Metastatic tumor antigen 1 contributes to hepatocarcinogenesis posttranscriptionally through RNA-binding function.

BACKGROUND AND AIMS: Both nuclear and cytoplasmic overexpression of metastatic tumor antigen 1 (MTA1) contributes to tumorigenesis of HCC. Most studies have focused on nuclear MTA1 whose function is mainly a chromatin modifier regulating the expression of various cancer-promoting genes. By contrast, the molecular mechanisms of cytoplasmic MTA1 in carcinogenesis remain elusive. Here, we reveal a role of MTA1 in posttranscriptional gene regulation. APPROACH AND RESULTS: We conducted the in vitro and in vivo RNA-protein interaction assays indicating that MTA1 could bind directly to the 3'-untranslated region of MYC RNA. Mutation at the first glycine of the conserved GXXG loop within a K-homology II domain-like structure in MTA1 (G78D) resulted in the loss of RNA-binding activity. We used gain- and loss-of-function strategy showing that MTA1, but not the G78D mutant, extended the half-life of MYC and protected it from the lethal -7-mediated degradation. The G78D mutant exhibited lower activity in promoting tumorigenesis than wild-type in vitro and in vivo. Furthermore, RNA-immunoprecipitation sequencing analysis demonstrated that MTA1 binds various oncogenesis-related mRNAs besides MYC . The clinical relevance of cytoplasmic MTA1 and its interaction with MYC were investigated using HBV-HCC cohorts with or without early recurrence. The results showed that higher cytoplasmic MTA1 level and MTA1- MYC interaction were associated with early recurrence. CONCLUSIONS: MTA1 is a generic RNA-binding protein. Cytoplasmic MTA1 and its binding to MYC is associated with early recurrence in patients with HBV-HCC. This function enables it to regulate gene expression posttranscriptionally and contributes to hepatocarcinogenesis.

Expression of Metastatic Tumor Antigen 1 Splice Variant Correlates With Early Recurrence and Aggressive Features of Hepatitis B Virus-Associated Hepatocellular Carcinoma.

Overexpression of metastatic tumor antigen 1 (MTA1) was correlated with poor prognosis of hepatitis B virus (HBV)-associated hepatocellular carcinoma (HBV-HCC). The aim of this study was to examine the clinical significance of the expression of MTA1 and its exon 4-excluded form (MTA1dE4), the most abundant spliced variant of MTA1, in patients receiving curative resection for HBV-HCC. We collected 102 patients with HBV-HCC and received curative resection retrospectively and examined the expressions level of total MTA1/MTA1dE4 in their paired nontumor and tumor liver tissues by using RT-qPCR. The association between MTA1/MTA1dE4 expression and various tumor features as well as tumor recurrence was analyzed. During the median follow-up period of 4 years, 25 patients (24.5%) showed early recurrence (within 12 months postresection) and 42 (54.5%) showed late recurrence. In Kaplan-Meier analysis, MTA1dE4 overexpression in tumor, but not MTA1, was associated with early recurrence (P = 0.0365), but not late recurrence. In multivariate analysis, only alpha-fetoprotein (AFP) ≥200 ng/mL (P = 0.006) and large tumor size (P = 0.027) were correlated with early recurrence. In the subgroup of patients with AFP <200 ng/mL, high MTA1dE4, but not total MTA1, expression could help predict early recurrence (P = 0.0195). In vitro, wound healing and invasion assays were performed in HCC cells, and MTA1dE4 was found to exhibit a higher ability in promoting migration and invasion of hepatoma cells than full-length MTA1. Conclusion: MTA1dE4 expression is correlated with more aggressive tumor characteristics and might serve as a more sensitive marker for early recurrence of HBV-HCC, especially for low-AFP patients.

Sorafenib and its derivative SC-1 exhibit antifibrotic effects through signal transducer and activator of transcription 3 inhibition.

