SUMOylated CPAP is required for IKK-mediated NF-κB activation and enhances HBx-induced NF-κB signaling in HCC

Shu Ting Yang, Chia Jui Yen, Chien Hsien Lai, Yih Jyh Lin, Kung Chao Chang, Jenq Chang Lee, Yao Wen Liu, Pey Yi Chang-Liao, Lu Shin Hsu, Wen Chang Chang, Wen Chun Hung, Tang K. Tang, Yi Wen Liu, Liang Yi Hung

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)


Background & Aims: Constitutive activation of NF-κB is an important event involved in chronic inflammation in hepatocellular carcinoma (HCC). CPAP, which plays important roles in centrosomal functions, was previously identified as the transcriptional co-activator of NF-κB. However, the molecular mechanism is unclear. The goal of this study was to investigate the role of CPAP in activating the NF-κB pathway in HCC. Methods: SK-Hep1, HuH7, HepG2, HepG2X, Hep3B, and Hep3BX cells with CPAP overexpression or CPAP siRNA were used to evaluate activation of NF-κB under TNF-α stimulation by reporter assay, RT-PCR, Q-PCR, and Western blot analysis. In vivo SUMO modification of CPAP was demonstrated by an in situ PLA assay. Human HCC tissues were used to perform Q-PCR, Western blot, and IHC. Results: CPAP siRNA abolished the interaction between IKKβ and NF-κB, whereas overexpression of CPAP enhanced this interaction and finally led to augmented NF-κB activation by increasing the phosphorylation of NF-κB. CPAP could enter nuclei by associating with NF-κB. Furthermore, CPAP was SUMO-1 modified upon TNF-α stimulus, and this is essential for its NF-κB co-activator activity. SUMO-1-deficient CPAP mutant lost its NF-κB co-activator activity and failed to enter nuclei. Importantly, SUMOylated CPAP could synergistically increase the HBx-induced NF-κB activity. Conclusions: CPAP is essential for the recruitment of the IKK complex to inactivated NF-κB upon TNF-α treatment. Expression of CPAP was positively correlated with a poor prognosis in HBV-HCC. CPAP has the potential to serve as a therapeutic target for inflammation and inflammation-related diseases.

Original languageEnglish
Pages (from-to)1157-1164
Number of pages8
JournalJournal of Hepatology
Issue number6
Publication statusPublished - Jun 2013


  • CPAP
  • HBx
  • HCC
  • IKK
  • NF-kB
  • SUMOylation
  • TNF-alpha

ASJC Scopus subject areas

  • Hepatology
  • Medicine(all)


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