TET1 downregulates epithelial-mesenchymal transition and chemoresistance in PDAC by demethylating CHL1 to inhibit the Hedgehog signaling pathway


Chemoresistance is a major obstacle to prolonging pancreatic ductal adenocarcinoma (PDAC) patient survival. TET1 is identified as the most important epigenetic modification enzyme that facilitates chemoresistance in cancers. However, the chemoresistance mechanism of TET1 in PDAC is unknown. This study aimed to determine the role of TET1 in the chemoresistance of PDAC. TET1-associated chemoresistance in PDAC was investigated in vitro and in vivo. The clinical significance of TET1 was analyzed in 228 PDAC patients by tissue microarray profiling. We identified that TET1 downregulation is caused by its promoter hypermethylation and correlates with poor survival in PDAC patients. In vitro and in vivo functional studies performed by silencing or overexpressing TET1 suggested that TET1 is able to suppress epithelial-mesenchymal transition (EMT) and sensitize PDAC cells to 5FU and gemcitabine. Then RNA-seq, whole genome bisulfite sequencing (WGBS) and ChIP-seq were used to explore the TET1-associated pathway, and showed that TET1 promotes the transcription of CHL1 by binding and demethylating the CHL1 promoter, which consequently inhibits the Hedgehog pathway. Additionally, inhibiting Hedgehog signaling by CHL1 overexpression or the Hedgehog pathway inhibitor, GDC-0449, reversed the chemoresistance induced by TET1 silencing. Regarding clinical significance, we found that high TET1 and high CHL1 expression predicted a better prognosis in resectable PDAC patients. In summary, we demonstrated that TET1 reverses chemoresistance in PDAC by downregulating the CHL1-associated Hedgehog signaling pathway. PDAC patients with a high expression levels of TET1 and CHL1 have a better prognosis.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Expression profile of TET1 in PDAC.
Fig. 2: Abrogation of TET1 expression increases PDAC cell chemotherapy resistance.
Fig. 3: TET1 upregulates CHL1 expression via demethylating its promoter.
Fig. 4: TET1 regulates chemoresistance via the CHL1-Hedgehog signaling pathway.
Fig. 5: TET1 and CHL1 are associated with the poor survival of patients with PDAC.
Fig. 6: TET1 and CHL1 are associated with the poor survival of patients with PDAC.


  1. 1.

    Adamska A, Domenichini A, Falasca M. Pancreatic ductal adenocarcinoma: current and evolving therapies. Int J Mol Sci. 2017;18:1338.

    Article  Google Scholar 

  2. 2.

    Wajed SA, Laird PW, DeMeester TR. DNA methylation: an alternative pathway to cancer. Ann Surg. 2001;234:10–20.

    CAS  Article  Google Scholar 

  3. 3.

    Zhang J, Zhang J, Xu S, Zhang X, Wang P, Wu H, et al. Hypoxia-induced TPM2 methylation is associated with chemoresistance and poor prognosis in breast cancer. Cell Physiol Biochem. 2018;45:692–705.

    CAS  Article  Google Scholar 

  4. 4.

    Han X, Zhou Y, You Y, Lu J, Wang L, Hou H, et al. TET1 promotes cisplatin-resistance via demethylating the vimentin promoter in ovarian cancer. Cell Biol Int. 2017;41:405–14.

    CAS  Article  Google Scholar 

  5. 5.

    Kang KA, Piao MJ, Kim KC, Kang HK, Chang WY, Park IC, et al. Epigenetic modification of Nrf2 in 5-fluorouracil-resistant colon cancer cells: involvement of TET-dependent DNA demethylation. Cell Death Dis. 2014;5:e1183.

    CAS  Article  Google Scholar 

  6. 6.

    Sun M, Song CX, Huang H, Frankenberger CA, Sankarasharma D, Gomes S, et al. HMGA2/TET1/HOXA9 signaling pathway regulates breast cancer growth and metastasis. Proc Natl Acad Sci USA. 2013;110:9920–5.

    CAS  Article  Google Scholar 

  7. 7.

    Wang C, Ye H, Zhang L, Cheng Y, Xu S, Zhang P, et al. Enhanced expression of ten-eleven translocation 1 reverses gemcitabine resistance in cholangiocarcinoma accompanied by a reduction in P-glycoprotein expression. Cancer Med. 2019;8:990–1003.

    CAS  Article  Google Scholar 

  8. 8.

