Effects of hepatitis B virus X protein (HBx) on cell-growth inhibition in a CCL13-HBx stable cell line.
OBJECTIVE
The known function of hepatitis B virus X protein (HBx) is to determine the fate of cells by modulating various signaling pathways. In our previous study, we demonstrated that HBx inhibits tumor formation in nude mice injected with CCL13-HBx stable cell lines; however, the mechanism underlying this inhibition is unclear.


METHODS
To investigate the possible mechanisms underlying HBx involvement in CCL13-HBx cells, gene profiles were initially analyzed by DNA microarray technology and subsequently confirmed by performing semiquantitative RT-PCR and Western blotting. Furthermore, the phenomenon of cell death via apoptosis was detected via DNA fragmentation, TUNEL staining, caspase-3 activity assay, and propidium iodide (PI) staining.


RESULTS
The results indicated that HBx induction downregulated Wnt-3 and beta-catenin that are involved in cell proliferation. Moreover, HBx induction repressed cell growth and downregulated the expressions of cyclin D1, CDK4, cyclin E, CDK2, and cyclin B1. Furthermore, HBx induction triggered cell death via apoptosis, as determined by DNA fragmentation, TUNEL staining, caspase-3 activity assay, and PI staining.


CONCLUSIONS
Most importantly, our results indicated that HBx induction in the CCL13-HBx stable cell line downregulated Wnt-3/beta-catenin expression and suppressed cell growth by repressing cell proliferation or triggering cell apoptosis.
Kuo
Chan-Yen
CY
Department of Life Science, Tunghai University, Taichung, Taiwan.
Wang
Jing-Chyi
JC
Wu
Cheng-Chung
CC
Hsu
Shih-Lan
SL
Hwang
Guang-Yuh
GY
D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D048708:Cell Growth Processes; D002460:Cell Line; D002470:Cell Survival; D016213:Cyclins / Q000096:biosynthesis; D053938:DNA Fragmentation; D015536:Down-Regulation; D020869:Gene Expression Profiling; D006515:Hepatitis B virus / Q000502:physiology*; D022781:Hepatocytes / Q000821:virology*; D006801:Humans; D020287:In Situ Nick-End Labeling; D020411:Oligonucleotide Array Sequence Analysis; D011419:Propidium / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000502:physiology*; D054334:Viral Regulatory and Accessory Proteins; D051153:Wnt Proteins / Q000096:biosynthesis; D060508:Wnt3 Protein; D051176:beta Catenin / Q000096:biosynthesis
D016213:Cyclins; D015534:Trans-Activators; D054334:Viral Regulatory and Accessory Proteins; C555507:WNT3 protein, human; D051153:Wnt Proteins; D060508:Wnt3 Protein; C555508:Wnt3 protein, mouse; D051176:beta Catenin; C057628:hepatitis B virus X protein; D011419:Propidium; D053148:Caspase 3