Emerging multifunctional aspects of cellular serine proteinase inhibitors in tumor progression and tissue regeneration

Multimeric Association of Purified Novel Bowman-Birk Inhibitor From the Medicinal Forage Legume Mucuna pruriens (L.) DC

A Bowman-Birk protease, i.e., Mucuna pruriens trypsin inhibitor (MPTI), was purified from the seeds by 55.702-fold and revealed a single trypsin inhibitor on a zymogram with a specific activity of 202.31 TIU/mg of protein. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under non-reducing conditions, the protease trypsin inhibitor fraction [i.e., trypsin inhibitor non-reducing (TINR)] exhibited molecular weights of 74 and 37 kDa, and under reducing conditions [i.e., trypsin inhibitor reducing (TIR)], 37 and 18 kDa. TINR-37 revealed protease inhibitor activity on native PAGE and 37 and 18 kDa protein bands on SDS-PAGE. TINR-74 showed peaks corresponding to 18.695, 37.39, 56.085, and 74.78 kDa on ultra-performance liquid chromatography (UPLC) coupled with electrospray ionization/quadrupole time-of-flight-mass spectrometry (ESI/QTOF-MS). Similarly, TINR-37 displayed 18.695 and 37.39 kDa peaks. Furthermore, TIR-37 and TIR-18 exhibited peaks corresponding to 37.39 and 18.695 kDa. Multiple peaks observed by the UPLC-ESI/QTOF analysis revealed the multimeric association, confirming the characteristic and functional features of Bowman-Birk inhibitors (BBIs). The multimeric association helps to achieve more stability, thus enhancing their functional efficiency. MPTI was found to be a competitive inhibitor which again suggested that it belongs to the BBI family of inhibitors, displayed an inhibitor constant of 1.3 × 10^-6 M, and further demonstrates potent anti-inflammatory activity. The study provided a comprehensive basis for the identification of multimeric associates and their therapeutic potential, which could elaborate the stability and functional efficiency of the MPTI in the native state from M. pruriens.

Identification of blood biomarkers in glioblastoma by SWATH mass spectrometry and quantitative targeted absolute proteomics

Molecular biomarkers in blood are needed to aid the early diagnosis and clinical assessment of glioblastoma (GBM). Here, in order to identify biomarker candidates in plasma of GBM patients, we performed quantitative comparisons of the plasma proteomes of GBM patients (n = 14) and healthy controls (n = 15) using SWATH mass spectrometry analysis. The results were validated by means of quantitative targeted absolute proteomics analysis. As a result, we identified eight biomarker candidates for GBM (leucine-rich alpha-2-glycoprotein (LRG1), complement component C9 (C9), C-reactive protein (CRP), alpha-1-antichymotrypsin (SERPINA3), apolipoprotein B-100 (APOB), gelsolin (GSN), Ig alpha-1 chain C region (IGHA1), and apolipoprotein A-IV (APOA4)). Among them, LRG1, C9, CRP, GSN, IGHA1, and APOA4 gave values of the area under the receiver operating characteristics curve of greater than 0.80. To investigate the relationships between the biomarker candidates and GBM biology, we examined correlations between plasma concentrations of biomarker candidates and clinical presentation (tumor size, progression-free survival time, or overall survival time) in GBM patients. The plasma concentrations of LRG1, CRP, and C9 showed significant positive correlations with tumor size (R² = 0.534, 0.495, and 0.452, respectively).

Serpin peptidase inhibitor, clade A member 3 (SERPINA3), is overexpressed in glioma and associated with poor prognosis in glioma patients

Glioma is the most common and aggressive human primary tumor in the central nervous system. Despite present clinical advancements, median survival time remains poor in this malignant tumor. Serpin peptidase inhibitor, clade A member 3 (SERPINA3), is a member of the serpin superfamily of protease inhibitors. Its aberrant expression has been observed in various tumors. However, its clinical significance and biological function in glioma remain unclear, especially for the prognosis of glioma patients. In this study, we investigated SERPINA3 expression in glioma tissue samples and its significance in predicting the prognosis of glioma patients. SERPINA3 protein expression was studied by immunohistochemistry, while real-time polymerase chain reaction was used to study SERPINA3 mRNA expression. We found that SERPINA3 was upregulated in glioma tissue at both mRNA and protein levels, compared with noncancerous brain tissues. We also found that high SERPINA3 expression in glioma tissues correlated significantly with advanced World Health Organization grade. Univariate and multivariate analyses revealed that high SERPINA3 expression was an independent prognostic factor for poor overall survival of glioma patients. Moreover, our findings were further validated by online Oncomine database. Taken together, our results suggest that SERPINA3 plays an oncogenic role in glioma progression and provide an insight into the application of SERPINA3 as a novel predictor of clinical outcomes and a potential biomarker of glioma.

