2. Academic Validation
  3. Ubiquitination of the DNA-damage checkpoint kinase CHK1 by TRAF4 is required for CHK1 activation

Ubiquitination of the DNA-damage checkpoint kinase CHK1 by TRAF4 is required for CHK1 activation

  • J Hematol Oncol. 2020 May 1;13(1):40. doi: 10.1186/s13045-020-00869-3.
Xinfang Yu 1 2,  Wei Li 1 2 3,  Haidan Liu 4,  Qipan Deng 1 2,  Xu Wang 1 2,  Hui Hu 1 2 5,  Zijun Y Xu-Monette 6,  Wei Xiong 7,  Zhongxin Lu 5,  Ken H Young 6,  Wei Wang 8,  Yong Li 9 10
Affiliations

Affiliations

  • 1 Department of Medicine, Baylor College of Medicine, Houston, TX, USA.
  • 2 Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA.
  • 3 Department of Radiology, The Third Xiangya Hospital of Central South University, Changsha, Hunan, China.
  • 4 Clinical Center for Gene Diagnosis and Therapy, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China.
  • 5 Department of Medical Laboratory, Central Hospital of Wuhan, Wuhan, Hubei, China.
  • 6 Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
  • 7 Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, Changsha, Hunan, China.
  • 8 Department of Radiology, The Third Xiangya Hospital of Central South University, Changsha, Hunan, China. cjr.wangwei@vip.163.com.
  • 9 Department of Medicine, Baylor College of Medicine, Houston, TX, USA. Yong.Li@bcm.edu.
  • 10 Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA. Yong.Li@bcm.edu.
PMID: 32357935 DOI: 10.1186/s13045-020-00869-3
Abstract

Background: Aberrant activation of DNA damage response (DDR) is a major cause of chemoresistance in colorectal Cancer (CRC). Chk1 is upregulated in CRC and contributes to therapeutic resistance. We investigated the upstream signaling pathways governing Chk1 activation in CRC.

Methods: We identified CHK1-binding proteins by mass spectrometry analysis. We analyzed the biologic consequences of knockout or overexpression of TRAF4 using immunoblotting, immunoprecipitation, and immunofluorescence. Chk1 and TRAF4 ubiquitination was studied in vitro and in vivo. We tested the functions of TRAF4 in Chk1 phosphorylation and CRC chemoresistance by measuring cell viability and proliferation, anchorage-dependent and -independent cell growth, and mouse xenograft tumorigenesis. We analyzed human CRC specimens by immunohistochemistry.

Results: TRAF4 catalyzed the ubiquitination of Chk1 in multiple CRC cell lines. Following DNA damage, ubiquitination of Chk1 at K132 by TRAF4 is required for Chk1 phosphorylation and activation mediated by ATR. Notably, TRAF4 was highly expressed in chemotherapy-resistant CRC specimens and positively correlated with phosphorylated Chk1. Furthermore, depletion of TRAF4 impaired Chk1 activity and sensitized CRC cells to fluorouracil and other chemotherapeutic agents in vitro and in vivo.

Conclusions: These data reveal two novel steps required for Chk1 activation in which TRAF4 serves as a critical intermediary and suggest that inhibition of the ATR-TRAF4-CHK1 signaling may overcome CRC chemoresistance.

Keywords

Checkpoint kinase 1; Chemoresistance; Colorectal cancer; Tumor necrosis factor receptor-associated factor 4; Ubiquitination.

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