Suppression of matrix metalloproteinase-2-mediated cell invasion in U87MG, human glioma cells by anti-microtubule agent: in vitro study

Dissecting and rebuilding the glioblastoma microenvironment with engineered materials

Glioblastoma (GBM) is the most aggressive and common form of primary brain cancer. Several decades of research have provided great insight into GBM progression; however, the prognosis remains poor with a median patient survival time of ~ 15 months. The tumour microenvironment (TME) of GBM plays a crucial role in mediating tumour progression and thus is being explored as a therapeutic target. Progress in the development of treatments targeting the TME is currently limited by a lack of model systems that can accurately recreate the distinct extracellular matrix composition and anatomic features of the brain, such as the blood-brain barrier and axonal tracts. Biomaterials can be applied to develop synthetic models of the GBM TME to mimic physiological and pathophysiological features of the brain, including cellular and ECM composition, mechanical properties, and topography. In this Review, we summarize key features of the GBM microenvironment and discuss different strategies for the engineering of GBM TME models, including 2D and 3D models featuring chemical and mechanical gradients, interfaces and fluid flow. Finally, we highlight the potential of engineered TME models as platforms for mechanistic discovery and drug screening as well as preclinical testing and precision medicine.

Expression and quantitative analysis of matrix metalloproteinase-2 and -9 in human gliomas

The matrix metalloproteinase (MMP) family members catalyze extracellular proteolysis. Recent reports have suggested that expression of MMP-2 and -9 might play a critical role in neoplastic tissue invasion or metastasis. In this study, the relationship between the expression of MMP-2 and -9 and the histological features of tissues from 21 cases of human glioma were investigated. MMP-2 and -9 proteins were detected by immnohistochemical studies. Amplification of MMP-2 and -9 mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR) assay. MMP-2 and -9 mRNA was measured quantitatively by the real-time RT-PCR method. Immunohistochemically, 38% of the cases were positive for MMP-2. Amplification of MMP-2 mRNA by RT-PCR was detected in 62% of the cases. There was no significant relationship between the expression of MMP-2 protein or mRNA and the biological nature of the tumors, including aggressiveness and histologic classification. The quantity of MMP-2 mRNA was 0.035 +/- 0.113 (MMP-2/GAPDH %), which was significantly elevated in cases of neoplastic dissemination or recurrence (P < 0.05). Tumor cells were immunohistochemically positive for MMP-9 in 81% of the samples. A positive reaction was found not only in neoplastic cells but also in endothelial cells, suggesting that the expression of MMP-9 protein might be associated with tumoral angiogenesis. The expression of mRNA in MMP-9 was detected in 91% of the cases, suggesting a close relationship between expression of MMP-9 and malignancy. The quantity of MMP-9 was 0.097 +/- 0.113 (MMP-9/GAPDH %) in all samples, which was significantly elevated in cases of glioblastoma (P < 0.05). The average Ki-67 labeling index was 8.14 +/- 5.26 in samples from G2 glioma, 19.92 +/- 11.29 in samples from G3 glioma, and 23.52 +/- 10.14 in samples from glioblastoma. All of the cases with elevated indices had recurrence or dissemination. The results of our study suggest that quantity analyses of MMP-2 and -9 mRNA and Ki-67 labeling index should be useful for discerning tumoral behaviors such as invasion, dissemination, and recurrence.

