Yuji Eso

Leptin Receptor Somatic Mutations Are Frequent in HCV-Infected Cirrhotic Liver and Associated With Hepatocellular Carcinoma

BACKGROUND & AIMS Hepatocellular carcinoma develops in patients with chronic hepatitis or cirrhosis via a stepwise accumulation of various genetic alterations. To explore the genetic basis of development of hepatocellular carcinoma in hepatitis C virus (HCV)-associated chronic liver disease, we evaluated genetic variants that accumulate in nontumor cirrhotic liver. METHODS We determined the whole exome sequences of 7 tumors and background cirrhotic liver tissues from 4 patients with HCV infection. We then performed additional sequencing of selected exomes of mutated genes, identified by whole exome sequencing, and of representative tumor-related genes on samples from 22 cirrhotic livers with HCV infection. We performed in vitro and in vivo functional studies for one of the mutated genes. RESULTS Whole exome sequencing showed that somatic mutations accumulated in various genes in HCV-infected cirrhotic liver tissues. Among the identified genes, the leptin receptor gene (LEPR) was one of the most frequently mutated in tumor and nontumor cirrhotic liver tissue. Selected exome sequencing analyses detected LEPR mutations in 12 of 22 (54.5%) nontumorous cirrhotic livers. In vitro, 4 of 7 (57.1%) LEPR mutations found in cirrhotic livers reduced phosphorylation of STAT3 to inactivate LEPR-mediated signaling. Moreover, 40% of Lepr-deficient (C57BL/KsJ-db/db) mice developed liver tumors after administration of thioacetamide compared with none of the control mice. CONCLUSIONS Based on analysis of liver tissue samples from patients, somatic mutations accumulate in LEPR in cirrhotic liver with chronic HCV infection. These mutations could disrupt LEPR signaling and increase susceptibility to hepatocarcinogenesis.

Clinical Characteristics of Non-B Non-C Hepatocellular Carcinoma: A Single-Center Retrospective Study

Background/Aims: To clarify risk factors and clinical features of both hepatitis B surface antigen and anti-HCV negative hepatocellular carcinoma (NBNC-HCC). Methods: HCC patients (n = 1,109) diagnosed at a single center were categorized based on the presence of serum hepatitis B surface antigen and HCVAb. Clinical characteristics of 127 NBNC-HCC patients were evaluated. Results: NBNC-HCC patients were stratified as those with alcoholic liver disease (ALD-HCC, n = 42) and alcohol-unrelated liver disease (non-ALD-HCC, n = 85). Compared with the ALD-HCC group, the non-ALD-HCC group had a higher prevalence of diabetes (p = 0.015), larger tumor size (p = 0.007), and higher tumor marker levels (p = 0.014). Liver function results were significantly worse in ALD-HCC than in non-ALD-HCC. Although the ALD-HCC group had a higher tendency toward recurrence than the non-ALD-HCC group, survival rates were similar between groups (p = 0.352). Conclusion: Alcohol consumption was the most common etiologic factor for NBNC-HCC, and diabetes may be related to the development of HCC in non-ALD-HCC patients. Non-ALD-HCC tended to be diagnosed at a more advanced stage, whereas liver function was worse, and tumor recurrence rate was higher in ALD-HCC patients. Further examination of the risk factors and establishment of a precise surveillance system are necessary for early diagnosis and the development of curative therapies for NBNC-HCC.

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.

Activation-Induced Cytidine Deaminase Contributes to Pancreatic Tumorigenesis by Inducing Tumor-Related Gene Mutations

Pancreatic ductal adenocarcinoma (PDAC) develops via an accumulation of various gene mutations. The mechanism underlying the mutations in PDAC development, however, is not fully understood. Recent insight into the close association between the mutation pattern of various cancers and specific mutagens led us to investigate the possible involvement of activation-induced cytidine deaminase (AID), a DNA editing enzyme, in pancreatic tumorigenesis. Our immunohistochemical findings revealed AID protein expression in human acinar ductal metaplasia, pancreatic intraepithelial neoplasia, and PDAC. Both the amount and intensity of the AID protein expression increased with the progression from precancerous to cancerous lesions in human PDAC tissues. To further assess the significance of ectopic epithelial AID expression in pancreatic tumorigenesis, we analyzed the phenotype of AID transgenic (AID Tg) mice. Consistent with our hypothesis that AID is involved in the mechanism of the mutations underlying pancreatic tumorigenesis, we found precancerous lesions developing in the pancreas of AID Tg mice. Using deep sequencing, we also detected Kras and c-Myc mutations in our analysis of the whole pancreas of AID Tg mice. In addition, Sanger sequencing confirmed the presence of Kras, c-Myc, and Smad4 mutations, with the typical mutational footprint of AID in precancerous lesions in AID Tg mice separated by laser capture microdissection. Taken together, our findings suggest that AID contributes to the development of pancreatic precancerous lesions by inducing tumor-related gene mutations. Our new mouse model without intentional manipulation of specific tumor-related genes provides a powerful system for analyzing the mutations involved in PDAC.

Education and imaging. Hepatobiliary and Pancreatic: Detection of early hepatocellular carcinoma by enhanced magnetic resonance imaging.

