ABSTRACT
Hepatitis B virus X protein (HBx) is involved in the pathogenesis of hepatocellular carcinoma (HCC). Overexpression of the transcripts from the P3 and P4 promoters of the insulin-like growth factor-II (IGF-II) gene is observed in HCC. The present study investigated the involvement of HBx in IGF-II overexpression and its epigenetic regulation. Firstly, the effects of HBx on P3 and P4 mRNA expression, the methylation status of the P3 and P4 promoters, and MBD2 expression were analyzed in human HCC cells and HCC samples. Next, interaction between HBx and MBD2 or CBP/p300 was assessed by co-immunoprecipitation, and HBx-mediated binding of MBD2 and CBP/p300 to the P3 and P4 promoters and the acetylation of the corresponding histones H3 and H4 were evaluated by quantitative chromatin immunoprecipitation. Finally, using siRNA knockdown, we investigated the roles of MBD2 and CBP/p300 in IGF-II overexpression and its epigenetic regulation. Our results showed that HBx promotes IGF-II expression via inducing the hypomethylation of the P3 and P4 promoters, and that HBx increases MBD2 expression, directly interacts with MBD2 and CBP/p300, and elevates their recruitment to the hypomethylated P3 and P4 promoters with increased acetylation levels of the corresponding histones H3 and H4. Further results showed that endogenous MBD2 and CBP/p300 are necessary for HBx-induced IGF-II overexpression and that CBP/p300 presence and CBP/p300-mediated acetylation of histones H3 and H4 are partially required for MBD2 binding and its demethylase activity. These data suggest that HBx induces MBD2-HBx-CBP/p300 complex formation via interaction with MBD2 and CBP/p300, which contributes to the hypomethylation and transcriptional activation of the IGF-II-P3 and P4 promoters and that CBP/p300-mediated acetylation of histones H3 and H4 may be a rate-limiting step for the hypomethylation and activation of these two promoters. This study provides an alternative mechanism for understanding the pathogenesis of HBx-mediated HCC.
ABSTRACT
BACKGROUND: Endoscopic retrograde cholangiopancreatography with fluoroscopy guidance is a well-established technique for providing biliary drainage in patients with biliary obstructions. However, fluoroscopic facilities may not always be available and fluoroscopy carries a risk of radiation exposure. AIM: We retrospectively compared the procedure success rate and efficacy of ultrasound-guided endoscopic biliary drainage (UG-EBD) and fluoroscopy-guided endoscopic biliary drainage (FG-EBD) in patients with biliary obstructions. METHODS: Patients who had received either UG-EBD or FG-EBD were included in the study. Main outcome measurements included the procedure success rate, procedure time, and clinical response. RESULTS: A total of 125 patients who had undergone UG-EBD (n = 63) and FG-EBD (n = 62) were identified. The total procedure success rate was 93.7 % in the UG-EBD group and 96.8 % in the FG-EBD group without statistical difference. Also, no significant difference was found in the procedure success rate of lower or upper/middle obstructions of the common bile duct (CBD) between the 2 groups. The mean procedure time was not different between the 2 groups [UG-EBD group 24.54 (9.52) min vs. FG-EBD group 21.74 (8.77) min, p = 0.09]. There were no differences in the normalization of clinical and laboratory parameters and immediate complication between the 2 groups. CONCLUSIONS: Endoscopic biliary drainage (EBD) under US-guidance and under fluoroscopy guidance is equally effective and safe for patients with lower or upper/middle obstructions of the CBD. The UG-EBD technique is especially suitable for special patients, such as critically ill patients, pregnant woman, etc.
