The expression and activation of matrix metalloproteinase-2 in rat brain after implantation of C6 rat glioma cells

Activating transcription factor 3 is overexpressed in human glioma and its knockdown in glioblastoma cells causes growth inhibition both in vitro and in vivo

Glioblastomas are highly malignant gliomas that are extremely invasive with high rates of recurrence and mortality. It has been reported that activating transcription factor 3 (ATF3) is expressed in elevated levels in multiple malignant tumors. The purpose of this study was to investigate the function of ATF3 in the development of glioma and its clinical significance. Immunohistochemical staining, western blot analysis and RT-qPCR revealed that the mRNA and protein levels of ATF3 and matrix metalloproteinase 2 (MMP2) were higher in the glioma than in the normal human brain tissues, and that their levels were proportional to the pathological grades. By contrast, the mRNA and protein levels of mammary serine protease inhibitor (maspin; SERPINB5) were significantly lower in the glioma than in the normal brain tissue, and maspin expression was inversely proportional to the glioma pathological grade. The transfection of U373MG glioblastoma cells with ATF3-siRNA induced a number of changes in cell behavior; the cell proliferative activity was decreased and flow cytometry revealed an increased proportion of cells arrested in the G₀/G₁ phase of the cell cycle. In addition, TUNEL staining indicated an increased proportion of cells undergoing apoptosis and Transwell assays revealed impaired cell mobility. The sizes of the tumors grown as xenografts in nude mice were also significantly reduced by treatment of host mice with ATF3-siRNA. Taken together, these results suggest that ATF3 promotes the progression of human gliomas.

Micropatterned surfaces functionalized with electroactive peptides for detecting protease release from cells

Matrix metalloproteinases (MMPs) regulate composition of the extracellular matrix and play a critical role in cancer, fibrosis, and wound healing. This article describes a novel peptide-based electrochemical biosensor for detecting activity of cell-secreted protease MMP9. In this sensing strategy, a peptide specific to MMP9 was modified with a redox label (methylene blue (MB)) and immobilized on microfabricated 300 μm diameter Au electrodes. Challenging the electrodes with known concentrations of MMP9 resulted in the cleavage of the MB containing peptide fragment and caused a decrease in electrical signal measured by square wave voltammetry (SWV). The limit of detection for MMP9 was determined to be 60 pM with a linear range extending to 50 nM. In preparation to detect cell-secreted MMP9, glass surfaces with Au electrode arrays were further micropatterned with poly(ethylene glycol) (PEG) gel to define annular cell adhesive regions next to electrodes and render the remainder of the surface nonfouling. The surfaces were further modified with CD14 antibody to promote attachment of monocytes. The peptide-modified electrode arrays were integrated into PDMS microfluidic devices and incubated with U-937 cells, transformed monocytes known to produce MMPs. These studies revealed a 3-fold higher electrochemical signal from ∼400 activated monocytes after 10 min activation compared to nonactivated monocytes. Whereas this article focuses on MMP9 detection, the general strategy of employing redox-labeled peptides on electrodes should be broadly applicable for detection of other proteases and should have clinical as well as basic science applications.

Studies on the neuroprotective role of Piper longum in C6 glioma induced rats

Many naturally occurring substances of plant origin ingested in human diet, exhibit anticarcinogenic and antimutagenic effects. One of the active phytochemical which shows the active anticarcinogenic role is Piper longum Linn. (Pl). Pl is widely used in ayurvedic industry due to its property in healing some of the bodily ailments. Despite being known for the antioxidant, antimicrobial and anticarcinogenic effects, its relation to brain and its tumour development is still scarce. Hence, the experimental glioma model was developed in rats using C6 glioma cells and the effect of Pl was evaluated in the brain tissue of experimental group of rats. From the study, the glioma induced animals showed an increased level of lipid peroxides (LPO), tissue marker enzymes lactate dehydrogenase (LDH), creatine kinase (CK), 5'nucleotidase (5'ND) and acetylcholine esterase (AChE). But Pl treatment (20 mg/kg body weight) significantly attenuated these alterations thereby showing potent anticancer effect in glioma induced rats. In addition, the anticarcinogenic effect of Pl was confirmed by microscopic analysis and the restoration of increased lipids and protein bound carbohydrates (PBCs) in the brain tissue of glioma induced rats. Hence our results implicate a major role for Pl in preventing the cancer development in the experimental glioma model.

Brain imaging in drug R&D

Magnetic resonance imaging (MRI), used as a clinical diagnostic tool since the early 1980s, is rapidly gaining traction as an integral part of the drug development process. Brain imaging research spans a wide area, covering both structure and function, and ranging from the physics and physiology associated with novel acquisition techniques, to the development of sophisticated image processing algorithms. This paper briefly describes two methods on either end of this spectrum: the "pipeline" framework for the fully automated morphometric analysis of brain imaging data, and molecular MRI, which holds promise for the non-invasive detection of molecular targets of new pharmacological compounds. The potential use of these technologies is illustrated by examples of their applications in multiple sclerosis, Alzheimer's disease, and oncology.

