ZIC2-dependent OCT4 activation drives self-renewal of human liver cancer stem cells
Pingping Zhu, … , Jiayi Wu, Zusen Fan
Pingping Zhu, … , Jiayi Wu, Zusen Fan
Published August 31, 2015
Citation Information: J Clin Invest. 2015;125(10):3795-3808. https://doi.org/10.1172/JCI81979.
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Research Article Oncology

ZIC2-dependent OCT4 activation drives self-renewal of human liver cancer stem cells

Abstract

Liver cancer stem cells (CSCs) have been identified and shown to have self-renewal and differentiation properties; however, the biology of these hepatic CSCs remains largely unknown. Here, we analyzed transcriptome gene expression profiles of liver CSCs and non-CSCs from hepatocellular carcinoma (HCC) cells lines and found that the transcription factor (TF) ZIC2 is highly expressed in liver CSCs. ZIC2 was required for the self-renewal maintenance of liver CSCs, as ZIC2 depletion reduced sphere formation and xenograft tumor growth in mice. We determined that ZIC2 acts upstream of the TF OCT4 and that ZIC2 recruits the nuclear remodeling factor (NURF) complex to the OCT4 promoter, thereby initiating OCT4 activation. In HCC patients, expression levels of the NURF complex were consistent with clinical severity and prognosis. Moreover, ZIC2 and OCT4 levels positively correlated to the clinicopathological stages of HCC patients. Altogether, our results indicate that levels of ZIC2, OCT4, and the NURF complex can be detected and used for diagnosis and prognosis prediction of HCC patients. Moreover, these factors may be potential therapeutic targets for eradicating liver CSCs.

Authors

Pingping Zhu, Yanying Wang, Lei He, Guanling Huang, Ying Du, Geng Zhang, Xinlong Yan, Pengyan Xia, Buqing Ye, Shuo Wang, Lu Hao, Jiayi Wu, Zusen Fan

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Figure 6

ZIC2 binds to the OCT4 promoter.

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ZIC2 binds to the OCT4 promoter. (A) Spheres derived from HCC primary ce...
(A) Spheres derived from HCC primary cell were lysed and performed a ChIP assay. Detected fragments of the OCT4 promoter were illustrated in the left panel. Enrichment of different regions of the OCT4 promoter was detected by quantitative RT-PCR (right panel). (B) ZIC2 binds to the promoter of OCT4. rGST-ZIC2 and the [r-32P]dATP-labeled OCT4 promoter fragment were incubated followed by an EMSA assay. Probe, non–[r-32P]dATP-labeled OCT4 promoter fragment. Upper black arrowhead denotes the binding of ZIC2 and probes, and lower black arrowhead denotes free probes. (C) ZIC2 deficiency increases resistance to DNase I digestion at the OCT4 locus. (D) ZIC2-deficient sphere cells were applied to a ChIP assay using anti-H3K4Me3 antibody. (E) ZIC2-depleted primary cells were applied to a ChIP assay using anti-H3K4Me3 antibody. (F) Sphere formation was analyzed in the ZIC2 binding sequence of OCT4 promoter–deficient cells. OCT4P-KO, ZIC2 binding region of OCT4 promoter KO. CR, conserved region; oeVec, overexpressed vector; oeZIC2, overexpressed ZIC2. Scale bars: 500 μm. Data are shown as means ± SD. Two-tailed Student’s t test was used for statistical analysis. *P < 0.05; **P < 0.01; and ***P < 0.001. Data are representative of at least 3 independent experiments.