ABSTRACT
<p><b>BACKGROUND</b>Angiogenesis is a prerequisite for tumor growth and plays an important role in rapidly growing tumors, such as malignant gliomas. A variety of factors controlling the angiogenic balance have been described, and among these, the endogenous inhibitor of angiogenesis, tumstatin, has drawn considerable attention. The current study investigated whether expression of tumstatin by glioma cells could alter this balance and prevent tumor formation.</p><p><b>METHODS</b>We engineered stable transfectants from human glioma cell line U251 to constitutively secrete a human tumstatin protein with c-myc and polyhistidine tags. Production and secretion of the tumstatin-c-myc-His fusion protein by tumstatin-transfected cells were confirmed by Western blotting analysis. In the present study, we identify the anti-angiogenic capacity of tumstatin using several in vitro and in vivo assays. Student's t-test and one-way analysis of variance (ANOVA) test were used to determine the statistical significance in this study.</p><p><b>RESULTS</b>The tumstatin transfectants and control transfectants (stably transfected with a control plasmid) had similar in vitro growth rates compared to their parental cell lines. However, the conditioned medium from the tumstatin transfected tumor cells significantly inhibits proliferation and causes apoptosis of endothelial cells. It also inhibits tube formation of endothelial cells on Matrigel. Examination of armpit tumors arising from cells overexpressing tumstatin repress the growth of tumor, accompanying the decreased density of CD31 positive vessels in tumors ((5.62 ± 1.32)/HP), compared to the control-transfectants group ((23.84 + 1.71)/HP) and wild type U251 glioma cells group ((29.33 + 4.45)/HP).</p><p><b>CONCLUSION</b>Anti-angiogenic gene therapy using human tumstatin gene may be an effective strategy for the treatment of glioma.</p>
Subject(s)
Animals , Humans , Mice , Autoantigens , Genetics , Brain Neoplasms , Therapeutics , Cell Line, Tumor , Cell Proliferation , Collagen Type IV , Genetics , Genetic Therapy , Glioma , Pathology , Therapeutics , Mice, Inbred BALB C , Neovascularization, Pathologic , Platelet Endothelial Cell Adhesion Molecule-1 , TransfectionABSTRACT
Previous studies indicated that B7-H4, the youngest B7 family, negatively regulates T cell-mediated immunity and is significantly overexpressed in many human tumors. Tumor stem cells are purported to play a role in tumor renewal and resistance to radiation and chemotherapy. However, the link between B7-H4 and tumor stem cells is unclear. In this study, we investigated B7-H4 expression in the medium of human glioma U251 cell cultures. Immunofluorescence results showed that U251 cells cultured in serum-free medium (supplemented with 2% B27, 20 ng/mL epidermal growth factor, 20 ng/mL basic fibroblast growth factor) maintained stem-like cell characteristics, including expression of stem cell marker CD133 and the neural progenitor cell markers nestin and SOX2. In contrast, U251 cells cultured in serum-containing medium highly expressed differentiation marker glial fibrillary acidic protein. Flow cytometry analysis showed serum-free medium-cultured U251 cells expressed higher intracellular B7-H4 than serum-containing medium-cultured U251 cells (24%-35% vs. 8%-11%, P < 0.001). Immunofluorescence in purified monocytes from normal human peripheral blood mononuclear cells revealed moderate expression of B7-H4 after stimulation with conditioned medium from U251 cells cultured in serum-containing medium. Moreover, conditioned medium from U251 stem-like cells had a significant stimulation effect on B7-H4 expression compared with serum-containing conditioned medium (P < 0.01). Negative costimulatory molecule B7-H4 was preferentially expressed in U251 stem-like cells, and conditioned medium from these cells more effectively induced monocytes to express B7-H4 than conditioned medium from U251 cells cultured in the presence of serum. Our results show that U251 stem-like cells may play a more crucial role in tumor immunoloregulation with high expression of B7-H4.
Subject(s)
Humans , AC133 Antigen , Antigens, CD , Metabolism , Brain Neoplasms , Metabolism , Pathology , Cell Line, Tumor , Cells, Cultured , Culture Media, Conditioned , Culture Media, Serum-Free , Gene Expression Regulation, Neoplastic , Glial Fibrillary Acidic Protein , Metabolism , Glioma , Metabolism , Pathology , Glycoproteins , Metabolism , Monocytes , Cell Biology , Metabolism , Neoplastic Stem Cells , Metabolism , Pathology , Nestin , Metabolism , Peptides , Metabolism , SOXB1 Transcription Factors , Metabolism , V-Set Domain-Containing T-Cell Activation Inhibitor 1 , MetabolismABSTRACT
<p><b>OBJECTIVE</b>Multilocular brain abscess in children is a serious neurosurgical emergency and remains a serious, life-threatening disease. This study evaluated the role of neuroendoscopy in treating multilocular brain abscess in children.</p><p><b>METHODS</b>Between January 2002 and June 2007, 16 children with multilocular brain abscess underwent an operation using a pure endoscopic procedure.</p><p><b>RESULTS</b>Increased intracranial pressure was relieved after operation in the 16 patients. CT/MRI after operation showed the abscess cavities disappeared and only the residual abscess walls existed in the 16 patients. Fourteen patients were followed up for 6 months to 5 years after surgery. Abscess walls disappeared in 13 patients and abscess recurred only in 1 patient.</p><p><b>CONCLUSIONS</b>Neuroendoscopy for treatment of multilocular brain abscess is safe and effective in children.</p>