Signal transducer and activator of transcription 3 (STAT3) had been involved in liver fibrogenesis. We aimed to explore the antifibrotic activities of sorafenib and its derivative SC-1 (devoid of Raf kinase inhibition activity) both in vivo and in vitro with special focus on the STAT3 pathway in hepatic stellate cells (HSCs). The clinical role of STAT3 in chronic hepatitis B (CHB) was also investigated. Experimental fibrosis mouse models were established by thioacetamide injection and bile duct ligation in Balb/C mice and treated with sorafenib and SC-1. Rat and human HSCs were used for mechanistic investigations. Forty CHB patients were enrolled to quantify the hepatic phospho-STAT3 (p-STAT3) levels and correlated with liver fibrosis. Both sorafenib and SC-1 ameliorated liver fibrosis in vivo and promoted HSC apoptosis in vitro. p-STAT3 and downstream signals were down-regulated after sorafenib and SC-1 treatment in HSC. STAT3 overexpression in HSC enhanced cell proliferation and undermined the apoptotic effects of sorafenib and SC-1, whereas STAT3-specific inhibition promoted HSC apoptosis. Sorafenib and SC-1 activated Src-homology protein tyrosine phosphatase-1 (SHP-1) and STAT3 inhibition followed. Of particular interest, in CHB patients with advanced liver fibrosis, p-STAT3 in HSC was significantly overexpressed and positively correlated with the severity of liver fibrosis and plasma IL-6 levels. In conclusion, sorafenib and SC-1 ameliorate liver fibrosis through STAT3 inhibition in HSC and STAT3 may potentially serve as a promising fibrotic biomarker and target in liver fibrosis. SHP-1 phosphatase-directed STAT3 inhibition may represent a previously unidentified strategy for antifibrotic drug discovery.

Micro-evolution of the hepatitis B virus genome in hepatitis B e-antigen-positive carriers: comparison of genotypes B and C at various immune stages.

BACKGROUND AND AIM: Patients with hepatitis B virus (HBV) genotype B infection experience hepatitis B e-antigen (HBeAg) seroconversion at an earlier stage than do patients with genotype C infection. Therefore, this study investigated whether the differential phenotypes are related to HBV genomic evolution. METHODS: Thirty-three HBeAg-positive patients with a mean follow-up of 3.1 years were enrolled: 16 at the immune tolerance stage (group I) and 17 at the immune clearance stage (group II). The evolution rates of paired viral genomes at enrollment and at the final follow-up in the full-length genome (µf), nonoverlapping regions (synonymous [µs] and nonsynonymous [µa]), and overlapping regions (µ) were calculated. The evolution rates were then compared according to serum alanine aminotransferase (ALT) levels and HBV genotype. RESULTS: The overall µf evolution rate was lower in group I than in group II (1.4 × 10(-5) ± 3.3 × 10(-5) vs 1.2 × 10(-3) ± 1.2 × 10(-3) nucleotide substitution/site/year, P < 0.001). We observed similar results for the µs, µa, and µ evolution rates. All evolution parameters were comparable between genotypes B and C. We determined a positive correlation between µa/y and the area under the average ALT time curve in genotype B (R(2) = 0.6935, P < 0.0001), but not in genotype C (R(2) = 0.1606, P = 0.124). CONCLUSION: The evolution rate of the HBV genome is higher at the immune clearance stage than at the immune tolerance stage. Host immune selection might play a role in triggering evolution of genotype B.

Clinical and virological features of occult hepatitis B in patients with HBsAg seroclearance post-treatment or spontaneously.

BACKGROUND: Occult hepatitis B virus (HBV) infection (OHB) may exist in patients experiencing hepatitis B surface antigen (HBsAg) seroclearance. AIMS: We examined the clinical and virological features of OHB in patients who lost HBsAg post-treatment or spontaneously. METHODS: We collected 44 patients with HBsAg seroclearance: 15 patients with dual HBV/hepatitis C virus (HCV) infection who lost HBsAg after peginterferon alfa-2a (PEG-IFN) plus ribavirin therapy; 13 HBV mono-infected patients who lost HBsAg after various oral antiviral therapies; and 16 patients who lost HBsAg spontaneously. OHB was defined as detectable serum HBV DNA in the absence of HBsAg. Viral mutations associated with OHB were identified by comparison with matched controls that remained positive for HBsAg, and further characterized in vitro. RESULTS: The prevalence of OHB was 34.1% (15/44) in all patients, which was not significantly different among three groups. One mutation in surface promoter/polymerase region, C3050T (preS1T68I), was identified to be associated with the seroclearance of HBsAg in six cases. This mutation does not change the amino acid sequence of the polymerase protein. The S promoter activity was significantly lower in the construct containing C3050T mutation as compared with the wild-type (P = 0.0008). However, this mutation did not affect HBV replication, transcription and translation in the context of the full-length HBV genome. OHB was not rare in patients with HBsAg seroclearance. CONCLUSIONS: One mutation, C3050T (preS1T68I), decreased S promoter activity; nevertheless, other factors may play more important role in the clearance of HBsAg in these OHB patients.

