西亚试剂：Sequential cancer mutations in cultured human intestinal st

Crypt stem cells represent the cells of origin for intestinal neoplasia. Both mouse and human intestinal stem cells can be cultured in medium containing the stem-cell-niche factors WNT, R-spondin, epidermal growth factor (EGF) and noggin over long time periods as epithelial organoids that remain genetically and phenotypically stable. Here we utilize CRISPR/Cas9 technology for targeted gene modification of four of the most commonly mutated colorectal cancer genes (APC,P53 (also known as TP53), KRAS and SMAD4) in cultured human intestinal stem cells. Mutant organoids can be seleced by removing individual growth factors from the culture medium. Quadruple mutants grow independently of all stem-cell-niche factors and tolerate the presence of the P53 stabilizer nutlin-3. Upon xenotransplantation into mice, quadruple mutants grow as tumours with features of invasive carcinoma. Finally, combined loss of APC and P53 is sufficient for the appearance of extensive aneuploidy, a hallmark of tumour progression.利用CRISPR/Cas9系统的精确的基因组编辑能力，Hans Clevers及同事将四个最常见的结肠直肠癌突变引入了由小肠或结肠细胞形成的人类器官培养中。在这样获得的体外结肠直肠癌发展模型中，APC、P53、KRAS 和SMAD4 的致癌突变消除了对干细胞龛的依赖性，将正常类器官转变成类肿瘤，后者在异种移植进小鼠体内后会长成腺瘤。该系统对于未来研究人类癌症生物学和建立新的治疗方法来说将会有重要价值

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