Shiou-Hwei Yeh

Associations between hepatitis B virus genotype and mutants and the risk of hepatocellular carcinoma.

Background The risk of hepatocellular carcinoma (HCC) increases with increasing level of hepatitis B virus (HBV) in serum (viral load). However, it is unclear whether genetic characteristics of HBV, including HBV genotype and specific genetic mutations, contribute to the risk of HCC. We examined the HCC risk associated with HBV genotypes and common variants in the precore and basal core promoter (BCP) regions. Methods From January 5, 1991, to December 21, 1992, baseline blood samples were collected from 2762 Taiwanese men and women who were seropositive for HBV surface antigen but had not been diagnosed with HCC; the samples were tested for HBV viral load by real-time polymerase chain reaction and genotyped by melting curve analysis. Participants who had a baseline serum HBV DNA level greater than 104 copies/mL (n = 1526) were tested for the precore G1896A and BCP A1762T/G1764A mutants by direct sequencing. Incident cases of HCC were ascertained through follow-up examinations and computerized linkage to the National Cancer Registry and death certification profiles. A Cox proportional hazards model was used to estimate the risk of HCC associated with HBV genotype and precore and BCP mutants after adjustment for other risk factors. All statistical tests were two-sided. Results A total of 153 HCC cases occurred during 33 847 person-years of follow-up. The HCC incidence rates per 100 000 person-years for participants infected with HBV genotype B or C were 305.6 (95% confidence interval [CI] = 236.9 to 388.1) and 785.8 (95% CI = 626.8 to 972.9), respectively. Among participants with a baseline HBV DNA level of at least 104 copies/mL, HCC incidence per 100 000 person-years was higher for those with the precore G1896 (wild-type) variant than for those with the G1896A variant (955.5 [95% CI = 749.0 to 1201.4] vs 269.4 [95% CI = 172.6 to 400.9]) and for those with the BCP A1762T/G1764A double mutant than for those with BCP A1762/G1764 (wild-type) variant (1149.2 [95% CI = 872.6 to 1485.6] vs 358.7 [95% CI = 255.1 to 490.4]). The multivariable-adjusted hazard ratio of developing HCC was 1.76 (95% CI = 1.19 to 2.61) for genotype C vs genotype B, 0.34 (95% CI = 0.21 to 0.57) for precore G1896A vs wild type, and 1.73 (95% CI = 1.13 to 2.67) for BCP A1762T/G1764A vs wild type. Risk was highest among participants infected with genotype C HBV and wild type for the precore 1896 variant and mutant for the BCP 1762/1764 variant (adjusted hazard ratio = 2.99, 95% CI = 1.57 to 5.70, P < .001). Conclusions HBV genotype C and specific alleles of BCP and precore were associated with risk of HCC. These associations were independent of serum HBV DNA level.

Gender Disparity of Hepatocellular Carcinoma: The Roles of Sex Hormones

Men have a higher incidence of hepatocellular carcinoma (HCC) than women. Epidemiologic and animal studies have suggested that it might be due to the stimulatory effects of androgen and the protective effects of estrogen. Recently, increasing molecular mechanisms underlying the carcinogenic effect of both sex hormones were reported. Knockout of androgen receptor (AR) expression in hepatocytes delayed the development of N′,N′-diethylnitrosamine (DEN)-induced HCC, suggesting the active AR pathway in augmenting the HCC risk. Moreover, an intriguing interaction between the viral protein of hepatitis B virus X protein (HBx) and the androgen pathway was established. HBx can enhance the transcriptional activity of AR in a ligand concentration-dependent manner, mainly through its effects on the c-Src and GSK-3β kinase pathways. The studies from the DEN-induced HCC mouse model further provided a mechanism for the protective role of estrogen in female HCC. Estrogen can protect hepatocytes from malignant transformation via downregulation of IL-6 release from Kupffer cells, a critical process in this mouse model. Intriguingly, suppression of the ERα protein by overexpression of miR-18a, which occurs preferentially in female HCC, was identified as a novel mechanism to block the tumor-protective function of estrogen in female HCC. In conclusion, the current studies demonstrated that the gender disparity of HCC is attributed by both androgen and estrogen sex hormone pathways, with distinct roles in each gender. Therefore, the ligand and the receptor factors of both sex hormones need to be included for assessing the relative risk of HCC patients of each gender.

