The long-term goal of this laboratory is to define the growth control mechanisms of malignant human gliomas (MHG). We believe that losses of function of specific genes (suppressor genes) through chromosomal loss, deletion, or mutation are critical steps in the evolution of these tumors. Our goals are to identify tumor suppressor genes which are important in human gliomas and to determine in which histologic stages of glioma progression alterations of these suppressor genes occur.
In specific aim (1), specific chromosomes and chromosomal regions which are lost in different histologic grades of gliomas will be identified by a combination of allelotyping and karyotyping of astrocytomas, anaplastic astrocytomas and glioblastomas (GBM) to define the locations of genetic losses associated with glioma progression. These studies will establish the basis for assessing the role of known tumor suppressor genes located in these regions and will provide the starting point for ultimately isolating new genes from locations which contain no known suppressor genes. Chromosomal and molecular studies have shown that loss of chromosome 10 occurs in most GBM but the gene located on this chromosome which is inactivated in gliomas has not been identified or regionally localized.
In specific aim (2), the region of chromosome 10 which is lost in MHG will be defined, constituting a major step toward the eventual isolation of a suppressor gene from this location. Specifically, a panel of polymorphic probes will be isolated from a chromosome 10 genomic library and regionally mapped. The region of chromosome 10 which is lost in MHG will be defined using microcell-mediated transfer of complete and fragments of human chromosome 10 and RFLP analysis of a large series of karyotyped GBM.
In specific aim (3), the role of known tumor suppressor genes will be determined in human gliomas. Normal copies of the p53 gene will be transfected into glioma cell lines with p53 gene mutations and normal copies of the retinoblastoma gene will be transfected into glioma lines which do not express this gene to determine if restoration of these normal genes reverses tumorigenicity, prevents growth in soft agar, or produces senescence. These studies will determine whether alterations of known tumor suppressor genes are critical to the development of human gliomas and will identify regions of chromosomal loss which are likely to harbor new tumor suppressor genes which contribute to the genesis and progression of these tumors. Definition of these regions of chromosomal loss will form the basis for the eventual isolation of the relevant suppressor genes in these locations. Characterization of these genes will elucidate regulatory mechanisms which are operative in repair, regeneration, development and differentiation of normal cells and these genes and antibodies against their products are potentially useful in the clinical and histological diagnosis and classification of human brain tumors.
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