Up-regulation of SERPINA3 correlates with high mortality of melanoma patients and increased migration and invasion of cancer cells

Serpin Peptidase Inhibitor, clade A member 3 (SERPINA3) was found to be abnormally overexpressed in a subset of melanoma tissue biopsies. High SERPINA3 expression was also associated with poor patient survival. In this study, we set out to test SERPINA3 protein's prognostic potential with a larger-sized and independent patient cohort, and to explore SERPINA3's function in melanoma cells. Tissue microarray-based immunohistochemistry analysis showed a significant increase in SERPINA3 expression in invasive and metastatic melanomas compared to normal nevi and melanoma-in-situ (P < 0.001, Chi-square test). In melanoma patients, high SERPINA3 expression was strongly associated with worse overall and disease specific survival at 5 years. Multivariate Cox regression analysis showed that SERPINA3 expression is an independent prognostic factor to predict melanoma patient clinical outcome. When SERPINA3 expression was selectively silenced using small interfering RNA molecules (siRNA) in cultured melanoma cell lines, cell migration and matrix invasion was significantly decreased, but no change in cell proliferation was observed.This study confirms the prognostic potential of SERPINA3 expression in human cutaneous melanoma and reveals the pro-migration and pro-invasion functions of this protein on melanoma cells.

Bowman-Birk protease inhibitor from Vigna unguiculata seeds enhances the action of bradykinin-related peptides

The hydrolysis of bradykinin (Bk) by different classes of proteases in plasma and tissues leads to a decrease in its half-life. Here, Bk actions on smooth muscle and in vivo cardiovascular assays in association with a protease inhibitor, Black eyed-pea trypsin and chymotrypsin inhibitor (BTCI) and also under the effect of trypsin and chymotrypsin were evaluated. Two synthetic Bk-related peptides, Bk₁ and Bk₂, were used to investigate the importance of additional C-terminal amino acid residues on serine protease activity. BTCI forms complexes with Bk and analogues at pH 5.0, 7.4 and 9.0, presenting binding constants ranging from 10³ to 10⁴ M⁻¹. Formation of BTCI-Bk complexes is probably driven by hydrophobic forces, coupled with slight conformational changes in BTCI. In vitro assays using guinea pig (Cavia porcellus) ileum showed that Bk retains the ability to induce smooth muscle contraction in the presence of BTCI. Moreover, no alteration in the inhibitory activity of BTCI in complex with Bk and analogous was observed. When the BTCI and BTCI-Bk complexes were tested in vivo, a decrease of vascular resistance and consequent hypotension and potentiating renal and aortic vasodilatation induced by Bk and Bk₂ infusions was observed. These results indicate that BTCI-Bk complexes may be a reliable strategy to act as a carrier and protective approach for Bk-related peptides against plasma serine proteases cleavage, leading to an increase in their half-life. These findings also indicate that BTCI could remain stable in some tissues to inhibit chymotrypsin or trypsin-like enzymes that cleave and inactivate bradykinin in situ.

Sj7170, a unique dual-function peptide with a specific α-chymotrypsin inhibitory activity and a potent tumor-activating effect from scorpion venom

A new peptide precursor, termed Sj7170, was characterized from the venomous gland cDNA library of the scorpion Scorpiops jendeki. Sj7170 was deduced to be a 62-amino acid peptide cross-linked by five disulfide bridges. The recombinant Sj7170 peptide (rSj7170) with chromatographic purity was produced by a prokaryotic expression system. Enzyme inhibition assay in vitro and in vivo showed that rSj7170 specifically inhibited the activity of α-chymotrypsin at micromole concentrations. In addition, Sj7170 not only promoted cell proliferation and colony formation by up-regulating the expression of cyclin D1 in vitro but also enhanced tumor growth in nude mice. Finally, Sj7170 accelerated cellular migration and invasion by increasing the expression of the transcription factor Snail and then inducing the epithelial-mesenchymal transition. Moreover, Sj7170 changed cell morphology and cytoskeleton of U87 cells by the GTPase pathway. Taken together, Sj7170 is a unique dual-function peptide, i.e. a specific α-chymotrypsin inhibitor and a potent tumorigenesis/metastasis activator. Our work not only opens an avenue of developing new modulators of tumorigenesis/metastasis from serine protease inhibitors but also strengthens the functional link between protease inhibitors and tumor activators.

