Yamada Tomoya, Okuda Yu, Kushida Masahiko, Sumida Kayo, Takeuchi Hayato, Nagahori Hirohisa, Fukuda Takako, Lake Brian G, Cohen Samuel M, Kawamura Satoshi
Environmental Health Science Laboratory, Sumitomo Chemical Company, Ltd, 3-1-98 Kasugade-naka, Konohana-ku, Osaka 554-8558, Japan
Environmental Health Science Laboratory, Sumitomo Chemical Company, Ltd, 3-1-98 Kasugade-naka, Konohana-ku, Osaka 554-8558, Japan.
Toxicol Sci. 2014 Nov;142(1):137-57. doi: 10.1093/toxsci/kfu173. Epub 2014 Aug 21.
High doses of sodium phenobarbital (NaPB), a constitutive androstane receptor (CAR) activator, have been shown to produce hepatocellular tumors in rodents by a mitogenic mode of action (MOA) involving CAR activation. The effect of 1-week dietary treatment with NaPB on liver weight and histopathology, hepatic CYP2B enzyme activity and CYP2B/3A mRNA expression, replicative DNA synthesis and selected genes related to cell proliferation, and functional transcriptomic and metabolomic analyses was studied in male CD-1 mice, Wistar Hannover (WH) rats, and chimeric mice with human hepatocytes. The treatment of chimeric mice with 1000-1500-ppm NaPB resulted in plasma levels around 3-5-fold higher than those observed in human subjects given therapeutic doses of NaPB. NaPB produced dose-dependent increases in hepatic CYP2B activity and CYP2B/3A mRNA levels in all animal models. Integrated functional metabolomic and transcriptomic analyses demonstrated that the responses to NaPB in the human liver were clearly different from those in rodents. Although NaPB produced a dose-dependent increase in hepatocyte replicative DNA synthesis in CD-1 mice and WH rats, no increase in replicative DNA synthesis was observed in human hepatocyte-originated areas of chimeric mice. In addition, treatment with NaPB had no effect on Ki-67, PCNA, GADD45β, and MDM2 mRNA expression in chimeric mice, whereas significant increases were observed in CD-1 mice and/or WH rats. However, increases in hepatocyte replicative DNA synthesis were observed in chimeric mice both in vivo and in vitro after treatment epidermal growth factor. Thus, although NaPB could activate CAR in both rodent and human hepatocytes, NaPB did not increase replicative DNA synthesis in human hepatocytes of chimeric mice, whereas it was mitogenic to rat and mouse hepatocytes. As human hepatocytes are refractory to the mitogenic effects of NaPB, the MOA for NaPB-induced rodent liver tumor formation is thus not relevant for humans.
高剂量苯巴比妥钠（NaPB）是一种组成型雄烷受体（CAR）激活剂，已被证明通过涉及CAR激活的促有丝分裂作用模式（MOA）在啮齿动物中产生肝细胞肿瘤。在雄性CD-1小鼠、Wistar Hannover（WH）大鼠和具有人肝细胞的嵌合小鼠中，研究了用NaPB进行1周饮食处理对肝脏重量和组织病理学、肝脏CYP2B酶活性和CYP2B/3A mRNA表达、复制性DNA合成以及与细胞增殖相关的选定基因，以及功能转录组学和代谢组学分析的影响。用1000 - 1500 ppm的NaPB处理嵌合小鼠，导致血浆水平比给予治疗剂量NaPB的人类受试者中观察到的水平高约3 - 5倍。在所有动物模型中，NaPB均使肝脏CYP2B活性和CYP2B/3A mRNA水平呈剂量依赖性增加。综合功能代谢组学和转录组学分析表明，人肝脏对NaPB的反应与啮齿动物明显不同。尽管NaPB在CD-1小鼠和WH大鼠中使肝细胞复制性DNA合成呈剂量依赖性增加，但在嵌合小鼠的人肝细胞起源区域未观察到复制性DNA合成增加。此外，用NaPB处理对嵌合小鼠中Ki-67、PCNA、GADD45β和MDM2 mRNA表达没有影响，而在CD-1小鼠和/或WH大鼠中观察到显著增加。然而，在经表皮生长因子处理后的嵌合小鼠体内和体外均观察到肝细胞复制性DNA合成增加。因此，尽管NaPB可在啮齿动物和人肝细胞中激活CAR，但NaPB并未增加嵌合小鼠人肝细胞中的复制性DNA合成，而对大鼠和小鼠肝细胞具有促有丝分裂作用。由于人肝细胞对NaPB的促有丝分裂作用具有抗性，因此NaPB诱导啮齿动物肝脏肿瘤形成的作用模式与人类无关。
