Shinichi Aishima

Dysregulated YAP1/TAZ and TGF-β signaling mediate hepatocarcinogenesis in Mob1a/1b-deficient mice

Significance Patients with intrahepatic cholangiocellular carcinoma (ICC) and combined hepatocellular and cholangiocarcinoma (cHC-CC) have worse prognoses than those with hepatocellular carcinoma and rarely show clinical responses to drugs. Our analyses of mice with liver-specific deletions of Mps One Binder Kinase Activator (MOB)1A/1B reveal that MOB1A/1B constitute the most important hub of Hippo signaling in mammalian liver. MOB1A/1B maintain hepatocyte stem/progenitor cell quiescence and are potent tumor suppressors, especially in cHC-CCs and ICCs. Because these functions depend on the Hippo target Yap1/Taz and the Yap1/Taz targets Tgfbs, our data point to a new therapeutic approach for liver cancer based on inhibition of MOB1-YAP1/TAZ and/or TGF-βs–SMADs signaling. Our demonstration that well-tolerated and already-approved antiparasitic drugs inhibit YAP1 signaling may point to a new route of treatment for these cancers that can be rapidly tested and implemented. Mps One Binder Kinase Activator (MOB)1A/1B are core components of the Hippo pathway that coactivate large tumor suppressor homolog (LATS) kinases. Mob1a/1b double deficiency in mouse liver (LMob1DKO) results in hyperplasia of oval cells and immature cholangiocytes accompanied by inflammatory cell infiltration and fibrosis. More than half of mutant mice die within 3 wk of birth. All survivors eventually develop liver cancers, particularly combined hepatocellular and cholangiocarcinomas (cHC-CCs) and intrahepatic cholangiocellular carcinomas (ICCs), and die by age 60 wk. Because this phenotype is the most severe among mutant mice lacking a Hippo signaling component, MOB1A/1B constitute the critical hub of Hippo signaling in mammalian liver. LMob1DKO liver cells show hyperproliferation, increased cell saturation density, hepatocyte dedifferentiation, enhanced epithelial–mesenchymal transition and cell migration, and elevated transforming growth factor beta(TGF-β)2/3 production. These changes are strongly dependent on Yes-Associated Protein-1 (Yap1) and partially dependent on PDZ-binding motif (Taz) and Tgfbr2, but independent of connective tissue growth factor (Ctgf). In human liver cancers, YAP1 activation is frequent in cHC-CCs and ICCs and correlates with SMAD family member 2 activation. Drug screening revealed that antiparasitic macrocyclic lactones inhibit YAP1 activation in vitro and in vivo. Targeting YAP1/TAZ with these drugs in combination with inhibition of the TGF-β pathway may be effective treatment for cHC-CCs and ICCs.

Pathogenesis and classification of intrahepatic cholangiocarcinoma: different characters of perihilar large duct type versus peripheral small duct type.

Intrahepatic cholangiocarcinomas (ICCs) are made up of heterogenous carcinomas arising from different anatomical sites of the liver. Two types of candidate stem/progenitor cells of the biliary tree are postulated to exist at the peribiliary glands for large bile ducts and at the canals of Hering for small ducts and hepatocytes. According to the recent observations, ICCs can be subclassified into two types: tumors involving the large bile ducts comparable in size to the intrahepatic second branches and composed of a tubular or papillary component with tall columnar epithelium, and tumors involving the smaller duct than segmental branches and composed of small tubules with cuboidal epithelium. Perihilar large duct type ICCs can be interpreted as arising from large bile duct type ICCs, and peripheral small duct type ICCs may arise from small bile duct type or ductular type ICCs. Chronic biliary inflammation induces neoplastic change of the large bile ducts and thereby progression to the perihilar large duct type ICC, which can be grossly classified into periductal filtrating type ICC and intraductal growth type ICC, while chronic hepatitis or cirrhosis induces mass‐forming peripheral small duct type ICC. The different morphological and molecular features, including stromal components and tumor vasculature, support the hypothesis that perihilar large duct type ICCs and peripheral small duct type ICCs arise from different backgrounds, have different carcinogenetic pathways, and exhibit different biologic behaviors.

