Tumor invasion, proteolysis, and angiogenesis

Endothelial caveolin and its scaffolding domain in cancer

Since the initial reports implicating caveolin-1 (CAV1) in neoplasia, the scientific community has made tremendous strides towards understanding how CAV1-dependent signaling and caveolae assembly modulate solid tumor growth. Once a solid neoplastic tumor reaches a certain size, it will increasingly rely on its stroma to meet the metabolic demands of the rapidly proliferating cancer cells, a limitation typically but not exclusively addressed via the formation of new blood vessels. Landmark studies using xenograft tumor models have highlighted the importance of stromal CAV1 during neoplastic blood vessel growth from preexisting vasculature, a process called angiogenesis, and helped identify endothelium-specific signaling events regulated by CAV1, such as vascular endothelial growth factor (VEGF) receptors as well as the endothelial nitric oxide (NO) synthase (eNOS) systems. This chapter provides a glimpse into the signaling events modulated by CAV1 and its scaffolding domain (CSD) during endothelial-specific aspects of neoplastic growth, such as vascular permeability, angiogenesis, and mechanotransduction.

Effect of tissue inhibitor of metalloprotease 1 on human pulp cells in vitro and rat pulp tissue in vivo

AIM

To evaluate the dentinogenetic effects of tissue inhibitor of metalloprotease (TIMP1) on human pulp cells in vitro and rat pulp tissue in vivo.

METHODOLOGY

The effect of TIMP1 on pulp cell functions related to hard tissue formation as part of the wound healing process (i.e. biocompatibility, proliferation, differentiation and mineralized nodule formation) was evaluated in vitro and using a direct pulp capping experimental animal model in vivo. The effects of different-sized cavity preparations on hard tissue formation induced by ProRoot MTA at 2 weeks were evaluated using micro-computed tomography (micro-CT). Tertiary dentine formation quality and quantity after pulp capping using TIMP1, ProRoot MTA and phosphate-buffered saline (PBS) was also evaluated after 4 weeks using micro-CT in term of dentine volume (DV), dentine mineral density (DVD) and histological analysis. The data were evaluated by Student's t-test, one-way ANOVA with Tukey's post hoc test, the Kruskal-Wallis test or the Steel-Dwass test. P values < 0.05 were considered statistically significant.

RESULTS

TIMP1 significantly stimulated dental pulp stem cell proliferation, differentiation, and mineralization and was more biocompatible compared with the PBS control (P < 0.05). In the pulp capping model, the amount of tertiary dentine that formed was directly proportional to the size of the pulp exposure; greater amounts of tertiary dentine were observed in pulps with larger exposures after 2 weeks. 4-week samples of TIMP1 and ProRoot MTA had similar characteristics, but both sample significantly induced tertiary dentine formation beneath the cavity compared with PBS (P <  0.05) under standardized cavity preparations.

CONCLUSIONS

TIMP1 has an important role in pulpal wound healing, which makes it a potential biological pulp capping material and candidate molecule for regenerative endodontic therapy.

Expression of a urokinase-type plasminogen activator during tumor growth leads to angiogenesis via galanin activation in tumor-bearing mice

Small-cell lung carcinoma releases progalanin. The released progalanin is activated via a nonclassical processing pathway, being processed into an active form of galanin (1-20) by plasmin in extracellular components. Plasmin is produced from plasminogen activators. To clarify the regulation of progalanin via plasminogen activation by urokinase and tissue-plasminogen activator (t-PA), we investigated the regulation mechanism for urokinase and t-PA expression and their effect on galanin activation. Additionally, we studied the effect of activated galanin on angiogenesis. To determine the effect of cell density, we measured the expression levels of urokinase and t-PA using real-time PCR and plasminogen/gelatin zymography in a cell culture. The urokinase expression increased under both high cell density and presence of cell membrane fractions. However, urokinase increments induced by conditioned medium were low. These results indicate that expression of plasminogen activators is regulated by cell membrane factors. We used tumor-bearing mice to clarify the expression of plasminogen activators and galanin activation. Real-time PCR showed that urokinase was substantially higher in the central parts of tumors compared to the periphery, and this was confirmed by plasminogen/gelatin zymography. To evaluate the biological effect of plasminogen activators on tumor growth, we used tranexamic acid as a plasminogen inhibitor. Tranexamic acid decreased galanin (1-20) and the hemoglobin content of tumors and suppressed tumor growth. Additionally, galanin had no effect on the hemoglobin content of tumors derived from cells lacking GALR2. These results demonstrate the regulation of urokinase expression in tumors through progalanin activation in extracellular compartments, and confirm that galanin plays a role in angiogenesis.

Modelling Tumor-induced Angiogenesis: Combination of Stochastic Sprout Spacing and Sprout Progression

BACKGROUND

Angiogenesis initiated by cancerous cells is the process by which new blood vessels are formed to enhance oxygenation and growth of tumor.

OBJECTIVE

In this paper, we present a new multiscale mathematical model for the formation of a vascular network in tumor angiogenesis process.

METHODS

Our model couples an improved sprout spacing model as a stochastic mathematical model of sprouting along an existing parent blood vessel, with a mathematical model of sprout progression in the extracellular matrix (ECM) in response to some tumor angiogenic factors (TAFs). We perform simulations of the siting of capillary sprouts on an existing blood vessel using finite difference approximation of the dynamic equations of some angiogenesis activators and inhibitors. Angiogenesis activators are chemicals secreted by hypoxic tumor cells for initiating angiogenesis, and inhibitors of the angiogenesis are chemicals that are produced around every new sprout during tumor angiogenesis to inhibit the formation of further sprouts as a feedback of sprouting in angiogenesis. Moreover, for modelling sprout progression in ECM, we use three equations for the motility of endothelial cells at the tip of the activated sprouts, the consumption of TAF and the production and uptake of Fibronectin by endothelial cells.

