Genetically-engineered Salmonella typhimurium expressing TIMP-2 as a therapeutic intervention in an orthotopic glioma mouse model.

Glioma is one of the most devastating and refractory cancers. The main factors underlying therapeutic failure include extremely invasive characteristics and lack of effective methods for drug delivery. Attenuated Salmonella strains presented a high concentration of tumor targets in various types of cancer models, suggesting a role as potential vectors for drug delivery. In this study, we genetically engineered an attenuated strain of Salmonella as an anti-invasive vector for the targeted delivery and expression of tissue inhibitor of metalloproteinases 2 (TIMP-2) in an orthotopic nude mouse model of glioma. The bioluminescence signals related to tumor size significantly declined in the TIMP-2-expressing Salmonella (SLpTIMP-2)-treated group compared with the control group. Compared with the control group with a survival rate of an average of 33 days, the SLpTIMP-2 group showed an extended survival rate by nearly 60% and lasted an average period of 53 days with TIMP-2 induction. These results indicated the promising therapeutic potential of S. typhimurium for targeted delivery and secretion of TIMP-2 in glioma.

PDIA6 regulation of ADAM17 shedding activity and EGFR-mediated migration and invasion of glioblastoma cells.

OBJECTIVE In patients with glioblastoma, local invasion of tumor cells causes recurrence and shortens survival. The goal of this study was to determine whether protein disulfide isomerase (PDI) A6 regulates migration and invasion of glioblastoma cells and the associated factors. METHODS U87MG cells were treated with either PDIA6 or ADAM17 small interfering RNA (siRNA) fragments or with both types of siRNA fragments, and expression was confirmed by reverse transcription-polymerase chain reaction and Western blot. Migration and invasion were assessed using a wound-healing assay, a Matrigel assay, and an organotypic culture system. After the U87MG cells were treated with siRNAs and epidermal growth factor receptor (EGFR) inhibitors, the expression of matrix metalloproteinase-2 (MMP-2), membrane Type 1-matrix metalloproteinase (MT1-MMP), integrin, phosphorylated focal adhesion kinase (pFAK), and phosphorylated EGFR (pEGFR) was detected by Western blotting and zymography. RESULTS U87MG cell migration and invasion increased significantly after inhibition of PDIA6. The MMP-2 activation ratio and ADAM17 activity (as a sheddase of the proligand) increased, and expression of pEGFR, pFAK, integrin α5ß3, and MT1-MMP was induced, compared with control levels. Furthermore, heparin-binding epidermal growth factor (EGFR signaling ligand) was highly expressed in PDIA6-knockdown cells. After siPDIA6-transfected U87MG cells were treated with EGFR signaling inhibitors, expression of pFAK, MMP-2, and MT1-MMP decreased and invasion decreased significantly. Simultaneous double-knockdown of PDIA6 and ADAM17 reduced pEGFR and pFAK expression, compared with control levels. CONCLUSIONS The authors propose that inhibiting PDIA6 could transduce EGFR signaling by activating and inducing ADAM17 during migration and invasion of U87MG glioblastoma cells. The results of this study suggest that PDIA6 is an important component of EGFR-mediated migration and invasion of U87MG cells. This is the first report of the effects of PDIA6 on migration and invasion in glioblastoma.

Nogo-A inhibits the migration and invasion of human malignant glioma U87MG cells.

Nogo or reticulon-4 (RTN4), also known as neurite outgrowth inhibitor, is a member of the reticulon family of genes. Nogo-A, one of the three isoforms, is enriched in the central nervous system (CNS). The extracellular domain of Nogo-A, Nogo-66, has neurite growth inhibitory activity that is specific for neurons and is mediated by the Nogo receptor. However, most of its functions are not known yet. We investigated whether Nogo-A modulates the migration and invasion of a glioblastoma cell line, as well as the factors that have an effect on Nogo-A. The expression of Nogo-A was evaluated using western blotting and immunohistochemistry in human brain tumor specimens. U87MG cells were transfected with a sense-Nogo-A cDNA construct (U87-Nogo-A cells expressing Nogo-A) and an empty vector (U87MG-E cells not expressing Nogo-A). The migration and invasion abilities of these cells were investigated using simple scratch and Matrigel invasion assays. Morphologic and cytoskeletal changes were documented by confocal microscopy. The proliferation rate was estimated using doubling time assay. The effects of Nogo-A on Rho activity and phosphorylated cofilin were determined by a Rho activity assay and western blotting. Among primary brain tumors, Nogo-A expression was found in a higher percentage of oligodendrogliomas (90.0%) compared with the percentage in the glioblastomas (68.4%). In addition, the percentage in mixed gliomas was 42.9%, while it was not expressed in pituitary adenomas or schwannomas. The migration and invasion abilities of the U87-Nogo-A cells were decreased compared with the control. In the U87-Nogo-A cell line, Rho activity and phosphorylated cofilin expression were also decreased and morphology became more flat in comparison with the U87MG-E cell line. Nogo-A may inhibit the migration and invasion of human malignant glioma cells via the downregulation of RhoA-cofilin signaling.