Combined viral quasispecies diversity and hepatitis B core-related antigen predict off-nucleos(t)ide analog durability in HBeAg-negative patients.

BACKGROUND: Viral quasispecies dynamics between pre- and post-nucleos(t)ide analog (NA) therapy remains unclear. AIM: This study aimed to investigate the HBV quasispecies evolution and its relationship with durability of off-therapy responses in HBeAg-negative chronic hepatitis B (CHB) patients who stopped NA therapy. METHODS: Fifty-four HBeAg-negative CHB patients who stopped NAs, including 19 virological controllers (VC) who maintained serum HBV DNA < 2000 IU/mL beyond 1-year off-therapy, and 35 virological relapsers (VR) experiencing virological relapse within 1-year off-therapy were recruited. Viral quasispecies was analyzed by deep sequencing. Hepatitis B core-related antigen (HBcrAg) and HBsAg were also measured. RESULTS: VC had significantly higher baseline viral quasispecies diversity of the precore/core gene, measured by nucleotide diversity, than VR. Low baseline viral nucleotide diversity (< 0.01) and high HBcrAg (≧ 2.0 KU/mL), but not HBsAg, at end of treatment (EOT) were significantly associated with higher risk of 1-year virological relapse (hazard ratio [HR] 6.09 and 3.31, respectively). Combination of low baseline viral nucleotide diversity and high HBcrAg at EOT could identify patients at high risk (HR 15.82). Further analysis of the evolution of HBV whole genome showed that HBV nucleotide diversity negatively correlated with serum HBV DNA levels. Notably, the viral quasispecies diversity between pre- and post-NA treatment remained relatively unchanged. CONCLUSION: Higher baseline HBV quasispecies diversity associates with more durable off-therapy viral suppression in HBeAg-negative CHB patients. Combination of baseline viral nucleotide diversity and HBcrAg at EOT can identify patients at high risk for virological relapse after stopping NAs.

Whole genome deep sequencing analysis of viral quasispecies diversity and evolution in HBeAg seroconverters.

BACKGROUND & AIMS: We aimed to investigate how viral quasispecies of the HBV whole genome evolves and diversifies in response to HBeAg seroconversion and viral control utilising next-generation sequencing (NGS). METHODS: Fifty HBeAg-positive chronic hepatitis B patients, including 18 treatment-naïve and 32 interferon (IFN)-treated individuals, were recruited. Serial HBV whole genomes in serum were analysed by NGS to determine sequence characteristics and viral quasispecies. RESULTS: HBV quasispecies diversity, measured by nucleotide diversity, was negatively correlated with viral load and hepatitis activity. Spontaneous HBeAg seroconverters exhibited significantly greater viral quasispecies diversity than treatment-naïve non-seroconverters from >1 year before seroconversion (0.0112 vs. 0.0060, p <0.01) to >1 year after seroconversion (0.0103 vs. 0.0068, p <0.01). IFN-induced HBeAg seroconverters tended to have higher viral genetic diversity than non-seroconverters along with treatment. Particularly, the IFN responders, defined as IFN-induced HBeAg seroconversion with low viraemia, exhibited significantly greater genetic diversity of whole HBV genome at 6 months post-IFN treatment than IFN non-responders (0.0148 vs. 0.0106, p = 0.048). Moreover, spontaneous HBeAg seroconverters and IFN responders exhibited significantly higher evolutionary rates and more intra-host single-nucleotide variants. Interestingly, in spontaneous HBeAg seroconverters and IFN responders, there were distinct evolutionary patterns in the HBV genome. CONCLUSIONS: Higher HBV quasispecies diversity is associated with spontaneous HBeAg seroconversion and IFN-induced HBeAg seroconversion with low viraemia, conferring a favourable clinical outcome. LAY SUMMARY: HBeAg seroconversion is a landmark in the natural history of chronic HBV infection. Using next-generation sequencing, we found that the nucleotide diversity of HBV was negatively correlated with viral load and hepatitis activity. Patients undergoing HBeAg seroconversion had more diverse HBV genomes and a faster viral evolution rate. Our findings suggest HBeAg seroconversion is driven by host selection pressure, likely immune selection pressure.

