Up-regulation of urokinase-type plasminogen activator in squamous cell carcinoma of human larynx

Differential Expression Levels of Urokinase-Type Plasminogen Activator and Cathepsin D in Locally Advanced Laryngeal Squamous Cell Carcinoma: Clinical Implications

The expression levels and the prognostic impact of urokinase-type plasminogen activator (uPA) and cathepsin D (CD) were evaluated in patients with locally advanced laryngeal squamous cell carcinoma (LSCC). uPA and CD protein levels were determined by immunoluminometric or immunoenzymatic assays in the cytosol of paired sets of tumor tissues and corresponding adjacent normal mucosa (NLM) from 57 patients with stage III/IV LSCC and were correlated with a number of clinicobiological parameters of this tumor including anatomical site, tumor grade, nodal status, clinical stage, DNA ploidy, proliferation rate, and patient outcome. Median uPA levels were significantly higher in LSCC than in NLM (1.8 ng/mg of protein vs 0.3 ng/mg; p<0.001) whereas median CD levels were not significantly increased in tumor tissue compared to NLM (24 pmol/mg vs 19 pmol/mg, p=0.063). No significant correlation was observed between uPA and CD concentrations in tumor tissues (r=-0.1; p=0.4). Furthermore, the distribution analysis of uPA and CD in tumors showed no correlation between expression levels of these proteinases and the parameters mentioned above including patient outcome. However, when data were matched according to each parameter examined it was observed that the differences in uPA content between LSCC and NLM, expressed as uPA tumor/normal tissue ratio (T/M), were more marked in clinically advanced and/or aggressive forms of LSCC (i.e., node positive, stage IV, poorly and moderately differentated, aneuploid multiclonal, low S-phase, subglottis tumors). These data suggest that in such tumors altered regulation of uPA may occur to a greater extent than in less aggressive and less advanced forms of LSCC. This phenomenon was not observed for CD. However, in tumors with a high proliferation rate, in stage IV tumors as well as in those located in the supraglottis, CD levels were significantly higher than those found in the corresponding NLM (p=0.008, p=0.02 and p=0.03, respectively). In conclusion, uPA is highly expressed in locally advanced LSCC and appears to be implicated in some key events of progression of this tumor such as local invasion and/or nodal involvement, whereas CD does not seem to have a role in promoting these processes. Nevetheless, neither of these proteinases seem to be prognostically useful in patients with stage III/IV tumors.

Involvement of urokinase-type plasminogen activator system in cancer: an overview

Currently, there are several studies supporting the role of urokinase-type plasminogen activator (uPA) system in cancer. The association of uPA to its receptor triggers the conversion of plasminogen into plasmin. This process is regulated by the uPA inhibitors (PAI-1 and PAI-2). Plasmin promotes degradation of basement membrane and extracellular matrix (ECM) components as well as activation of ECM latent matrix metalloproteases. Degradation and remodeling of the surrounding tissues is crucial in the early steps of tumor progression by facilitating expansion of the tumor mass, release of tumor growth factors, activation of cytokines as well as induction of tumor cell proliferation, migration, and invasion. Hence, many tumors showed a correlation between uPA system component levels and tumor aggressiveness and survival. Therefore, this review summarizes the structure of the uPA system, its contribution to cancer progression, and the clinical relevance of uPA family members in cancer diagnosis. In addition, the review evaluates the significance of uPA system in the development of cancer-targeted therapies.

Hippocampus-specific deletion of tissue plasminogen activator "tPA" in adult mice impairs depression- and anxiety-like behaviors

Anxiety and depression are multifactorial disorders that have become prominent health problems all over the world. Neurotrophic factors have emerged underlying pathogenesis of these diseases. Although a number of studies indicate that the hippocampus-brain-derived neurotrophic factor (BDNF) may be involved in these psychiatric illnesses, little is known about the molecular mediators of these disorders. In this study we further investigate the role of tissue plasminogen activator (tPA), a serine protease involved in pro-BDNF cleavage to BDNF, in depression and anxiety-like behaviors in adult mice. To address this issue, we investigated the effect of hippocampus tPA manipulation, using viral vectors, on anxiety- and depression-like behaviors, including the marble burying test (MBT), elevated plus maze (EPM), tail suspension test (TST), novelty suppressed feeding (NSF) and forced swim test (FST). Our results showed that tPA knock-down - using lentiviral vectors expressing specific short hairpin RNAs (LV-shRNA) - increased the number of buried marbles together with the digging time in the MBT and decreased the time spent in open the arms of an EPM. In addition, tPA-knock down in the hippocampus increased immobility in the FST and TST, and increased time to feed in the NSF test. These effects were reversed when tPA-over-expressing vectors (LV-tPA) were injected in the hippocampus. We also found that BDNF protein levels were elevated in the hippocampus of mice receiving tPA-expressing vectors. Together, our results imply that tPA manipulation may provide an effective therapeutic intervention for depression and anxiety disorders.