Identification of potential prognostic biomarkers in patients with untreated, advanced pancreatic cancer from a phase 3 trial (Cancer and Leukemia Group B 80303)

BACKGROUND

Patients with advanced stage adenocarcinoma of the pancreas have a poor prognosis. The identification of prognostic and/or predictive biomarkers may help stratify patients so that therapy can be individualized.

METHODS

Serum samples from patients enrolled in the Cancer and Leukemia Group B 80303 phase 3 trial, "Randomized Study of Gemcitabine With Versus Without Bevacizumab in Patients With Locally Advanced or Metastatic Adenocarcinoma of the Pancreas" were used to discover novel biomarkers. For the discovery phase, 40 sera were selected based on length of survival and type of therapy, and subjected to liquid chromatography coupled to tandem mass spectrometry analysis (LC-MS-MS). The top features (proteins) were then further selected for validation by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Quantification by nano-LC-MS-MS resulted in 1452 peptides mapping to 156 proteins across all 40 samples, 92 of which had 2 or more peptides. After curation of the data, the authors selected 1 putative prognostic protein, alpha 1-antichymotrypsin (AACT), and 2 putative predictive proteins, histidine-rich glycoprotein (HRG) and complement factor H (CFH), for validation by ELISA. AACT was found to be negatively correlated with overall survival (τ = -0.30 [-0.38, -0.22]; P < .00001). There was no evidence for interaction with bevacizumab and HRG, but there was some evidence for a weak positive correlation of HRG with overall survival (τ = 0.11 [0.03, 0.19]; P < .01). CFH was found to be neither a predictive nor a prognostic factor for overall survival.

CONCLUSIONS

AACT may be a useful prognostic marker in patients with advanced stage pancreatic carcinoma, although additional validation studies are needed.

Alpha1-antitrypsin inhibits the activity of the matriptase catalytic domain in vitro

Matriptase is a type II transmembrane protease that is characterized by an N-terminal transmembrane and multiple extracellular domains, in addition to the conserved extracellular serine protease catalytic domain. The expression pattern of matriptase suggests that this protease may play broad roles in the biology of surface lining epithelial cells. In this study we report that alpha1-antitrypsin (AAT), an endogenous inhibitor of serine proteases, inhibits the catalytic domain of human recombinant matriptase in vitro. Co-incubation of AAT with matriptase (at a molar ratio 1:2) resulted in the formation of heat stable complexes, clearly seen in sodium dodecyl sulfate electrophoresis and Western blots. AAT was found to be a slow, tight-binding inhibitor of the catalytic domain of matriptase with a second order reaction rate constant of 0.31 x 10(3) M(-1)s(-1). Notably, the oxidized form of AAT, which lacks serine protease inhibitor activity, failed to generate matriptase complexes and to inhibit matriptase activity. Since matriptase is involved in a number of physiologic processes, including activation of epithelial sodium channels, our findings offer considerable new insights into new regulatory function of AAT in vivo.

Roles of Kunitz domains in the anti-invasive effect of hepatocyte growth factor activator inhibitor type 1 in human glioblastoma cells

Hepatocyte growth factor activator inhibitor type 1 (HAI-1) is a membrane-bound serine proteinase inhibitor having two extracellular Kunitz-type proteinase inhibitor domains (KD) namely KD-1 and KD-2. It efficiently inhibits hepatocyte growth factor activator, matriptase, hepsin, prostasin and trypsin. We have previously reported that the expression of HAI-1 suppresses the in vitro invasive capability of human glioblastoma cells. In this study we examined the role of each KD in the anti-invasive effect of HAI-1. Engineered over-expression of the mature membrane-form HAI-1 suppressed in vitro fibrin gel invasion of two human glioblastoma cell lines, U251 and YKG-1. The migratory activity on type IV collagen was also suppressed by the HAI-1 expression. These effects were not affected by the deletion of intracytoplasmic domain of HAI-1. A truncated secreted form of HAI-1 also suppressed in vitro invasion of the cells, indicating that the extracellular portion of HAI-1 was responsible for the anti-invasive effect. To determine the roles of each KD in the anti-invasive effect of HAI-1 in vitro, we constructed expression plasmids for HAI-1 with or without mutation at the P1 position of the reactive site of each KD. The results revealed that the proteinase inhibitor activity of N-terminal KD (KD-1) is responsible for the anti-invasion effect of HAI-1.