Quantifying the A1AR distribution in peritumoural zones around experimental F98 and C6 rat brain tumours

Quantification of growth in experimental F98 and C6 rat brain tumours was performed on 51 rat brains, 17 of which have been further assessed by 3D tumour reconstruction. Brains were cryosliced and radio-labelled with a ligand of the peripheral type benzodiazepine-receptor (pBR), (3)H-Pk11195 [(1-(2-chlorophenyl)-N-methyl-N-(1-methyl-propylene)-3-isoquinoline-carboxamide)] by receptor autoradiography. Manually segmented and automatically registered tumours have been 3D-reconstructed for volumetric comparison on the basis of (3)H-Pk11195-based tumour recognition. Furthermore automatically computed areas of -300 microm inner (marginal) zone as well as 300 microm and 600 microm outer tumour space were quantified. These three different regions were transferred onto other adjacent slices that had been labelled by receptor autoradiography with the A(1) Adenosine receptor (A(1)AR)-ligand (3)H-CPFPX ((3)H-8-cyclopentyl-3-(3-fluorpropyl)-1-propylxanthine) for quantitative assessment of A(1)AR in the three different tumour zones. Hence, a method is described for quantifying various receptor protein systems in the tumour as well as in the marginal invasive zones around experimentally implanted rat brain tumours and their representation in the tumour microenvironment as well as in 3D space. Furthermore, a tool for automatically reading out radio-labelled rat brain slices from auto radiographic films was developed, reconstructed into a consistent 3D-tumour model and the zones around the tumour were visualized. A(1)AR expression was found to depend upon the tumour volume in C6 animals, but is independent on the time of tumour development. In F98 animals, a significant increase in A(1)AR receptor protein was found in the Peritumoural zone as a function of time of tumour development and tumour volume.

Interleukin-1β and Interleukin-6 Stimulate Matrix Metalloproteinase-9 Secretion in Cultured Myenteric Glia

Western blotting of culture media of myenteric glia stained positive for GFAP revealed increased secretion of matrix metalloproteinase-9 (MMP-9) in interleukin-1beta (IL-1beta) stimulated cells (10 ng/mL) versus control (142 +/- 19 versus 42 +/- 19, P < 0.05). Interleukin-6 (IL-6) stimulated cells also showed increased expression of MMP-9 (10 ng/mL) versus control (69 +/- 14 versus 4 +/- 2, P < 0.01). Control and cytokine-stimulated cells secreted MMP-2 constituitively. Gelatin zymography demonstrated that products were biologically active. Cytoplasmic staining for MMP-9 was detected in IL-1beta and IL-6-stimulated cells but was negligible in controls. Cultured myenteric glia are responsive to IL-1beta and IL-6 stimulation by secreting MMPs into the extracellular environment.

Irradiated C6 glioma cells induce angiogenesis in vivo and activate endothelial cells in vitro

Malignant gliomas are angiogenesis dependent and present a remarkable degree of resistance to radiotherapy. In the present work, we studied the effect of irradiation of C6 glioma cells on their proliferation and activation in vitro and on glioma cell-induced angiogenesis in vivo and in vitro. Irradiation of C6 glioma cells decreased cell proliferation in a dose-dependent manner. Interestingly, metalloproteinase-2 and -9 expression and secretion, as well as integrin alpha(v) expression, increased with elevated doses of X rays 48 hr after irradiation and was mostly evident at the higher doses used. When pre-irradiated C6 cells were implanted on nonirradiated chicken embryo chorioallantoic membranes (CAMs), there was a significant dose-dependent increase in tumor induced angiogenesis, compared to angiogenesis induced by nonirradiated cells. Similar results were obtained when C6 cells were irradiated 48 hr after their inoculation onto nonirradiated CAMs. In the same line, conditioned medium from irradiated C6 cells significantly increased endothelial cell proliferation and migration in vitro, in a manner dependent on the dose of X rays. These results explain at least in part the low effectiveness of radiation therapy of malignant gliomas and support the notion that inhibition of angiogenesis in parallel with radiotherapy may represent a new therapeutic approach.

Inhibition of tumor angiogenesis by cannabinoids

Cannabinoids, the active components of marijuana and their derivatives, induce tumor regression in rodents (8). However, the mechanism of cannabinoid antitumoral action in vivo is as yet unknown. Here we show that local administration of a nonpsychoactive cannabinoid to mice inhibits angiogenesis of malignant gliomas as determined by immunohistochemical analyses and vascular permeability assays. In vitro and in vivo experiments show that at least two mechanisms may be involved in this cannabinoid action: the direct inhibition of vascular endothelial cell migration and survival as well as the decrease of the expression of proangiogenic factors (vascular endothelial growth factor and angiopoietin-2) and matrix metalloproteinase-2 in the tumors. Inhibition of tumor angiogenesis may allow new strategies for the design of cannabinoid-based antitumoral therapies.

In vivo glioma growth requires host-derived matrix metalloproteinase 2 for maintenance of angioarchitecture

Glioma, the most common form of brain tumor, has been shown mostly by in vitro studies to utilize matrix metalloproteinase (MMP) for invasive growth through degradation of the extracellular matrix. In order to examine the in vivo role of MMP, we established a rodent model of glioma progression using C6 rat glioma cells and analyzed the effect of tissue inhibitors of metalloproteinases (TIMPs). TIMP-2 rather than TIMP-1 caused significant reduction of the tumor size accompanied by the presence of degenerated blood vessels and ischemic necrosis. Because TIMP-2 inhibits MMP-2 preferentially, we then examined glioma growth in MMP-2-deficient mice and observed essentially identical consequences. While MMP-2 activity was present in the tumor and adjacent tissues of the wild-type mice, no MMP-2 activity was detected even in the tumor of the null mice, although C6 cells are known to express MMP-2. These observations suggest that glioma induces MMP-2 and utilizes its activity in the host tissue to support angiogenesis and to maintain angioarchitecture.