Potentially novel candidate biomarkers for head and neck squamous cell carcinoma identified using an integrated cell line-based discovery strategy

Head and neck squamous cell carcinomas (HNSCC) can arise from the oral cavity, oropharynx, larynx or hypopharynx, and is the sixth leading cancer by incidence worldwide. The 5-year survival rate of HNSCC patients remains static at 40-60%. Hence, biomarkers which can improve detection of HNSCC or early recurrences should improve clinical outcome. Mass spectrometry-based proteomics methods have emerged as promising approaches for biomarker discovery. As one approach, mass-spectrometric identification of proteins shed or secreted from cancer cells can contribute to the identification of potential biomarkers for HNSCC and our understanding of tumor behavior. In the current study, mass spectrometry-based proteomic profiling was performed on the conditioned media (i.e. secretome) of head and neck cancer (HNC) cell lines (FaDu, UTSCC8 and UTSCC42a) in addition to gene expression microarrays to identify over-expressed transcripts in the HNSCC cells in comparison to a normal control cell line. This integrated data set was systematically mined using publicly available resources (Human Protein Atlas and published proteomic/transcriptomic data) to prioritize putative candidates for validation. Subsequently, quantitative real-time PCR (qRT-PCR), Western blotting, immunohistochemistry (IHC), and ELISAs were performed to verify selected markers. Our integrated analyses identified 90 putative protein biomarkers that were secreted or shed to the extracellular space and over-expressed in HNSCC cell lines, relative to controls. Subsequently, the over-expression of five markers was verified in vitro at the transcriptional and translational levels using qRT-PCR and Western blotting, respectively. IHC-based validation conducted in two independent cohorts comprising of 40 and 39 HNSCC biopsies revealed that high tumor expression of PLAU, IGFBP7, MMP14 and THBS1 were associated with inferior disease-free survival, and increased risk of disease progression or relapse. Furthermore, as demonstrated using ELISAs, circulating levels of PLAU and IGFBP7 were significantly higher in the plasma of HNSCC patients compared with healthy individuals.

Prognostic value of plasminogen activator inhibitor-1 in head and neck squamous cell carcinoma

BACKGROUND

Tumor cell biological factors, such as urokinase plasminogen activator (uPA) and its inhibitor plasminogen activator inhibitor-1 (PAI-1), cathepsin D, and c-myc play a role in tumor invasion, metastasis, and proliferation. In this study, the prognostic importance of these factors in patients with primary head and neck squamous cell carcinoma (HNSCC) was evaluated and correlated with clinicopathologic variables.

METHODS

In 46 paired primary tumors and normal tissues, levels of uPA, PAI-1, cathepsin D, and c-myc amplification were determined. The clinical follow-up was over 10 years. Relationships between cell biological factors and patient and tumor characteristics were studied by the Mann-Whitney test. The Cox proportional hazard model was used for univariate and multivariate analysis.

RESULTS

In this study, only a high level of PAI-1 was associated with a significantly shorter disease-free survival (p < .01). PAI-1 levels were higher in tumors with perineural invasion (p < .01). Both PAI-1 and uPA levels were higher in patients who smoked (p < .01 and p = .02). In univariate analysis, smoking (p= .04), excessive alcohol intake (p = .02), perineural invasion (p = .001), and vaso-invasion (p = .009) were associated with a shorter disease-free survival. The only factor related to overall survival was perineural invasion (p = .045). The combination of a high PAI-1 level and perineural invasion appeared to be a significant predictor of a shorter disease-free interval (p = .01).

