Open AccessThe hepatitis B virus X protein downregulates NF-κB signaling pathways through decreasing the Notch signaling pathway in HBx-transformed L02 cells
Author(s) -
Jing Luo,
Haiyan Zhou,
Fan Wang,
Xi Xia,
Qian Sun,
Ronghua Wang,
Bin Cheng
Publication year - 2013
Publication title -
international journal of oncology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.405
H-Index - 122
ISSN - 1019-6439
DOI - 10.3892/ijo.2013.1842
Subject(s) - hbx , notch signaling pathway , signal transduction , hes3 signaling axis , biology , cancer research , nf κb , microbiology and biotechnology , jag1 , downregulation and upregulation , hepatitis b virus , immunology , gene , virus , genetics
Hepatitis B virus X protein (HBx) is implicated in the pathogenesis of hepatocellular carcinoma, which has been found to be associated with Notch and NF-κB signaling. This study aimed to investigate the crosstalk between Notch and NF-κB pathways in HBx-related hepatocellular carcinoma. An HBx-transformed non-tumor hepatic cell line L02 (L02/HBx) was previously established. Immunofluorescence assays were performed to visualize HBx and the Notch intracellular domain (NICD) in cell nuclei. Co-immunoprecipitation assays were used to investigate physical interactions between HBx and components of the Notch signaling pathway (NICD and JAG1), NF-κB signaling pathway (p65 and p50) or IκBα. L02/HBx cells were treated with the Notch signal inhibitor DAPT or Notch1 siRNA to inhibit the Notch1 pathway. qRT-PCR was used to quantify the expression of the p65, p50 and IκBα genes. Protein expression changes in cytoplasm and nuclei after treatment with DAPT or Notch1 siRNA were analyzed by western blotting and EMSA assays. We found that HBx directly regulated Notch1 signaling, which cross-talked with the NF-κB pathway. Downregulation of Notch1 decreased the binding of NF-κB p65 to its target gene promoter, reduced NF-κB expression and enhanced IκBα expression. The results suggest that HBx functions through the Notch signaling pathway; Notch contributes to hepatocarcinogenesis partially by regulating the NF-κB pathway. Our findings provide new insights into the role of Notch and NF-κB signaling in the progression of hepatocellular carcinoma related to HBx.