse-free survival. Conversely, p27 expression was not related to RFS and c-erbB-2 expression appeared to have only a short-term effect on patient prognosis. TLI and tumor size, tested in multivariate analysis along with ER and menopausal status, maintained their independent prognostic relevance. The study, performed on a large series of node-negative patients given loco-regional treatment alone, for the first time prospectively recruited, showed the prognostic relevance of TLI and its independence from other clinico-pathologic and biologic factors over a five-year period.

Can axillary dissection be avoided by improved molecular biological diagnosis?

Axillary dissection is presently a routine staging procedure in the management of breast cancer. The use of adjuvant systemic treatment is largely based on the diagnosis of axillary metastases. Routine axillary dissection leads to acute and chronic side-effects in a large proportion of patients. The sentinel node technique is presently explored with the aim of decreasing the need for standard axillary dissection. A complementary way forward is to analyse the primary breast cancer for molecular markers with prognostic significance with reference to the risk for metastatic capacity and thereby obtain a 'biological staging' and identify those patients in need of systemic adjuvant therapy. A large number of molecular biological factors have been shown to have prognostic significance in breast cancer e.g. c-erbB-2, p53, uPA, PAI-I and VEGF. This article reviews the expression of these and other factors in the primary breast cancers in relation to the risk for axillary and systemic metastatic disease, with the long-term aim of excluding routine axillary dissection.