Inhibition of cell invasion by indomethacin on glioma cell lines: in vitro study

Malignant glioma invasion into the surrounding brain tissue is still a major problem for any therapeutical methods. Matrix metalloproteinases (MMPs) have been implicated as important factors in this pathological process. In this study, one of the non-steroidal anti-inflammatory drugs (NSAIDs) indomethacin was employed to investigate the effect of inhibition of cell invasion mediated by MMP-2 and MMP-9 in human malignant glioma cell lines, A172, U87MG, U251MG, and U373MG in vitro. MTT assay was firstly examined to determine non-cytotoxic dose range, then gelatin zymography, matrigel invasion assay, migration assay and MMP-2 activity assay for 24 h exposure in indomethacin were employed to assess the inhibitory effect of indomethacin. MTT assay revealed that dose with 0, 50, and 500 microM/ml were non-cytotoxic. Zymography demonstrated: (a) expression of MMP-2 and MMP-9 activity was downregulated along with elevated dose of indomethacin. (b) MMP-2 activity that changed from pro-MMP-2 to active form of MMP-2 in supernatants of cell lines could not be inhibited by indomethacin. Invasion assay disclosed that the number of invading cells through the matrigel were significantly decreased in a dose dependent manner. Migration assay indicated indomethacin did not affect cells migration. MMP-2 activity assay showed the total and active MMP-2 secretion was suppressed by 500 microM/ml of indomethacin. Our present study is the first report on inhibitive effect of indomethacin mediated by MMP-2 and MMP-9 in invasion assay of glioma cell lines. The current study suggested that non-cytotoxic level of indomethacin was able to reduce the cell invasion of malignant gliomas mediated by MMP-2 and MMP-9, but it did not affected on cell motility. It also lowered down the activity of MMP-2 and MMP-9, and could reduce of MMP-2 secretion of cell lines. Thus, high concentration of indomethacin within non-cytotoxic dose might offer a new therapeutic strategy to impair cell invasion of gliomas.

Microtubule-dependent matrix metalloproteinase-2/matrix metalloproteinase-9 exocytosis: prerequisite in human melanoma cell invasion

Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases that cleave and degrade a wide spectrum of extracellular matrix components. By enhancing turnover of extracellular matrix, MMP activity is also known to play a key role in tumor cell invasion. Because extracellular protease activity requires efficient release of these proteases to the cellular surface, we investigated storage, transport, and exocytosis of MMP-2 and MMP-9 in human melanoma cells using immunofluorescence, electrical, and biochemical techniques. Immunolabeling of melanoma cells with antibodies specific for MMP-2 and MMP-9 led to the identification of two distinct populations of small cytoplasmatic vesicles containing MMP-2 or MMP-9, respectively. In combination with alpha-tubulin-specific antibodies, both vesicle populations were found to be aligned along the microtubular network. Moreover, the molecular motor protein kinesin is shown to be localized on most of these vesicles, providing evidence that the identified vesicles are actively propelled along microtubules toward the plasma membrane. The functional relevance of these findings is demonstrated using low dosage (5.9 nmol/L) of paclitaxel to affect the microtubular function of melanoma cells. Although cell proliferation is not altered, paclitaxel treatment impairs secretion of MMP-2/MMP-9 and significantly reduces invasive activity in our new cell invasion assay. In conclusion, we demonstrate in melanoma cells that microtubule-dependent traffic of MMP-containing vesicles and exocytosis are critical steps for invasive behavior and therefore are potential targets for specific antitumor drugs.

The expression of matrix metalloproteinase-2 and -9 in human gliomas of different pathological grades

Matrix metalloproteinases (MMPs) have been implicated to play a critical role in glioma invasiveness. In this study, we aimed to investigate the expression of MMP-2 and MMP-9 in human gliomas of different degrees of malignancy, and evaluated the correlation between MMP-2 and MMP-9 expression in gliomas. The samples from 65 cases of glioma were divided into four groups according to the WHO classification: there were 16 cases of grade I, 17 cases of grade II, 20 cases of grade III, and 12 cases of grade IV. Normal brain samples served as the control group, and biopsy specimens were obtained from 8 glioma patients with a needle placed into the adjacent brain 1 cm from the margin after tumor resection. All the samples were stained with hematoxylin and eosin and immunohistochemistry. A computer-aided image-analysis system was employed to measure the integral optical density (IOD) of positive slides. No positive staining was found in the control group. The positive staining was localized in the cytoplasm of glioma cells, the extracellular matrix (ECM), the basement membrane (BM), and the endothelial cells of blood vessels. Positive staining rates increased significantly when the degree of malignancy of gliomas was elevated. The IOD value of MMP-2 and MMP-9 also indicated that the intensity of MMP-2 and MMP-9 expression was elevated significantly with the degree of malignancy of the gliomas. There was a positive correlation between MMP-2 and MMP-9 expression in gliomas. Glioma invasion and angiogenesis were particularly seen in the biopsied tissues, and MMP-9 immunostaining seemed to be much more intense and extensive than MMP-2 immunostaining in these samples. These results suggest that MMP-2 and MMP-9 staining in gliomas is localized in the cytoplasm of tumor cells, BM, and endothelial cells, and that MMP-2 and MMP-9 together play an important role in the invasiveness of gliomas, mediating the degradation of the ECM and angiogenesis. MMP-2 and MMP-9 could be molecular targets in the treatment of malignant glioma.