RESULTS

Coupling these two basic models not only does provide a better time estimation of angiogenesis process, but also it is more compatible with reality.

CONCLUSION

This model can be used to provide basic information for angiogenesis in the related studies. Related simulations can estimate the position and number of sprouts along parent blood vessel during the initial steps of angiogenesis and models the process of sprout progression in ECM until they vascularize a tumor.

High-Level Expression and Prognostic Significance of Matrix Metalloprotease-19 and Matrix Metalloprotease-20 in Human Pancreatic Ductal Adenocarcinoma

OBJECTIVE

Matrix metalloproteinase (MMP)-19 and MMP-20 are important members of the MMP family, and their roles in tumor survivorship and progression are continually reported. This work aimed to determine the expression and prognostic significance of MMP-19 and MMP-20 in pancreatic ductal adenocarcinoma (PDAC).

METHODS

Immunohistochemistry was used to investigate the levels of MMP-19 and MMP-20 expression in carcinoma tissues and paracancerous tissues from 102 PDAC patients.

RESULTS

The MMP-19 and MMP-20 were, respectively, expressed in 71.6% (73/102) and 70.6% (72/102) of carcinoma tissues, and the expression was positively correlated (r = 0.643, P < 0.001). High-level expression of MMP-19 and MMP-20 was strongly correlated with aggressive clinicopathological characteristics. Kaplan-Meier analysis showed that high-level expression of MMP-19 and MMP-20 was significantly associated with decreased event-free survival (P < 0.001) and overall survival (P < 0.001). Multivariate analysis showed that high-level expression of MMP-19 could act as an independent predictive biomarker for poor event-free survival and overall survival.

CONCLUSIONS

Levels of MMP-19 and MMP-20 expression are significantly increased in PDAC. High-level expression of MMP-19 and MMP-20 is closely correlated to progression and prognosis of PDAC, and these may be considered as promising markers for unfavorable prognoses.

MMP2 gene-735 C/T and MMP9 gene -1562 C/T polymorphisms in JAK2V617F positive myeloproliferative disorders

BACKGROUND

Myeloproliferative disorders (MPDs) are clonal hematologic malignancies originating at the level of the pluripotent hematopoietic stem cell. Matrix metalloproteases (MMPs) are proteolytic enzymes that contribute to all stages of malignancy progression. Genetic variants in the MMP genes may influence the biological function of these enzymes and change their role in carcinogenesis and progression. To our knowledge, this is the first investigation of associations between the -735 C/T and -1562 C/T polymorphisms in the MMP2 and MMP9 genes, respectively, and the risk of essential thrombocytosis (ET), and polycythemia vera (PV).

MATERIALS AND METHODS

The case-control study included JAK2V617F mutation positive 102 ET and PV patients and 111 controls. Polymorphisms were determined by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and electrophoresis.

RESULTS

No statistically significant differences were detected between patient (ET+PV) and control groups regarding genotype distribution for MMP2 gene-735 C/T and MMP9 gene -1562 C/T polymorphisms and C/T allele frequency (p>0.050). Statistically borderline significance was observed between PV and control groups regarding genotype distribution for the MMP9 gene -1562 C/T polymorphism (p=0.050, OR=2.26, 95%Cl=0.99-5.16).

CONCLUSIONS

Consequently this study supported that CC genotype of MMP9 gene -1562 C/T polymorphism may be related with PV even if with borderline significance.

The anomalous diffusion of a tumor invading with different surrounding tissues

We simulated the invasion of a proliferating, diffusing tumor within different surrounding tissue conditions using a hybrid mathematical model. The in silico invasion of a tumor was addressed systematically for the first time within the framework of a generalized diffusion theory. Our results reveal that a tumor not only migrates using typical Fickian diffusion, but also migrates more generally using subdiffusion, superdiffusion, and even ballistic diffusion, with increasing mobility of the tumor cell when haptotaxis and chemotaxis toward the host tissue surrounding the proliferative tumor are involved. Five functional terms were included in the hybrid model and their effects on a tumor's invasion were investigated quantitatively: haptotaxis toward the extracellular matrix tissue that is degraded by matrix metalloproteinases; chemotaxis toward nutrients; cell-cell adhesion; the proliferation of the tumor; and the immune response toward the tumor. Haptotaxis and chemotaxis, which are initiated by extracellular matrix and nutrient supply (i.e., glucose) respectively, as well as cell-cell adhesions all drastically affect a tumor's diffusion mode when a tumor invades its surrounding host tissue and proliferates. We verified the in silico invasive behavior of a tumor by analyzing experimental data gathered from the in vitro culturing of different tumor cells and clinical imaging observations that used the same approach as was used to process the simulation data. The different migration modes of a tumor suggested by the simulations generally conform to the results observed in cell cultures and in clinical imaging. Our study not only discloses some migration modes of a tumor that proliferates and invades under different host tissues conditions, but also provides a heuristic method to characterize the invasion of a tumor in clinical medical imaging analysis.

Front instabilities and invasiveness of simulated avascular tumors

We study the interface morphology of a 2D simulation of an avascular tumor composed of identical cells growing in an homogeneous healthy tissue matrix (TM), in order to understand the origin of the morphological changes often observed during real tumor growth. We use the Glazier-Graner-Hogeweg model, which treats tumor cells as extended, deformable objects, to study the effects of two parameters: a dimensionless diffusion-limitation parameter defined as the ratio of the tumor consumption rate to the substrate transport rate, and the tumor-TM surface tension. We model TM as a nondiffusing field, neglecting the TM pressure and haptotactic repulsion acting on a real growing tumor; thus, our model is appropriate for studying tumors with highly motile cells, e.g., gliomas. We show that the diffusion-limitation parameter determines whether the growing tumor develops a smooth (noninvasive) or fingered (invasive) interface, and that the sensitivity of tumor morphology to tumor-TM surface tension increases with the size of the dimensionless diffusion-limitation parameter. For large diffusion-limitation parameters, we find a transition (missed in previous work) between dendritic structures, produced when tumor-TM surface tension is high, and seaweed-like structures, produced when tumor-TM surface tension is low. This observation leads to a direct analogy between the mathematics and dynamics of tumors and those observed in nonbiological directional solidification. Our results are also consistent with the biological observation that hypoxia promotes invasive growth of tumor cells by inducing higher levels of receptors for scatter factors that weaken cell-cell adhesion and increase cell motility. These findings suggest that tumor morphology may have value in predicting the efficiency of antiangiogenic therapy in individual patients.

