The clinicopathological and prognostic relevance of cytokeratin 7 and 19 expression in hepatocellular carcinoma. A possible progenitor cell origin

Hepatocellular Carcinomas: Towards a pathomolecular approach

Molecular analysis of primary liver malignancies has provided a refinement of the pathological diagnosis of this entity and the identification of an increasing number of tumor subtypes of hepatocellular proliferation, either malignant (hepatocellular carcinomas) or benign (hepatocellular adenomas). Besides the diagnosis, a combined pathomolecular approach can also provide further insights into patient prognosis, and help select patients who can benefit from targeted therapies. Hepatocellular carcinomas define a heterogeneous group of malignant hepatocellular proliferation at various levels: macroscopic, histological and molecular. While most carcinomas occur in patients with chronic liver diseases and advanced fibrosis in the background liver, some arise from the malignant transformation of a pre-existing hepatocellular adenoma. TERT promoter mutations are the most frequent genomic alterations observed in the process of malignancy, and they occur early in the process of liver carcinogenesis. Overall, a more active biopsy strategy should be considered a key step in the management of patients with HCC.

Application of Immunohistochemistry in the Pathological Diagnosis of Liver Tumors

Although radiological diagnostics have been progressing, pathological diagnosis remains the most reliable method for diagnosing liver tumors. In some cases, definite pathological diagnosis cannot be obtained by histological evaluation alone, especially when the sample is a small biopsy; in such cases, immunohistochemical staining is very useful. Immunohistochemistry is the most frequently used technique for molecular pathological diagnosis due to its broad application, ease of performance and evaluation, and reasonable cost. The results occasionally reflect specific genetic mutations. The immunohistochemical markers of hepatocellular carcinoma include those of hepatocellular differentiation—such as hepatocyte paraffin 1 and arginase-1—and those of malignant hepatocytes—such as glypican-3, heat shock protein 70, and glutamine synthetase (GS). To classify the subtypes of hepatocellular adenoma, examination of several immunohistochemical markers, such as liver fatty acid-binding protein, GS, and serum amyloid A, is indispensable. Immunohistochemical staining for GS is also important for the diagnosis of focal nodular hyperplasia. The representative immunohistochemical markers of intrahepatic cholangiocarcinoma include cytokeratin (CK) 7 and CK19. In this article, we provide an overview of the application of immunohistochemistry in the pathological diagnosis of liver tumors referring to the association with genetic alterations. Furthermore, we aimed to explain the practical points in the differential diagnosis of liver tumors by immunohistochemical staining.

The strength of cytomorphology and efficacy of immuno-cytochemistry in distinguishing hepatocellular carcinoma from its mimics on fine-needle aspiration cytology

BACKGROUND

Cytomorphologic distinction of hepatocellular carcinoma (HCC) from its mimics on fine-needle aspiration cytology (FNAC) is often problematic. The present study evaluates the strength of cytomorphology and the utility of an immuno-panel of arginase-1, glypican-3, HepPar-1, thyroid transcription factor (TTF-1) and CK-19 in resolving this diagnostic issue.

METHODS

FNAC features of 71 nodular hepatic lesions were studied with an immunocyto/ histochemical (ICC/IHC) panel of arginase-1, glypican-3, HepPar-1, TTF-1 taking 10% positivity as "cut-off." Cytomorpholologic diagnoses were compared with diagnoses made on combined cytomorphologic and ICC/IHC approach.