A woman, aged 75, with cirrhosis caused by hepatitis C had a routine ultrasound study for surveillance for hepatocellular carcinoma. A possible nodule was identified in segment VI but it was difficult to identify the contours or margins of the nodule. A contrast-enhanced ultrasound (US) study with perfluorobutane (Sonazoid®) showed no enhancement or washout of the nodule in either the vascular or Kupffer phases. Computed tomography (CT) during hepatic arteriography (CTHA) or arterial portography (CTAP) also failed to show a liver lesion (Figure 1, left and middle panel). In contrast, gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Primovist®)-enhanced magnetic resonance imaging (MRI) clearly revealed a low-signal nodule during the hepatobiliary phase (Figure 1, right). The appearance was consistent with either a dysplastic nodule or a well-differentiated hepatocellular carcinoma. As the nodule could not be detected on US or CT, we performed real-time virtual sonography synchronizing B-mode US images with the hepatobiliary phase of enhanced MRI which allowed for the same area to be displayed in real time as both MR and B-mode US images (Figure 2). Using this technique, the nodule was clearly visualized and an aspiration biopsy was performed. Histology revealed a well-to-moderately differentiated hepatocellular carcinoma that was treated by percutaneous radiofrequency ablation guided by real-time virtual sonography with contrast-enhanced MRI. Radiofrequency ablation is widely used for the treatment of hepatocellular carcinoma. However, to achieve successful ablation, it is important to have a clear view of the margins of the nodule. Although most larger hepatocellular carcinomas are hypervascular, early carcinomas can be hypovascular and can be difficult to detect with contrast-enhanced US, contrast-enhanced CT or CT during hepatic arteriography. The recent introduction of contrast-enhanced MRI appears to have improved the detection of early liver tumors and may be helpful for the differentiation of early hepatocellular carcinoma from dysplastic nodules. Real-time virtual sonography is a system in which a B-mode US image can be synchronized with CT images. To our knowledge, this is the first report of the successful use of real-time virtual sonography with enhanced MRI for the detection and treatment of an early hepatocellular carcinoma. This technology may facilitate the diagnosis and treatment of hepatocellular carcinoma at an earlier stage.

Novel approaches for molecular targeted therapy against hepatocellular carcinoma: Molecular targeted therapy for liver cancer

Systemic chemotherapy using a multitargeted tyrosine kinase inhibitor is an established treatment for advanced‐stage tumors in various organs. Comprehensive genomic analyses using next‐generation sequencing technology revealed the intra‐ and intertumor heterogeneity of human hepatocellular carcinomas (HCCs), and provided evidence for the use of therapeutic agents effective against multiple targets in tumor cells. Recently, the efficacy and safety of a multitargeted tyrosine kinase inhibitor, lenvatinib, was confirmed by a randomized global phase III trial; thus, lenvatinib was approved as first‐line therapy for HCC, providing a new therapeutic option for patients at an advanced stage. In this article, we introduce the application of molecular targeted therapy using lenvatinib and discuss future aspects of therapeutic options for advanced HCC.

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.

Hepatobiliary and Pancreatic: Detection of early hepatocellular carcinoma by enhanced magnetic resonance imaging

A woman, aged 75, with cirrhosis caused by hepatitis C had a routine ultrasound study for surveillance for hepatocellular carcinoma. A possible nodule was identified in segment VI but it was difficult to identify the contours or margins of the nodule. A contrast-enhanced ultrasound (US) study with perfluorobutane (Sonazoid®) showed no enhancement or washout of the nodule in either the vascular or Kupffer phases. Computed tomography (CT) during hepatic arteriography (CTHA) or arterial portography (CTAP) also failed to show a liver lesion (Figure 1, left and middle panel). In contrast, gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Primovist®)-enhanced magnetic resonance imaging (MRI) clearly revealed a low-signal nodule during the hepatobiliary phase (Figure 1, right). The appearance was consistent with either a dysplastic nodule or a well-differentiated hepatocellular carcinoma. As the nodule could not be detected on US or CT, we performed real-time virtual sonography synchronizing B-mode US images with the hepatobiliary phase of enhanced MRI which allowed for the same area to be displayed in real time as both MR and B-mode US images (Figure 2). Using this technique, the nodule was clearly visualized and an aspiration biopsy was performed. Histology revealed a well-to-moderately differentiated hepatocellular carcinoma that was treated by percutaneous radiofrequency ablation guided by real-time virtual sonography with contrast-enhanced MRI. Radiofrequency ablation is widely used for the treatment of hepatocellular carcinoma. However, to achieve successful ablation, it is important to have a clear view of the margins of the nodule. Although most larger hepatocellular carcinomas are hypervascular, early carcinomas can be hypovascular and can be difficult to detect with contrast-enhanced US, contrast-enhanced CT or CT during hepatic arteriography. The recent introduction of contrast-enhanced MRI appears to have improved the detection of early liver tumors and may be helpful for the differentiation of early hepatocellular carcinoma from dysplastic nodules. Real-time virtual sonography is a system in which a B-mode US image can be synchronized with CT images. To our knowledge, this is the first report of the successful use of real-time virtual sonography with enhanced MRI for the detection and treatment of an early hepatocellular carcinoma. This technology may facilitate the diagnosis and treatment of hepatocellular carcinoma at an earlier stage.

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.