Biology and potential clinical implications of tissue inhibitor of metalloproteinases-1 in colorectal cancer treatment

Colorectal cancer (CRC) is the second leading cause of cancer-related death in the industrialized world. About half of "curatively" resected patients develop recurrent disease within the next 3-5 years despite the lack of clinical, histological and biochemical evidence of remaining overt disease after resection of the primary tumour. Availability of validated biological markers for early detection, selection for adjuvant therapy, prediction of treatment efficacy and monitoring of treatment efficacy would most probably increase survival. Tissue inhibitor of metalloproteinases-1 (TIMP-1) may be such a marker. TIMP-1 inhibits the proteolytic activity of metalloproteinases, which are centrally involved in tumour invasion and metastases. However, in clinical investigations high tumour tissue or plasma levels of TIMP-1 have shown a strong and independent association with a shorter survival time in CRC patients, suggesting that TIMP-1 could have a tumour-promoting function. Furthermore, measurement of plasma TIMP-1 has been shown to be useful for disease detection, with a high sensitivity and high specificity for early-stage colon cancer. This review describes some basic information on the current knowledge of the biology of TIMP-1 as well as the potential use of TIMP-1 as a biological marker in the management of CRC patients.

Comparison of the in vitro and in vivo effects of retinoids either alone or in combination with cisplatin and 5-fluorouracil on tumor development and metastasis of melanoma

PURPOSE

Retinoids have previously been reported to inhibit proliferation of melanoma cell lines in vitro. However, the relative antimetastatic efficacy of various retinoids on melanoma in vivo is unknown. Therefore, we investigated the effects of different retinoids on the invasion and metastasis of murine melanoma B16-F10 cells in vitro and in vivo. Based on the findings, the antitumor effects of a selected retinoid either alone or in combination with cisplatin were also investigated in a preclinical mouse melanoma model.

METHODS

Cell proliferation and invasion analyses of murine melanoma B16-F10 cells were assessed in the presence of different retinoids, either alone or in combination with cisplatin (CDDP) or 5-fluorouracil (5-FU). Experimental lung metastasis assay was performed in this study to investigate the antimetastatic efficacy of retinoids. Additionally, a mouse melanoma model was used to assess the antitumor efficacy of a selected retinoid in combination with cisplatin.

RESULTS

Retinoids showed significant antiproliferation and anti-invasion effects on murine melanoma B16-F10 cells. Pretreatment with retinoids increased the sensitivity to CDDP but not to 5-FU in in-vitro. Moreover, the number of metastatic colonies formed in the lungs of mice injected intravenously with B16-F10 cells was significantly reduced by injecting the respective retinoid once a day for 10 days. Treatment with a combination of cisplatin and 13-cis-retinoic acid resulted in a significant reduction in primary tumor size and the number of lung metastatic nodules in melanoma-bearing mice.

CONCLUSION

These results suggest that retinoids not only exhibit antimetastatic effect, but also enhance the antitumor activity of cisplatin in vivo.

The fibrinolytic system facilitates tumor cell migration across the blood-brain barrier in experimental melanoma brain metastasis

BACKGROUND

Patients with metastatic tumors to the brain have a very poor prognosis. Increased metastatic potential has been associated with the fibrinolytic system. We investigated the role of the fibrinolytic enzyme plasmin in tumor cell migration across brain endothelial cells and growth of brain metastases in an experimental metastatic melanoma model.

METHODS

Metastatic tumors to the brain were established by direct injection into the striatum or by intracarotid injection of B16F10 mouse melanoma cells in C57Bl mice. The role of plasminogen in the ability of human melanoma cells to cross a human blood-brain barrier model was studied on a transwell system.

RESULTS

Wild type mice treated with the plasmin inhibitor epsilon-aminocaproic acid (EACA) and plg-/- mice developed smaller tumors and survived longer than untreated wild type mice. Tumors metastasized to the brain of wild type mice treated with EACA and plg-/- less efficiently than in untreated wild type mice. No difference was observed in the tumor growth in any of the three groups of mice. Human melanoma cells were able to cross the human blood-brain barrier model in a plasmin dependent manner.

CONCLUSION

Plasmin facilitates the development of tumor metastasis to the brain. Inhibition of the fibrinolytic system could be considered as means to prevent tumor metastasis to the brain.