CONCLUSION

PAI-1 may present a novel prognostic factor for patients with HNSCC. Perineural invasion and PAI-1 level combined seemed to be prognostic for disease-free survival.

Profiling serine protease substrate specificity with solution phase fluorogenic peptide microarrays

A novel microarray-based proteolytic profiling assay enabled the rapid determination of protease substrate specificities with minimal sample and enzyme usage. A 722-member library of fluorogenic protease substrates of the general format Ac-Ala-X-X-(Arg/Lys)-coumarin was synthesized and microarrayed, along with fluorescent calibration standards, in glycerol nanodroplets on microscope slides. The arrays were then activated by deposition of an aerosolized enzyme solution, followed by incubation and fluorometric scanning. The specificities of human blood serine proteases (human thrombin, factor Xa, plasmin, and urokinase plasminogen activator) were examined. The arrays provided complete maps of protease specificity for all of the substrates tested and allowed for detection of cooperative interactions between substrate subsites. The arrays were further utilized to explore the conservation of thrombin specificity across species by comparing the proteolytic fingerprints of human, bovine, and salmon thrombin. These enzymes share nearly identical specificity profiles despite approximately 390 million years of divergent evolution. Fluorogenic substrate microarrays provide a rapid way to determine protease substrate specificity information that can be used for the design of selective inhibitors and substrates, the study of evolutionary divergence, and potentially, for diagnostic applications.

Differential expression of c-jun and c-fos mRNAs in squamous cell carcinoma of the head and neck: associations with uPA, gelatinase B, and matrilysin mRNAs

BACKGROUND

Head and neck squamous cell carcinomas (HNSCC) are known for their invasive behavior. The invasiveness of these tumors requires proteases, some of which as urokinase-type plasminogen activator (uPA), gelatinase B and matrilysin are regulated through AP-1 dependent transcriptional mechanisms. AP-1 consists of several proteins, including those encoded by the proto-oncogenes c-jun and c-fos. The aim of this study was to: first, evaluate the expression levels of matrix metalloproteases (matrilysin and gelatinase B) and uPA mRNAs; second, examine whether these genes might be associated with c-jun and c-fos expression; third, examine the relationship between the expression of these genes and HNSCC clinico-pathological features.

METHODS

We have analyzed 38 HNSCC primary tumors and matched mucosa tissues for uPA, gelatinase B, matrilysin, c-fos, and c-jun by Northern-blot analysis.

RESULTS

uPA, gelatinase B, matrilysin, and c-jun mean levels were statistically higher in the tumors than in the normal adjacent mucosa, whereas no difference was found when c-fos mRNA values were compared, c-jun mRNA expression correlated directly with gelatinase B and matrilysin mRNA levels, but no association with uPA mRNA was observed, c-fos mRNA levels were not associated with the tested proteases, but low levels were determined in tumors from older patients who subsequently developed a 2(nd) tumor. No evidence of correlation between expression of uPA, matrilysin, and c-jun in tumors and clinico-pathological features was found. Gelatinase B mRNA high levels were associated to presence of cervical recurrences.

CONCLUSION

Expression of c-jun seems to be involved in the regulation of gelatinase B and matrilysin being not related to uPA. Lack of association with c-fos may indicate that other fos family members might play a role in the transcriptional activity of the analyzed proteases in HNSCC tumors.

Transforming growth factor beta1, urokinase-type plasminogen activator and plasminogen activator inhibitor-1 mRNA expression in head and neck squamous carcinoma and normal adjacent mucosa

BACKGROUND

A balance between urokinase-type plasminogen activator (uPA) and its main inhibitor type-1 (PAI-1) appears to be important for cancer invasive behavior. Since uPA/PAI-1 system seems to be regulated by transforming growth factor beta1 (TGFbeta1) in different cell types, our aim was to investigate the relationship between the expression of the three genes and lymph node status in head and neck squamous cell carcinomas (HNSCC) at specific sites.

MATERIALS AND METHODS

uPA, PAI-1, and TGFbeta1 mRNAs were determined by Northern analysis in tumor, and paired normal mucosa samples were obtained from 91 operable HNSCC patients.