Rapid growth of a hepatocellular carcinoma and the driving mutations revealed by cell-population genetic analysis of whole-genome data

We present the analysis of the evolution of tumors in a case of hepatocellular carcinoma. This case is particularly informative about cancer growth dynamics and the underlying driving mutations. We sampled nine different sections from three tumors and seven more sections from the adjacent nontumor tissues. Selected sections were subjected to exon as well as whole-genome sequencing. Putative somatic mutations were then individually validated across all 9 tumor and 7 nontumor sections. Among the mutations validated, 24 were amino acid changes; in addition, 22 large indels/copy number variants (>1 Mb) were detected. These somatic mutations define four evolutionary lineages among tumor cells. Separate evolution and expansion of these lineages were recent and rapid, each apparently having only one lineage-specific protein-coding mutation. Hence, by using a cell-population genetic definition, this approach identified three coding changes (CCNG1, P62, and an indel/fusion gene) as tumor driver mutations. These three mutations, affecting cell cycle control and apoptosis, are functionally distinct from mutations that accumulated earlier, many of which are involved in inflammation/immunity or cell anchoring. These distinct functions of mutations at different stages may reflect the genetic interactions underlying tumor growth.

Hepatitis C Virus Seromarkers and Subsequent Risk of Hepatocellular Carcinoma: Long-Term Predictors From a Community-Based Cohort Study

PURPOSE Hepatitis C virus (HCV) contributes to one third of hepatocellular carcinoma cases worldwide. Long-term predictors for HCV-related hepatocellular carcinoma are essential for early intervention. Serum HCV RNA and ALT levels and HCV genotype were assessed for their predictability of hepatocellular carcinoma risk. METHODS A prospective cohort of 925 participants positive for antibodies against HCV and age 30 to 65 years was recruited and followed from 1991 to 2006. Serum HCV RNA and ALT levels and HCV genotypes at enrollment and during follow-up were examined. Newly developed hepatocellular carcinoma was identified by health examination and computerized linkage with national cancer registration and death certification profiles. Multivariate adjusted hazard ratios with 95% CIs were estimated using Cox regression models. RESULTS Fifty-five participants newly developed hepatocellular carcinoma during 8,476 person-years of follow-up, giving an incidence rate of 648.9 per 100,000 person-years. The cumulative hepatocellular carcinoma risk increased from 1.1% for HCV RNA seronegative status to 6.4% for low HCV RNA levels and to 14.7% for high HCV RNA levels (P < .001). The cumulative risk also increased with elevated serum ALT levels from 1.7% for persistently ≤ 15 U/L to 4.2% for ever more than 15 U/L but never more than 45 U/L and to 13.8% for ALT ever ≥ 45 U/L (P < .001). Having HCV genotype 1 was associated with a higher cumulative hepatocellular carcinoma risk (12.6%) than not having HCV genotype 1 (4.5%; P < .001). CONCLUSION Elevated serum levels of HCV RNA and ALT and HCV genotype 1 infection are independent risk predictors of hepatocellular carcinoma. These findings have strong implications for the management of chronic HCV.

Identification of androgen response elements in the enhancer I of hepatitis B virus: A mechanism for sex disparity in chronic hepatitis B

Hepatitis B virus (HBV)‐related hepatocellular carcinoma (HCC) occurs more often in men than in women. Male HBV carriers usually have higher viral loads, which is a well‐known risk factor for HCC. Whether and how the male androgen axis regulates HBV transcription and replication is investigated here. We used HBV transgenic mice to evaluate any sex disparity of serum hepatitis B surface antigen and HBV titers as well as the castration effect on this disparity. Compared to females, HBV transgenic male mice showed higher hepatitis B surface antigen and viral titers, which were lessened by castration of the males. In a cell culture system, HepG2 cells transfected with HBV and androgen receptor (AR) constructs were used to study the effect of the androgen pathway on viral transcription and replication. We found the ligand‐stimulated AR could increase the transcription of HBV RNAs through its transcription activation domain. A genomic region within HBV enhancer I was identified that is responsible for the transcriptional activation of AR. The results from chromatin immunoprecipitation and in vitro binding assays further demonstrated a direct binding of AR to this region, in a ligand‐dependent manner. Two androgen‐responsive element motifs in this region were identified, and their mutations can significantly abolish the AR effects. Conclusion: This study demonstrated that the androgen pathway can increase the transcription of HBV through direct binding to the androgen‐responsive element sites in viral enhancer I. This may explain a higher HBV titer in male carriers and an increased risk of HCC. (HEPATOLOGY 2009.)