RESULTS

Of 71 cases, 32, 10 and 29 had histopathologic, cell block and clinico-radiologic correlation respectively with 55 metastatic adenocarcinomas (MAC), 13 HCCs and one case each of hepatic adenoma (HA), cirrhotic nodule (CN) and intrahepatic cholangiocarcinoma (CC). Cytoplasmic positivity of HepPar-1 and glypican-3 were noted in 11/13 and 8/13 HCCs respectively; while only 3/13 and 1/13 HCCs revealed cytoplasmic positivity for arginase-1 and TTF-1 respectively. Benign hepatic lesions were negative for glypican-3 and TTF-1, but expressed both arginase-1and HepPar-1. Twenty-one of 55 MACs and the lone case of CC were positive for CK-19; however, all MACs and CC cases were negative for HepPar-1, arginase-1, glypican-3 and TTF-1. The immune-panel had sensitivity, specificity and diagnostic accuracy of 100%, 88.9% and 90.6%, respectively, for differentiating HCC from its morphologic mimics.

CONCLUSION

Though a meticulous cytologic evaluation in conjunction with clinicoradiologic profile helps in distinguishing HCC from its benign and malignant mimics; an immunopanel of arginase-1, glypican-3, HepPar-1, TTF-1 and CK-19 drastically improves the diagnostic accuracy.

Pathologic and molecular features of hepatocellular carcinoma: An update

Morphological diversity and several new distinct pathologic subtypes of hepatocellular carcinoma (HCC) are now well-recognized. Recent advances in tumor genomics and transcriptomics have identified several recurrent somatic/genetic alterations that are closely related with histomorphological subtypes and have therefore, greatly improved our understanding of HCC pathogenesis. Pathologic subtyping allows for a diagnosis which is clinically helpful and can have important implication in patient prognostication as some of these subtypes are extremely aggressive with vascular invasion, early recurrence, and worst outcomes. Several targeted treatments are now being considered in HCC, and the reporting of subtypes may be quite useful for personalized therapeutic purpose. This manuscript reviews the recently identified histomorphological subtypes and molecular alterations in HCC.

Circulating Tumor Cells Undergoing the Epithelial-Mesenchymal Transition: Influence on Prognosis in Cytokeratin 19-Positive Hepatocellular Carcinoma

Purpose

The purpose of this study was to elucidate the relationship between cytokeratin 19 (CK19) expression and levels of circulating tumor cells (CTCs) in preoperative peripheral blood of patients with hepatocellular carcinoma (HCC), and the potential influence of that relationship on prognosis.

Patients and Methods

CanPatrol™ CTC-enrichment technique and in situ hybridization (ISH) were used to enrich and classify CTCs undergoing the epithelial–mesenchymal transition (EMT) from blood samples of 105 HCC patients. CK19 immunohistochemistry staining was performed on HCC tissues and compared with demographic and clinical data.

Results

In total, 27 of 105 (25.7%) HCC patients were CK19-positive. CK19-positive patients had significantly lower median tumor-free survival (TFS) than CK19-negative patients (5 vs 10 months, P = 0.047). In total, 98 (93.3%) patients showed pre-surgery peripheral blood CTCs (range: 0–76, median: 6), and 57 of 105 (54.3%) patients displayed CTC counts ≥6. Furthermore, CK19-positive patients with CTC count ≥6 showed significantly higher percentage than CK19-negative ones (77.8% vs 46.2%, P = 0.004). CK19-positive patients showed a significantly higher proportion of mesenchymal CTCs among CTCs undergoing EMT than CK19-negative patients (mean rank: 62.28 vs 49.79, P = 0.046). We also found that CK19-positive patients with high CTC count showed significantly shorter median tumor-free survival than CK19-negative patients with low CTC count (5 vs 16 months, P = 0.039).

Conclusion

High CTC count and high percentage of mesenchymal CTCs are closely related to the expression of CK19, which is associated with poor prognosis in HCC patients.

