CELL AND MOLECULAR BIOLOGY OF RAT HEPATOCARCINOGENESIS

这项研究计划旨在了解 调节正常、癌前和 大鼠的肿瘤性肝脏。 所采用的方法将是研究 精细结构的调控的几个基因，其表达在 肿瘤前和/或肿瘤性肝脏与 正常，以更完整地描述进展阶段，并 在转基因模型中表征肝癌发生， 化学品诱发大鼠多阶段癌变。 的 丝氨酸调节组分的结构和功能 脱氢酶（SDH）、醛脱氢酶（3型）（ALDH）和γ- 谷氨酰转肽酶（GGT）基因，其表达均异常 在肝癌发生过程中，将被表征。 表征 将包括确定特定的核苷酸序列 参与调节这些基因在体内的表达， 鉴定和表征结合至所述蛋白质的蛋白质 这些基因的调控序列，这些蛋白质的水平， 正常、癌前和恶性肝细胞的细胞核，和 这些基因的调控序列在其 在瘤前和明显瘤形成期间表达。 利用本实验室开发的用于研究多- 阶段性肝癌发生，我们计划更好地开发 方法来量化的进展阶段的发展， 肝癌发生，以表征这一阶段的细胞， 和分子水平，并制定定量方法， 进展剂的鉴定。 舞台意志的表征 涉及对几种已知的和 潜在的“标记”基因利用细胞化学方法。 染色体 在肝细胞形成早期发生的异常 癌在大鼠的进展阶段和特异性 将确定该阶段演变的这种异常。 潜在的肿瘤抑制基因，特别是p53基因，将被 其特征在于它们的染色体定位和任何突变， 它们的序列，后者最初与p53基因有关。 我们还将使用一群携带SV 40 T抗原的转基因大鼠 转基因在小鼠白蛋白启动子/增强子的控制下， 比较遗传程序性肝癌与化学 诱发肝癌。 启蒙、提升和 将在转基因模型中描绘进展，并与 这些阶段发生在化学诱导过程中， 肝癌发生 环境因素的影响，包括 激素，饮食和外源性物质对遗传的自然历史 将确定程序性肝癌发生。 表征 肿瘤和形态正常的肝细胞， 转基因动物将在体外进行。 这些研究 这将使我们能够更准确地定义关键的遗传因素， 大鼠多阶段肝癌发生的特点， 特别是在发展阶段，并获得更好的 了解遗传异常的机制， 具有提升和进展阶段特征的表达。

This research program is directed toward an understanding of the regulation of genetic expression in normal, preneoplastic, and neoplastic liver in the rat. The approach utilized will be to study the fine structure of regulation of several genes whose expression in preneoplastic and/or neoplastic liver is significantly different from normal, to characterize more completely the stage of progression, and to characterize hepatocarcinogenesis in a transgenic model as compared to multi-stage carcinogenesis induced by chemicals in the rat. The structure and function of the regulatory components of the serine dehydratase (SDH), aldehyde dehydrogenase (Type 3) (ALDH) and gamma- glutamyl transpeptidase (GGT) genes, all of whose expression is abnormal during hepatocarcinogenesis, will be characterized. Characterization will include the determination of the specific nucleotide sequences involved in the regulation of the expression of these genes in vivo, the identification and characterization of protein(s) that bind to the regulatory sequences of these genes, the levels of such proteins in nuclei of normal, preneoplastic and malignant hepatocytes, and functioning of the regulatory sequences of these genes in their expression during preneoplasia and overt neoplasia. Utilizing a model developed in this laboratory for the study of multi- stage hepatocarcinogenesis in rat liver, we plan to develop better methods to quantitate the development of the stage of progression in hepatocarcinogenesis, to characterize this stage at both the cellular and molecular levels and to develop quantitative methods for the identification of progressor agents. Characterization of the stage will involve a study of the regulation of the expression of several known and potential "marker" genes utilizing cytochemical methods. Chromosomal abnormalities which develop early during the formation of hepatocellular carcinoma in the rat in the stage of progression and the specificity of such abnormalities for the evolution of this stage will be determined. Potential tumor suppressor genes, especially the p53 gene, will be characterized as to their chromosomal localization and any mutation in their sequences, the latter initially in relation to the p53 gene. We will also use a colony of transgenic rats carrying the SV40 T antigen transgene under the control of the mouse albumin promoter/enhancer to compare genetically programmed hepatocarcinogenesis with chemically induced hepatocarcinogenesis. The stages of initiation, promotion, and progression will be delineated in the transgenic model and compared with these stages occurring during the chemical induction of hepatocarcinogenesis. The effect of environmental factors including hormones, diet, and xenobiotics on the natural history of genetically programmed hepatocarcinogenesis will be determined. Characterization of both neoplastic and morphologically normal hepatocytes from the transgenic animals will be carried out in vitro. Together these studies should enable us to define more accurately the critical genetic characteristics of multi-stage hepatocarcinogenesis in the rat, especially during the stage of progression, and to gain a better understanding of the mechanisms of the abnormalities in genetic expression characteristic of the stages of promotion and progression.