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

描述(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11号染色体与包括肝母细胞瘤和肝细胞癌在内的多种人类肿瘤的发生有关，并与大鼠1号染色体同源，而大鼠1号染色体在许多大鼠肝肿瘤细胞系中结构发生改变，提示这些染色体可能含有共同的肝肿瘤抑制基因。我们认为，利用人染色体和大鼠肝肿瘤细胞系进行染色体转移研究，可以方便地定位、鉴定和克隆与肝脏肿瘤抑制有关的人类基因。为此，我们使用微细胞杂交模型来证明人类11号染色体上存在肝癌抑制基因，将其定位于11p11.2，并确定候选EST/基因。这项研究的长期目标是确定人11p11.2抑癌基因在肝细胞癌分子发病机制中的作用，并确定该抑癌基因在人类多步骤肝癌发生中功能丧失的机制。拟议的研究集中在最初资助期间发现的一小部分候选肝肿瘤抑制基因，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。该建议的目的是(I)利用siRNA在体外和体内表征候选肝癌抑制基因在抑制大鼠肝肿瘤细胞系的肿瘤表型中的作用，(Ii)使用转基因细胞系确定候选基因在体内表达肿瘤抑制活性的能力，(Iii)评估表观遗传学机制对候选肝癌抑制基因表达的可能贡献，(Iv)检测遗传改变(LOH和/或突变)在候选肝癌抑制基因表达失活中的作用，(V)确定候选肝癌抑制基因表达的变化是否代表多步骤肝癌发生的早期或晚期分子变化，以及(Vi)确定肝癌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.