Tomonori Matsumoto

Adalimumab-induced lethal hepatitis B virus reactivation in an HBsAg-negative patient with clinically resolved hepatitis B virus infection

cholestatic liver diseases such as PBC and PSC, failure to recognize the presence of concomitant thyroid disease may lead to a misdiagnosis of deterioration of the underlying liver disease or lack of response to therapy, with potential negative impact on recommendations for treatment of the underlying liver disease and timing for liver transplantation. Furthermore, cholestatic liver diseases are frequently associated with fatigue, metabolic bone disease and hyperlipidaemia, which can be exacerbated in patients with untreated thyroid diseases, resulting in impaired quality of life. Clinicians should, therefore, recognize the association of thyroid diseases with autoimmune liver diseases and offer symptomatic care for the thyroid process (3). Finally, although the association is not well understood and has not been evaluated in autoimmune liver diseases, recent studies have suggested higher prevalence of hypothyroidism in patients with hepatocellular carcinoma (4, 5), underscoring the clinical importance of concurrent thyroid disease in patients with liver diseases. Therefore, though the mechanisms by which thyroid diseases and autoimmune liver diseases are associated are not well understood, clinicians caring for these patients should be aware of the existing association and its potential impact in the clinical management of the patient. Marina G. Silveira and Keith D. Lindor Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, USA

Expression of APOBEC2 is transcriptionally regulated by NF-κB in human hepatocytes

Apolipoprotein B mRNA‐editing enzyme catalytic subunit 2 (APOBEC2) is a member of the nucleic‐acid‐editing enzymes. However, the physiological function of APOBEC2 remains unclear. We demonstrate that APOBEC2 expression is strongly enhanced in response to both tumour necrosis factor‐α (TNF‐α) and interleukin‐1β. Inhibition of NF‐κB activation invariably blocks TNF‐α‐induced APOBEC2 expression. The promoter region of APOBEC2 contains functional NF‐κB response elements in the 5′ untranslated region of the gene at −625/−616. These results show that APOBEC2 expression is regulated by pro‐inflammatory cytokines via NF‐κB activation and suggest a possible role of APOBEC2 in the pathophysiology of hepatic inflammation.

Excessive activity of apolipoprotein B mRNA editing enzyme catalytic polypeptide 2 (APOBEC2) contributes to liver and lung tumorigenesis

Apolipoprotein B mRNA editing enzyme catalytic polypeptide 2 (APOBEC2) was originally identified as a member of the cytidine deaminase family with putative nucleotide editing activity. To clarify the physiologic and pathologic roles, and the target nucleotide of APOBEC2, we established an APOBEC2 transgenic mouse model and investigated whether APOBEC2 expression causes nucleotide alterations in host DNA or RNA sequences. Sequence analyses revealed that constitutive expression of APOBEC2 in the liver resulted in significantly high frequencies of nucleotide alterations in the transcripts of eukaryotic translation initiation factor 4 gamma 2 (Eif4g2) and phosphatase and tensin homolog (PTEN) genes. Hepatocellular carcinoma developed in 2 of 20 APOBEC2 transgenic mice at 72 weeks of age. In addition, constitutive APOBEC2 expression caused lung tumors in 7 of 20 transgenic mice analyzed. Together with the fact that the proinflammatory cytokine tumor necrosis factor‐α induces ectopic expression of APOBEC2 in hepatocytes, our findings indicate that aberrant APOBEC2 expression causes nucleotide alterations in the transcripts of the specific target gene and could be involved in the development of human hepatocellular carcinoma through hepatic inflammation.

Hepatic inflammation facilitates transcription-associated mutagenesis via AID activity and enhances liver tumorigenesis.

Chronic inflammation triggers the aberrant expression of a DNA mutator enzyme, activation-induced cytidine deaminase (AID), and contributes to tumorigenesis through the accumulation of genetic aberrations. To gain further insight into the inflammation-mediated genotoxic events required for carcinogenesis, we examined the role of chronic inflammation in the emergence of genetic aberrations in the liver with constitutive AID expression. Treatment with thioacetamide (TAA) at low-dose concentrations caused minimal hepatic inflammation in both wild-type (WT) and AID transgenic (Tg) mice. None of the WT mice with low-dose TAA administration or AID Tg mice without hepatic inflammation developed cancers in their liver tissues over the 6 month study period. In contrast, all the AID Tg mice with TAA treatment developed multiple macroscopic hepatocellular carcinomas during the same observation period. Whole exome sequencing and additional deep-sequencing analyses revealed the enhanced accumulation of somatic mutations in various genes, including dual specificity phosphatase 6 (Dusp6), early growth response 1 (Egr1) and inhibitor of DNA binding 2 (Id2), which are putative tumor suppressors, in AID-expressing liver with TAA-mediated hepatic inflammation. Microarray and quantitative reverse transcription-polymerase chain reaction analyses showed the transcriptional upregulation of various genes including Dusp6, Egr1 and Id2 under hepatic inflammatory conditions. Together, these findings suggest that inflammation-mediated transcriptional upregulation of target genes, including putative tumor suppressor genes, enhances the opportunity for inflamed cells to acquire somatic mutations and contributes to the acceleration of tumorigenesis in the inflamed liver tissues.