    Wu J, Li H, Shi M, Zhu Y, Ma Y, Zhong Y, et al. TET1-mediated DNA hydroxymethylation activates inhibitors of the Wnt/beta-catenin signaling pathway to suppress EMT in pancreatic tumor cells. J Exp Clin Cancer Res. 2019;38:348.

    Article  Google Scholar 

  9. 9.

    Zheng X, Carstens JL, Kim J, Scheible M, Kaye J, Sugimoto H, et al. Epithelial-to-mesenchymal transition is dispensable for metastasis but induces chemoresistance in pancreatic cancer. Nature. 2015;527:525–30.

    CAS  Article  Google Scholar 

  10. 10.

    Eto K, Kawakami H, Kuwatani M, Kudo T, Abe Y, Kawahata S, et al. Human equilibrative nucleoside transporter 1 and Notch3 can predict gemcitabine effects in patients with unresectable pancreatic cancer. Br J Cancer. 2013;108:1488–94.

    CAS  Article  Google Scholar 

  11. 11.

    Baharudin R, Ab Mutalib NS, Othman SN, Sagap I, Rose IM, Mohd Mokhtar N, et al. Identification of predictive DNA methylation biomarkers for chemotherapy response in colorectal cancer. Front Pharm. 2017;8:47.

    Article  Google Scholar 

  12. 12.

    Bhateja P, Cherian M, Majumder S, Ramaswamy B. The Hedgehog signaling pathway: a viable target in breast cancer? Cancers (Basel). 2019;11:1126.

    CAS  Article  Google Scholar 

  13. 13.

    Thomson JP, Ottaviano R, Unterberger EB, Lempiainen H, Muller A, Terranova R, et al. Loss of Tet1-associated 5-hydroxymethylcytosine is concomitant with aberrant promoter hypermethylation in liver cancer. Cancer Res. 2016;76:3097–108.

    CAS  Article  Google Scholar 

  14. 14.

    Fu HL, Ma Y, Lu LG, Hou P, Li BJ, Jin WL, et al. TET1 exerts its tumor suppressor function by interacting with p53-EZH2 pathway in gastric cancer. J Biomed Nanotechnol. 2014;10:1217–30.

    CAS  Article  Google Scholar 

  15. 15.

    Feng J, Wang Q, Li G, Zeng X, Kuang S, Li X, et al. TET1-mediated different transcriptional regulation in prostate cancer. Int J Clin Exp Med. 2015;8:203–11.

    CAS  PubMed  PubMed Central  Google Scholar 

  16. 16.

    Pei YF, Tao R, Li JF, Su LP, Yu BQ, Wu XY, et al. TET1 inhibits gastric cancer growth and metastasis by PTEN demethylation and re-expression. Oncotarget. 2016;7:31322–35.

    Article  Google Scholar 

  17. 17.

    Hsu CH, Peng KL, Kang ML, Chen YR, Yang YC, Tsai CH, et al. TET1 suppresses cancer invasion by activating the tissue inhibitors of metalloproteinases. Cell Rep. 2012;2:568–79.

    CAS  Article  Google Scholar 

  18. 18.

    Tang H, Jiang L, Zhu C, Liu R, Wu Y, Yan Q, et al. Loss of cell adhesion molecule L1 like promotes tumor growth and metastasis in esophageal squamous cell carcinoma. Oncogene. 2019;38:3119–33.

    CAS  Article  Google Scholar 

  19. 19.

    Ognibene M, Pagnan G, Marimpietri D, Cangelosi D, Cilli M, Benedetti MC, et al. CHL1 gene acts as a tumor suppressor in human neuroblastoma. Oncotarget. 2018;9:25903–21.

    Article  Google Scholar 

  20. 20.

    Chen J, Jiang C, Fu L, Zhu CL, Xiang YQ, Jiang LX, et al. CHL1 suppresses tumor growth and metastasis in nasopharyngeal carcinoma by repressing PI3K/AKT signaling pathway via interaction with Integrin beta1 and Merlin. Int J Biol Sci. 2019;15:1802–15.

    CAS  Article  Google Scholar 

  21. 21.

    Martin-Sanchez E, Mendaza S, Ulazia-Garmendia A, Monreal-Santesteban I, Blanco-Luquin I, Cordoba A, et al. CHL1 hypermethylation as a potential biomarker of poor prognosis in breast cancer. Oncotarget. 2017;8:15789–801.

    Article  Google Scholar 

  22. 22.

    Zhou P, Li B, Liu F, Zhang M, Wang Q, Liu Y, et al. The epithelial to mesenchymal transition (EMT) and cancer stem cells: implication for treatment resistance in pancreatic cancer. Mol Cancer. 2017;16:52.

