COMPARISON OF METABOLISM AND EXPOSURE BIOMARKERS IN ANIMAL AND HUMAN TISSUES

动物和人体组织中代谢和暴露生物标志物的比较

• 批准号: 6432312
• 负责人: BURHAN I GHANAYEM
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6432312
• 关键词: acyl coA; biomarker; carcinogen testing; chemical carcinogen; chemical carcinogenesis; cytochrome P450; drug metabolism; environment related neoplasm /cancer; environmental toxicology; enzyme activity; herbicides; human tissue; laboratory mouse; laboratory rat; liver neoplasms; mixed tissue /cell culture; mutagen testing; mutagens; oxidoreductase; peroxisome

Wyeth-14643 (WY), a peroxisome proliferator (PP), is a liver carcinogen in rats and mice. However, the potential human carcinogenicity of this chemical is currently uncertain. WY is known to induce the expression of genes involved in peroxisomal fatty acid metabolism as well as DNA synthesis in the liver. Earlier work in this laboratory showed that nonparenchymal cells (NPC) play a role in WY-induced DNA synthesis in rat hepatocytes in vitro. This increase could be inhibited by either 11-undecynoic acid, an inhibitor of P450 4A1, or indomethacin, which inhibits cyclooxygenases (Cox). Present work was initiated to further characterize the respective roles of hepatocytes and NPC in the mechanisms of WY-induced carcinogenicity. Four month-old male B6C3F1 mice were treated with 200 or 100 mg WY/kg body weight by oral gavage for 4 or 12 hr, respectively. Following a two-step collagenase perfusion hepatocytes and NPC were isolated and purified. RNA was isolated from both cell fractions and gene expression was measured by reverse transcriptase polymerase chain reaction. Expression of genes, such as CYP 4A1, the liver fatty acid binding protein (LFABP), and acyl CoA oxidase (ACoAse) was significantly induced in hepatocytes as early as 4 h after dosing. A similar but weaker pattern observed in the NPC fraction was attributed to trace contamination of NPC with hepatocytes. The constitutive Cox 1 enzyme was expressed in NPC but not in hepatocytes and was not induced by WY. Present work also indicated that Cox 2 mRNA was not detectable in NPC or HPC obtained from control or WY-treated mice. However, treatment of mice with WY resulted in increased expression of Cox 2 protein in NPC. These results suggest that the effect of NPC on WY-induced DNA synthesis in hepatocytes may be mediated by fatty acid metabolites formed via Cox enzymes.

Wyeth-14643 (WY) 是一种过氧化物酶体增殖剂 (PP)，是大鼠和小鼠的肝癌致癌物。 然而，这种化学物质对人类的潜在致癌性目前尚不确定。 WY 已知可诱导肝脏中参与过氧化物酶体脂肪酸代谢和 DNA 合成的基因表达。该实验室的早期工作表明，非实质细胞 (NPC) 在体外 WY 诱导的大鼠肝细胞 DNA 合成中发挥作用。 这种增加可以通过 11-十一碳酸（P450 4A1 的抑制剂）或吲哚美辛（抑制环氧合酶 (Cox)）来抑制。 目前的工作是为了进一步确定肝细胞和 NPC 在 WY 诱导致癌机制中各自的作用。 四个月大的雄性 B6C3F1 小鼠分别以 200 或 100 mg WY/kg 体重口服管饲 4 或 12 小时。两步胶原酶灌注后，分离并纯化肝细胞和 NPC。从两种细胞组分中分离RNA，并通过逆转录酶聚合酶链式反应测量基因表达。 给药后 4 小时，肝细胞中 CYP 4A1、肝脏脂肪酸结合蛋白 (LFABP) 和酰基辅酶 A 氧化酶 (ACoAse) 等基因的表达就被显着诱导。 在 NPC 部分中观察到的类似但较弱的模式归因于 NPC 与肝细胞的痕量污染。 组成型 Cox 1 酶在 NPC 中表达，但在肝细胞中不表达，并且不被 WY 诱导。 目前的工作还表明，在从对照或 WY 处理的小鼠获得的 NPC 或 HPC 中未检测到 Cox 2 mRNA。 然而，用 WY 治疗小鼠会导致 NPC 中 Cox 2 蛋白的表达增加。 这些结果表明 NPC 对 WY 诱导的肝细胞 DNA 合成的影响可能是由 Cox 酶形成的脂肪酸代谢物介导的。