1. Stimulation of B7-H1 in hepatocarcinoma cells by hepatitis B virus X antigen.
- Author
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Wu S, Yang C, Guo S, Fei L, Luo N, Fu X, Chen Y, and Wu Y
- Subjects
- Antibodies, Blocking pharmacology, Antigens, CD genetics, Antigens, CD immunology, Apoptosis drug effects, Apoptosis immunology, B7-H1 Antigen, Carcinoma, Hepatocellular pathology, Coculture Techniques, Hep G2 Cells, Humans, Microarray Analysis, NF-kappa B metabolism, Promoter Regions, Genetic immunology, Protein Binding genetics, Protein Binding immunology, T-Lymphocytes drug effects, T-Lymphocytes immunology, T-Lymphocytes pathology, Transcriptional Activation genetics, Transcriptional Activation immunology, Viral Fusion Proteins genetics, Viral Fusion Proteins immunology, Antigens, CD metabolism, Carcinoma, Hepatocellular immunology, Carcinoma, Hepatocellular virology, Hepatitis B virus immunology, T-Lymphocytes metabolism, Viral Fusion Proteins metabolism
- Abstract
The cross-talk between the hepatitis B virus X protein (HBx) and B7-H1 in hepatocarcinoma (HCC) is unclear. This study analyzed the potential relationships between HBx and B7-H1 in hepatocarcinogenesis. One of human HCC cell lines, HepG2 cells, was transfected to stably express HBx protein (HBx(+)-HepG2). The transcription of B7-H1 mRNA was increased significantly in these cells compared to cells transfected with control vector (HBx(-)-HepG2), as confirmed by a comparative genome-wide microarray analysis (Capitalbio) and real time quantitative PCR (qPCR). Flow cytometry and western-blot further demonstrated that B7-H1 protein synthesis was enhanced in HBx(+)-HepG2 cells. Site-directed mutagenesis of promoter constructs revealed that the transcription factor (NF)-κB binding site between 128 and 137 bp upstream of B7-H1 gene transcriptional start site is primarily responsible for HBx-mediated B7-H1 expression. Co-culture experiments with HBx(+)-HepG2/T cells showed that the number of apoptotic T cells increased profoundly, and this effect could be partially prevented when a neutralizing mAb against B7-H1 was added to the culture, demonstrating that B7-H1 signaling can promote T cell apoptosis. Our results suggest that the expression of B7-H1 in hepatocarcimona cells can be initiated by HBx antigen, thus inducing T cell apoptosis and finally potentially facilitates the genesis of HCC.
- Published
- 2010
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