8-OHDG AND A CARCINOGENIC CHOLINE-DEFICIENT DIET

我们使用了一种基于喂养大鼠的肝癌模型。 胆碱缺乏(CD)饮食，作为引发剂或促进剂。 这种方法会导致肝硬变的出现，因为在人类中有60%-90% 在肝硬变中发展的肝癌，它可能允许IS 仔细考察两者是否有共同的机制(S) 流程。与我们调查的长期目标一致， 即阐明肝细胞癌的发生机制(S)。 在伴随纤维化的情况下，有什么发现 给予Cd饲料24周的F344大鼠表现出预期的 癌前病变，此外，积聚8- 羟基脱氧鸟苷(8-OHdG)。这种DNA加合物，由反应性产生 氧物种，通常在大鼠的肝脏中给予足够的低氧 胆碱。应测量它的适当治疗时间 然而，在经过处理的动物中，这一点尚不清楚。因此，它将成为 必须评估不同饲喂时间的8-OHdG含量 CD节食。我们还发现了PVG株的F344和两性 的大鼠对癌前标志物的发展具有抵抗力， 与肝硬变和8-OHdG的变化有关。我们的假设是 Cd饮食导致氧自由基和氧化水平增加 损伤，8-OHdG的积累。这一点，如果不修复，会提示DNA 突变和/或缺失。伴随着DNA的改变，氧化 变化会导致细胞毒性和坏死，其次是细胞 增殖和纤维化。为了支持这一论点， 8-OHdG上的抗氧化剂将与数量和大小一起测定 病灶和肝纤维化的影响。我们也会衡量这些价值观 血清丙氨酸氨基转移酶与增殖细胞核抗原/环素的存在 大鼠肝组织。通过估计毒性和细胞复制 方式，并结合前面的变量，我们将尝试 以解释8-OHdG的毒性和水平是否耦合或可分离。 大鼠Cd抗性品系的鉴定将为今后的研究提供理论依据 有机会调查这些现象是否有遗传基础 观察到的。因此，我们建议对杂交后代进行遗传分析。 敏感株(F344)和抗性株(PVG)。身份识别 将使用8-OHdG的量来检测创业发育不全的特定基因座 和阳性灶。未来的实验，如果我们的假设是正确的， 将努力绘制出这种变化的图谱，最有可能的是利用分子生物学 技巧。这些研究将提供新的证据 活性氧自由基参与机体氧化损伤的过程 肝硬变与大鼠肝癌发生的启动/促进

We have used a model of liver carcinogenesis based on feeding rats a choline deficient (CD) diet, either as an initiator or as a promoter. The method causes the appearance of cirrhosis, and since in humans 60-90% of hepatocarcinomas develop in cirrhotic livers, it may allow is to scrutinize whether there are common mechanism(s) involved in both processes. Consistent with the long-term goal of our investigations, i.e., to elucidate the mechanism(s) of liver carcinogenesis under conditions in which there is concomitant fibrosis, what have found that F344 rats given a CD diet for 24 wks show the expected formation of preneoplastic foci and in addition, an accumulation of 8- hydroxydeoxyguanosine (8-OHdG). This DNA adduct, generated by reactive oxygen species, is normally low in the liver of rats given sufficient choline. The appropriate treatment time at which it should be measured in treated animals, however, is not known. Hence, it will become imperative to evaluate the 8-OHdG content at various time of feeding the CD diet. We have fond also the F344 and both sexes of the PVG strain of rats are resistant to the development of preneoplastic markers, to cirrhosis and to changes in the values of 8-OHdG. our hypothesis is that the CD diet induces increased levels of oxygen free radical and oxidative damage, with accumulation of 8-OHdG. This, if not repaired, prompts DNA mutations and/or deletions. Along with the DNA alterations, oxidative changes result in cellular toxicity and necrosis, followed by cell proliferation and fibrosis. To support this thesis, the effect of antioxidants on 8-OhdG will be determined together with number and size of foci and of the liver fibrosis. We will measure, as well, the values of serum alanine aminotransferase and the existence of PCNA/Cycline in rat liver tissues. By estimating toxicity and cell replication in this manner, and in conjunction with the preceding variables, we will attempt to explain if toxicity and levels of 8-OHdG are coupled or separable. The identification of CD resistant strain of rats will provide the opportunity to investigate if there is a genetic basis for the phenomena observed. Consequently, we propose to do a genetic analysis in crosses of susceptible (F344) and resistant (PVG) strains. The identification of specific loci for preneoplasia will be don using the amounts of 8-OHdG and positive foci. Future experiments, if our assumptions are correct, will strive to map the change, most likely utilizing molecular biology techniques. These studies will furnish new evidence for the participation of reactive oxygen free radicals in the process of cirrhosis and initiation/promotion during rat liver hepatocarcinogenesis.