Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology.
Pathogenetic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University.
J Toxicol Sci. 2019;44(8):565-574. doi: 10.2131/jts.44.565.
Nonalcoholic fatty liver disease (NAFLD) is characterized by excessive deposition of droplets in hepatocytes. Patients with NAFLD can be at risk for nonalcoholic steatohepatitis, which can lead to hepatocellular carcinoma. Autophagy is a cellular pathway that is crucial for survival and homeostasis, and which protects against pathophysiological changes like obesity and cancer. We determined the expression of autophagy markers in preneoplastic hepatic lesions and the effects of an autophagy repressor chloroquine (CQ) or inducer amiodarone (AM) in a steatosis-related hepatocarcinogenesis model. Male F344 rats were fed a control diet or high fat diet (HFD), and subjected to initiation and promotion steps with N-nitrosodiethylamine injection at week 0 and a partial hepatectomy at week 3. Several HFD-fed rats were administered 0.1% CQ and 0.5% AM in their drinking water during week 2 and 8. CQ and AM did not improve HFD-induced obesity. AM, but not CQ, significantly decreased the number of glutathione S-transferase placental form-positive preneoplastic liver foci in the liver. Autophagosome markers LC3 and the LC3-binding protein p62 were heterogeneously expressed in the preneoplastic foci. CQ might inhibit autophagy by significantly increased p62/LC3 ratio, while AM might have a potential of inducing autophagy by showing an increased gene expression of the autophagy regulator, Atg5. These results suggest that preneoplastic lesions express autophagosome markers and that AM might decrease steatosis-related early hepatocarcinogenesis by potentially inducing autophagy in HFD-fed rats, while inhibition of autophagy by CQ did not alter the hepatocarcinogenesis. However, an immunohistochemical trial revealed a technical limitation in detecting autophagosome markers because there were variations in each preneoplastic lesion.
非酒精性脂肪性肝病（NAFLD）的特征是肝细胞内液滴过度沉积。NAFLD 患者可能有发生非酒精性脂肪性肝炎的风险，后者可导致肝细胞癌。自噬是一种对生存和内稳态至关重要的细胞途径，可防止肥胖和癌症等病理生理变化。我们测定了前瘤性肝病变中自噬标志物的表达，并在脂肪变性相关的肝癌发生模型中检测了自噬抑制剂氯喹（CQ）或诱导剂胺碘酮（AM）的作用。雄性 F344 大鼠喂饲对照饮食或高脂肪饮食（HFD），在第 0 周接受 N-亚硝基二乙胺注射启动步骤和第 3 周接受部分肝切除术促进步骤。在第 2 周和第 8 周，HFD 喂养的若干大鼠给予 0.1%CQ 和 0.5%AM 饮水。CQ 和 AM 并未改善 HFD 诱导的肥胖。AM 而非 CQ 显著降低了肝脏中谷胱甘肽 S-转移酶胎盘型阳性前瘤性肝灶的数量。自噬体标志物 LC3 和 LC3 结合蛋白 p62 在前瘤性病灶中呈异质性表达。CQ 可能通过显著增加 p62/LC3 比值来抑制自噬，而 AM 可能通过显示自噬调节剂 Atg5 的基因表达增加而具有诱导自噬的潜力。这些结果表明，前瘤性病变表达自噬体标志物，而 AM 可能通过在 HFD 喂养的大鼠中潜在诱导自噬来降低脂肪变性相关的早期肝癌发生，而 CQ 抑制自噬并未改变肝癌发生。然而，免疫组织化学试验显示出检测自噬体标志物的技术局限性，因为每个前瘤性病变都存在差异。