Gene expression profiles in primary pancreatic tumors and metastatic lesions of Ela-c-myc transgenic mice

Background

Pancreatic carcinoma usually is a fatal disease with no cure, mainly due to its invasion and metastasis prior to diagnosis. We analyzed the gene expression profiles of paired primary pancreatic tumors and metastatic lesions from Ela-c-myc transgenic mice in order to identify genes that may be involved in the pancreatic cancer progression. Differentially expressed selected genes were verified by semi-quantitative and quantitative RT-PCR. To further evaluate the relevance of some of the selected differentially expressed genes, we investigated their expression pattern in human pancreatic cancer cell lines with high and low metastatic potentials.

Results

Data indicate that genes involved in posttranscriptional regulation were a major functional category of upregulated genes in both primary pancreatic tumors (PT) and liver metastatic lesions (LM) compared to normal pancreas (NP). In particular, differential expression for splicing factors, RNA binding/pre-mRNA processing factors and spliceosome related genes were observed, indicating that RNA processing and editing related events may play critical roles in pancreatic tumor development and progression. High expression of insulin growth factor binding protein-1 (Igfbp1) and Serine proteinase inhibitor A1 (Serpina1), and low levels or absence of Wt1 gene expression were exclusive to liver metastatic lesion samples.

Conclusion

We identified Igfbp1, Serpina1 and Wt1 genes that are likely to be clinically useful biomarkers for prognostic or therapeutic purposes in metastatic pancreatic cancer, particularly in pancreatic cancer where c-Myc is overexpressed.

Inactivation of serine protease Matriptase1a by its inhibitor Hai1 is required for epithelial integrity of the zebrafish epidermis

Epithelial integrity requires the adhesion of cells to each other as well as to an underlying basement membrane. The modulation of adherence properties is crucial to morphogenesis and wound healing, and deregulated adhesion has been implicated in skin diseases and cancer metastasis. Here, we describe zebrafish that are mutant in the serine protease inhibitor Hai1a (Spint1la), which display disrupted epidermal integrity. These defects are further enhanced upon combined loss of hai1a and its paralog hai1b. By applying in vivo imaging, we demonstrate that Hai1-deficient keratinocytes acquire mesenchymal-like characteristics, lose contact with each other, and become mobile and more susceptible to apoptosis. In addition, inflammation of the mutant skin is evident, although not causative of the epidermal defects. Only later, the epidermis exhibits enhanced cell proliferation. The defects of hai1 mutants can be phenocopied by overexpression and can be fully rescued by simultaneous inactivation of the serine protease Matriptase1a (St14a), indicating that Hai1 promotes epithelial integrity by inhibiting Matriptase1a. By contrast, Hepatocyte growth factor (Hgf), a well-known promoter of epithelial-mesenchymal transitions and a prime target of Matriptase1 activity, plays no major role. Our work provides direct genetic evidence for antagonistic in vivo roles of Hai1 and Matriptase1a to regulate skin homeostasis and remodeling.

Immunohistochemical detection of uPA, uPAR, PAI-1, and maspin in ameloblastic tumors

BACKGROUND

To evaluate the roles of extracellular matrix (ECM)-degrading serine proteinase in progression of odontogenic tumors, expression of urokinase-type plasminogen activator (uPA), uPA receptor (uPAR), plasminogen activator inhibitor-1 (PAI-1), and maspin was analyzed in ameloblastic tumors as well as in tooth germs.

METHODS

Tissue specimens of 10 tooth germs, 45 ameloblastomas, and 5 malignant ameloblastic tumors were examined immunohistochemically with the use of antibodies against uPA, uPAR, PAI-1, and maspin.

RESULTS

Immunohistochemical reactivity for uPA, uPAR, PAI-1, and maspin was detected in normal and neoplastic odontogenic tissues: uPA was recognized predominantly in mesenchymal cells, uPAR was evident in epithelial cells, PAI-1 was found in both epithelial and mesenchymal cells, and maspin was expressed only in epithelial cells. The levels of uPA and uPAR immunoreactivity in ameloblastic tumors were slightly higher than the levels in tooth germs, while PAI-1 reactivity in ameloblastomas tended to be lower than that in tooth germs. The level of maspin immunoreactivity in ameloblastomas was significantly higher than that in tooth germs, and ameloblastic carcinoma showed decreased maspin reactivity.

CONCLUSION

Expression of uPA, uPAR, PAI-1, and maspin in tooth germs and ameloblastic tumors suggests that interactions among these molecules contribute to ECM degradation and cell migration during tooth development and tumor progression. Altered expression of the serine proteinase and its associated molecules in ameloblastic tumors may be involved in oncogenesis of odontogenic epithelium.

