CANCER SUPPRESSING & DEVELOPMENTAL FUNCTIONS OF RB GENE

这项研究的目的是为了深入了解 隐性致癌基因在癌症中的作用。 几种方法已被应用于确定遗传因素 与肿瘤发生有关 癌基因最初定义于 肿瘤诱导逆转录病毒和肿瘤DNA能够 在培养中转化非肿瘤细胞。 大多数癌基因是 存在于正常细胞中的原癌基因的激活版本。 另一类癌症基因已经被提出， 基因功能与肿瘤发生有关。 的参与 这些基因已经被认为用于许多肿瘤类型，例如， 视网膜母细胞瘤，乳腺癌，结肠癌，肾细胞癌， 等 由于肿瘤的形成与基因缺失有关， 功能而不是激活，后一类基因已经被 称为“隐性癌基因”或“抑癌基因”。 视网膜母细胞瘤易感性（RB）基因是唯一的人类 迄今为止克隆的隐性癌基因。 RB基因定位于 染色体13 q14带。 我们和其他研究人员发现 RB基因的失活不仅在视网膜母细胞瘤中， 在骨肉瘤和软组织中， 肉瘤 染色体上肿瘤抑制基因的存在 13对于一些乳腺癌已经建议。 研究 果蝇也表明24个基因座与组织- 特殊肿瘤 两个等位基因的失活 致死（2）巨大幼虫（l（2）gl）基因导致恶性神经母细胞瘤 在幼虫的大脑和肿瘤的想象盘。 此外，委员会认为， l（2）gl的发育调节表达对于 正常增长。 本文主要从两个方面对RB的功能进行了研究：（1）RB基因 参与乳腺癌的发生和（2）发展 RB基因的作用，使用果蝇作为模型。 I. RB基因在乳腺癌中的功能 我们检测到 9例乳腺癌细胞中有2例RB基因突变 线 RB基因将在原发性乳腺肿瘤中进行研究 失活 通过逆转录病毒介导的基因转移， 将正常RB基因导入缺失RB的乳腺肿瘤细胞系 用于测试其体内肿瘤抑制活性， 体外转化表型的可逆性。 此外，本发明还提供了一种方法， 转化生长因子受体的调节， 将探索RB基因对表皮生长因子的影响。 二. 的 果蝇RB基因同源物。 我们将使用Drosphila系统作为 研究RB的发育、表达和功能的模型。 我们的初步数据表明，在这一过程中存在RB同源物。 有机体 果蝇RB基因（dRB）的基因组和cDNA克隆 将被彻底地描述。 此外，dRB将被 定位于多线染色体。 经典遗传操作 将用于鉴定推定的dRB突变体。 然后我们将使用 P元件介导的dRB基因的胚系转化研究 在正常的环境中。

The aim of the research proposed in this grant is to gain insight into the action of recessive oncogenes in cancer. Several approaches have been applied to identify genetic elements involved in turmorigenesis. Oncogenes were initially defined in tumor-inducing retroviruses and in tumor DNA capable of transforming nonneoplastic cells in culture. Most onocogenes are activated versions of proto-oncogenes that exist in normal cells. Another class of cancer genes has been proposed for which loss of gene function is associated with oncogenesis. The involvement of such genes has been suggested for many tumor types, e.g. retinoblastoma, breast cancer, colon cancer, renal cell carcinoma, etc. Since tumor formation is associated with loss of gene function instead of activation, the latter class of genes have been termed "recessive oncogenes" or cancer suppressor genes". The retinoblastoma susceptibility (RB) gene is the only human recessive onocogene cloned to date. RB gene is localized in chromosome band 13q14. We and other have found mutational inactivation of the RB gene not only in retinoblastomas but also in a significant percentage of osteosarcomas and soft tissue sarcomas. The presence of a tumor suppressor gene on chromosome 13 for some breast caners has been suggested. Studies in Drosophila also suggest the association of 24 loci with tissue- specific tumors. Inactivation of both alleles of the lethal(2)giant larvae (l(2)gl) gene causes malignant neuroblastoma in the larval brain and tumors of the imaginal discs. Moreover, developmentally regulated expression of l(2)gl is important for normal growth. This proposal focuses on two aspects of RB function: (1) RB gene involvement in the genesis of breast cancer and (2) a developmental role for the RB gene using the fruit fly Drosophila as a model. I. Function of the RB gene in breast cancer. We have detected mutation of the RB gene in two outy of nine breast tumor cell lines. Priminary breast tumors will be stuied for RB gene inactivation. By retrovirus mediated gene transfer we will introduce normal RB gene into breast tumor cell lines lacking RB function to test for its tumor suppression activity invivo and reversibility of transformed phenotype in vitro. In addition, modulation of receptors for transforming growth factor and epidermal growth factor by the RB gene will be explored. II. The RB gene homolog in Drosphila. We will use the Drosphila system as a model to study the development expression and function of RB. Our preliminary data suggests the presence of a RB homolog in this organism. Genomic and cDNA clones of the Drosphila RB gene (dRB) will be extesnivley characterized. In addition, dRB wil be localized to polytene chromosomes. Classical gentic procedures will be used to identify putative dRB mutants. We will then use P-element mediated germ line transformation to study the dRB gene in its normal environment.