MSH2 dysregulation is triggered by proinflammatory cytokine stimulation and is associated with liver cancer development

Inflammation predisposes to tumorigenesis in various organs by potentiating a susceptibility to genetic aberrations. The mechanism underlying the enhanced genetic instability through chronic inflammation, however, is not clear. Here, we demonstrated that TNFα stimulation induced transcriptional downregulation of MSH2, a member of the mismatch repair family, via NF-κB-dependent miR-21 expression in hepatocytes. Liver cancers developed in ALB-MSH2(-) (/) (-)AID(+), ALB-MSH2(-) (/) (-), and ALB-AID(+) mice, in which MSH2 is deficient and/or activation-induced cytidine deaminase (AICDA) is expressed in cells with albumin-producing hepatocytes. The mutation signatures in the tumors developed in these models, especially ALB-MSH2(-) (/) (-)AID(+) mice, closely resembled those of human hepatocellular carcinoma. Our findings demonstrated that inflammation-mediated dysregulation of MSH2 may be a mechanism of genetic alterations during hepatocarcinogenesis. Cancer Res; 76(15); 4383-93. ©2016 AACR.

Proliferating EpCAM-Positive Ductal Cells in the Inflamed Liver Give Rise to Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) originates from regenerating liver cells with genetic alterations in chronically inflamed liver. Ductal cells and hepatocytes proliferate for liver regeneration, and proliferating ductal cells (PDC) derived from bile ductules have long been considered putative liver stem/progenitor cells and candidate cellular origins of HCC. The potential of PDC as tumor-originating cells, however, remains controversial in contrast to accumulating evidence that HCC originates from hepatocytes. Here, we demonstrate that PDCs expressing the established surface and cancer stem cell marker EpCAM give rise to HCC in inflamed liver. EpCAM-expressing PDCs were specifically labeled in newly developed EpcamCreERT2 mice and traced in a chemically induced liver injury model. Stepwise accumulation of genetic alterations in EpCAM-positive cells was induced by the mutagenesis activity of activation-induced cytidine deaminase using conditional transgenic mice. Lineage-tracing experiments revealed that labeled PDC differentiated into cholangiocytes, but not into hepatocytes, in the chemically damaged liver. Nevertheless, EpCAM-positive PDC with genetic alterations gave rise to HCC after 8 months of chemical administration. PDC-derived HCC showed histologic characteristics of concomitant ductule-like structures resembling human cholangiolocellular carcinoma (CLC) and exhibited serial transitions from PDC-like CLC cells to hepatocyte-like HCC cells. The Wnt signaling pathway was specifically upregulated in the CLC components of PDC-derived HCC. Our findings provide direct experimental evidence that EpCAM-expressing PDC could be a cellular origin of HCC, suggesting the existence of stem/progenitor-derived hepatocarcinogenesis. Cancer Res; 77(22); 6131-43. ©2017 AACR.

Sonazoid-enhanced ultrasonography guidance improves the quality of pathological diagnosis in the biopsy of focal hepatic lesions.

Background/aim Contrast-enhanced ultrasonography (US) has improved the detection and characterization of focal hepatic lesions. Recently, the importance of obtaining high-quality samples in the biopsy of hepatic lesions has been increasing not only in the field of pathological diagnosis but also in molecular analysis for predicting the effectiveness of anticancer agents and molecular targeted drugs. We evaluated the utility of Sonazoid-enhanced ultrasonography (SEUS) in guiding percutaneous biopsy of focal hepatic lesions by comparing the results of histopathological diagnosis between B-mode US and SEUS guidance. Methods and materials This retrospective study examined 121 focal hepatic lesions in 108 patients (mean age: 63.8 years) referred for US-guided percutaneous biopsy. The technical success rate was defined as the percentage of the lesions diagnosed clearly at the initial biopsy. Results Among 121 lesions, 56 lesions were subjected to biopsy with B-mode US guidance whereas 65 were subjected to SEUS guidance. The technical success rate was significantly higher under SEUS guidance than under B-mode US guidance (92.3 vs. 76.8%, respectively, P<0.05). When biopsies were performed to diagnose or rule out malignancy in indeterminate lesions, the technical success rate was also significantly higher under SEUS guidance than under B-mode US guidance (100 vs. 73.9%, respectively, P<0.05). SEUS guidance resulted in a significantly higher rate of successful single-puncture attempts compared with B-mode US guidance (55.4 vs. 35.7%, respectively, P<0.05). Conclusion SEUS guidance is recommended for more accurate localization of suitable hepatic lesion biopsy areas as it increases conspicuity and differentiates viable areas from denaturalization or necrosis.