Hepatitis B virus X protein enhances androgen receptor-responsive gene expression depending on androgen level

Persistent hepatitis B virus (HBV) infection is a major risk of hepatocellular carcinoma (HCC). One intriguing feature of HBV-related HCC is the male predominance, with a male to female ratio of 5–7:1. This dominance has been attributed to the elevated androgen level and the enhanced androgen receptor (AR)-mediated activity in the host. How HBV infection and AR signaling modulate HCC is unknown. We investigated whether the HBV nonstructural protein, X protein (HBx) could cooperate with the AR signaling pathway to enhance carcinogenesis. We found that HBx increased the anchorage-independent colony-formation potency of AR in a nontransformed mouse hepatocyte cell line. We also found that HBx functioned as a positive transcriptional coregulator to increase AR-mediated transcriptional activity. This transcription enhancement was increased in the presence of androgen in a concentration-responsive manner, thus explaining a more prominent effect in males. HBx did not physically associate with ligand-bound AR in the nucleus, and it likely augmented AR activity by increasing the phosphorylation of AR through HBx-mediated activation of the c-Src kinase signaling pathway. Our study documents HBx as a previously undescribed class of noncellular positive coregulators for AR. The results reveal a mechanism for the vulnerability of males to microbial infections and the subsequent development of cancer.

Influence of mutations in hepatitis B virus surface protein on viral antigenicity and phenotype in occult HBV strains from blood donors

BACKGROUND & AIMS This study aimed at investigating mutations in the hepatitis B surface protein (HBsAg) in occult hepatitis B virus (HBV) infection (OBI) and their influence on viral antigenicity and phenotype. METHODS The characteristics of 61 carriers with OBI (OBI group), 153 HBsAg(+) carriers with serum HBsAg ≤ 100 IU/ml (HBsAg-L group) and 54 carriers with serum HBsAg >100 IU/ml (HBsAg-H group) from 38,499 blood donors were investigated. Mutations in the major hydrophilic region (MHR) of the viral sequences were determined. Thirteen representative MHR mutations observed in OBI sequences were antigenically characterized with a panel of monoclonal antibodies (MAbs) and commercial HBsAg immunoassays and functionally characterized in HuH7 cells and hydrodynamically injected mice. RESULTS Of 61 OBI sequences, 34 (55.7%) harbored MHR mutations, which was significantly higher than the frequency in either the HBsAg-L (34.0%, p=0.003) or the HBsAg-H group (17.1%, p<0.001). Alterations in antigenicity induced by the 13 representative MHR mutations identified in the OBI group were assessed by reacting recombinant HBV mutants with 30 different MAbs targeting various epitopes. Four out of the 13 mutations (C124R, C124Y, K141E, and D144A) strongly decreased the analytical sensitivity of seven commercial HBsAg immunoassays, and 10 (G119R, C124Y, I126S, Q129R, S136P, C139R, T140I, K141E, D144A, and G145R) significantly impaired virion and/or S protein secretion in both HuH7 cells and mice. CONCLUSIONS MHR mutations alter antigenicity and impair virion secretion, both of which may contribute to HBsAg detection failure in individuals with OBI.