Characterization of metastatic tumor antigen 1 and its interaction with hepatitis B virus X protein in NF-κB signaling and tumor progression in a woodchuck hepatocellular carcinoma model.

The metastatic tumor antigen 1 (MTA1) protein is associated with tumor invasiveness and poor prognosis in patients with hepatocellular carcinoma (HCC), particularly in those with hepatitis B virus (HBV)-related HCC. Chronically woodchuck hepatitis virus (WHV)-infected woodchuck is an ideal animal model for studying the pathogenesis of HBV-associated liver diseases, including HCC. To investigate the roles of MTA1 in HBV-associated hepatocarcinogenesis in the woodchuck model, we cloned the woodchuck MTA1 (wk-MTA1) complementary (c)DNA and characterized its molecular functions. The sequence and organization of the wk-MTA1 protein were highly conserved among different species. Similar to its expression in human HCC, wk-MTA1 was upregulated in woodchuck HCC, as determined at RNA and protein levels. Furthermore, an MTA1-spliced variant, wk-MTA1dE4, was overexpressed in woodchuck HCC, and it was attributed to approximately 50% of the total transcripts. The percentage of wk-MTA1dE4-overexpressed woodchuck HCCs was higher than that of the total wk-MTA1-overexpressed HCCs (77.8% vs 61.1%) and wk-MTA1dE4 may represent a more sensitive marker than the total wk-MTA1 in woodchuck HCC. We overexpressed or knocked down wk-MTA1 in a woodchuck HCC cell line and demonstrated that wk-MTA1 could interact with the WHV X protein (WHx) and play indispensable roles in WHx-mediated NF-κB activation and tumor cell migration- and invasion-promoting activities. In conclusion, our results support the hypothesis that woodchuck HCC recapitulates HBV-associated HCC with respect to the molecular characteristics of MTA1 and provides new clues for conducting mechanistic studies of MTA1 in HBV-associated hepatocarcinogenesis, including the possible clinical significance of wk-MTA1dE4.

Clinical significance of circulating miR-122 in patients with dual chronic hepatitis B and C virus infection.

BACKGROUND: The clinical significance of serum microRNA-122 (miR-122) has been shown in viral hepatitis B and C, respectively. Specifically, miR-122 stimulates hepatitis C virus (HCV) replication but suppresses hepatitis B virus (HBV) replication. The profile and clinical significance of serum miR-122 in patients with dual chronic hepatitis B and C would be an interesting and important clinical issue. METHODS: A total of 76 patients with HBV/HCV dual infection, 105 with HCV monoinfection and 39 with HBV monoinfection were enrolled. All patients received peginterferon alfa-2a (PEG-IFN)-based treatment. Serum miR-122 levels were quantified by using a sensitive hybridization-based assay. RESULTS: At baseline, the serum miR-122 level was lower in HCV-monoinfected patients than in HBV-monoinfected patients, whereas HBV coinfection increased the expression of miR-122. In multivariate analysis, the serum miR-122 level was positively correlated with the serum HBsAg level in patients with HBV/HCV dual infection and those with HBV monoinfection. In dually infected patients who received PEG-IFN-based treatment, a high baseline miR-122 level was positively correlated with a greater reduction of the posttreatment serum HBsAg level. CONCLUSION: In summary, the serum miR-122 level is highly correlated with the HBsAg level in HBV/HCV dually infected patients and may serve as a biomarker to predict posttreatment HBsAg decline.

Clinical significance and evolution of hepatic HBsAg expression in HBeAg-positive patients receiving interferon therapy.