    Article  Google Scholar 

  23. 23.

    Gaianigo N, Melisi D, Carbone C. EMT and treatment resistance in pancreatic cancer. Cancers (Basel). 2017;9:122.

  24. 24.

    Lei J, Ma J, Ma Q, Li X, Liu H, Xu Q, et al. Hedgehog signaling regulates hypoxia induced epithelial to mesenchymal transition and invasion in pancreatic cancer cells via a ligand-independent manner. Mol Cancer. 2013;12:66.

    CAS  Article  Google Scholar 

  25. 25.

    Kumar V, Chaudhary AK, Dong Y, Zhong HA, Mondal G, Lin F, et al. Design, synthesis and biological evaluation of novel Hedgehog inhibitors for treating pancreatic cancer. Sci Rep. 2017;7:1665.

    Article  Google Scholar 

  26. 26.

    Voutsadakis IA. Molecular predictors of gemcitabine response in pancreatic cancer. World J Gastrointest Oncol. 2011;3:153–64.

    Article  Google Scholar 

  27. 27.

    Infante P, Alfonsi R, Ingallina C, Quaglio D, Ghirga F, D’Acquarica I, et al. Inhibition of Hedgehog-dependent tumors and cancer stem cells by a newly identified naturally occurring chemotype. Cell Death Dis. 2016;7:e2376.

    CAS  Article  Google Scholar 

  28. 28.

    De Jesus-Acosta A, Sugar EA, O’Dwyer PJ, Ramanathan RK, Von Hoff DD, Rasheed Z, et al. Phase 2 study of vismodegib, a hedgehog inhibitor, combined with gemcitabine and nab-paclitaxel in patients with untreated metastatic pancreatic adenocarcinoma. Br J Cancer. 2019;122:498–505.

    Article  Google Scholar 

  29. 29.

    Zhang SR, Li H, Wang WQ, Jin W, Xu JZ, Xu HX, et al. Arpin downregulation is associated with poor prognosis in pancreatic ductal adenocarcinoma. Eur J Surg Oncol. 2019;45:769–75.

    Article  Google Scholar 

  30. 30.

    Li H, Zhou ZQ, Yang ZR, Tong DN, Guan J, Shi BJ, et al. MicroRNA-191 acts as a tumor promoter by modulating the TET1-p53 pathway in intrahepatic cholangiocarcinoma. Hepatology. 2017;66:136–51.

    CAS  Article  Google Scholar 

  31. 31.

    Wang Y, Zhang H, Chen Y, Sun Y, Yang F, Yu W, et al. LSD1 is a subunit of the NuRD complex and targets the metastasis programs in breast cancer. Cell. 2009;138:660–72.

    CAS  Article  Google Scholar 

  32. 32.

    Dahl JA, Collas P. A rapid micro chromatin immunoprecipitation assay (microChIP). Nat Protoc. 2008;3:1032–45.

    CAS  Article  Google Scholar 

Download references


We thank Wei Jin and Long-Yun Ye for technical assistance.


This work was supported by grants from the National Science Foundation for Distinguished Young Scholars of China [81625016]; the National Natural Science Foundation of China [81871941, 81872366, 81827807, 81802675, 81702341, and 81802380]; the Outstanding Academic Leader Program of the “Technological Innovation Action Plan” in Shanghai Science and Technology Commission [18XD1401200]; Scientific Innovation Project of Shanghai Education Committee (2019-01-07-00-07-E00057) and the Young Talented Specialist Training Program of Shanghai. The funding agencies had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Author information




H.L., W.J., X-N.L., and L-Y.Y. contributed to data acquisition and manuscript drafting; S.L., S-S X., W-H.Z., H-L.G., X.H., C-T.W., T-J.L., and W-Q.W. collected clinical data and samples and provided technical support; L.L., H-X.X., and X-J.Y. contributed to funding the research, study design, and supervision. All authors read and approved the final manuscript.

Corresponding authors

Correspondence to Xian-Jun Yu or Hua-Xiang Xu or Liang Liu.

Ethics declarations

Conflict of interest

The authors declare that they have no conflict of interest.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Li, H., Jiang, W., Liu, X. et al. TET1 downregulates epithelial-mesenchymal transition and chemoresistance in PDAC by demethylating CHL1 to inhibit the Hedgehog signaling pathway. Oncogene 39, 5825–5838 (2020). https://doi.org/10.1038/s41388-020-01407-8

Download citation