Establishment and Characterization of 7 New Monoclonal Antibodies to Tissue Inhibitor of Metalloproteinases-1

Tissue inhibitor of metalloproteinases-1 (TIMP-1) plays a pivotal role in tissue remodeling processes, such as inflammation, wound healing and cancer invasion. Experimental results have pointed to a role in angiogenesis, cell proliferation, apoptosis and in malignant transformation. In clinical investigations high tumor tissue or plasma levels of TIMP-1 have been shown to have a strong and independent association with shorter survival time for breast and colorectal cancer patients, respectively. The purpose of this study has been to develop and characterize new anti-TIMP-1 monoclonal antibodies that may be useful in future development of TIMP-1 immunoassays.Peptide-based epitope mapping reveals linear epitopes. Surface plasmon resonance was used to determine antibody affinity and ability of antibodies to sandwich with each other. Antigen recognition was tested using ELISA and a chemiluminescence microtiter immunoassay format. Three antibodies recognized linear peptides. Estimated antibody affinities for TIMP-1 ranged from 6.6 x 10(8) to>10(10) 1/M. Antibodies demonstrated different abilities in 'capture' and 'detection' positions in the sandwich experiment. All antibody pairs bound TIMP-1:ProMMP-9 complexes. TIMP-1:MMP-9 complexes were marginally reactive with five antibody pairs. The results suggest that the antibodies are unique. They may be useful in designing assays that recognize various forms of TIMP-1. Future studies will clarify whether the use of different combinations of antibodies will increase the clinical value of TIMP-1 measurements in the treatment of cancer patients.

Progress Report on the Potential of Angiogenesis Inhibitors for Neuro-Oncology

New therapies for brain tumors are urgently needed. Brain tumors are highly vascularized, supporting the potential of anti-angiogenic therapies in their treatment. The promise of blocking tumor growth through inhibiting new blood vessel formation with anti-angiogenic agents has been heralded as a therapeutic breakthrough, and pre-clinical data supported this enthusiasm. However, early clinical trials in humans have been somewhat disappointing. Nonetheless, great optimism for these agents remains, and many new anti-angiogenic agents and strategies are being evaluated pre-clinically and in clinical trials. A number of issues need to be considered in the application of these agents to neuro-oncology. In this review, we discuss the biology of blood vessel formation in the brain and brain tumors as it relates to anti-angiogenic therapies. The difficulties inherent in performing clinical trials of anti-angiogenic therapies in patients with brain tumors are outlined. Finally, we consider numerous individual antiangiogenic and antivascular therapies now in pre-clinical testing or in clinical trials.

Increased Circulating Matrix Metalloproteinase-2 in Patients With Hypertrophic Cardiomyopathy With Systolic Dysfunction

BACKGROUND

Some patients with hypertrophic cardiomyopathy (HCM) develop left ventricular (LV) wall thinning associated with LV dilatation and systolic dysfunction. Recently, matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) were reported to be involved in ventricular remodeling, however, little is known about MMPs and TIMPs in patients with HCM.

METHODS AND RESULTS

Enzyme-linked immunoassays were used to measure the plasma concentrations of MMP-2, MMP-3, MMP-9, TIMP-1, and TIMP-2 in 11 patients with HCM accompanied by systolic dysfunction (fractional shortening (FS) <25%, group A), 17 patients with HCM who had preserved systolic function (FS> or =25%, group B), and 50 age-matched clinically healthy control subjects (mean age: 57 years). The concentration of MMP-2 in group A was significantly higher than in group B and the control subjects (1,124 +/- 84, 792 +/- 49, 809 +/- 26 ng/ml, respectively), whereas there was no significant difference between group B and the control subjects. MMP-2 concentrations significantly increased as the New York Heart Association functional class increased in patients with HCM. TIMP-2 was also significantly higher in group A patients than in group B and the control subjects (45.3 +/- 4.7, 34.6 +/- 2.2, 33.7 +/- 1.8 ng/ml, respectively), but there was no difference between group B and control subjects. TIMP-1 was significantly higher in HCM patients than in control subjects. MMP-3 and MMP-9 concentrations did not differ among the 3 groups. Both MMP-2 and TIMP-2 correlated significantly with FS and LV dimension, negatively and positively, respectively.

CONCLUSIONS

These results suggest that changes in the release and activity of MMP-2 and TIMP-2 may be associated with the mechanisms responsible for cardiac remodeling in patients with HCM.

Both u-PA inhibition and vitronectin binding by plasminogen activator inhibitor 1 regulate HT1080 fibrosarcoma cell metastasis

Overexpression of plasminogen activator inhibitor 1 (PAI-1) reduces tumor cell migration in vitro and metastasis in mice in vivo by mechanisms involving either inhibition of urokinase plasminogen activator (u-PA) activity or competition for an integrin binding site on vitronectin. To analyze the effects of PAI-1 on tumor cell migration in vitro and metastasis in vivo, recombinant adenoviral vectors expressing wild-type or mutant PAI-1 proteins were constructed. The mutant PAI-1 proteins were defective in either vitronectin binding (PAI-1(VN-)), plasminogen activator inhibition (PAI-1(INH-)) or both (PAI-1(VN-,INH-)). In vitro, migration of HT1080 human fibrosarcoma cells through a reconstituted extracellular matrix (ECM) was reduced 73% by overexpression of wild-type PAI-1 and 65% by PAI-1(VN-) compared with control virus-infected cells. Migration of cells infected by virus expressing either PAI-1(INH-) or PAI-1(VN-,INH-) was unaffected, indicating a requirement for plasminogen activator inhibitory activity. In vivo, however, only overexpression of wild-type PAI-1 reduced the burden of metastasis by 68% compared with the control group. This indicates that both u-PA inhibition and PAI-1 ECM interactions contribute to the mechanism of PAI-1-mediated regulation of cell migration.

Betulinic acid inhibits growth factor-induced in vitro angiogenesis via the modulation of mitochondrial function in endothelial cells

Betulinic acid (BetA), a pentacyclic triterpene, is a selective apoptosis-inducing agent that works directly in mitochondria. Recent study has revealed that BetA inhibits in vitro enzymatic activity of aminopeptidase N (APN, EC 3.4.11.2), which is known to play an important role in angiogenesis, but the anti-angiogenic activity of BetA has not been reported yet. Data presented here show that BetA potently inhibited basic fibroblast growth factor (bFGF)-induced invasion and tube formation of bovine aortic endothelial cells (BAECs) at a concentration which had no effect on the cell viability. To access whether the anti-angiogenic nature of BetA originates from its inhibitory action against aminopeptidase N (APN) activity, the effect of BetA on APN was investigated. Surprisingly, BetA did not inhibit in vivo APN activity in endothelial cells or APN-positive tumor cells. On the other hand, BetA significantly decreased the mitochondrial reducing potential, and treatment with mitochondrial permeability transition (MPT) inhibitors attenuated BetA-induced inhibition of endothelial cell invasion. These results imply that anti-angiogenic activity of BetA occurs through a modulation of mitochondrial function rather than APN activity in endothelial cells.