Crystal structure of the catalytic domain of DESC1, a new member of the type II transmembrane serine proteinase family

DESC1 was identified using gene-expression analysis between squamous cell carcinoma of the head and neck and normal tissue. It belongs to the type II transmembrane multidomain serine proteinases (TTSPs), an expanding family of serine proteinases, whose members are differentially expressed in several tissues. The biological role of these proteins is currently under investigation, although in some cases their participation in specific functions has been reported. This is the case for enteropeptidase, hepsin, matriptase and corin. Some members, including DESC1, are associated with cell differentiation and have been described as tumor markers. TTSPs belong to the type II transmembrane proteins that display, in addition to a C-terminal trypsin-like serine proteinase domain, a differing set of stem domains, a transmembrane segment and a short N-terminal cytoplasmic region. Based on sequence analysis, the TTSP family is subdivided into four subfamilies: hepsin/transmembrane proteinase, serine (TMPRSS); matriptase; corin; and the human airway trypsin (HAT)/HAT-like/DESC subfamily. Members of the hepsin and matriptase subfamilies are known structurally and here we present the crystal structure of DESC1 as a first member of the HAT/HAT-like/DESC subfamily in complex with benzamidine. The proteinase domain of DESC1 exhibits a trypsin-like serine proteinase fold with a thrombin-like S1 pocket, a urokinase-type plasminogen activator-type S2 pocket, to accept small residues, and an open hydrophobic S3/S4 cavity to accept large hydrophobic residues. The deduced substrate specificity for DESC1 differs markedly from that of other structurally known TTSPs. Based on surface analysis, we propose a rigid domain association for the N-terminal SEA domain with the back site of the proteinase domain.

Tissue kallikrein and kinin receptor expression in an angiogenic co-culture neuroblastoma model

The sprouting of new blood vessels from pre-existing vasculature (angiogenesis) is essential for tumour survival, influenced by tumour cell-endothelial cell interactions and is tightly regulated by biochemical cues including the kallikrein-kinin system (KKS). We examined the structural interaction between neuroblastomas and endothelial cells (HUVECs) in 2-D and 3-D (matrigel) in vitro, co-culture models by light microscopy, and performed in situ mono- and co-labelling of various KKS proteins. Neuroblastomas formed footplate-like multiple contacts on angiogenic HUVECs without disrupting differentiation of HUVECs into cord-like structures. Tissue kallikrein and the kinin B1R and B2R receptors were demonstrated on interacting neuroblastomas and HUVECs to varying degrees, as well as at actual heterogeneous contact zones in both 2-D and 3-D models. This KKS immuno-reactivity was generally confined to peri-nuclear regions on HUVECs but concentrated on cell extensions on neuroblastomas. The KKS, known to enhance DNA synthesis and process pro-angiogenic precursors of both tumour cells and the extra-cellular matrix, may, by its multi-functional activities at sites of tumour-blood vessel interactions, regulate aspects of both angiogenesis and tumourigenesis.

Serum hepatocyte growth factor activator inhibitor type I (HAI-I) and type 2 (HAI-2) in prostate cancer

BACKGROUND

Hepatocyte growth factor activator inhibitor type 1 (HAI-1) and type 2 (HAI-2) are Kunitz-type serine protease inhibitors for hepatocyte growth factor activator (HGFA). We attempted to clarify whether serum levels of HAI-1 and HAI-2 could be a useful marker in patients with prostate cancer.

METHODS

Serum levels of HAI-1 and HAI-2 were measured by enzyme-linked immunosorbent assay in 27 patients with benign prostatic hyperplasia (BPH) and 118 patients with prostate cancer.

RESULTS

The mean serum levels of HAI-1 in patients with prostate cancer were significantly higher than those in patients with BPH. Furthermore, the serum HAI-1 levels in patients with distant metastasis and hormone resistant prostate cancer were significantly elevated compared with those in patients with organ-confined diseases. There were no significant differences in serum HAI-2 levels among prostate cancer subgroups according to clinical stage. Significantly elevated levels of HAI-1 were detected in 38 patients with prostate cancer before any treatment.

CONCLUSIONS

HAI-1 may be a potential tumor marker for prostate cancer. Further studies in large groups of patients are needed to define the clinical value of HAI-1.

Diverse roles of hepatocyte growth factor activator inhibitor type 1 (HAI-1) in the growth of glioblastoma cells in vivo

Hepatocyte growth factor activator inhibitor type-1 (HAI-1) is an integral-membrane proteinase inhibitor. In this study, we examined the effects of HAI-1 on human glioblastoma cells. Two glioblastoma cell lines (YKG-1, U251) were stably transfected with expression plasmid harboring mature membrane-form or truncated secreted-form HAI-1. Culture characteristics were not altered by the expression of HAI-1, whereas in vitro invasiveness of U251 was suppressed. On the other hand, the expression of membrane-form HAI-1 resulted in significantly enhanced tumorigenicity of both cell lines in vivo. In contrast, secreted-form HAI-1 did not promote the tumorigenicity. These results suggest that HAI-1 may play complex roles in progression of glioblastoma cells, and membrane-form HAI-1 may mediate an undefined important signaling in the cells.

