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 7

ZIC2 interacts with the NURF complex.

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ZIC2 interacts with the NURF complex. (A) ZIC2 associates with RBBP4. Ye...
(A) ZIC2 associates with RBBP4. Yeast strain AH109 was cotransfected with Gal4 DNA-binding domain (BD) fused the DNA binding region–deleted (aa 255-415) ZIC2 gene (BD-ZIC2ΔDB), and Gal4-AD–fused RBBP4. Selected clones were detected for β-galactosidase activity. p53 and large T antigen were used as a positive control. (B) Anti-ZIC2 antibody precipitated the NURF complex from primary sphere lysates by Co-IP assay. (C and D) HCC sample sphere cells were treated with 1% formaldehyde for crosslinking. Then anti-ZIC2 (C) or anti-BPTF antibody (D) was incubated with treated lysates for ChIP assays, followed by size fractionation with sucrose gradient ultracentrifugation. Eluate gradients were used for Western blot and PCR assays. (E) ZIC2 colocalizes with BPTF. HCC primary nonsphere cells and spheres were stained for BPTF and ZIC2, counterstained with DAPI. SNF2L and RBBP4 were also merged with ZIC2 (data not shown). Scale bar: 10 μm. (F) ZIC2 and BPTF were costained by IHC staining. Blue arrowhead denotes ZIC2, red arrowhead indicates BPTF, and black arrowhead indicates merge of ZIC2 and BPTF. Scale bars: 50 μm. Data are representative of at least 3 independent experiments.