Isolation of a Human 11p11.2 Liver Tumor Suppressor Gene

描述（由申请人提供）：大量研究表明，一个或多个肿瘤抑制基因的失活可能是肝脏肿瘤转化的早期和/或必要步骤。人类第11号染色体参与了包括肝母细胞瘤和肝细胞癌在内的几种人类肿瘤的发病机制，并且与大鼠第1号染色体是同源的，在许多大鼠肝脏肿瘤细胞系中，1号染色体在结构上发生了改变，这表明这些染色体可能含有一种常见的肝脏肿瘤抑制基因。我们认为，利用人类染色体和大鼠肝脏肿瘤细胞系进行染色体转移研究，可能有助于人类肝脏肿瘤抑制基因的定位、鉴定和克隆。为此，我们采用微细胞杂交模型证明了人类11号染色体上存在一个肝脏肿瘤抑制因子，将其定位到11p11.2，并鉴定了候选ESTs/基因。本研究项目的长期目标是确定人类11p11.2肝肿瘤抑制基因在肝细胞癌分子发病机制中的作用，并确定该肿瘤抑制基因在人类多步骤肝癌发生过程中功能丧失的调控机制。拟议的研究重点是在初始资助期间确定的一小部分候选肝脏肿瘤抑制基因，并扩展/推进我们正在进行的旨在表征这些候选基因的研究。本提案的目标是：(1)表征候选肝脏肿瘤抑制基因在体外和体内使用siRNA抑制大鼠肝脏肿瘤细胞系的肿瘤表型的参与，(2)确定候选基因在体内使用转染细胞系表达肿瘤抑制活性的能力，(3)评估表观遗传机制对候选肝脏肿瘤抑制基因表达调控的可能贡献。（iv）检查基因改变（LOH和/或突变）在候选肝脏肿瘤抑制基因表达失活中的作用，(v)确定候选肝脏肿瘤抑制基因表达的改变是否代表多步骤肝癌发生过程中早期或后期的分子改变，以及（vi）确定肝脏肿瘤细胞系中受候选基因表达直接或间接修饰的分子靶点和途径。

DESCRIPTION (provided by applicant): Numerous studies suggest that inactivation of one or more tumor suppressor genes may represent early and/or necessary steps in the neoplastic transformation of liver. Human chromosome 11 has been implicated in the pathogenesis of several human tumors, including hepatoblastoma and hepatocellular carcinoma, and is syntenic to rat chromosome 1, which is structurally altered in many rat liver tumor cell lines, suggesting that these chromosomes may contain a common liver tumor suppressor gene. We have suggested that chromosome tranfer studies utilizing human chromsomes and rat liver tumor cell lines may facilitate the facile localization, identification, and cloning of human genes responsible for tumor suppression in liver. To this end, we have employed a microcell hybrid model to demonstrate the existence of a liver tumor suppressor on human chromosome 11, map its location to 11p11.2, and identify candidate ESTs/genes. The continuing long-term goal of this research project is to determine the role of the human 11p11.2 liver tumor suppressor gene in the molecular pathogenesis of hepatocellular carcinoma, and to determine the mechanisms that govern the loss of function of this tumor suppressor in multi-step hepatocarcinogenesis in humans. The proposed investigations focus on a small group of candidate liver tumor suppressor genes that were identified during the initial funding period, and extend/advance our ongoing studies aimed at characterizing these candidate genes. The goals of this proposal are to (i) characterize the involvement of candidate liver tumor suppressor genes in the suppression of the neoplastic phenotype of rat liver tumor cell lines using siRNA in vitro and in vivo, (ii) determine the ability of candidate genes to express tumor suppressor activity in vivo using transfected cell lines, (iii) evaluate the possible contributions of epigenetic mechanisms to the regulation of candidate liver tumor suppressor gene expression, (iv) examine the role of genetic alterations (LOH and/or mutation) in the inactivation of candidate liver tumor suppressor gene expression, (v) determine if alterations in candidate liver tumor suppressor gene expression represent early or later molecular alterations in multi-step hepatocarcinogenesis, and (vi) identify molecular targets and pathways in liver tumor cell lines that are subject to direct or indirect modification in response to candidate gene expression.