ABSTRACT
A two-step strategy was developed consisting of differential display reverse transcriptase polymerase chain reaction (DDRT-PCR) with cultured normal human fetal astrocytes and U-373MG glioma cells followed by reverse Northern analysis of normal brain and primary tumor tissues. hu-dek, alpha-NAC, ribosomal proteins L7a and L35a, and five novel genes were identified. Since none of these genes has been previously shown to be associated with malignant brain tumor formation, this approach may be useful to identify novel targets for the diagnosis and treatment of brain tumors.
Subject(s)
Brain Neoplasms/genetics , Drosophila Proteins , Glioblastoma/genetics , Glioma/genetics , Receptors, Eph Family , Reverse Transcriptase Polymerase Chain Reaction/methods , Astrocytes/physiology , Blotting, Northern , Brain/physiology , Gene Expression , Genetic Therapy/methods , Humans , Middle Aged , Molecular Chaperones , Receptor Protein-Tyrosine Kinases/biosynthesis , Receptor Protein-Tyrosine Kinases/genetics , Ribosomal Proteins/biosynthesis , Ribosomal Proteins/genetics , Trans-Activators/biosynthesis , Trans-Activators/genetics , Tumor Cells, CulturedABSTRACT
The metastatic potential of tumor cells has been shown to be correlated with the expression of tri- and tetra-antennary beta1,6-N-acetylglucosamine (beta1,6-GlcNAc)-bearing N-glycans, which are recognized by Phaseolus vulgaris leukoagglutinating lectin (L-PHA). The expression of beta1,6-GlcNAc-bearing N-glycans also has been used as a marker of tumor progression in human breast and colon cancers. In this report, the role of N-glycan branching in regulating glioma migration and invasion was examined. The expression of beta1,6-GlcNAc-bearing N-glycans was found in human glioma specimens, whereas astrocytes from normal adult brain were negative. The expression of N-acetylglucosaminyltransferase V (GnT-V) mRNA, which is responsible for the biosynthesis of beta1,6-GlcNAc-bearing N-glycans, was high in glioma cell lines with robust ets-1 expression. To study the molecular mechanism of GnT-V expression in human glioma cells, an inducible ets-1 gene was stably transfected into SNB-19 cells using a tetracycline repressor system. GnT-V mRNA expression was increased by the induction of c-ets-1, suggesting that the Ets-1 transcription factor directly regulates the transcription of GnT-V. Stable transfection of GnT-V into human glioma U-373 MG cells resulted in changes in cell morphology and focal adhesions and a marked increase in glioma invasivity in vitro. L-PHA has little effect on cell migration. On the contrary, Phaseolus vulgaris erythroagglutinating lectin (E-PHA), which recognizes bisecting beta1,4-GlcNAc-bearing N-glycans, strongly inhibits cell migration (haptotaxis) on a fibronectin substrate in U-373 MG transfectants and other glioma cell lines tested. These results suggest that the increased beta1,6-GlcNAc-bearing N-glycan expression found in malignant gliomas is modulated by GnT-V through the Ets-1 transcription factor, and that the branching of complex type N-glycans plays a major role in glioma invasivity.
Subject(s)
Brain Neoplasms/metabolism , Glioma/metabolism , N-Acetylglucosaminyltransferases/metabolism , Neoplasm Proteins/metabolism , Polysaccharides/metabolism , Proto-Oncogene Proteins/metabolism , Transcription Factors/metabolism , Adult , Brain/metabolism , Brain Neoplasms/pathology , Cell Movement/drug effects , Glioma/pathology , Humans , Neoplasm Invasiveness , Phytohemagglutinins/pharmacology , Proto-Oncogene Protein c-ets-1 , Proto-Oncogene Proteins c-ets , RNA, Messenger/metabolism , Tumor Cells, CulturedABSTRACT
CMP-NeuAc: Galbeta1,3(4)GlcNAc alpha2,3-sialyltransferase (alpha2,3-ST) mRNA was expressed in human glioma specimens, human fetal astrocytes, and a panel of brain tumor cell lines. Maackia amurensis agglutinin staining revealed the presence of alpha2,3-linked sialic acids on glioma cell surfaces and extracellular matrices whereas normal human adult astrocytes were negative. Increased expression of alpha2,3-linked glycoprotein sialylation may play a role in glial tumorigenesis.
Subject(s)
Brain Neoplasms/metabolism , Glioma/metabolism , Glycoproteins/metabolism , RNA, Messenger/metabolism , Sialyltransferases/genetics , Adenocarcinoma/metabolism , Astrocytes/metabolism , Astrocytoma/metabolism , Brain Neoplasms/secondary , Carbohydrate Conformation , Glioblastoma/metabolism , Humans , Tumor Cells, Cultured , beta-Galactoside alpha-2,3-SialyltransferaseABSTRACT
The expression of CMP-NeuAc: Gal beta 1,4GlcNAc alpha 2,6 sialyltransferase (alpha 2,6-ST) [EC 2.4.99.1] and glycoproteins bearing alpha 2,6-linked sialic acids were examined in primary human brain tumours and cell lines. 79% (19/24) of the meningiomas expressed alpha 2,6-ST mRNA, 42% (10/24) of which showed very high expression. alpha 2,6-ST mRNA expression was undetectable in normal brain tissue. In contrast, only 1/13 of the gliomas examined expressed detectable alpha 2,6-ST mRNA. Metastases to the brain did not express measurable amounts of alpha 2,6-ST mRNA. Less expression was found in malignant (i.e. anaplastic) compared to benign (i.e. meningothelial) meningiomas. Two-dimensional SDS-PAGE of glioma and meningioma proteins, followed by Sambucus nigra lectin staining, revealed the presence of a glycoprotein bearing alpha 2,6-linked sialic acids, M(r) = 53 kDa and a pI = 7.0 (MEN-1) that appeared in all seven of the meningiomas examined, but was expressed at barely detectable levels, if at all, in seven out of the seven glioblastomas examined. Thus, decreased alpha 2,6-ST expression may play a role in the aggressive nature of anaplastic meningiomas, but appears to be virtually absent in all tumours of glial origin.
Subject(s)
Brain Neoplasms/metabolism , Glycoproteins/biosynthesis , Meningeal Neoplasms/metabolism , Sialic Acids/analysis , Sialyltransferases/biosynthesis , Base Sequence , Brain Neoplasms/chemistry , Brain Neoplasms/enzymology , Glioma/metabolism , Glycoproteins/chemistry , Histocytochemistry , Humans , Meningeal Neoplasms/chemistry , Meningeal Neoplasms/enzymology , Meningioma/metabolism , Molecular Sequence Data , Tumor Cells, Cultured , beta-D-Galactoside alpha 2-6-SialyltransferaseABSTRACT
A random computer selection of 21 patients who underwent 28 operations for acoustic neurinoma between 1974 and 1980 using conventional methods, including the operating microscope and microtechnique, was compared with a cohort of 22 patients who underwent 25 operations between 1980 and 1984 utilizing a carbon dioxide laser. Completeness of tumor removal, anatomical and functional preservation of the facial nerve, preservation of hearing, morbidity and mortality, average hospital stay, and eventual outcome were used as markers and were compared. Utilizing P values, the study demonstrated a significantly superior outcome, and as a result a better life quality, in patients who were operated on utilizing a CO2 laser in addition to conventional microsurgical technique.
