In this study liver tumours produced in male and female mice of the low spontaneous liver tumour incidence C57BL/10J strain treated for 99 weeks with 1000 ppm in the diet with the model constitutive androstane receptor (CAR) activator sodium phenobarbital (NaPB) were analysed for β-catenin mutations by Western immunoblotting and DNA/RNA analysis. Some gene array analysis was also performed to identify genes involved in CAR activation and in β-catenin and Hras gene mutations. Analysis of 8 male and 2 female NaPB-induced liver tumour samples (comprising 2 adenomas, 6 carcinomas and 2 samples containing separate adenomas and carcinomas) revealed truncated β-catenin forms in just 4 male liver tumour samples, with the presence of the truncated β-catenin forms being confirmed by β-catenin exon 1-3 mutation analysis. Microarray gene expression analysis was performed with three of the NaPB-induced male mouse liver tumour samples where β-catenin mutations had not been identified by Western immunoblotting and DNA/RNA analysis and with three liver samples from both NaPB-induced non-tumour tissue and control animals. Treatment with NaPB resulted in induction of Cyp2b subfamily gene expression in both NaPB-induced mouse liver tumours and in NaPB-treated non-tumour tissue. In addition, the gene expression analysis demonstrated that the β-catenin and Hras pathways were not modified in NaPB-induced mouse liver tumours not exhibiting truncated β-catenin forms. Overall, while chronic administration of the model CAR activator NaPB results in both hepatocellular adenoma and carcinoma in the low spontaneous liver tumour incidence C57BL/10J mouse strain, only 40 % of the liver tumours evaluated in this study had β-catenin mutations. These results are in agreement with previous studies with the CAR activator oxazepam and demonstrate that mouse liver tumours induced by nongenotoxic CAR activators in the absence of initiation with a genotoxic agent are due to a number of mechanisms, including those largely independent of either the Wnt/β-catenin signalling pathway or Hras oncogene mutations.

中文翻译：

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慢性给予苯巴比妥钠致C57BL / 10J小鼠肝肿瘤中β-catenin基因突变和基因表达的分析。

在这项研究中，分析了在低自发性肝肿瘤发病率C57BL / 10J品系的雄性和雌性小鼠中产生的肝肿瘤，用模型组成型雄激素受体（CAR）激活剂苯巴比妥钠（NaPB）在饮食中以1000 ppm处理了99周。通过Western免疫印迹和DNA / RNA分析得出β-catenin突变。还进行了一些基因阵列分析，以鉴定参与CAR活化以及β-catenin和Hras基因突变的基因。分析了8位男性和2位女性NaPB诱导的肝肿瘤样本（包含2例腺瘤，6例癌和2例分别包含腺瘤和癌的样本），发现仅4例男性肝肿瘤样本中存在截短的β-连环蛋白形式，并且存在截短的β β-catenin外显子1-3突变分析可确定β-catenin的形式。微阵列基因表达分析是利用NaPB诱导的三只雄性小鼠肝脏肿瘤样本（其中尚未通过Western免疫印迹和DNA / RNA分析鉴定出β-catenin突变）以及来自NaPB诱导的非肿瘤组织和三只肝样本的三份肝样本进行的。控制动物。NaPB的治疗导致在NaPB诱导的小鼠肝肿瘤和NaPB治疗的非肿瘤组织中均诱导Cyp2b亚家族基因表达。此外，基因表达分析表明，在NaPB诱导的小鼠肝肿瘤中，β-catenin和Hras通路没有被修饰，没有表现出截断的β-catenin形式。总体而言，虽然长期使用模型CAR激活剂NaPB会导致低自发性肝肿瘤C57BL / 10J小鼠品系的肝细胞腺瘤和癌，在这项研究中评估的肝肿瘤中，只有40％具有β-catenin突变。这些结果与先前使用CAR活化剂奥沙西m的研究相吻合，并表明由非遗传毒性CAR活化剂诱导的小鼠肝脏肿瘤在没有遗传毒性剂启动的情况下归因于多种机制，包括那些基本上独立于Wnt / β-catenin信号通路或Hras癌基因突变。