Delivery of Transferrin-Conjugated Polysaccharide Nanoparticles in 9L Gliosacoma Cells.

To investigate the possibility of drug targeting via the transferrin receptor-mediated pathway, iron-saturated transferrin was conjugated with chitosan (Tr-chitosan) and complexed with doxorubicin-conjugated methoxy poly(ethylene glycol)-b-dextran succinate (DEX-DOX). DEX-DOX nanoparticles have spherical morphologies with less than 150 nm particle sizes. When Tr-chitosan was complexed with DEX-DOX nanoparticles (TR nanoparticle), particle sizes were increased to higher than 200 nm. Viability of 9L cells with treatment of doxorubicin (DOX) or DEX-DOX nanoparticle was dose-dependently decreased regardless of transferrin receptor blocking. However, cytotoxicity of TR nanoparticles was reduced by blocking of transferrin receptor. Flow cytometric analysis and confocal microscopic observation showed that fluorescence intensity of tumor cells with treatment of TR nanoparticles was significantly decreased by blocking of transferring receptor while DEX-DOX nanoparticles were not affected by blocking of transferring receptor. These results indicated that TR nanoparticles are promising candidates for brain tumor drug delivery.

Sublethal dose of irradiation enhances invasion of malignant glioma cells through p53-MMP 2 pathway in U87MG mouse brain tumor model.

BACKGROUND: Glioblastoma is a highly lethal neoplasm that frequently recurs locally after radiotherapy, and most of these recurrences originate from near the irradiated target field. In the present study, we identified the effects of radiation on glioma invasion and p53, TIMP-2, and MMP-2 expression through in vitro and in vivo experiments. METHODS: The U87MG (wt p53) and U251 (mt p53) human malignant glioma cell lines were prepared, and the U2OS (wt 53) and Saos2 (del p53) osteosarcoma cell lines were used as p53 positive and negative controls. The four cell lines and p53 knock-downed U87MG cells received radiation (2-6 Gy) and were analyzed for expression of p53 and TIMP-2 by Western blot, and MMP-2 activity was detected by zymography. In addition, the effects of irradiation on directional invasion of malignant glioma were evaluated by implanting nude mice with bioluminescent u87-Fluc in vivo followed by MMP-2, p53, and TIMP-2 immunohisto-chemistry and in situ zymography. RESULTS: MMP-2 activity and p53 expression increased in proportional to the radiation dose in cell lines with wt p53, but not in the cell lines with del or mt p53. TIMP-2 expression did not increase in U87MG cells. MMP-2 activity decreased in p53 knock-downed U87MG cells but increased in the control group. Furthermore, radiation enhanced MMP-2 activity and increased tumor margin invasiveness in vivo. Tumor cells invaded by radiation overexpressed MMP-2 and p53 and revealed high gelatinolytic activity compared with those of non-radiated tumor cells. CONCLUSION: Radiation-induced upregulation of p53 modulated MMP-2 activity, and the imbalance between MMP-2 and TIMP-2 may have an important role in glioblastoma invasion by degrading the extracellular matrix. Bioluminescent "U87-Fluc"was useful for observing tumor formation without sacrifice after implanting tumor cells in the mouse brain. These findings suggest that the radiotherapy involved field for malignant glioma needs to be reconsidered, and that future trials should investigate concurrent pharmacologic therapies that inhibit invasion associated with radiotherapy.

Immunohistochemical profile of the dural tail in intracranial meningiomas.

OBJECTIVE: The dural tail sign was first described as a thin, tapering rim of dural enhancement, in continuity with meningiomas on enhanced T1-weighted magnetic resonance (MR) images. However, the exact nature of the dural tail is still unclear. This study investigated the immunohistochemical (IHC) characteristics of the dural tail in intracranial meningiomas and the correlation between clinicopathological profiles and tumor invasion of the dural tail. METHODS: The study group consisted of 36 patients of meningioma with the dural tail noted on MR imaging and in pathological findings, and 18 patients of meningioma without the dural tail as the control group. IHC staining of tumor masses and dural tails for vascular endothelial growth factor (VEGF), epithelial membrane antigen, CD34, Ki-67, and vimentin were performed. RESULTS: The data showed that 61.1 % (22/36) of cases in the study group revealed tumor invasion of dural tail, and 55.6 % (30/54) of all the cases demonstrated dura mater invasion in all the samples. The dura mater invasion was significantly positively related to invasion of the dural tail in the study group (p = 0.009). IHC staining detected higher expression of VEGF and CD34 in the dural tail than in the main tumor mass. CONCLUSIONS: Considering the high proportion of patients with tumor invasion into the dural tail, we tried to perform wide resection of the dural tail during intracranial meningioma surgery. Furthermore, VEGF was strongly expressed in tumor cells that invaded into the dural tail, and hence VEGF can be used as a marker to differentiate tumor cells from normal meningeal cells in the dural tail.