Use of serum secretory leukocyte protease inhibitor levels in patients to improve specificity of ovarian cancer diagnosis

OBJECTIVE

To assess the clinical relevance of serum secretory leukocyte protease inhibitor (SLPI) levels in distinguishing patients with ovarian cancers from those with benign ovarian cysts, we determined concentrations with reference to the FIGO stage and other clinical characteristics.

METHODS

Preoperative serum SLPI levels were measured in women with invasive epithelial ovarian cancer (n = 55), benign ovarian cysts (n = 25), or normal controls (n = 38) using an enzyme-linked immunosorbent assay (ELISA).

RESULTS

The serum SLPI concentration was significantly elevated in the ovarian cancer patients (median 67 ng/ml, interquartile range 26-124 ng/ml) as compared to the benign cyst patients (37 and 25-66 ng/ml) or healthy women (32 and 25-43 ng/ml). Using an SLPI cutoff of 50 ng/ml and a CA125 cutoff of 30 units/ml, with both markers elevated the sensitivity was 95%, the specificity was 100%, the positive predictive value was 100%, and the negative predictive value was 89% between the malignant and benign cyst patients.

CONCLUSION

Serum SLPI levels could be useful for differentiating benign ovarian cysts from malignancies and to improve the specificity of diagnosis.

Tumor–host interactions contribute to the elevated expression level of α1-antichymotrypsin in metastatic breast tumor xenografts

We investigated alpha1-antichymotrypsin (ACT) gene expression in xenograft tumors generated by two isogenic human breast cancer cell lines derived from the same parent, MDA-MB-435, which display opposite metastatic behaviors. Microarray and real-time PCR experiments showed an overexpression of this serine protease inhibitor in the metastatic tumors (M-4A4T) and its derived metastases (M4-Mets) compared with the weakly metastatic tumors (NM-2C5T), and its release into the blood was confirmed by western-blotting. However, functional assays in vivo using genetically engineered tumor cells demonstrated that ACT up-regulation was not, by itself, responsible for the metastatic phenotype. We also made observations that ACT gene regulation was sensitive to tumor-host interactions: inoculation of these lines into the mouse mammary gland greatly increased ACT production and accentuated the intrinsic difference observed when they are cultured in vitro. Sensitivity of tumor cells to their environment was further analyzed by in vitro experiments, which demonstrated that a purified ECM environment and soluble components from normal host mammary cells were both able to significantly promote ACT expression. In addition, we took advantage of the xenogeneic nature of the model to measure ACT expression by the host cells (mouse) and the tumor cells (human) within the neoplasm using species-specific primers in real-time PCR experiments. It was found that the presence of tumor cells, irrespective of their metastatic capabilities, induced local ACT production by host cells at the primary and secondary tumor sites. Thus, this work indicates that there is a specific association of ACT overexpression with the metastatic phenotype in our breast cancer metastasis model. Moreover, because of the xenogeneic nature of our system, we were able to provide evidence of tumor-host reciprocal regulation of ACT production.

Early signals for fracture healing

Fracture healing requires the cooperation of multiple molecular signaling pathways. To better understand this cascade of transcriptional events, we compared the gene expression profiles between intact bone and fractured bone at days 1, 2, and 4 using a rat femur model of bone healing. Cluster analysis identified several groups of genes with dynamic temporal expression patterns and stage-specific functions. The immediate-response genes are highlighted by binding activity, transporter activity, and energy derivation. We consider these activities as critical signals for initiation of fracture healing. The continuously increased genes are characterized by those directly involved in bone repair, thus, representing bone specific forefront workers. The constantly upregulated genes tend to regulate general cell growth and are enriched with genes that are involved in tumorigenesis, suggesting common pathways between two processes. The constantly downregulated genes predominantly involve immune response, the significance of which remains for further investigation. Knowledge acquired through this analysis of transcriptional activities at the early stage of bone healing will contribute to our understanding of fracture repair and bone-related pathological conditions.

alpha1-antitrypsin and its C-terminal fragment attenuate effects of degranulated neutrophil-conditioned medium on lung cancer HCC cells, in vitro

Background

Tumor microenvironment, which is largely affected by inflammatory cells, is a crucial participant in the neoplastic process through promotion of cell proliferation, survival and migration. We measured the effects of polymorphonuclear neutrophil (PMN) conditioned medium alone, and supplemented with serine proteinase inhibitor α-1 antitrypsin (AAT) or its C-terminal fragment (C-36 peptide), on cultured lung cancer cells.

