ISOLATION OF GENES IN GLIOMAGENESIS

恶性胶质瘤是最常见的原发性脑肿瘤。 本研究的长期目标是建立一种能够概括恶性胶质瘤基本特征的小鼠模型。 胶质瘤的发生是一个多步骤的过程，可能涉及癌基因的扩增和肿瘤抑制因子的失活。 INK 4a肿瘤抑制基因座与胶质瘤发生有关。 INK 4a无效星形胶质细胞在培养物中是永生的，但不能在体内形成胶质瘤。 提出了在胶质瘤形成中与INK 4a位点无效突变协同作用的肿瘤抑制基因和/或癌基因的鉴定。 来自INK 4a无效星形胶质细胞的遗传抑制元件（GSE）的表达选择将用于鉴定与神经胶质瘤形成中的INK 4a缺陷合作的肿瘤抑制基因。 该文库将包含几乎所有细胞基因的抑制子，例如肿瘤抑制子。 为了分离胶质瘤中扩增的癌基因，将胶质母细胞瘤细胞系的全长cDNA文库引入INK 4a缺失星形胶质细胞中。 或者，将进行逆转录病毒插入诱变以鉴定神经胶质瘤中扩增的癌基因。 将评估推定的肿瘤抑制因子和癌基因候选物在细胞生长、凋亡和细胞周期调节中的作用。 将产生一种推定的肿瘤抑制基因和一种癌基因候选基因的敲除和转基因小鼠，并与INK 4a缺失小鼠杂交，以了解这些新基因与INK 4a在神经胶质瘤发生中的关系。将检查所得化合物小鼠的神经胶质瘤形成。

Malignant gliomas are the most common primary brain tumors. The long-term objective of this proposal is to establish a mouse model of malignant gliomas, which recapitulate the essential features of the tumor. Gliomagenesis is a multi-step process, which likely involves the amplification of oncogenes and inactivation of tumor suppressors. The INK4a tumor suppressor locus has been implicated in gliomagenesis. INK4a null astrocytes are immortal in cultures but unable to form glioma in vivo. Identification of tumor suppressor and/or oncogenes, which cooperate with the null mutation of INK4a locus in gliomagenesis is proposed. An expression selection of genetic suppressor elements (GSEs) derived from INK4a null astrocytes will be employed to identify tumor suppressor genes cooperating with the INK4a deficiency in gliomagenesis. This library would contain suppressors of practically all cellular genes such as tumor suppressors. To isolate the amplified oncogenes in gliomas, full-length cDNA library of a glioblastoma cell line will be introduced into INK4a null astrocytes. Alternatively, retroviral insertion mutagenesis will be performed to identify the amplified oncogenes in gliomas. Roles of the putative tumor suppressors and oncogene candidates in cell growth, apoptosis, and cell cycle regulation will be evaluated. Knock-out and transgenic mice of one putative tumor suppressor and one oncogene candidate will be generated and crossed with the INK4a null mice to understand the relationship between these new genes and INK4a in gliomagenesis. The resultant compound mice will be examined for the formation of gliomas.