NCI CLINICAL INVESTIGATOR AWARD PROGRAM

在胚胎发育过程中，中枢神经系统的所有细胞 系统起源于原始神经上皮细胞，一个群体 快速增殖的细胞排列在中枢神经管中。 髓母细胞瘤是一种恶性脑肿瘤， 目前无法治愈且通常致命的儿童。 是 认为髓母细胞瘤是由突变事件引起的， 影响原始神经上皮细胞， 分化为有丝分裂后的神经元。 我已经发现 人髓母细胞瘤细胞系TE 671含有激活的 N-ras癌基因在DNA介导下转化NIH 3 T3细胞 基因转移实验 本研究的目的 建议研究TE中致癌激活的机制 671细胞和人髓母细胞瘤肿瘤中。 这一目标 将沿着沿着三条调查路线进行。 第一、 通过体外增强的寡核苷酸杂交测定 N-ras编码序列的扩增将用于鉴定 N-ras基因的点突变导致其激活 在TE 671细胞中。 第二，为了识别隐性癌基因， 在髓母细胞瘤患者中，体细胞和肿瘤DNA对 将通过南方转移分析进行检查， 人类染色体的高度多态性DNA标记。 一 以这种方式发现的肿瘤特异性染色体缺失将 指向一个隐性基因，它可能在正常的 神经元分化 第三，扩增的基因， 将在TE 671细胞中寻找新的癌基因， 髓母细胞瘤凝胶变性-复性 技术. 这项研究提供的任何见解， 髓母细胞瘤中控制肿瘤发生的分子事件将 不仅对神经肿瘤学有重要意义， 神经发育

During embryonic development all cells of the central nervous system originate from primitive neuroepithelial cells, a population of rapidly-proliferating cells lining the central neural tube. Medulloblastoma is a malignant brain tumor afflicting young children which is presently incurable and usually fatal. It is believed that medulloblastoma are caused by mutational events affecting primitive neuroepithelial cells and preventing their differentiation into post-mitotic neurons. I have found that the human medulloblastoma cell line, TE 671, contains an activated N-ras oncogene which transforms NIH 3T3 cells in DNA-mediated gene transfer experiments. The objective of this research proposal is to study the mechanism of oncogenic activation in TE 671 cells and in human medulloblastoma tumors. This objective will be approached along three lines of investigation. First, oligonucleotide hybridization assays enhanced through in vitro amplification of N-ras coding sequences will be used to identify the point mutation in the N-ras gene responsible for its activation in TE 671 cells. Second, in order to identify recessive oncogenes in medulloblastoma patients, pairs of somatic and tumor DNA's will be examined by Southern transfer analysis using a panel of highly polymorphic DNA markers for human chromosomes. A tumor-specific chromosome deletion discovered in this way would point to a recessive gene which may play a role in normal neuronal differentiation. Third, amplified genes which may represent novel oncogenes will be sought in TE 671 cells and in medulloblastoma tumors by gel denaturation-renaturation techniques. Any insights which this study provides into the molecular events governing oncogenesis in medulloblastomas will have important implications for not only neuro-oncology, but also neural development.