Induction of MMP-9 in normal human bronchial epithelial cells by TNF-alpha via NF-kappa B-mediated pathway

In this study, we determined whether the proinflammatory cytokines tumor necrosis factor (TNF)-alpha and interleukin-1 beta contribute to the regulation of matrix metalloproteinase (MMP)-9 in human bronchial epithelial cells and whether the induction of MMP-9 is regulated by the transcription factor nuclear factor (NF)-kappa B. We demonstrated that TNF-alpha induced MMP-9 at both the protein and mRNA levels in human bronchial epithelial cells and that interleukin-1 beta did not. In contrast, induction of the tissue inhibitor of metalloproteinase-1 by TNF-alpha was less than that of interleukin-1 beta. Increased expression of MMP-9 and NF-kappa B activation induced by TNF-alpha were inhibited by pyrrolidine dithiocarbamate and N-acetyl-L-cysteine but were not inhibited by curcumin. These results suggest that TNF-alpha induces the expression of MMP-9 in human bronchial epithelial cells and that this induction is mediated via the NF-kappa B-mediated pathway.

Biological mechanisms of glioma invasion and potential therapeutic targets

The current understanding of glioma biology reveals targets for anti-invasive therapy which include manipulations of extracellular matrix and receptors, growth factors and cytokines, proteases, cytoskeletal components, oncogenes and tumor suppressor genes. A better understanding of the complex regulation and the signalling molecules involved in glioma invasion is still needed in order to design new and effective treatment modalities towards invasive tumor cells. Representative and valid in vitro experimental systems and animal models of gliomas are necessary for the characterization of the invasive phenotype and further development of anti-invasive therapy. In the future, it will probably be important to move from comparative genomic modelling through protein characterization based on advanced proteomic techniques to analyse tissue samples, where the aim for gliomas should be to compare invaded and non-invaded tissue. This will hopefully render promising new therapeutic targets for gliomas.

Quantitation of TIMP-1 in plasma of healthy blood donors and patients with advanced cancer

A kinetic enzyme-linked immunosorbent assay (ELISA) for plasma tissue inhibitor of metalloproteinase (TIMP)-1 was developed in order to examine the potential diagnostic and prognostic value of TIMP-1 measurements in cancer patients. The ELISA enabled specific detection of total TIMP-1 in EDTA, citrate and heparin plasma. The assay was rigorously tested and requirements of sensitivity, specificity, stability and good recovery were fulfilled. TIMP-1 levels measured in citrate plasma (mean 69.2+/-13.1 microg I(-1)) correlated with TIMP-1 measured in EDTA plasma (mean 73.5+/-14.2 microg I(-1)) from the same individuals in a set of 100 healthy blood donors (Spearman's rho = 0.62, P< 0.0001). The mean level of TIMP-1 in EDTA plasma from 143 patients with Dukes' stage D colorectal cancer was 240+/-145 microg I(-1) and a Mann-Whitney test demonstrated a highly significant difference between TIMP-1 levels in healthy blood donors and colorectal cancer patients (P < 0.0001). Similar findings were obtained for 19 patients with advanced breast cancer (mean 292+/-331 microg I(-1)). The results show that TIMP-1 is readily measured in plasma samples by ELISA and that increased levels of TIMP-1 are found in patients with advanced cancer. It is proposed that plasma measurements of TIMP-1 may have value in the management of cancer patients.

Reduction of tumor cell migration and metastasis by adenoviral gene transfer of plasminogen activator inhibitors

Recombinant adenoviral vectors expressing u-PA, t-PA, PAI-1 and PAI-2 were employed to correlate the expression of components of the fibrinolytic system with the invasiveness of HT 1080 tumor cells. Migration through Transwell inserts in vitro in the presence of plasminogen was increased up to 22% by overexpression of u-PA, whereas t-PA had no effect. Gene transfer of PAI-1 or PAI-2 both reduced migration in a dose-dependent manner by up to 43% with PAI-1 and 29% with PAI-2. Two routes of gene transfer were used to alter metastasis of subcutaneously implanted HT 1080 cells expressing firefly luciferase in nude mice. Infection of cultured tumor cells with adenovirus expressing either PAI-1 or PAI-2 before implantation significantly reduced the incidence of lung metastasis by 60% compared with control virus. However, only PAI-2 reduced the incidence of lung and brain metastasis following liver gene transfer. Although PAI gene transfer by either route reduced primary tumor size, it had little effect on tumor vascularization or host survival. The migratory and metastatic phenotype of HT 1080 tumor cells is thus directly dependent on u-PA expression levels and can be altered by gene transfer of u-PA or plasminogen activator inhibitors.

