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将人类和/或小鼠肝脏肿瘤中常见的几种基因变化在肝癌发生中的作用分配给每一种。为了实现这一目标，采用了一种新开发的、新颖的体内检测系统--比较肝细胞生长检测。作为起始材料，这项测试使用了通过标准转基因或基因靶向方法产生的转基因小鼠。从这些小鼠身上分离出肝细胞，然后移植到特殊设计的受体小鼠的肝脏中。对供体细胞在新的宿主环境中随后的克隆生长的评估可以量化单个或联合的基因修饰对以下方面的影响：(1)肝细胞在生长刺激条件下的增殖速度；(2)肝细胞在静止的肝环境中持续生长的能力；(3)肝细胞向恶性转化的风险。每一项指标都反映了肿瘤细胞的一个重要特征。这些数据的量化性质提供了对每个基因变化单独或与其他基因变化结合在一起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性生长的变化相关联，将该系统用作癌症基因发现的工具。这项建议有以下具体目标。目的1：明确肝细胞基因改变组合的小鼠的癌症发病率、潜伏期、多样性、组织类型和进展。目的2：量化体内与明确的肝细胞基因变化相关的生长变化和转化频率。目的3：鉴定转化肝细胞的生物学行为和分子特征。这些实验的成功完成将(1)确定在肝癌发生过程中几个高度相关的基因变化之间的特定相互作用(协同或相加互补，或不互补)；(2)提供系统和比较的评估，以评估遗传和环境变化对肝细胞生长潜力的影响，这些基因和环境变化是根据与肝癌相关的因素而被挑选出来的；(3)将确定在肿瘤进展过程中与癌基因合作的基因组。

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.