Role of Growth Factor Receptor-Bound Protein 7 in Hepatocellular Carcinoma

The human growth factor receptor–bound protein 7 (Grb7) is an adaptor molecule and is related to cell invasion. In this present study, we investigated the clinical and biological significance of Grb7 expression in human hepatocellular carcinoma (HCC). We reviewed 64 consecutive patients who had undergone liver resection for HCC, and we investigated the correlation between Grb7 expression and clinical outcome. To analyze the biological behavior of Grb7 in vitro and in vivo, we established Grb7 stable knockdown HCC cells using RNA interference technology. The positive staining of Grb7 protein was correlated with portal venous invasion (P < 0.01), hepatic venous invasion (P < 0.01), and intrahepatic metastasis (P < 0.05). Positive expression of Grb7 was significantly correlated with focal adhesion kinase (FAK) protein levels in HCC (P < 0.01). The Grb7- and FAK-positive group showed a significantly poorer prognosis as compared with the Grb7- and FAK-negative group (P < 0.05). Grb7 knockdown HCC cells exhibited significantly lower levels of invasion potential (P < 0.05) and motility (P < 0.05) than the control cells in vitro; moreover, Grb7 knockdown HCC cells showed delayed onset of the tumors compared with the control cells in vivo. Grb7 expression can modulate the invasive phenotype of HCC. Grb7 plays an important role in HCC progression and is strongly associated with expression of FAK. Grb7 could be a therapeutic target in HCC. (Mol Cancer Res 2007;5(7):667–73)

Cytokeratin immunohistochemistry improves interobserver variability between unskilled pathologists in the evaluation of tumor budding in T1 colorectal cancer

Tumor budding is a major risk factor for T1 colorectal cancer. Quality control of the pathological diagnosis of budding is crucial, irrespective of the pathologists experience. This study examines the interobserver variability according to pathologists experience and evaluates the influence of cytokeratin (CK) immunostaining in the assessment of budding. Hematoxylin‐eosin (HE) and CK‐immunostained slides of 40 cases with T1 primary colorectal cancer were examined. Budding grades were individually evaluated by 12 pathologists who we categorized into three groups by their experience (expert, with >10 years of experience (n = 4), senior, with 5–10 years (n = 4), and junior, < 5 years (n = 4)). The results revealed a tendency for the more experienced pathologists to assign higher budding grades compared to the less‐experienced pathologists. In the junior group, the interobserver variability obtained with HE slides was poor, but it was markedly improved in the evaluation using CK‐immunostained slides. The benefit of CK immunostaining was only slight in the expert group. CK immunostaining would be useful when a pathologist is not experienced enough or does not have enough confidence in the assessment of budding.

Primary hepatic tumors with myxoid change: Morphologically unique hepatic adenomas and hepatocellular carcinomas

Mucin production in primary liver neoplasms is typically interpreted as evidence for biliary differentiation. However, we have observed benign and malignant liver tumors that have abundant extracellular myxoid/mucinous material, yet have only evidence of hepatocellular differentiation. To further characterize these unusual findings, 9 cases were identified and further studied. Four cases were hepatic adenomas, whereas 5 were hepatocellular carcinomas. Extracellular myxoid/mucinous material was diffuse in 7 cases and patchy in 2 cases. The extracellular myxoid/mucinous material was typically weakly mucicarmine positive (N=6) and Alcian blue positive (N=8). All tumors were well differentiated, and none had evidence for biliary differentiation by morphology or immunohistochemistry. The hepatic adenomas arose in nondiabetic and nonobese patients. Both the hepatic adenomas and the hepatocellular carcinomas were strongly and diffusely HepPar1 positive, CK19 negative, and showed loss of LFABP protein expression. These findings indicate that extracellular myxoid/mucinous material in isolation should not be interpreted as cholangiocarcinoma. Furthermore, the unique morphology, the clinical characteristics, and the immunophenotype results suggest that myxoid hepatic adenomas and hepatocellular carcinoma may be unique tumor variants.

Mass-forming intrahepatic cholangiocarcinoma: Enhancement patterns in the arterial phase of dynamic hepatic CT - Correlation with clinicopathological findings.

AbstractObjectivesTo evaluate the relationship between the enhancement pattern of intrahepatic cholangiocarcinomas (ICCs) in the hepatic arterial phase (HAP) of dynamic hepatic CT and the clinicopathological findings with special reference to the perihilar type and the peripheral type.MethodsForty-seven patients with pathologically proven ICCs were enrolled. Based on the enhancement pattern in the HAP, the lesions were classified into three groups: a hypovascular group (n=13), rim-enhancement group (n=18), and hypervascular group (n=16). The clinicopathological findings were compared among the three groups.ResultsPerihilar-type ICCs were significantly more frequently observed in the hypovascular group than in the rim-enhancement and hypervascular groups (p=0.006 and p <0.001, respectively). Lymphatic invasion, perineural invasion, and biliary invasion were significantly more frequent in the hypovascular group than the rim- enhancement group (p=0.001, p=0.025 and p=0.029, respectively) or hypervascular group (p <0.001, p <0.001 and p=0.025, respectively). Patients with hypovascular lesions showed significantly poorer disease-free survival than patients with rim-enhancing or hypervascular lesions (p=0.001 and p=0.001, respectively). Hypovascularity was an independent preoperative prognostic factor for disease-free survival (p<0.001).ConclusionsHypovascular ICCs in the HAP tend to be of perihilar type and to have more malignant potential than other ICCs.Key Points• Hypovascular ICCs have greater malignant potential than rim-enhancing and hypervascular ICCs.n • Hypovascular ICCs show a higher frequency of perihilar-type ICCs.n • Perihilar-type ICCs do not always display distal ductal wall thickening.