Activated Endothelial Cells Induce Apoptosis in Leukemic Cells by Endothelial Interleukin-8

Tumor cells are eradicated by several systems, including Fas ligand-Fas and tumor necrosis factor (TNF)-tumor necrosis factor receptor (TNFR). In the previous study, we purified an apoptosis-inducing factor (AIF) to homogeneity from a medium conditioned by PDBu-treated HL-60 cells. N-terminal sequence analysis showed that AIF is identical to endothelial interleukin-8 (IL-8). A novel apoptosis system, in which endothelial cells participate via endothelial IL-8 release, is identified here. Human umbilical vein cells (VE cells) produce and secrete IL-8 by stimulation of IL-1 and TNF-. Endothelial IL-8, which is secreted from VE cells by stimulation of IL-1 and TNF- , induces apoptosis in myelogenous leukemia cell line K562 cells. Monocyte-derived IL-8 could not induce apoptosis in K562 cells. Moreover, interaction between VE cells and K562 cells induces the release of endothelial IL-8 from VE cells, and the attached K562 cells undergo apoptosis. Moreover, interactions between VE cell and other cell lines, such as HL-60, U937, Jurkat, and Daudi, induce the secretion of endothelial IL-8 and the induction of apoptosis in cell lines. Endothelial IL-8 significantly inhibits tumor growth of intraperitoneal and subcutaneous tumor mass of K562 cells and induces apoptosis in their cells in vivo. Endothelial IL-8 plays an important role in apoptosis involving endothelial cells, which may provide us with a new therapy for hematological malignancies.

© 1998 by The American Society of Hematology.

Activated Endothelial Cells Induce Apoptosis in Leukemic Cells by Endothelial Interleukin-8

Tumor cells are eradicated by several systems, including Fas ligand-Fas and tumor necrosis factor (TNF)-tumor necrosis factor receptor (TNFR). In the previous study, we purified an apoptosis-inducing factor (AIF) to homogeneity from a medium conditioned by PDBu-treated HL-60 cells. N-terminal sequence analysis showed that AIF is identical to endothelial interleukin-8 (IL-8). A novel apoptosis system, in which endothelial cells participate via endothelial IL-8 release, is identified here. Human umbilical vein cells (VE cells) produce and secrete IL-8 by stimulation of IL-1 and TNF-. Endothelial IL-8, which is secreted from VE cells by stimulation of IL-1 and TNF- , induces apoptosis in myelogenous leukemia cell line K562 cells. Monocyte-derived IL-8 could not induce apoptosis in K562 cells. Moreover, interaction between VE cells and K562 cells induces the release of endothelial IL-8 from VE cells, and the attached K562 cells undergo apoptosis. Moreover, interactions between VE cell and other cell lines, such as HL-60, U937, Jurkat, and Daudi, induce the secretion of endothelial IL-8 and the induction of apoptosis in cell lines. Endothelial IL-8 significantly inhibits tumor growth of intraperitoneal and subcutaneous tumor mass of K562 cells and induces apoptosis in their cells in vivo. Endothelial IL-8 plays an important role in apoptosis involving endothelial cells, which may provide us with a new therapy for hematological malignancies.

© 1998 by The American Society of Hematology.

The importance of cell density in the interpretation of growth factor effects on collagenase IV activity release and extracellular matrix production from C6 astrocytoma cells

We have examined the influence of basic fibroblast growth factor (FGF-2) and vascular endothelial growth factor (VEGF) on the release of collagenase type IV activity and the production of extracellular matrix (ECM) molecules using C6 astrocytoma cells in monolayer culture. Collagenase type IV activity was significantly increased in a dose dependent manner in the low cell density group by treatment with FGF-2 and VEGF but significantly decreased in a dose dependent fashion in the high cell density group. These results were corroborated using Western blot technique with an antibody to gelatinase A. Addition of exogenous laminin and fibronectin to the media decreased collagenase type IV activity in a dose dependent fashion with the minimum concentration of 0.1 microgram/ml. Laminin and fibronectin reached a concentration of 0.1 microgram/ml in only the high cell density group after treatment with the growth factors tested. These findings indicate that C6 astrocytoma cells appear to have two regulatory mechanisms for collagenase type IV activity which are dependent on cell density. In a low cell density, C6 astrocytoma cells respond to the dominant effect of FGF-2 and VEGF by increasing the release of collagenase IV activity. In a high cell density collagenase type IV activity is decreased due to it's down regulation by released ECM molecules in response to FGF-2 and VEGF. These regulatory mechanisms may be crucial to the understanding of the coordination of tumor-associated angiogenesis by malignant glial cells.

Reduction of mouse mammary tumor formation and metastasis by lovastatin, an inhibitor of the mevalonate pathway of cholesterol synthesis

Lovastatin, a fungal antibiotic used in the treatment of hypercholesterolemia, is an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, the key regulatory enzyme in the mevalonate pathway of cholesterol synthesis. We examined the antitumor properties of lovastatin on the F3II sarcomatoid mammary carcinoma, a highly invasive and metastatic murine tumor model. Female BALB/c inbred mice were inoculated subcutaneously with F3II tumor cells and injected i.p. daily with 10 mg/kg body weight of lovastatin or administered p.o. at a level corresponding to the human dosage of 1-2 mg/kg/day. Treatment significantly prolonged tumor latency and reduced tumor formation and metastatic dissemination to the lungs from established mammary tumors. In vitro, antitumor properties of lovastatin were strongly associated with inhibition of tumor cell attachment and migration. These actions were prevented by addition of mevalonate but not by equivalent concentrations of farnesyl pyrophosphate. In accordance, Western blot assays showed that lovastatin effects did not appear to be related to modifications in Ras oncoproteins in our model. The present data indicate that lovastatin could be an antitumor agent with potentially useful clinical applications in breast cancer.