RESULTS

In oral cavity, excluding tongue, TGFbeta1, PAI-1, and uPA mRNAs values were consistently lower in the normal tissues than in tumors. In larynx tumors, TGFbeta1 expression was increased, but no statistically significant differences were found for uPA or PAI-1 mRNAs as compared with normal tissues. Tongue tumors overexpressed only uPA mRNA, and uPA levels showed significant parallel variations with TGFbeta1 and PAI-1 mRNAs mainly in pN+ tumors. In oral cavity tumors, an inverse correlation between TGFbeta1 and uPA was observed in pN0 subgroup, elevated uPA mRNA was counterbalanced by high PAI-1 mRNA TGFbeta1, and PAI-1 were not coordinately expressed. Correlations between the three markers were not found in larynx. Hypopharynx tumors, all staged as pN+, expressed the lowest TGFbeta1 mRNA mean values.

CONCLUSIONS

Combined information about TGFbeta1, uPA, and PAI-1 mRNAs may add some clues to the understanding of the pathophysiological role of uPA system in head and neck squamous cell carcinoma.

Species specificity of amidine-based urokinase inhibitors

Inhibition of the proteolytic activity of urokinase has been shown to inhibit the progression of tumors in rodent models and is being investigated for use in human disease. Understanding the rodent/human species-specificity of urokinase inhibitors is therefore critical for interpretation of rodent cancer progression models that use these inhibitors. We report here studies with a panel of 11 diverse urokinase inhibitors in both human and mouse enzymatic assays. Inhibitors such as amiloride, B428, and naphthamidine, that occupy only the S1 subsite pocket were found to be nearly equipotent between the human and the murine enzymes. Inhibitors that access additional, more distal, pockets were significantly more potent against the human enzyme but there was no corresponding potency increase against the murine enzyme. X-ray crystallographic structures of these compounds bound to the serine protease domain of human urokinase were solved and examined in order to explain the human/mouse potency differences. The differences in inhibitor potency could be attributed to four amino acid residues that differ between murine and human urokinases: 60, 99, 146, and 192. These residues are Asp, His, Ser, and Gln in human and Gln, Tyr, Glu, and Lys in mouse, respectively. Compounds bearing a cationic group that interacts with residue 60 will preferentially bind to the human enzyme because of favorable electrostatic interactions. The hydrogen bonding to residue 192 and steric considerations with residues 99 and 146 also contribute to the species specificity. The nonparallel human/mouse enzyme inhibition observations were extended to a cell-culture assay of urokinase-activated plasminogen-mediated fibronectin degradation with analogous results. These studies will aid the interpretation of in vivo evaluation of urokinase inhibitors.

Urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor type 1 (PAI-1) in tissue and serum of head and neck squamous cell carcinoma patients

The aim of this study was to determine urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor type 1 (PAI-1) concentrations in tumour and adjacent normal tissue samples from 58 patients, and in serum samples from 40 of 58 patients with squamous cell carcinoma of the head and neck obtained at diagnosis and after completion of therapy. uPA and PAI-1 serum concentrations were also measured in 28 healthy volunteers who served as controls. Measurements were made using enzyme-linked immunosorbent assay (ELISA) techniques. For both uPA and PAI-1, significantly elevated concentrations were measured in tumour tissue as compared with normal tissue (uPA: 8.89 versus 0.41 ng/mg total protein (mgp), P < 0.0001; PAI-1: 23.9 versus 1.47 ng/mgp, P < 0.0001). A statistically significant difference in uPA concentrations was found between normal laryngeal and nonlaryngeal tissue (0.52 versus 0.3 ng/mgp, P = 0.008), and in PAI-1 concentrations between T1 + 2 and T3 + 4 stage of disease (17.32 versus 35.63 ng/mgp, P = 0.04). The uPA concentrations positively correlated with those of PAI-1 measured in both tumour (Rs = 0.62, P < 0.0001) and normal tissue (Rs = 0.30, P = 0.02). In serum samples, lower concentrations of PAI-1 were measured in the control group than in patients with cancer (412.0 versus 680.5 ng/ml serum (mls), P = 0.0006). The time of collection of the serum sample did not influence uPA and PAI-1 concentrations, and no association was observed between their concentrations and any clinical and histopathological prognostic factors tested. Our results indicate that both uPA and PAI-1 may play a specific role in the process of invasion and metastasis, and might also be of prognostic value in squamous cell carcinoma of the head and neck.