Vaish Vivek, Kim Joohwee, Shim Minsub
Department of Biological Sciences, Center for Colon Cancer Research, University of South Carolina, Columbia, SC, 29208.
Genes Chromosomes Cancer. 2016 Jul;55(7):577-90. doi: 10.1002/gcc.22361. Epub 2016 May 2.
In this study, we have developed a novel mouse model for sporadic colorectal cancer (CRC) by utilizing APC conditional knockout (Apc(CKO) ) mouse and lentivirus encoding Cre recombinase and a reporter gene (EGFP or LacZ). Lentiviral transduction of colonic crypt stem cells allowed for the long-term expression of reporter gene as well as excision of floxed Apc alleles, which resulted in tumor development. Tumors represented adenoma stages along with the nuclear accumulation of β-catenin. Loss of E-cadherin at the cellular junctions and strong expression of Vimentin suggested the sign of active epithelial-mesenchymal transition. Moreover, nuclear staining of Ki67 inside epithelial cells of aberrant crypts demonstrated their higher proliferative nature. Erratic downstream signaling of activated Wnt/β-catenin, AKT/mTOR, and Notch pathways provided strong evidence towards the higher proliferative index of epithelial cells inside the aberrant crypts. These results do recapitulate the findings of previous APC mutant mouse models. Our model represents sporadic CRC more precisely as (i) tumors result from somatic mutations but not from germline; (ii) tumors develop in colon not in small intestine; (iii) few tumors develop at the distal end of colons. Additionally, our model allows for the long-term expression of the gene(s), which get integrated into the host cell genome and provides an ability to track the tumor growth. © 2016 Wiley Periodicals, Inc.
在本研究中，我们通过利用APC条件性敲除（Apc(CKO)）小鼠以及编码Cre重组酶和报告基因（EGFP或LacZ）的慢病毒，开发了一种用于散发性结直肠癌（CRC）的新型小鼠模型。结肠隐窝干细胞的慢病毒转导允许报告基因的长期表达以及floxed Apc等位基因的切除，这导致了肿瘤的发生。肿瘤呈现腺瘤阶段，伴有β-连环蛋白的核积聚。细胞连接处E-钙黏蛋白的缺失和波形蛋白的强表达提示了活跃的上皮-间质转化迹象。此外，异常隐窝上皮细胞内Ki67的核染色证明了它们较高的增殖特性。活化的Wnt/β-连环蛋白、AKT/mTOR和Notch信号通路的不稳定下游信号为异常隐窝内上皮细胞较高的增殖指数提供了有力证据。这些结果确实概括了先前APC突变小鼠模型的研究结果。我们的模型更精确地代表散发性CRC，因为（i）肿瘤由体细胞突变而非种系突变导致；（ii）肿瘤在结肠而非小肠中发生；（iii）结肠远端很少发生肿瘤。此外，我们的模型允许整合到宿主细胞基因组中的基因长期表达，并提供追踪肿瘤生长的能力。©2016威利期刊公司。