Chemically modified tetracyclines inhibit human melanoma cell invasion and metastasis

Recent work has shown that chemically modified tetracyclines (CMTs) are potent inhibitors of matrix metalloproteinase (MMP) activity, both in vitro and in vivo, which is distinct from their antimicrobial activities (Golub et al. Crit Rev Oral Biol Med, 2, 297-321, 1991; Ryan et al. Curr Opin Rheumatol, 8, 23847, 1996). The process of tumor cell invasion requires MMP-mediated degradation of extracellular matrix barriers as a key step in the metastasic cascade. In this study, we examined the effect(s) of doxycycline and CMTs on extracellular levels of gelatinase A and B activity from a highly invasive and metastatic human melanoma cell line C8161, and correlated these observations with changes in the cells' biological behavior in an in vitro invasion assay and in an in vivo SCID mouse model. The results indicate that coincident with the ability of these compounds to differentially suppress extracellular levels of gelatinase activity, C8161 cells treated with doxycycline, CMT-1, CMT-3, or CMT-6 were less invasive in vitro in a dose-dependent manner (3-50 microg/ml). Furthermore, data derived from the in vivo model indicate that SCID mice dosed orally with CMT-1 or CMT-3 contained a reduced number of lung metastases following i.v. injection of C8161 cells via tail vein inoculation. These observations suggest that careful screening of different CMTs could lead to the identification of compounds which suppress the formation and magnitude of metastases associated with certain cancers, and if used as an adjunct to other treatment regimes, lead to greater efficacy in the treatment of metastatic cancers.

Localization of TIMP-1, TIMP-2, TIMP-3, gelatinase A and gelatinase B in pathological human corneas

PURPOSE

Determine the tissue distribution patterns for tissue inhibitors of metalloproteinases (TIMP-1, TIMP-2, TIMP-3), gelatinase A and gelatinase B in normal and pathologic corneas.

METHODS

Corneas were examined by immunohistochemistry, using antibodies to TIMP-1, TIMP-2, TIMP-3, gelatinase A or gelatinase B.

RESULTS

In normal corneas, TIMP-1 antibody stained the epithelium and endothelium. TIMP-2 and TIMP-3 stained the epithelium, keratocytes and endothelium. Gelatinase A staining was weak and restricted to the epithelial cells. Radial keratotomy scars showed increased staining for TIMP-1 and TIMP-2 around the epithelial cell plug and along the incision. Bullous keratopathy corneas showed TIMP staining patterns similar to normal corneas and increased gelatinase A staining in regions of subepithelial fibrosis. Stromal scars of keratoconus corneas also had increased staining with TIMP-1 and TIMP-2 antibodies. In many keratoconus corneas, the TIMP-3 staining pattern was similar to normal corneas. However, in some keratoconus corneas, when Bowman's layer was missing, the stroma beneath was completely devoid of TIMP-3 antibody staining. No gelatinase B was seen in either the normal or diseased corneas.

CONCLUSION

These data suggest that TIMP-1 and TIMP-2 are important for scar formation and corneal remodeling, since they were found in increased amounts at radial keratotomy incision sites and keratoconus scars. The significance of the focal stromal defects in TIMP-3 staining, associated with absence of Bowman's layer on keratoconus corneas, needs to be elucidated. At the stages of disease examined in this study, gelatinase B may not play a significant role in these pathological processes, since it was not seen in any of the corneas examined.

Translational research models in neuro-oncology

Tumor development and progression in the nervous system are poorly understood. Consequently, even though there seems to be little possibility of major advances in existing clinical modalities used to treat malignant brain tumors, no targeted molecular therapies have risen to take their place. The variability and plasticity of brain neoplasms make them an illusive target for study and therapeutic intervention. Further complicated by infiltration of vital nervous tissue, clinical studies have serious practical limitations and the ability to assess tumor progression in vivo is still a developing technology. Evaluation of potential new therapies for brain tumors is heavily dependent on the development of more informative and cognate experimental models. To develop and validate new models, it is particularly important to integrate clinical, pathological, and cell biological characterizations of malignant brain tumors. This discussion provides an overview of developments in tumor cell culture and the impact of animal models on brain tumor research. Studies of malignant glial neoplasms associated with a dismal prognosis in patients receive particular attention.

Regulation of capillary formation by laminin and other components of the extracellular matrix

The process of angiogenesis (vessel formation) and the resulting stabilization of the mature vessel are complex events that are highly regulated and require signals from both serum and the extracellular matrix. Endothelial cells rest on a specialized thin extracellular matrix known as the basement membrane. Endothelial cells lining normal blood vessels are usually quiescent. When a proper stimulus is present, angiogenesis beings when endothelial cells degrade their basement membrane and invade the surrounding extravascular matrix. Formation of new vessels involves the migration and proliferation of cells. To assist the cells in their migration, the extravascular matrix provides an environment rich in stromal collagen fibers, fibrin, hyaluoronic acid, vitronectin and fibronectin. Once the endothelial cells assemble to form a new vessel, the cells secrete a basement membrane that helps to stabilize and maintain the vessel wall. The basement membrane adheres tightly to cells comprising the vessel wall, provides inductive signals, and plays a important role in the homeostasis of new vessels. We have demonstrated that two major components of the basement membrane, laminin and collagen IV, possess endothelial cell binding sites which regulate vessel stability. In this chapter, we will define the role of these molecules in endothelial cell behavior.

Expression of tissue inhibitor of metalloproteinases TIMP-2 in human colorectal cancer--a predictor of tumour stage

The aim of this study was to investigate whether immunohistochemical staining patterns of tissue inhibitor of metalloproteinases TIMP-2 and matrix metalloproteinases MMP-2 and MMP-9 can be predictors of tumour stage and survival time in colorectal cancer. Frozen tumour sections from 212 patients operated on between January 1987 and November 1990 were investigated. Three mouse monoclonal antibodies--T2-101 against TIMP-2, CA-4001 against MMP-2 and GE-213 against MMP-9--were used. Positive expression of TIMP-2 (a) in basement membranes and (b) diffusely in stroma with (c) subglandular enhancement was found significantly (P < 0.01, P < 0.05, P < 0.05) more often in localized tumours than in tumours with regional or distant metastases. Neither pattern correlated with tumour differentiation. Patterns (a) and (c) correlated with longer survival time (P < 0.05); (b) reached near significance (P < 0.07). When the survival analyses were restricted to potentially cured patients, neither pattern could foretell death from cancer. Positive expression of MMP-2 in tumour epithelium and of MMP-9 in tumour-infiltrating macrophages were both independent of tumour stage and were without correlation with survival time. A large number of MMP-9-positive macrophages correlated (P < 0.05) with poor tumour differentiation, whereas weak or absent epithelial MMP-2 staining reached near significance (P < 0.08). Exploration of TIMP-2 expression is valuable for the discrimination between macroscopically localized and metastatic colorectal cancer, but it cannot predict which of the potentially cured patients are likely to have micrometastases. MMP-2 and MMP-9 stainings are of minor value in staging and prognostic prediction.