Activation of TNF-α-AID axis and co-inhibitory signals in coordination with Th1-type immunity in a mouse model recapitulating hepatitis B

&NA; Hepatitis B virus (HBV) infection evokes host immune responses that primarily determine the outcome of HBV infection and the clinical features of HBV‐associated liver disease. The precise mechanisms by which host factors restrict HBV replication, however, are poorly understood due to the lack of useful animal models that recapitulate immune responses to HBV. Here, we performed comprehensive immunologic gene expression profiling of the liver of a mouse model recapitulating anti‐HBV immune response using a high sensitivity direct digital counting system. Anti‐HBV cellular immunity with liver inflammation was elicited in mice hydrodynamically injected with a CpG‐depleted plasmid encoding hepatitis B surface antigen (HBsAg) gene after preimmunization with HBsAg vaccine. Comprehensive expression analyses revealed the upregulation of Th1‐associated genes including tumor necrosis factor (Tnf) and negative regulators of T cell function in the inflamed liver. Interestingly, activation‐induced cytidine deaminase (Aicda, termed AID in humans), which reportedly suppresses HBV infection in vitro, was upregulated in hepatocytes in the course of anti‐HBV immunity. Hepatocytic expression of Aicda in a Tnf‐dependent manner was confirmed by the administration of Tnf antagonist into Aicda‐tdTomato mice with anti‐HBV immunity. Our findings suggest that activation of Tnf–Aicda axis and co‐inhibitory signals to T cells in coordination with Th1‐type immunity has critical roles in the immune response against HBV infection. HighlightsA mouse model recapitulating liver inflammation associated with anti‐HBV immunity was developed by hydrodynamic injection.In this model, nonspecific immune response potentially caused by injection was avoided by using a CpG‐free plasmid.Comprehensive analysis showed the upregulation of Th1 genes and negative regulators to T cells in the inflamed liver.Aicda (AID), which contributes to noncytolytic immunity against HBV was also upregulated in hepatocytes via Tnf signaling.

Exploring the Mechanisms of Gastrointestinal Cancer Development Using Deep Sequencing Analysis.

Next-generation sequencing (NGS) technologies have revolutionized cancer genomics due to their high throughput sequencing capacity. Reports of the gene mutation profiles of various cancers by many researchers, including international cancer genome research consortia, have increased over recent years. In addition to detecting somatic mutations in tumor cells, NGS technologies enable us to approach the subject of carcinogenic mechanisms from new perspectives. Deep sequencing, a method of optimizing the high throughput capacity of NGS technologies, allows for the detection of genetic aberrations in small subsets of premalignant and/or tumor cells in noncancerous chronically inflamed tissues. Genome-wide NGS data also make it possible to clarify the mutational signatures of each cancer tissue by identifying the precise pattern of nucleotide alterations in the cancer genome, providing new information regarding the mechanisms of tumorigenesis. In this review, we highlight these new methods taking advantage of NGS technologies, and discuss our current understanding of carcinogenic mechanisms elucidated from such approaches.

Genetic features of multicentric/multifocal intramucosal gastric carcinoma: Genetic features of multiple early gastric cancer

Chronic gastritis caused by Helicobacter pylori (H. pylori) infection could lead to the development of gastric cancer. The finding that multiple gastric cancers can develop synchronously and/or metachronously suggests the development of field cancerization in chronically inflamed, H. pylori‐infected gastric mucosa. The genetic basis of multiple tumorigenesis in the inflamed stomach, however, is not well understood. In this study, we analyzed the microsatellite instability (MSI) status and copy number aberrations (CNAs) of 41 multiple intramucosal early gastric cancers that synchronously or metachronously developed in 19 patients with H. pylori infection. Among the 41 intramucosal gastric carcinomas, 9 (22%) exhibited MSI, and the remaining 32 (78%) exhibited the microsatellite stable (MSS) phenotype. Metachronous multiple intramucosal gastric carcinoma exhibit inter‐tumor heterogeneity by individually acquiring genetic aberrations. All synchronous multiple intramucosal gastric carcinoma pairs shared a common MSI/MSS profile, and CNA analysis revealed that synchronous multiple intramucosal gastric carcinoma pairs with the MSS phenotype shared common aberrations of representative tumor‐suppressor genes, including focal deletion of APC, TP53, CDKN2A, and CDKN2B. Multiregional CNA analysis revealed that heterogeneous gene amplifications/deletions, including PDL1 amplification, evolved under the presence of shared “trunk” genetic alterations in a subpopulation of individual intramucosal gastric carcinomas. These data suggest that multiple gastric carcinomas develop in a multicentric/multifocal manner exhibiting features of inter‐ and intra‐tumor heterogeneity in H. pylori‐infected gastric mucosa, whereas synchronous multiple intramucosal gastric carcinomas could share partially common genetic alterations, possibly via common oncogenic pathways.