Phospholipase D2 stimulates cell protrusion in v-Src-transformed cells

Phospholipase D (PLD) activity has been implicated in several aspects of cell physiology including vesicle transport, signal transduction, cell proliferation, cytoskeletal structure, and oncogenic transformation. Two PLD isoforms (PLD1 and PLD2) have been identified and characterized. We have expressed both wild-type and catalytically inactive forms of PLD1 and PLD2 in 3Y1 rat fibroblasts and in 3Y1 cells transformed by v-Src, a tyrosine kinase that elevates PLD activity. The v-Src-transformed 3Y1 cells have small, but distinct cell protrusions, implicated in cell migration and metastasis. We report here that elevated expression of PLD2 substantially increased the length of the cell protrusions and that a catalytically inactive PLD2 mutant abolished the cell protrusions. The extended protrusions in the PLD2-overexpressing cells were dependent upon microtubule assembly. These data suggest a role for PLD2 in the v-Src-mediated formation of cell protrusions that may be critical for the invasive properties of v-Src-transformed cells.

Involvement of level I neck lymph nodes in advanced squamous carcinoma of the larynx

This study was performed to evaluate the incidence of metastasis at level I in patients with squamous laryngeal cancer. One hundred consecutive patients with squamous carcinoma of the larynx were submitted to surgical treatment including radical neck dissection. The tumor stage was T3 or T4, and the neck stage was N1-N2c. Lymph node metastases were pathologically confirmed in 80 patients. Metastases were concentrated within level II in 59% of cases, level III in 17% of cases, level IV in 11% of cases, and level V in 6% of cases. Only 2 patients (2%) had detectable tumors in the lymph nodes of the submandibular triangle (level IB). This study shows that patients with laryngeal cancer rarely present metastases at the submandibular triangle, even in advanced local disease with cervical metastasis staged as N1 to N2c. Therefore, dissection of the submandibular triangle is indicated only in the presence of clinical, radiographic, or cytologic evidence of metastatic disease at level I.

Induction of apoptosis by estramustine phosphate mediated by phosphorylation of bcl-2

Estramustine phosphate (EMP) is an anti-microtubule agent that induces apoptosis of glioma cells. We investigated whether EMP caused apoptosis through the alkylating effect of its nitrogen mustard component or by phosphorylation of bcl-2 like other anti-microtubule agents in normal human astrocyte and human malignant glioma cell lines. Apoptosis was seen in glioma cells treated either with nitrogen mustard or EMP and expression of bcl-2 mRNA was not changed by exposure to the drug. An immunoprecipitation study only found phosphorylation bcl-2 in glioma cells exposed to EMP and not in cells exposed to nitrogen mustard. These results indicate that induction of apoptosis in glioma cells by EMP is mediated by phosphorylation of bcl-2.