Are bacterial proteases important virulence factors?

The contribution of bacterial proteases to virulence has been relatively understudied. It is a simple matter to argue that bacterial proteases have the potential to destroy the structural and functional proteins that constitute host tissues as well as to destroy proteins important in host defense. Systematically demonstrating that such interactions occur during disease pathogenesis is more difficult, although a few studies have suggested that the ability of a pathogen to use proteases to cross proteinaceous barriers within the host contributes to bacterial virulence. This manuscript reviews concepts of bacterial virulence. Next, it describes how the host regulates the activities of its own proteases to maintain a state of health, and examines evidence suggesting that dysregulation of host proteases results in disease. Finally, evidence supporting a role for endogenous microbial proteases or acquisition of host proteases by microbes as virulence determinants is discussed as are suggestions for future directions for research in this area.

Regulation of angiogenesis in malignant gliomas

Gliomas are highly resistant to conventional therapeutic measures, requiring the development of novel treatments. Since gliomas are particularly vascular tumors, one approach involves treatments directed at inhibiting angiogenic mechanisms. Although multiple factors contribute to the ultimate vascularization of any tumor, some are especially relevant to gliomas. Early experimental work directed at inhibiting angiogenic pathways has shown promise toward achieving control of tumor growth. This article focuses on the evidence that angiogenesis and related vascular cell responses play important roles in glioma biology, and reviews those biochemical pathways known through experimentation to be involved in the vascular response to gliomas. Finally, contemporary vessel-targeted approaches that have been used to inhibit glioma growth are discussed.

Enhanced RNA expression of tissue inhibitor of metalloproteinases-1 (TIMP-1) in human breast cancer

Tissue inhibitor of metalloproteinases-1 (TIMP-1) is known to have at least 2 distinct types of activity, i.e., as a regulator of collagenolytic activity, and erythroid potentiating activity (EPA). In this study, we examined the expression of TIMP-1 in human mammary carcinomas, non-malignant breast tissues and benign breast tumors. A total of 53 samples were subjected to Northern-blot analysis, including 23 of primary breast cancer, 26 of non-malignant breast tissues, and 4 benign tumors. Of the 53 samples, 10 were paired malignant and non-malignant breast-tissue samples from the same patient. TIMP-1 RNA expression was significantly higher in the malignant tumor tissues than in the non-malignant counterpart. Similar differences were observed in the level of TIMP-1 protein expression in the paired breast samples examined. Moreover, breast-cancer cell lines secreted larger amounts of TIMP-1 in vitro than non-neoplastic breast epithelial lines. The up-regulation of TIMP-1 expression in breast cancer may suggest that TIMP-1 has an additional role to that of metalloproteinase inhibitor.

Management of primary malignant brain tumours

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Morphologic, immunologic, biochemical, and cytogenetic characteristics of the human glioblastoma-derived cell line, SNB-19

Human glioma-derived cell cultures and lines have proven to be of significant value in the study of the basic properties that contribute to the highly malignant, invasive and angiogenic phenotype of glioblastoma multiforme tumors. It is frequently difficult to establish lines that retain glial tumor properties in long term culture. The SNB-19 cell line has maintained and exhibited properties of transformation, differentiation, autocrine growth response, and tumorigenesis while remaining in culture for over 13 yr and undergoing over 200 passages. This human line has been utilized in a wide range of studies related to the basic properties of human glioblastoma multiforme. In this report, we summarize the immunologic, biochemical, and cytogenetic properties of this versatile cell line and its utility for additional mechanistic investigation into the pathophysiology of the progression of human malignant gliomas.

Degradation of collagen type IV by C6 astrocytoma cells

The key event associated with the initiation of angiogenesis is the localized degradation of the vascular basement membrane. Because of its complex structure, any remodelling and/or modification of the basement membrane must involve the co-ordinated function of a number of different enzyme systems. Type IV collagen is a major protein component (60-90%) of the basement membrane and its degradation is crucial to the initiation of angiogenesis. This study has focused on the mechanisms by which C6 astrocytoma cells degrade human type IV collagen. C6 astrocytoma cells use components of two major degradative pathways to degrade collagen type IV. The major matrix metalloproteinase identified is the activated form (68-KDa) of gelatinase A (72-KDa matrix metalloproteinase) and a serine sensitive 1000-KDa collagenase type IV degrading activity which appears to have the characteristics of a novel extracellular proteasome.

Interactions of glioma cells and extracellular matrix

The communication between tumor cells and extracellular matrix (ECM) is responsible for clinically important features of malignant gliomas, such as cerebral invasion and leptomeningeal spread. The synthesis of ECM components, ECM-degrading activities and ECM receptors as well as the interaction between ECM components and their receptors represents the molecular basis for these processes. Recent studies have shown that proteases and integrins, the major group of ECM receptors, may be over-expressed by astrocytic tumor cells. Furthermore, integrins and the hyaluronate receptor CD44 have been found to be involved in adhesion and basement membrane invasion of glioma cells. Critical issues which are poorly understood so far include the ECM composition of the normal human brain and of brain tumors, the function of individual ECM components and receptors in a neuro-oncological context, and the molecular processes mediating the diffuse invasion of glioma cells into the brain.