| Aims p28GANK is a novel oncogene which overexpresses in human hepatocellular carcinoma (HCC). We investigated whether dowregulation of p28GANK by RNA interference (RNAi) in HepG2 cells induces apoptosis and the precise mechanisms Methods Apoptotic cells were analyzed using flow cytometry. Expression of Bcl-2-related proteins, p53 and mitogen-activated protein kinases (MAPKs) were investigated by Western blotting, transcriptional activity of p53 by reporter gene assay, alteration of mitochondrial transmembrane potential (Δψm) and generation of reactive oxygen species (ROS) using fluorescent probe. Results (1) p28GANK knockdown induced apoptosis in HepG2 cells which was inhibited by caspase-9 inhibitor. (2) Downregulation of p28GANK induced p38 phosphorylation, moreover, p38 inhibitor (SB203580) suppressed the apoptotic event. (3) Loss ofΔψm and release of cytochrome c were observed and inbibited by Bongkeric Acid (BA ,a potent inhibitor of mitochondrial megachannel) and SB203580 respectively. (4) Mitochondrial translocation of Bax, and mitochondrial and nuclear accumulation of p53 were observed during p28GANK knockdown-induced apoptosis. All of these events were suppressed by p38 inhibitor. (5) p28GANK knockdown increased generation of ROS which mediated p38 phosphorylation and participated in apoptosis. Conlusion The results provide a rationale for using p28GANK as a therapeutic target in HCC. |