Regulation of MMP-9 (type IV collagenase) production and invasiveness in gliomas by the extracellular signal-regulated kinase and jun amino-terminal kinase signaling cascades

Our previous studies have shown that MMP-9 levels are significantly elevated during the progression of human gliomas. In the current study, we examined the role of JNK- and ERK-dependent signaling modules in the regulation of MMP-9 production and the invasive behavior of the human glioblastoma cell line SNB19, in which JNK/ERK1 is constitutively activated. SNB19 cells that were transfected with dominant-negative JNK, MEKK, and ERK1 expression vectors showed reduced MMP-9 promoter activity. In addition, conditioned medium collected from SNB19 cells transfected with these expression vectors showed diminished MMP-9 activity in the presence of phorbol myristate acetate, as determined by gelatin zymography. The cotransfection of SNB19 cells with kinase-deficient c-raf also diminished MMP-9 promoter activity. Further, in the presence of a specific inhibitor of MEKK (PD098059), the Matrigel invasion assay showed the invasiveness of dominant-negative SNB19 cells transfected with dominant-negative JNK1 or ERK1 to be remarkably reduced. In conclusion, our studies showed for the first time that MMP-9 production and the invasive behavior of SNB 19 cells are regulated by JNK- and ERK-dependent signaling modules and that interfering with either of the pathways reduces invasiveness.

Regulation of MMP-9 (type IV collagenase) production and invasiveness in gliomas by the extracellular signal-regulated kinase and jun amino-terminal kinase signaling cascades

Our previous studies have shown that MMP-9 levels are significantly elevated during the progression of human gliomas. In the current study, we examined the role of JNK- and ERK-dependent signaling modules in the regulation of MMP-9 production and the invasive behavior of the human glioblastoma cell line SNB19, in which JNK/ERK1 is constitutively activated. SNB19 cells that were transfected with dominant-negative JNK, MEKK, and ERK1 expression vectors showed reduced MMP-9 promoter activity. In addition, conditioned medium collected from SNB19 cells transfected with these expression vectors showed diminished MMP-9 activity in the presence of phorbol myristate acetate, as determined by gelatin zymography. The cotransfection of SNB19 cells with kinase-deficient c-raf also diminished MMP-9 promoter activity. Further, in the presence of a specific inhibitor of MEKK (PD098059), the Matrigel invasion assay showed the invasiveness of dominant-negative SNB19 cells transfected with dominant-negative JNK1 or ERK1 to be remarkably reduced. In conclusion, our studies showed for the first time that MMP-9 production and the invasive behavior of SNB 19 cells are regulated by JNK- and ERK-dependent signaling modules and that interfering with either of the pathways reduces invasiveness.

Suppression of matrix metalloproteinase-2 and -9 mediated invasiveness by a novel matrix metalloproteinase inhibitor, BE16627B

Cell invasion is a nature of malignant gliomas, demeriting to many efforts of the treatment. Matrix metalloproteinase (MMP) is acknowledged as a key factor in this complicated process. The aim of this study was to investigate whether inhibition of MMP activity in malignant glioma cells could be achieved by a novel agent, BE16627B (BE). Malignant glioma cell lines, U87MG, U251MG, and U373MG, were employed to evaluate inhibitory effect on zymogram, type IV collagenolysis assay, and haptoinvasion assay for 24 h exposure of BE, following preliminar

The bleb formation of the extracellular pseudopodia; early evidence of microtubule depolymerization by estramustine phosphate in glioma cell; in vitro study

Estramustine phosphate (EMP) is an anti-microtubule agent that depolymerizes microtubules and also causes apoptosis of glioma cells. Both of these pharmacological actions have been previously studied within the same cytotoxic range of EMP concentrations. The purpose of this study was to investigate which of these two phenomena occurred before the other. A preliminary MTT assay was done to distinguish non-cytotoxic (0.005-0.1 microM) and cytotoxic (0.5-10 microM) of EMP for BT4C cells. To investigate apoptotic changes, transmission electron microscopy (TEM), DNA laddering, and in situ endo-labeling (TUNEL) method were employed. A chemotaxis assay was used to assess cell motility. Scanning electron microscopy and TEM immunocytochemistry with an anti-beta tubulin antibody were applied to detect morphological changes of the microtubules. Suppression of cell motility by cytotoxic doses of EMP (0.5-10 microM) group was attributed by the cyto-reductive effect, relating to apoptosis. At 0.01-0.1 microM (non-cytotoxic doses), EMP did not indue apoptosis. At these concentrations, TEM and immunohistochemistry revealed the formation of blebs on the tip of the pseudopodia that contained abnormally depolymerized microtubules, a finding that was not observed at a low temperature or during cell migration. Cell chemotaxis was significantly inhibited by cytostatic EMP doses (0.05 and 0.1 microM). Bleb formation of the pseudopodia might be evidence of the abnormal disassembly of microtubules by cytostatic EMP concentrations, prior to the induction of apoptosis. In glioma cells EMP probably initiates apoptosis by causing the depolymerization of microtubules. Inhibition of cell motility by cytostatic doses of EMP could be beneficial to support other therapies.