Methods

Lung cancer HCC cells were grown in a regular medium or in a PMN-conditioned medium in the presence or absence of AAT (0.5 mg/ml) or its C-36 peptide (0.06 mg/ml) for 24 h. Cell proliferation, invasiveness and release of IL-8 and VEGF were analyzed by [³H]-thymidine incorporation, Matrigel invasion and ELISA methods, respectively.

Results

Cells exposed to PMN-conditioned medium show decreased proliferation and IL-8 release by 3.9-fold, p < 0.001 and 1.3-fold, p < 0.05, respectively, and increased invasiveness by 2-fold (p < 0.001) compared to non-treated controls. In the presence of AAT, PMN-conditioned medium loses its effects on cell proliferation, invasiveness and IL-8 release, whereas VEGF is up-regulated by 3.7-fold (p < 0.001) compared to controls. Similarly, C-36 peptide abolishes the effects of PMN-conditioned medium on cell invasiveness, but does not alter its effects on cell proliferation, IL-8 and VEGF release. Direct HCC cell exposure to AAT enhances VEGF, but inhibits IL-8 release by 1.7-fold (p < 0.001) and 1.4-fold (p < 0.01) respectively, and reduces proliferation 2.5-fold (p < 0.01). In contrast, C-36 peptide alone did not affect these parameters, but inhibited cell invasiveness by 51.4% (p < 0.001), when compared with non-treated controls.

Conclusions

Our data provide evidence that neutrophil derived factors decrease lung cancer HCC cell proliferation and IL-8 release, but increase cell invasiveness. These effects were found to be modulated by exogenously present serine proteinase inhibitor, AAT, and its C-terminal fragment, which points to a complexity of the relationships between tumor cell biological activities and local microenvironment.

The hepatocyte growth factor regulatory factors in human breast cancer

PURPOSE

Hepatocyte growth factor (HGF) stimulates tumor cell-cell interactions, matrix adhesion, migration, invasion, and angiogenesis. This factor is produced as an inactive precursor called pro-HGF, which requires proteolytic conversion, by HGF activator (HGFA) and matriptase, to evoke a biological response. Two new HGFA inhibitors, HAI-1 and HAI-2, inhibit the generation of biologically active HGF, through their interaction with HGFA. This study determined the expression of this HGF regulatory system in breast cancer. We examined HGF, the HGF receptor (c-Met), HGFA, matriptase, and the activation inhibitors (HAI-1 and HAI-2), tissues from patients with breast cancer.

EXPERIMENTAL DESIGN

Breast cancer tissue (n = 100) and normal background tissue (n = 20) was obtained immediately after surgery. The median follow-up for the patients was 72 months. HGF, c-Met, HGFA, matriptase-1, HAI-1, and HAI-2 expression was quantified using real-time quantitative PCR. The distribution of these factors in mammary tissues was also examined through immunohistochemistry.

RESULTS

The breast cancer specimens expressed a significantly higher level of HGF, c-Met, HGFA, HAI-1, and HAI-2, but not matriptase, compared with the normal background tissues. Tumor tissues from node-positive patients expressed a higher level of HGFA than from the patients without nodal involvement. Interestingly, HAI-2 was expressed to a lower degree in positive nodes than that of the node-negative breast cancer tissues. HAI-1 and HAI-2 were both significantly reduced in grade 3 tumors compared with the well-differentiated tumors. In addition, on comparison of Tumor-Node-Metastasis (TNM) classification groups, HAI-2 was also found to be statistically lower in the TNM 3 breast cancer group when compared with TNM groups 1 and 2, thus associated with a poor prognosis.

CONCLUSIONS

This study shows that there are aberrant levels of HGF, c-Met, HGFA, HAI-1, and HAI-2 expressed in breast cancer tissues compared with background breast tissue. HAI-1 and HAI-2 are expressed to a significantly lower level in poorly differentiated breast tumors, and HAI-2 is also inversely correlated with nodal involvement and tumor spread. Overall a low level of HAI-2 in the breast cancer tissues was associated with an overall poor outlook. Therefore, the HGF regulatory system may have an important role in the progression of breast cancer.

