Nishida Naoshi, Yada Norihisa, Hagiwara Satoru, Sakurai Toshiharu, Kitano Masayuki, Kudo Masatoshi
Department of Gastroenterology and Hepatology, Kinki University Faculty of Medicine, Osaka-sayama, Japan.
J Gastroenterol Hepatol. 2016 Sep;31(9):1646-53. doi: 10.1111/jgh.13318.
Non-alcoholic fatty liver disease (NAFLD) is an increasing cause of hepatocellular carcinoma (HCC). Previously, we reported that DNA oxidation induced epigenetic alteration of tumor suppressor genes (TSGs) and contributed to HCC emergence. Here, we examine the associations between clinicopathological characteristics of NAFLD and advanced oxidative DNA damage that is associated with TSG methylation in the NAFLD liver.
Liver biopsies from 65 NAFLD patients were analyzed for clinicopathological features and oxidative DNA damage using immunohistochemistry of 8-hydroxydeoxyguanosine (8-OHdG). Abnormal DNA methylation in the promoters of 6 TSGs, HIC1, GSTP1, SOCS1, RASSF1, CDKN2A, and APC, was examined using MethyLight. Associations between clinicopathological characteristics, methylation of TSGs, and accumulation of 8-OHdG were analyzed.
We found that aspartate aminotransferase/alanine aminotransferase ratio, the fibrosis-4 index, and serum α-fetoprotein (AFP) level were associated with degree of 8-OHdG, and AFP was an independent factor among them (P = 0.0271). Regarding pathological findings, hepatocellular ballooning and stage of fibrosis were also associated with oxidative DNA damage (P = 0.0021 and 0.0054); ballooning was an independent risk for detecting high degree of 8-OHdG in hepatocytes (odds ratio 7.38, 95% confidence interval 1.41-49.13, P = 0.0171). Accumulation of methylated TSGs was significantly associated with deposition of 8-OHdG (P = 0.0362).
Patients with high serum AFP and high degree of ballooning showed accumulation of oxidative DNA damage that could be a seed of DNA methylation responsible for hepatocarcinogenesis. These characteristics could be risk of HCC; such patients require urgent intervention such as lifestyle modification.
非酒精性脂肪性肝病（NAFLD）是肝细胞癌（HCC）日益常见的病因。此前，我们报道DNA氧化诱导肿瘤抑制基因（TSGs）的表观遗传改变并促使HCC发生。在此，我们研究NAFLD的临床病理特征与NAFLD肝脏中与TSG甲基化相关的晚期氧化性DNA损伤之间的关联。
对65例NAFLD患者的肝活检组织进行临床病理特征分析，并使用8-羟基脱氧鸟苷（8-OHdG）免疫组化法检测氧化性DNA损伤。使用甲基化荧光定量法检测6个TSG（HIC1、GSTP1、SOCS1、RASSF1、CDKN2A和APC）启动子中的异常DNA甲基化。分析临床病理特征、TSG甲基化与8-OHdG积累之间的关联。
我们发现天冬氨酸氨基转移酶/丙氨酸氨基转移酶比值、纤维化-4指数和血清甲胎蛋白（AFP）水平与8-OHdG程度相关，且AFP是其中的独立因素（P = 0.0271）。关于病理结果，肝细胞气球样变和纤维化分期也与氧化性DNA损伤相关（P = 0.0021和0.0054）；气球样变是肝细胞中检测到高度8-OHdG的独立危险因素（比值比7.38，95%置信区间1.41 - 49.13，P = 0.0171）。甲基化TSG的积累与8-OHdG的沉积显著相关（P = 0.0362）。
血清AFP高且气球样变程度高的患者表现出氧化性DNA损伤的积累，这可能是导致肝癌发生的DNA甲基化的根源。这些特征可能是HCC的危险因素；此类患者需要诸如改变生活方式等紧急干预措施。
