Background and Aims: The chemical carcinogen diethylnitrosamine (DEN) is often used to induce hepatocellular carcinoma (HCC) in mice. Curiously, several labs have reported that removal of oncoproteins from hepatocytes exacerbated DEN-induced HCC, with mechanisms unknown. This study aimed at deciphering molecular mechanisms underlying the tumor suppressive effect of oncoproteins. Methods and Results: We generated mutant mouse lines with hepatocyte-specific deletions of Met, Ptpn11/Shp2, Ikk, or ctnnb1/-catenin, and assessed DEN-induced tumorigenesis in the wild type (WT) and mutant mice. To systematically examine genetic and molecular signaling alternations, we performed whole exome and RNA sequencing on liver samples collected at the pre-cancer and established cancer stages. Although the mutational profiles of DEN-induced tumors were barely different in WT and mutant mice, oncoprotein ablation increased DEN-induced mutational burdens, especially in Shp2-deficient tumors. RNA-sequencing revealed multiple changes in signaling pathways, in particular upregulated epithelial-mesenchymal transition (EMT), cell migration and tumor metastasis as well as downregulated small molecule metabolism that were affected by oncoprotein ablation. We identified key molecules and pathways that are associated with hepatic innate immunity and implicated in liver tumorigenesis. In addition, we unveiled markedly changed expression of a few miRNAs in human HCC database. Conclusion: The aggravation of DEN-induced HCC progression seen on oncoprotein ablation could be caused by common and distinct genomic and signaling alterations. This study reveals a new level of complexity in hepato-carcinogenesis and elucidates molecular mechanisms underlying tumor evolution and recurrence.

中文翻译：

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癌蛋白丢失加剧化学肝癌发生的基因组和转录组学分析


背景和目的： 化学致癌物二乙基亚硝胺 （DEN） 通常用于诱导小鼠肝细胞癌 （HCC）。奇怪的是，几个实验室报告说，从肝细胞中去除癌蛋白会加剧 DEN 诱导的 HCC，机制尚不清楚。本研究旨在破译癌蛋白抑制肿瘤作用的分子机制。方法和结果： 我们生成了具有 Met 、 Ptpn11/Shp2 、 Ikk 或 ctnnb1/-catenin 肝细胞特异性缺失的突变小鼠系，并评估了 DEN 诱导的野生型 （WT） 和突变小鼠的肿瘤发生。为了系统地检查遗传和分子信号传导的变化，我们对在癌前和已确定的癌症阶段收集的肝脏样本进行了全外显子组和 RNA 测序。尽管 WT 和突变小鼠 DEN 诱导的肿瘤的突变谱几乎没有差异，但癌蛋白消融增加了 DEN 诱导的突变负荷，尤其是在 Shp2 缺陷型肿瘤中。RNA 测序揭示了信号通路的多种变化，特别是上皮-间充质转化 （EMT） 、细胞迁移和肿瘤转移上调，以及受癌蛋白消融影响的小分子代谢下调。我们确定了与肝脏先天免疫相关并与肝脏肿瘤发生有关的关键分子和通路。此外，我们在人 HCC 数据库中发现了一些 miRNAs 的表达发生显著变化。结论： 癌蛋白消融术中观察到的 DEN 诱导的 HCC 进展加重可能是由常见和不同的基因组和信号改变引起的。这项研究揭示了肝癌发生的复杂性达到了一个新的水平，并阐明了肿瘤演变和复发的分子机制。