Hepatitis C Virus Infection and Increased Risk of Cerebrovascular Disease

Background and Purpose— The association between hepatitis C virus (HCV) infection and cerebrovascular disease remains controversial. This study aimed to assess the risk of lethal cerebrovascular diseases associated with chronic HCV infection. Methods— In this community-based prospective cohort study, 23 665 residents (aged 30 to 65 years) were enrolled in 1991 to 1992. They were personally interviewed using structured questionnaires and provided blood samples for various serological and biochemical tests at study entry. Serum HCV RNA level and HCV genotype were tested for participants seropositive for antibodies against HCV (anti-HCV). Deaths from cerebrovascular disease during follow-up were ascertained by computerized linkage with National Death Certification profiles from 1991 to 2008 (International Classification of Diseases, 9th Revision 430 to 438). Multivariate-adjusted hazard ratio with 95% CI was estimated for each risk predictor. Results— There were 255 cerebrovascular deaths during 382 011 person-years of follow-up. The cumulative risk of cerebrovascular deaths was 1.0% and 2.7% for seronegatives and seropositives of anti-HCV, respectively (P<0.001). The hazard ratio (95% CI) of cerebrovascular death was 2.18 (1.50 to 3.16) for anti-HCV seropositives after adjustment for several conventional risk factors of cerebrovascular disease. Compared with participants seronegative for anti-HCV as the referent, the multivariate-adjusted hazard ratio (95% CI) was 1.40 (0.62 to 3.16), 2.36 (1.42 to 3.93), and 2.82 (1.25 to 6.37), respectively, for anti-HCV-seropositive participants with undetectable, low, and high serum levels of HCV RNA (P<0.001 for trend). However, no significant association was observed between HCV genotype and cerebrovascular death. Conclusions— Chronic HCV infection is an independent risk predictor of cerebrovascular deaths showing a biological gradient of cerebrovascular mortality with increasing serum HCV RNA level.

Role of microRNAs in hepatitis B virus replication and pathogenesis.

The hepatitis B virus (HBV) is a widespread human pathogen and chronic HBV infection is a major risk factor for hepatocellular carcinoma (HCC). The role of microRNA (miRNA) in the replication and pathogenesis was reviewed. So far none of HBV-encoded miRNA has been identified. Cellular miRNAs have shown able to regulate HBV at the transcription level either by targeting to cellular transcriptions factors required for HBV gene expression, or by a directly binding to HBV transcripts. We also summarized the changed patterns of cellular miRNAs from hepatitis B progressing to cirrhosis and then liver cancer. The changing of a few of miRNAs, such as miR-122 or miR-21, were reproduced and worthy of further research by a deep sequencing and functional validation. These HBV-specific miRNAs should potentially become biomarkers for HBV infection and HBV-positive HCC diagnosis. The understanding of miRNA biology paved the way for applying miRNAs-based RNAi against HBV replication with minimal toxicities. This article is part of a Special Issue entitled: MicroRNAs in viral gene regulation.

Hepatitis B virus X protein enhances the transcriptional activity of the androgen receptor through c‐Src and glycogen synthase kinase‐3β kinase pathways

Hepatitis B virus (HBV)‐related hepatocellular carcinoma (HCC) occurs predominantly in men. By enhancing the transcriptional activity of the androgen receptor (AR) gene in a ligand‐dependent manner, the HBV X protein (HBx) might contribute to this disparity between sexes. To dissect the mechanisms underlying HBx‐enhanced AR transactivation, we investigated the effect of HBx on two critical steps in the regulation of ligand‐stimulated AR activities. One step is the dimerization of AR (through the interaction of its N‐termini and C‐termini), and the other step is the activation of the AR N‐terminal transactivation domain (NTD). HBx increased the NTD activation of the AR through c‐Src kinase. HBx also enhanced AR dimerization by inhibiting glycogen synthase kinase‐3β (GSK‐3β) activity, which acts as a negative regulator of the interaction between AR and the N‐termini and C‐termini. The HBx‐enhanced AR transactivation was abolished by blocking c‐Src and activating GSK‐3β kinases simultaneously, suggesting that these two kinases act as major switches in the activation process. The regulatory function of both kinases has been further verified in primary hepatocytes isolated from the livers of HBx transgenic male mice. Conclusion: Our study thus identified two key kinases through which HBx enhances the AR transcriptional activity. These kinases might be potential candidates for future prevention or therapy for HBV‐related HCC in men. (HEPATOLOGY 2009.)