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Small molecule promotes β-catenin citrullination and inhibits Wnt signaling in cancer


Wnt (wingless)/β-catenin signaling is critical for tumor progression and is frequently activated in colorectal cancer as a result of the mutation of adenomatous polyposis coli (APC); however, therapeutic agents targeting this pathway for clinical use are lacking. Here we report that nitazoxanide (NTZ), a clinically approved antiparasitic drug, efficiently inhibits Wnt signaling independent of APC. Using chemoproteomic approaches, we have identified peptidyl arginine deiminase 2 (PAD2) as the functional target of NTZ in Wnt inhibition. By targeting PAD2, NTZ increased the deamination (citrullination) and turnover of β-catenin in colon cancer cells. Replacement of arginine residues disrupted the transcriptional activity, and NTZ induced degradation of β-catenin. In Wnt-activated colon cancer cells, knockout of either PAD2 or β-catenin substantially increased resistance to NTZ treatment. Our data highlight the potential of NTZ as a modulator of β-catenin citrullination for the treatment of cancer patients with Wnt pathway mutations.

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Figure 1: NTZ inhibits Wnt/β-catenin signaling.
Figure 2: NTZ promotes β-catenin degradation.
Figure 3: PAD2 is the direct target of NTZ.
Figure 4: PAD2 directly binds to and citrullinates β-catenin.
Figure 5: NTZ stabilizes PAD2 and increases protein citrullination.
Figure 6: PAD2 inhibits the growth of Wnt activated cancer cells.


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We thank H.M. Hoang for DNA microarray profiling, M. Eidsheim for immunohistochemistry and S.M. Leh for clinical materials. We thank C. Lv for the calcium measurement, and X. Zu and X. Liu for the LC–Q-TOF–MS analysis. We thank the Flow Cytometry Core Facility, Department of Clinical Science, University of Bergen. We thank R. Nusse (Stanford University, Stanford, CA) for the Wnt reporter 7TGC, O.J. Sansom (Cancer Research UK Beatson Institute, Glasgow, UK) for the mutant Apc and Ctnnb1 organoids, and S. Coonrod for the PAD2 expression vector and valuable discussion. We acknowledge funding from Einar Galtung Døsvig, Espen Galtung Døsvig, Jan Einar Greve, Bjarne Rieber, Herman Friele, Trond Mohn, Thorstein Selvik, Kåre Rommetveit, Tordis and Fritz C. Rieber's legacy to K.H.K., Bergen Research Foundation to X.K., Helse Vest grants 911778 to Y.Q., 911626 and 912062 to K.H.K., 911747 to X.K., Professor of Chang Jiang Scholars Program and NSFC (81230090, 81520108030) to W.Z., the Society for Skin Cancer Research to M.P.L. and the EU Horizon 2020 Collaborative Research Project SOUND (633974) to P.F.C.

Author information




Y.Q. and X.K. designed the project, performed experiments, analyzed data, interpreted results and wrote the manuscript; J.R.O. performed experiments; X.Y. and W.Z. performed mice experiments, LC–Q-TOF–MS analysis and calcium measurement; P. F. C. and M.P.L. performed data analysis; P.S.H. provided materials; A.M.O. performed DNA microarray profiling; K.A.B. performed immunohistochemistry staining; K.-H.K. designed the project, interpreted results and wrote the manuscript.

Corresponding authors

Correspondence to Weidong Zhang, Karl-Henning Kalland or Xisong Ke.

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Competing interests

X.S., Y.Q., K.H.K. & A.M.O. are listed as inventors of the patent-pending (PCT/EP2016/076171) filed by Bergen Teknologioverføring AS.

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Supplementary Results, Supplementary Tables 1–3 and Supplementary Figures 1–23 (PDF 4628 kb)

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Qu, Y., Olsen, J., Yuan, X. et al. Small molecule promotes β-catenin citrullination and inhibits Wnt signaling in cancer. Nat Chem Biol 14, 94–101 (2018).

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