Induced nitric oxide synthetase and peroxiredoxin expression in intramucosal poorly differentiated gastric cancer of young patients

To investigate the relationship between oxidative stress and gastric carcinogenesis of poorly differentiated adenocarcinoma in young patients, we analyzed the surgically resected specimens of 22 young patients (21–30 years) and 29 older patients (41–72 years) with intramucosal gastric cancer of the poorly differentiated type. We used immunohistochemical staining to evaluate the expression of 8‐hydroxydeoxyguanosine (8OHdG), induced nitric oxide synthetase (iNOS), and antioxidant enzymes (thioredoxin [TRX] and peroxiredoxin [PRDX1, 2 and 3]). We assessed these proteins in the cancer, noncancerous gastric foveolar epithelium and noncancerous mucosal neck. In both the young and older patient groups, the 8OHdG and TRX expressions were gradually increased in cancer cells compared with the noncancerous foveolar epithelial cells and the noncancerous mucosal neck cells (P < 0.001). Although the iNOS and PRDXs expressions were increased in the noncancerous mucosal neck cells compared with the noncancerous foveolar epithelial cells, regardless of age (P < 0.001), the iNOS and PRDX2 expression in the cancer cells were significantly reduced in the young patients compared with the older patients (P < 0.001, P < 0.05). In conclusion, the reduced expression of iNOS or PRDX2 may play an important role in the carcinogenesis of gastric cancer associated with Helicobacteru2009pylori‐induced chronic active gastritis in young patients.

Bile duct adenoma and von Meyenburg complex-like duct arising in hepatitis and cirrhosis: pathogenesis and histological characteristics.

Morphologic features and neoplastic potentials of bile duct adenoma (BDA) and von Meyenburg complex (VMC)‐like duct arising in chronic liver disease were unknown. Thirty‐five BDAs and 12 VMC‐like duct lesions were observed in 39 cases with chronic liver disease. BDAs were divided into the EMA‐cytoplasmic type (n = 14) and EMA‐luminal type (n = 21). EMA‐cytoplasmic BDA composed of a proliferation of cuboidal to low‐columnar cells forming an open lumen with NCAM(+)/MUC6(‐), resembling an interlobular bile duct. EMA‐luminal BDA showed uniform cuboidal cells with narrow lumen, and NCAM(++)/MUC6(++), resembling a ductular reaction. VMC‐like duct showed positive MUC1 expression and negative MUC6. The expression of S100P, glucose transporter‐1 (GLUT‐1) and insulin‐like growth factor II mRNA‐binding protein 3 (IMP‐3) were not detected in three lesions. p16 expression was higher than those of the ductular reaction, and the Ki67 and p53 indexes were very low (<1.0%). Large‐sized EMA‐luminal BDA shows sclerotic stroma. We classified small nodular lesions of ductal or ductular cells in chronic hepatitis and cirrhosis into the following groups: BDA, interlobular bile duct type; BDA, ductular/peribiliary gland type; and VMC‐like duct. They may be reactive proliferation rather than neoplastic lesions.

Spalt-like transcription factor 4 immunopositivity is associated with epithelial cell adhesion molecule expression in combined hepatocellular carcinoma and cholangiocarcinoma

Combined hepatocellular carcinoma (HCC) and cholangiocarcinoma (CC) (cHCC‐CC) is a rare biphasic liver cancer. Recent studies have demonstrated that cHCC‐CC originates from hepatic progenitor cells (HPCs). Spalt‐like transcription factor 4 (SALL4) is a marker for a progenitor subclass of HCC with an aggressive phenotype. However, little has been revealed about SALL4 expression in cHCC‐CC. The aims of this study were to report SALL4 immunopositivity and the results of clinicopathological analysis in cHCC‐CC, and to examine the two different nuclear immunostaining patterns for SALL4.

cHCC-CCA: Consensus terminology for primary liver carcinomas with both hepatocytic and cholangiocytic differentation

Primary liver carcinomas with both hepatocytic and cholangiocytic differentiation have been referred to as “combined (or mixed) hepatocellular‐cholangiocarcinoma.” These tumors, although described over 100 years ago, have attracted greater attention recently because of interest in possible stem cell origin and perhaps because of greater frequency and clinical recognition. Currently, because of a lack of common terminology in the literature, effective treatment and predictable outcome data have been challenging to accrue. This article represents a consensus document from an international community of pathologists, radiologists, and clinicians who have studied and reported on these tumors and recommends a working terminology for diagnostic and research approaches for further study and evaluation. Conclusion: It is recommended that diagnosis is based on routine histopathology with hematoxylin and eosin (H&E); immunostains are supportive, but not essential for diagnosis. (Hepatology 2018;68:113‐126).