Novel strategies and therapeutics for the treatment of prostate carcinoma

BACKGROUND

An increased understanding of the biology of prostate carcinoma has led to the clinical evaluation of mechanism-based and targeted therapies. Modulating the immune system has been pursued through the use of both active and passive immunity as well as the ex vivo genetic manipulation of effector cells. A variety of gene therapies has been proposed not only to replace defective genes but to localize activation of prodrugs. Angiogenesis and tumor invasion also have been targeted, as have cell cycling and signal transduction. Strategies promoting apoptosis and augmenting differentiation are also under study.

METHODS

This study is a review of current clinical strategies using biologic, immunologic, and genetic approaches for the treatment of prostate carcinoma.

RESULTS

The clinical development of therapy targeting differentiation, apoptosis, cell signaling, angiogenesis, metastasis, immune surveillance, and others are in various stages of clinical development. A disease states model is used to discuss treatment groups, outcome measures, and other trial design elements in relation to specific therapeutic strategies.

CONCLUSIONS

Development of novel agents requires consideration of where in the natural history of the disease they should be applied. In addition, understanding the genetic and molecular alterations that occur as the disease progresses from a localized to a metastatic state, and from androgen dependence to independence, is necessary. Clinical trial design will require consideration of cytostatic and cytotoxic effects, the status of pathways not directly targeted, and potentially unexpected influences on prostate specific antigen expression by these agents.

Suppression of cell invasion on human malignant glioma cell lines by a novel matrix-metalloproteinase inhibitor SI-27: in vitro study

Matrix metalloproteinase (MMP) has come to be highlighted by its close relation to the cell invasion of gliomas. Suppression of MMP activity in malignant glioma cells would be meriting to local delivery of genes or chemotherapeutic agents. In this study, we employed a novel MMP inhibitor, SI-27 to investigate inhibition of cell invasiveness in human malignant glioma cell lines, U87MG, U251MG, and U373MG. We evaluated with zymogram, reverse zymogram, and cell invasion assay after exposure of SI-27 for 24 h followed by preliminary MTT assay to find non-cytotoxic dose range, 5, 10, 50, 100 microg/ml compared with non-treatment group as the control. Common to three glioma cell lines, zymogram disclosed that expressions of MMP-2 and -9 were suppressed in a dose-dependent fashion, meanwhile those of tissue inhibitor of MMP (TIMMP) in reverse zymogram were not. The numbers of invading cells through Boyden chamber were significantly reduced in a dose-dependent manner, while those with 5 microg/ml were not diminished common to those three lines. In conclusion, dose concentration ranging 10-100 microg/ml of SI-27 inhibited MMP-2 and -9 mediated cell invasiveness in malignant glioma cell lines. This is the first report for chemotherapeutic effect of SI-27 on glioma cells.

