Transcriptional modulator ZBED6 affects cell cycle and growth of human colorectal cancer cells
Transcriptional modulator ZBED6 affects cell cycle and growth of human colorectal cancer cells
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DOI：
10.1073/pnas.1509193112
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发表时间：
2015-06-23
影响因子：
11.1
通讯作者：
Sjoblom, Tobias
中科院分区：
文献类型：
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作者：
Ali, Muhammad Akhtar;Younis, Shady;Sjoblom, Tobias
转录因子ZBED6 （zinc finger, BED-type containing 6）是IGF2的抑制因子，其作用影响胎盘哺乳动物的发育、细胞增殖和生长。在人类结直肠癌中，IGF2过表达与PI3K信号组分的体细胞突变是相互排斥的，这为IGF2参与PI3K通路提供了遗传学证据。为了了解ZBED6在肿瘤发生中的作用，我们在人类结直肠癌细胞系RKO和HCT116中设计并验证了体细胞ZBED6敲除。ZBED6的消融影响了细胞周期，导致RKO细胞的生长速率增加，而HCT116细胞的生长速率降低。这一显著差异反映在转录组分析中，该分析揭示了两种细胞系中差异表达基因中细胞周期相关过程的富集，但细胞系之间变化的方向往往不同。ChIP测序分析显示，在敲除ZBED6的克隆中，ZBED6与上调基因的结合富集，这与ZBED6主要通过抑制转录来调节基因表达的观点一致。10个差异表达基因被确定为可能的直接靶基因，并通过实验验证了它们被ZBED6下调。其中8个基因与Wnt、Hippo、tgf - β、EGF受体或PI3K通路有关，这些通路都与结直肠癌的发生有关。本研究结果表明，ZBED6对肿瘤发展的影响取决于其靶基因的遗传背景和转录状态。
The transcription factor ZBED6 (zinc finger, BED-type containing 6) is a repressor of IGF2 whose action impacts development, cell proliferation, and growth in placental mammals. In human colorectal cancers, IGF2 overexpression is mutually exclusive with somatic mutations in PI3K signaling components, providing genetic evidence for a role in the PI3K pathway. To understand the role of ZBED6 in tumorigenesis, we engineered and validated somatic cell ZBED6 knock-outs in the human colorectal cancer cell lines RKO and HCT116. Ablation of ZBED6 affected the cell cycle and led to increased growth rate in RKO cells but reduced growth in HCT116 cells. This striking difference was reflected in the transcriptome analyses, which revealed enrichment of cell-cycle-related processes among differentially expressed genes in both cell lines, but the direction of change often differed between the cell lines. ChIP sequencing analyses displayed enrichment of ZBED6 binding at genes up-regulated in ZBED6-knockout clones, consistent with the view that ZBED6 modulates gene expression primarily by repressing transcription. Ten differentially expressed genes were identified as putative direct gene targets, and their down-regulation by ZBED6 was validated experimentally. Eight of these genes were linked to the Wnt, Hippo, TGF-beta, EGF receptor, or PI3K pathways, all involved in colorectal cancer development. The results of this study show that the effect of ZBED6 on tumor development depends on the genetic background and the transcriptional state of its target genes.