BACKGROUND: Serum hepatitis B surface antigen (HBsAg) level is important in the management of chronic hepatitis B (CHB). However, it is unclear whether serum HBsAg reflects its expression in liver and the hepatic HBsAg evolution following interferon therapy. METHODS: Forty-five HBeAg-positive CHB patients receiving interferon-based therapy within a randomized, controlled, multicenter study during 1998-1999 were included. The hepatic HBsAg expressions were categorized into cytoplasmic, inclusion, marginal and negative patterns by immunohistochemical staining. The HBsAg-positive hepatocytes were quantified by image-based cytometry and correlated to HBV serological and virological profiles for clinical implications. The evolution of hepatic HBsAg levels was analyzed among 22 patients with paired liver biopsies before and after interferon therapy, sequentially. RESULTS: There was a positive correlation between pretreatment serum HBsAg and hepatic HBsAg levels (r = 0.67, P < 0.0001). The hepatic HBsAg expression pattern significantly evolved from cytoplasmic/inclusion pattern to marginal/negative pattern after interferon treatment. The serum HBV-DNA, HBsAg and hepatic HBsAg levels all decreased significantly after interferon therapy. Among 36 % patients with HBeAg loss after therapy, pretreatment hepatic HBsAg levels were significantly lower compared with those without HBeAg loss. After multivariate analysis, low pretreatment hepatic HBsAg levels rather than serum HBsAg titers were associated with a higher rate of HBeAg loss (OR: 4.97, 95 % CI: 1.12-22.00, P = 0.035). CONCLUSIONS: The serum HBsAg level positively reflects the HBsAg level in liver which evolves significantly after interferon therapy. A lower hepatic HBsAg level is associated with HBeAg loss after interferon treatment. Hepatic HBsAg may have clinical significance in CHB patients receiving interferon treatment.

Host genetic factors affecting spontaneous HBsAg seroclearance in chronic hepatitis B patients.

Spontaneous clearance of hepatitis B surface antigen (HBsAg) in chronic hepatitis B (CHB) patients usually indicates a remission of hepatitis activity and a favorable outcome. Two single nucleotide polymorphisms (SNP), rs3077 near HLA-DPA1 region and rs9277535 near HLA-DPB1 region, have been shown to be associated with HBV persistence after acute HBV infection. However, little is known about the impact of these 2 SNPs on spontaneous HBsAg clearance in CHB patients. In this case-control study, a total of 100 male HBeAg-negative chronic HBV carriers who cleared HBsAg spontaneously (case group) and 100 age-matched HBeAg-negative male patients with persistent HBsAg positivity (control group) were enrolled. We investigated the relationship between these 2 SNPs and HBsAg clearance. There was a higher frequency of rs9277535 non-GG genotype in the case group (57% vs. 42%). Patients with rs9277535 non-GG genotype had a higher chance to clear HBsAg [Odds ratio (OR): 1.83, 95% confidence interval (CI): 1.04∼3.21, P = 0.034]. Compared to GG haplotype of rs3077 and rs9277535, GA haplotype had a higher chance of achieving spontaneous HBsAg loss (OR: 2.17, 95% CI: 1.14∼4.16, P = 0.030). In conclusion, rs9277535 non-GG genotype is associated with a higher likelihood of spontaneous HBsAg seroclearance in CHB patients.

Hepatitis B virus basal core promoter mutation and DNA load correlate with expression of hepatitis B core antigen in patients with chronic hepatitis B.

BACKGROUND: Expression of intrahepatic hepatitis B core antigen (HBcAg) is related to the immunopathogenesis of hepatitis B virus (HBV) infection. This study investigated the role that HBV genotype and basal core promoter (BCP) mutation play in the expression of HBcAg. METHODS: A total of 70 hepatitis B e antigen (HBeAg)-positive patients with chronic hepatitis (genotype B in 52 patients and genotype C in 18 patients; BCP mutation T1762/A1764 in 16 patients) were enrolled. Clinical, virologic, and histologic features were compared with regard to localization and expression of intrahepatic HBcAg. The effects that HBV genotype and BCP mutation T1762/A1764 had on expression of HBcAg were further evaluated by in vitro assays. RESULTS: Cytoplasmic, mixed cytoplasmic/nuclear, and nuclear localization of intrahepatic HBcAg was found in 38 (56.7%), 25 (37.3%), and 4 (6.0%) patients, respectively; HBcAg was not discernible in 3 patients. A total of 58 (82.9%) of these patients expressed a high level of HBcAg. In multivariate analysis, cytoplasmic localization of HBcAg correlated only with a low HBV load in serum (P = .045) and BCP mutation (P = .04). A high expression level of HBcAg also correlated with a high HBV load in serum (P = .015) and with BCP wild-type sequence (P = .037). In vitro assays indicated that the HBV BCP mutant strain had lower subcellular expression of HBcAg than did the BCP wild-type strain. CONCLUSIONS: HBV BCP mutation and HBV load, but not genotype, contribute to the expression of intrahepatic HBcAg.