Genetic and epigenetic changes in rat preneoplastic liver tissue induced by 2-acetylaminofluorene
Genetic and epigenetic changes in rat preneoplastic liver tissue induced by 2-acetylaminofluorene
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DOI：
10.1093/carcin/bgm303
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发表时间：
2008-03-01
期刊：
影响因子：
4.7
通讯作者：
Pogribny, Igor P.
中科院分区：
文献类型：
--
作者：
Bagnyukovay, Tetyana V.;Tryndyaky, Volodymyr P.;Pogribny, Igor P.
基因毒性致癌物，包括2-乙酰氨基芴（2-AAF），除了发挥其基因毒性作用外，还经常在细胞中引起各种非基因毒性改变。据信，这些非基因毒性作用可能是肿瘤发生中不可缺少的事件；然而，目前还没有足够的知识来阐明致癌物在癌前组织的遗传和表观遗传变化中的作用，并且缺乏关于表观遗传改变与致癌物暴露之间联系的结结性信息。在目前的研究中，我们研究了2- aaf诱导的肝癌发生机制是否包括基因毒性（遗传）和非基因毒性（表观遗传）改变。雄性和雌性Sprague-Dawley大鼠分别饲喂含有0.02% 2-AAF的NIH-31日粮6、12、18和24周。采用高效液相色谱联用电喷雾串联质谱法（HPLC-ES-MS/MS）测定肝脏和肾脏组织中2-AAF DNA加合物的含量。N-（脱氧鸟苷-8-基）-2-氨基芴是两种组织在所有时间点检测到的主要加合物。通过基于hpai的胞嘧啶延伸试验和HPLC-ES-MS/MS测定，肝脏和肾脏的整体DNA甲基化在24周内没有变化。在雄性大鼠的肝脏中，整体和长穿插的核苷酸元件1相关组蛋白H4赖氨酸20三甲基化逐渐减少，p16（INK4A）基因的高甲基化也逐渐减少。在雌性大鼠的肝脏或雌雄大鼠的肾脏中没有观察到这些表观遗传变化。重要的是，肿瘤形成和发展的形态学证据仅在雄性大鼠的肝脏中观察到。总之，我们已经证明，暴露于遗传毒性肝癌原2-AAF的大鼠，除了形成2-AAF特异性DNA病变外，还导致细胞表观遗传状态的实质性改变。
Genotoxic carcinogens, including 2-acetylaminofluorene (2-AAF), in addition to exerting their genotoxic effects, often cause a variety of non-genotoxic alterations in cells. It is believed that these non-genotoxic effects may be indispensable events in tumorigenesis; however, there is insufficient knowledge to clarify the role of carcinogens in both the genetic and epigenetic changes in premalignant tissues and a lack of conclusive information on the link between epigenetic alterations and carcinogenic exposure. In the current study, we investigated whether or not the mechanism of 2-AAF-induced hepatocarcinogenesis consists of both genotoxic (genetic) and non-genotoxic (epigenetic) alterations. Male and female Sprague-Dawley rats were fed NIH-31 diet containing 0.02% of 2-AAF for 6, 12, 18 or 24 weeks. The levels of DNA adducts obtained from 2-AAF in liver and kidney tissues were assessed by high-performance liquid chromatography combined with electrospray tandem mass spectrometry (HPLC-ES-MS/MS). N-(Deoxyguanosine-8-yl)-2-aminofluorene was the major adduct detected at all time points in both tissues. Global DNA methylation in the livers and kidneys, as determined by an HpaII-based cytosine extension assay and by HPLC-ES-MS/MS, did not change over the 24-week period. In the livers of male rats, there was a progressive decrease of global and long interspersed nucleotide element-1-associated histone H4 lysine 20 trimethylation, as well as hypermethylation of the p16(INK4A) gene. These epigenetic changes were not observed in the livers of female rats or the kidneys of both sexes. Importantly, morphological evidence of formation and progression of neoplastic process was observed in the liver of male rats only. In conclusion, we have demonstrated that exposure of rats to genotoxic hepatocarcinogen 2-AAF, in addition to formation of 2-AAF-specific DNA lesions, resulted in substantial alterations in cellular epigenetic status.