Drug-induced apoptosis by anti-microtubule agent, estramustine phosphate on human malignant glioma cell line, U87MG; in vitro study

The drug effect of estramustine phosphate (EMP), an anti-microtubule agent on human glioma cells has been studied with the focus being mainly its cytotoxity or its targeting of organelles. However, the pharmacological knowledge of estramustine with respect to its cytotoxity and mechanism is limited. To acquire such knowledge, the present study investigates the ability of EMP to induce apoptosis in a human malignant glioma cell line. Transmission electron microscope (TEM) images were examined to monitor periodic changes. Agarose gel electrophoresis was also examined. Cellular DNA fragmentation ELISA was performed to investigate the DNA fragmentation rates and an MTT assay was studied to evaluate the ID50. A TEM study revealed condensing and fragmentation of the chromatin. Laddering of the bands was observed in all EMP exposure groups in agarose gel electrophoresis. DNA fragmentation in all EMP groups began at 0.5 h following an exposure with EMP and increased in a dose- and time-dependent manner as revealed by DNA ELISA fragmentation. ID50 at 24 h was 5.0 microM according to the MTT assay, a value close to 4.8 microM of ID50 was revealed by the DNA fragmentation assay. None of the above mentioned changes was observed in the control group. These results indicated that EMP caused a drug-induced apoptosis in the human malignant glioma cell line, U87MG.

Modulation of urokinase-type plasminogen activator and metalloproteinase activities in cultured mouse mammary-carcinoma cells: enhancement by paclitaxel and inhibition by nocodazole

Paclitaxel is a potent anti-tumor drug used in the treatment of breast cancer. It induces de-centralization of the microtubular system in tumor cells, blocking cell division. In the search for dissemination to a secondary site, cancer cells are capable of degrading most components of the extracellular matrix via an extracellular proteolytic cascade, including urokinase-type plasminogen activator (uPA) and the matrix metalloproteinases (MMPs). In the present study, the effects of paclitaxel and nocodazole, 2 drugs known to affect microtubules with opposite mechanisms of action, have been tested for their effect on the secretion of uPA and MMPs in cultures of F3II mouse mammary-tumor cells. Tumor-derived uPA activity significantly increased after pre-treatment of tumor cells for 24 hr with micromolar concentrations of paclitaxel (4 microM), while decreasing after pre-treatment with nocodazole (1 microM). A similar modulation was found for MMP-9 by zymographic analysis. Immunofluorescence and Western-blot analysis confirmed the formation of parallel microtubule fragments in paclitaxel-treated cells and almost complete de-polymerization of microtubules in nocodazole-treated ones. Our data suggest that, through opposite actions on microtubule organization and dynamics, paclitaxel and nocodazole exert inverse modulation of tumor-derived proteolytic activity in mammary tumor cells.

Expression of the proteolytic factors, tPA and uPA, PAI-1 and VEGF during malignant glioma progression

Various proteases and their inhibitors have been shown to be important in tumor invasion. Angiogenesis is further a prerequisite for the growth and progression of solid tumors. Since these systems are functionally linked, in situ hybridization and in situ zymography were used to investigate the spatial and temporal expression of factors representative of the plasmin/plasminogen system and of an angiogenic factor in the BT4C glioma model. This tumor is invasive with a high grade of neovascularization. Tissue-type plasminogen activator urokinase-type plasminogen activator and plasminogen activator inhibitor-1 mRNA were expressed in glioma cells during the entire tumor growth. Early in the tumor development the expression was found throughout the small tumor (approximately 10 mm3) while later in the time course the expression was found predominantly in the invasive tumor border of the tumor. The in situ zymography demonstrated that the plasminogen activators were translated into functional proteins. Vascular endothelial growth factor mRNA was expressed following a similar spatial and temporal pattern with an early expression in the entire small tumor while later, in larger tumors, it was exclusively expressed in the invasive tumor edge. In normal brain, the ventricular ependyma, meninges, as well as scattered neurons expressed tissue-type plasminogen activator mRNA. Vascular endothelial growth factor mRNA was observed in the choroid plexus, and in scattered cells in normal brain tissue. Our finding may suggest a functional co-operation of tissue-type plasminogen activator, urokinase-type plasminogen activator, plasminogen activator inhibitor-1 and vascular endothelial growth factor during glioma progression. This model could be of value when evaluating different treatment modalities aimed at blocking the migrating capacity and growth of glial tumors.