ABSTRACT
Diagnosis of a glioblastoma (GBM) is triggered by the onset of symptoms and is based on cerebral imaging and histological examination. Serum-based biomarkers may support detection of GBM. Here, we explored serum protein concentrations of GBM patients and used data mining to explore profiles of biomarkers and determine whether these are associated with the clinical status of the patients. Gene and protein expression data for astrocytoma and GBM were used to identify secreted proteins differently expressed in tumors and in normal brain tissues. Tumor expression and serum concentrations of 14 candidate proteins were analyzed for 23 GBM patients and nine healthy subjects. Data-mining methods involving all 14 proteins were used as an initial evaluation step to find clinically informative profiles. Data mining identified a serum protein profile formed by BMP2, HSP70, and CXCL10 that enabled correct assignment to the GBM group with specificity and sensitivity of 89 and 96%, respectively (p < 0.0001, Fischer's exact test). Survival for more than 15 months after tumor resection was associated with a profile formed by TSP1, HSP70, and IGFBP3, enabling correct assignment in all cases (p < 0.0001, Fischer's exact test). No correlation was found with tumor size or age of the patient. This study shows that robust serum profiles for GBM may be identified by data mining on the basis of a relatively small study cohort. Profiles of more than one biomarker enable more specific assignment to the GBM and survival group than those based on single proteins, confirming earlier attempts to correlate single markers with cancer. These conceptual findings will be a basis for validation in a larger sample size.
Subject(s)
Biomarkers, Tumor/blood , Blood Proteins/metabolism , Brain Neoplasms/blood , Brain/metabolism , Glioblastoma/blood , Adult , Aged , Brain Neoplasms/diagnosis , Case-Control Studies , Female , Glioblastoma/diagnosis , Humans , Immunoenzyme Techniques , Magnetic Resonance Imaging , Male , Middle Aged , Prognosis , Proteomics , Survival Rate , Young AdultABSTRACT
Glioblastoma multiforme are highly invasive brain tumors. Experimental approaches focus on unravelling the mechanisms of invasion, this being a major reason for the poor prognosis of these tumors. Our previous results hinted towards involvement of the iron metabolism in invasion. In this study, we examined the effect of iron depletion on the invasive phenotype of glioblastoma cells. Transwell Matrigel invasion assays were used to monitor iron-dependent invasion of human glioblastoma cell lines U373MG and DBTRG05MG. Intracellular iron concentrations were modulated by applying desferrioxamine (DFO) and ferric ammonium citrate (FAC). We detected enhanced invasion of glioblastoma cells upon DFO-induced iron depletion. Treatment of cells with FAC strongly inhibited invasion. DFO treatment resulted in hypoxia-inducible factor 1 (Hif-1)-mediated induction of urokinase plasminogen activator receptor and matrix metalloproteinase 2. Further, RNA interference-mediated repression of urokinase plasminogen activator receptor inhibited DFO-induced invasion. Our data demonstrate a direct effect of DFO on Hif-1 expression resulting in activation of factors associated with ECM degradation and invasion of glioma cells. These findings caution on utilization of DFO and other iron chelators in the treatment of tumors with invasive potential.
Subject(s)
Brain Neoplasms/metabolism , Deferoxamine/pharmacology , Glioblastoma/metabolism , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , Iron Chelating Agents/pharmacology , Neoplasm Invasiveness/pathology , Blotting, Western , Brain Neoplasms/pathology , Cell Line, Tumor , Cell Separation , Flow Cytometry , Glioblastoma/pathology , Humans , Hypoxia-Inducible Factor 1, alpha Subunit/drug effects , Iron/metabolism , Matrix Metalloproteinase 2/drug effects , Matrix Metalloproteinase 2/metabolism , RNA, Small Interfering , Receptors, Cell Surface/drug effects , Receptors, Cell Surface/metabolism , Receptors, Urokinase Plasminogen Activator , TransfectionABSTRACT
Invasion of tumor cells into adjacent brain areas is one of the major problems in treatment of glioma patients. To identify genes that might contribute to invasion, fluorescent F98 glioma cells were allowed to invade an organotypic brain slice. Gene expression analysis revealed 5 up-regulated and 14 down-regulated genes in invasive glioma cells as compared to non-invasive glioma cells. Two gene products, ferritin and cyclin B1, were verified in human gliomas by immunohistochemistry. Ferritin exhibited high mRNA levels in migratory F98 cells and also showed higher protein expression in the infiltrating edge of human gliomas. Cyclin B1 with high mRNA expression levels in stationary F98 cells showed marked protein expression in the central portions of gliomas. These findings are compatible with the concept of tumor cells either proliferating or migrating. Our study is the first to apply brain slice cultures for the identification of differentially regulated genes in glioma invasion.
