Involvement of hepatitis B X-interacting protein (HBXIP) in proliferation regulation of cells

Abstract

Aim: To investigat the effect of Hepatitis B X-interacting protein (HBXIP) on cell proliferation. Methods: A rabbit antibody against HBXIP was generated. The RNA interference (RNAi) fragment of the HBXIP gene was constructed in the pSilencer-3.0-H1 vector termed pSilencer-hbxip. Plasmids of the pcDNA3-hbxip encoding HBXIP gene and pSilencer-hbxip were transfected into human breast carcinoma MCF-7 cells, hepatoma H7402 cells, and the normal human hepatic cell line L-O2, respectively. 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay and 5-bromo-2-deoxyuridine incorporation assay were applied to detect cell proliferation. MCF-7 cells and L-O2 cells in the cell cycle were examined by flow cytometry. The proteins involved in cell proliferation and cell cycle were investigated by Western blot. Results: Overexpression of HBXIP resulted in the promotion of proliferation of MCF-7, H7402, and L-O2 cells. Flow cytometry showed that the overexpression of HBXIP promoted the cell proliferation of MCF-7 and L-O2 cells, and led to an increased cell proliferative index in MCF-7 cells (from 46.25% to 58.28%) and L-O2 cells (from 29.62% to 35.54%). Western blot showed that expression levels of c-Myc, Bcl-2, and proliferating cell nuclear antigen were upregulated in MCF-7, H7402, or L-O2 cells, whereas that of p27 was downregulated. However, the RNAi of HBXIP brought opposite results. Conclusion: One of the functions of HBXIP is its involvement in cell proliferation.

The Nuclear Import of Oncoprotein Hepatitis B X-interacting Protein Depends on Interacting with c-Fos and Phosphorylation of Both Proteins in Breast Cancer Cells

“…We previously demonstrated that HBXIP was a novel important oncoprotein in the development of cancer. HBXIP was overexpressed in clinical breast cancer tissues and could promote proliferation and migration through NF-B, MAPK/ERK, or PI3K/AKT pathways in breast cancer cells (6,7). Recently, we have discovered that HBXIP acts as a novel oncogenic coactivator of transcription factors, such as STAT4, SP1, E2F1, and TFIID to transactivate S100A4, LMO4, Skp2, and Lin28B in promotion of growth and migration of breast cancer cells (8 -11).…”

Hepatitis B virus X protein promotes liver cell proliferation via a positive cascade loop involving arachidonic acid metabolism and p-ERK1/2

“…The stained cells were passed through a nylon-mesh sieve to remove cell clumps and were then analyzed by a FACScan flow cytometer (Becton Dickinson, San Jose, CA, USA); the results were analyzed using CellQuest software (Becton Dickinson). The cell PI was calculated as the sum of the S and G2/ M phase cells, expressed as a fraction of the total cell population (PI=((S+G2/M)/(G0/G1+S+G2/M))×100) [53]. The flow cytometry experiment was repeated three times.…”

Transformation of human liver L-O2 cells mediated by stable HBx transfection

“…The data showed that L-O2-X cells grew faster than controls. The proliferation index (PI) is the sum of the S and G 2 /M phase activities of the cell cycle expressed as a fraction of the total cell population, that is PI=[(S+G 2 /M)/(G 0 / G 1 +S+G 2 /M)] ×100% [30] . A high PI value corresponds with fast cell proliferation.…”

“…The following luciferase reporters were used: pGL3-Survivin, pGL3-NF-κB, pGL3-hTERT, and pGL3-AP-1, pGL3-basic, pGL3-control and the Renilla Luciferase Reporter Vector pRL-TK vector. Cells were harvested after 48 h and lysed in 1×passive lysis buffer according to the manufacturer's protocol [30] . The luciferase activity was determined and normalized to a cotransfected control reporter by using the Dual-Luciferase Reporter® Assay System (Promega, USA) on a Luminometer (TD-20/20, Turner Desings) according to the manufacturer's instructions.…”