Tumour metabolites regulate tissue kallikrein in human umbilical vein endothelial cells

Angiogenesis, the sprouting of new blood vessels, is tightly mediated via a myriad of endogenous factors. A pro-angiogenic alteration facilitates the formation of neovascular tumour networks, thereby providing mechanisms for uncontrolled growth. The kallikrein-kinin system is postulated to be pro-angiogenic since its components have been detected in both endothelial cells and tumour tissue. No studies have, however, focussed on the role of tissue kallikrein (TK) in human angiogenic endothelial cell-tumour interactions. This study has optimised a challenge model whereby endothelial cells are presented with neuroblastoma metabolites, and vice versa. Image analysis of immunoreactive TK revealed a dose-dependant, significant reduction of TK localisation within endothelial cells, while gene expression remained unchanged, the latter determined by in situ RT-PCR. Neuroblastoma cells, when challenged with endothelial cell metabolites, displayed no change in TK synthesis or localisation. Alterations in TK synthesis and/or storage by angiogenic endothelial cells may be mediated by tumour-released signals and possibly indicate a shift from a proteolytic to a mitogenic function of TK. The challenge model provides a relatively simple experimental system to study angiogenic factors in tumour-endothelial cell interaction, and is the first to localise both TK and its mRNA within angiogenic endothelial and tumour cells.

Purification and pH stability characterization of a chymotrypsin inhibitor from Schizolobium parahyba seeds

Schizolobium parahyba chymotrypsin inhibitor (SPCI) was completely purified as a single polypeptide chain with two disulfide bonds, by TCA precipitation and ion exchange chromatography. This purification method is faster and more efficient than that previously reported: SPCI is stable from pH 2 to 12 at 25 degrees C, and is highly specific for chymotrypsin at pH 7-12. It weakly inhibits elastase and has no significant inhibitory effect against trypsin and alpha-amylase. SPCI is a thermostable protein and resists thermolysin digestion up to 70 degrees C.

Secretory leukocyte protease inhibitor promotes the tumorigenic and metastatic potential of cancer cells

Because of their ability to inhibit proteases, protease inhibitors have generally been considered to counteract tumor progression and metastasis. However, expression of serine protease inhibitors (SPIs) in tumors is often associated with poor prognosis of cancer patients. Moreover, there is growing evidence that SPIs may even promote malignancy of cancer cells, opening new avenues for their use as biomarkers in malignancy. To isolate cancer promoting genes, we applied the suppression subtractive hybridization method to low-malignant Lewis Lung Carcinoma 3LL-S versus high-malignant 3LL-S-sc cells. This resulted in the identification of the SPI secretory leukocyte protease inhibitor (SLPI), as one of the genes whose expression was higher in 3LL-S-sc than in 3LL-S cells. By stable transfection of 3LL-S cells with mouse or human SLPI, we demonstrated that elevated levels of SLPI expression increased both the tumorigenicity and lung-colonizing potential of 3LL-S cells. Moreover, we showed that this function of SLPI depended on its protease inhibitory capacity. Our results also reveal that although SLPI enhanced the proliferation of 3LL-S cells in vitro, its promalignant activity in vivo was not solely due to its effect on cell proliferation. In this study, we report a causal role for SLPI in the malignant behavior of cancer cells, underscoring the potential malignancy-promoting activities of SPIs.

Expression of hepatocyte growth factor activator inhibitor type 2 (HAI-2) in human testis: identification of a distinct transcription start site for the HAI-2 gene in testis

Hepatocyte growth factor activator inhibitor type 1 (HAI-1) and type 2 (HAI-2) are recently identified integral membrane Kunitz-type proteinase inhibitors. They have important regulatory roles in pericellular activation of hepatocyte growth factor/scatter factor (HGF/SF) which is critically involved in the development and regeneration of various tissues. Recent reports suggest that HGF/SF is also involved in testicular development and spermatogenesis. In this study, we analyzed the expression of HAIs in the testis. In human testis, HAI-2 was strongly expressed whereas HAI-1 mRNA was hardly detectable. Of interest was the observation that the mRNA size of HAI-2 was shorter in the testis (1.2 kb) than those in the other tissues such as placenta (1.5 kb). Subsequent experiments revealed that there are two major transcription start sites of the HAI-2 gene, which are -30 bp and -360 bp upstream from the translation initiation ATG codon. Although the latter site appeared to be mainly used in the placenta and other non-testicular organs, only the former site is used in testis, resulting in the -300 bp shorter mRNA. An immunohistochemical study using a specific monoclonal antibody raised against human HAI-2 protein indicated that HAI-2 is expressed exclusively in primary spermatocytes. These results suggest a distinct regulation of HAI-2 gene expression in testis and that HAI-2 may play a role in the process of spermatogenesis.