The central hypothesis of this Specialized Center of Research on Malignant Human Gliomas and Medulloblastoma is that there are qualitatively and quantitatively distinctive molecular expression patterns associated with these brain neoplasms that are different from those of normal adult central nervous system and other body organs and tissues; and that these molecular differences may be biologically important. Moreover, we hypothesize and have preliminary data to support the idea, that monoclonal antibodies that are monospecific or that react with restricted epitopes on these brain tumor-associated molecules can be prepared (Project Ia), and that they can be exploited diagnostically and therapeutically against gliomas and medulloblastoma, first in human xenograft systems (Projects IIb, IIc) and ultimately in human clinical trials (Project III). The purpose of Project Ia1 is to provide state-of-the-art support in ganglioside and carbohydrate biochemistry for the monoclonal antibody development and characterization against gangliosides in Project Ia and to identify any antibodies generated in Projects Ib and Ic that react with carbohydrate epitopes, expressed both on gangliosides, glycolipids, and glycoproteins. Our project will first identify cell lines, xenografts, and glioma and medulloblastoma biopsies that contain qualitatively or quantitatively distinctive ganglioside molecules and purify and structurally characterize these molecules. This will provide both cellular and molecular reagents for immunization and monoclonal antibody selection. We will then assist in epitope mapping and identify antibodies of most restricted specificity. These well- characterized monoclonal antibodies will then be used to identify any new tumor-associated gangliosides cross-reactive with these antibodies through shared epitopes.
Our specific aims are: a) To examine gangliosides from various areas of the human nervous system, peripheral nerves, glioma cell lines, carcinomas of the gastrointestinal tract and meconium, characterize their chemical structure and to make a quantitative determination of their distribution. b) To isolate pure gangliosides from the sources which the quantitative determinations have shown to be optimal from a quantitative and qualitative point of view. c) To develop quantitative analytical methods, including thin-layer chromatography, mass-spec-trometry, permethylation, enzymatic degradation and immunoaffinity determinations, for the characterization of the gangliosides, and for the determination of the antigenic determinants (epitope specificity) of monoclonal antibodies directed against gangliosides.
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