Quantifying Gene Effects on Hepatic Cancer in Vivo

描述（由申请人提供）：这项拟议研究的总体目标是为人类和/或小鼠肝脏肿瘤中常见的几种遗传变化分配在肝癌发生中的作用。为了实现这一目标，采用了新开发的新型体内测定系统，即比较肝细胞生长测定。作为起始材料，该测定使用通过标准转基因或基因靶向方法产生的转基因小鼠。从这些小鼠中分离出肝细胞，然后移植到专门设计的受体小鼠的肝脏中。对供体细胞在新宿主环境中随后的克隆生长进行评估，可以量化单个或组合遗传修饰对以下方面的影响：（1）生长刺激条件下肝细胞增殖的速率； (2)肝细胞在静止肝脏环境中持续生长的能力； (3)肝细胞进展为恶变的风险。每项测量都反映了肿瘤细胞的一个重要特征。数据的定量性质提供了对每种基因变化（单独或与其他基因变化组合）对肝癌进展过程的具体贡献的更精细的理解。最终目标是通过将基因表达模式的变化与将被识别的肝细胞克隆生长的变化相关联，将该系统用作癌症基因发现的工具。该提案有以下具体目标。目标 1：通过确定的肝细胞基因变化组合来确定小鼠的癌症发病率、潜伏期、多重性、组织型和进展。目标 2：量化与体内特定肝细胞基因变化相关的生长改变和转化频率。目标 3：鉴定转化肝细胞的生物学行为和分子特征。成功完成这些实验将（1）定义肝癌发生过程中几个高度相关的遗传变化（协同或加性互补，或无互补）之间的特定相互作用； (2) 对遗传和环境改变（根据其与肝癌的相关性而选择）对肝细胞生长潜力的影响进行系统和比较评估； (3) 将鉴定在肿瘤进展过程中与癌基因配合的基因组。

DESCRIPTION (provided by applicant): The overall goal of this proposed research is to assign a role in hepatocarcinogenesis to each of several genetic changes commonly identified in human and/or mouse liver tumors. To accomplish this objective, a newly developed, novel in vivo assay system is employed, the comparative hepatocyte growth assay. As starting material, this assay uses genetically modified mice generated by standard transgenic or gene-targeting methodologies. Hepatocytes are isolated from these mice, and then transplanted into liver of specially designed recipient mice. Evaluation of the subsequent clonal growth of donor cells in the new host environment allows quantification of the influence of single or combined genetic modifications on (1) the rate at which hepatocytes proliferate under growth stimulatory conditions; (2) the capacity for sustained hepatocyte growth in a quiescent liver environment; and (3) the risk for hepatocyte progression to malignant transformation. Each measure reflects an important characteristic of neoplastic cells. The quantitative nature of the data provides a more refined understanding of the specific contribution of each genetic change, alone and in combination with others, to the process of liver cancer progression. The final objective is to use this system as a tool for cancer gene discovery, by correlating changes in patterns of gene expression with the changes in hepatocyte clonal growth that will be identified. This proposal has the following specific aims. Aim 1: Define cancer incidence, latency, multiplicity, histotype, and progression in mice with defined combinations of hepatocyte gene changes. Aim 2: Quantify growth alterations and transformation frequency associated with defined hepatocyte gene changes in vivo. Aim 3: Identify biological behaviors and molecular characteristics of transformed hepatocytes. Successful completion of these experiments will (1) define specific interactions between several highly relevant genetic changes (synergistic or additive complementation, or no complementation) during hepatic carcinogenesis; (2) provide a systematic and comparative evaluation of the influence of genetic and environmental alterations, selected for their relevance to liver cancer, on hepatocyte growth potential; and (3) will identify gene sets that cooperate with oncogenes during tumor progression.