Targeting Orthotopic Glioma in Mice with Genetically Engineered Salmonella typhimurium.

OBJECTIVE: With the growing interests of bacteria as a targeting vector for cancer treatment, diverse genetically engineered Salmonella has been reported to be capable of targeting primary or metastatic tumor regions after intravenous injection into mouse tumor models. The purpose of this study was to investigate the capability of the genetically engineered Salmonella typhimurium (S. typhimurium) to access the glioma xenograft, which was monitored in mouse brain tumor models using optical bioluminescence imaging technique. METHODS: U87 malignant glioma cells (U87-MG) stably transfected with firefly luciferase (Fluc) were implanted into BALB/cAnN nude mice by stereotactic injection into the striatum. After tumor formation, attenuated S. typhimurium expressing bacterial luciferase (Lux) was injected into the tail vein. Bioluminescence signals from transfected cells or bacteria were monitored using a cooled charge-coupled device camera to identify the tumor location or to trace the bacterial migration. Immunofluorescence staining was also performed in frozen sections of mouse glioma xenograft. RESULTS: The injected S. typhimurium exclusively localized in the glioma xenograft region of U87-MG-bearing mouse. Immunofluorescence staining also demonstrated the accumulation of S. typhimurium in the brain tumors. CONCLUSION: The present study demonstrated that S. typhimurium can target glioma xenograft, and may provide a potentially therapeutic probe for glioma.

Molecular dynamics study on the correlation between structure and sensitivity for defective RDX crystals and their PBXs.

Molecular dynamics simulation was applied to investigate the sensitivities of perfect and defective RDX (cyclotrimethylene trinitramine) crystals, as well as their PBXs (polymer-bonded explosives) with the polymeric binder F(2311), in the NPT (constant number of particles, constant pressure, constant temperature) ensemble using the COMPASS force field. Five kinds of defects-two dislocations, one vacancy, and two types of doping-were considered separately. The bond length distribution and the maximum (L (max)) and average (L (ave)) bond lengths of the N-NO(2) trigger bonds in RDX were obtained and their relationships to the sensitivities of RDX and PBXs are discussed. L (max) was found to be an important structural parameter for judging the relative sensitivity, and defects were observed to have little effect on the sensitivities of PBXs, due to the strong desensitizing effect of the polymer F(2311).

Possible role of matrix metalloproteinases (MMPs) in hyperostosis of intracranial meningiomas.

OBJECT: Although bone invasion and hyperostosis are common phenomena in patients with intracranial meningiomas, the basic pathomechanism is not fully understood. Based on an immunohistochemical study of surgically resected samples with hyperostosis, we postulate a possible mechanism of hyperostosis in patients with intracranial meningiomas. MATERIALS AND METHODS: Forty-six meningiomas were evaluated in this study. Twenty-six meningiomas associated with hyperostosis specimens served as the study group, and 20 meningiomas without any bony changes served as controls. An immunohistochemical staining technique was used to detect the expression of matrix metalloproteinase (MMP)-2, -9, and -13, membrane type (MT)1-MMP, estrogen receptor (ER), and progesterone receptor (PR) in the main tumor and hyperostotic portions of the studied samples. RESULTS: In the non-hyperostosis group, expression of MMP-13, MT1-MMP, and ER was significantly less than in the main tumor portion of hyperostotic meningiomas, while there was no difference in the expression of MMP-2 and -9 and PR in the main tumor between the two groups. In the hyperostosis group, the immunoreactivity of MMP-2 in the hyperostotic portion revealed a higher pattern of expression than the main tumor (p < 0.002). The expression of MMP-9, MT1-MMP, ER, and PR had relatively positive immunoreactivity in the main tumor portion (P < 0.05). CONCLUSIONS: Increased expression of MMP-13 and MT1-MMP in the tumor portion of hyperostosis of meningiomas might contribute to the initiation of osteolysis. Activated MMP-2 in hyperostotic lesions may change the physiological metabolism of the skull bone, thus playing an important role in hyperostosis formation.