An overview of hepatocellular carcinoma with atypical enhancement pattern: spectrum of magnetic resonance imaging findings with pathologic correlation

BACKGROUND

In the setting of cirrhotic liver, the diagnosis of hepatocellular carcinoma (HCC) is straightforward when typical imaging findings consisting of arterial hypervascularity followed by portal-venous washout are present in nodules larger than 1 cm. However, due to the complexity of hepatocarcinogenesis, not all HCCs present with typical vascular behaviour. Atypical forms such as hypervascular HCC without washout, isovascular or even hypovascular HCC can pose diagnostic dilemmas. In such cases, it is important to consider also the appearance of the nodules on diffusion-weighted imaging and hepatobiliary phase. In this regard, diffusion restriction and hypointensity on hepatobiliary phase are suggestive of malignancy. If both findings are present in hypervascular lesion without washout, or even in iso- or hypovascular lesion in cirrhotic liver, HCC should be considered. Moreover, other ancillary imaging findings such as the presence of the capsule, fat content, signal intensity on T2-weighted image favour the diagnosis of HCC. Another form of atypical HCCs are lesions which show hyperintensity on hepatobiliary phase. Therefore, the aim of the present study was to provide an overview of HCCs with atypical enhancement pattern, and focus on their magnetic resonance imaging (MRI) features.

CONCLUSIONS

In order to correctly characterize atypical HCC lesions in cirrhotic liver it is important to consider not only vascular behaviour of the nodule, but also ancillary MRI features, such as diffusion restriction, hepatobiliary phase hypointensity, and T2-weighted hyperintensity. Fat content, corona enhancement, mosaic architecture are other MRI feautures which favour the diagnosis of HCC even in the absence of typical vascular profile.

Hyperpolyploidization of hepatocyte initiates preneoplastic lesion formation in the liver

Hepatocellular carcinoma (HCC) is the most predominant primary malignancy in the liver. Genotoxic and genetic models have revealed that HCC cells are derived from hepatocytes, but where the critical region for tumor foci emergence is and how this transformation occurs are still unclear. Here, hyperpolyploidization of hepatocytes around the centrilobular (CL) region is demonstrated to be closely linked with the development of HCC cells after diethylnitrosamine treatment. We identify the CL region as a dominant lobule for accumulation of hyperpolyploid hepatocytes and preneoplastic tumor foci formation. We also demonstrate that upregulation of Aurkb plays a critical role in promoting hyperpolyploidization. Increase of AURKB phosphorylation is detected on the midbody during cytokinesis, causing abscission failure and hyperpolyploidization. Pharmacological inhibition of AURKB dramatically reduces nucleus size and tumor foci number surrounding the CL region in diethylnitrosamine-treated liver. Our work reveals an intimate molecular link between pathological hyperpolyploidy of CL hepatocytes and transformation into HCC cells.

Immune microenvironment of hepatocellular carcinoma, intrahepatic cholangiocarcinoma and liver metastasis of colorectal adenocarcinoma: Relationship with histopathological and molecular classifications

Tumor tissue is composed of tumor cells and tumor stroma. Tumor stroma contains various immune cells and non-immune stromal cells, forming a complex tumor microenvironment which plays pivotal roles in regulating tumor growth. Recent successes in immunotherapies against tumors, including immune checkpoint inhibitors, have further raised interests in the immune microenvironment of liver carcinoma. The immune microenvironment of tumors is formed because of interactions among tumor cells, immune cells and non-immune stromal cells, including fibroblasts and endothelial cells. Different patterns of immune microenvironment are observed among different tumor subtypes, and their clinicopathological significance and intertumor/intratumor heterogeneity are being intensively studied. Here, we review the immune microenvironment of hepatocellular carcinoma, intrahepatic cholangiocarcinoma and liver metastasis of colorectal adenocarcinoma, focusing on its histopathological appearance, clinicopathological significance, and relationship with histological and molecular classifications. Understanding the comprehensive histopathological picture of a tumor immune microenvironment, in addition to molecular and genetic approaches, will further potentiate the effort for precision medicine in the era of tumor-targeting immunotherapy.

Clinico-Radio-Pathological and Molecular Features of Hepatocellular Carcinomas with Keratin 19 Expression

Hepatocellular carcinoma (HCC) is a heterogeneous neoplasm, both from the molecular and histomorphological aspects. One example of heterogeneity is the expression of keratin 19 (K19) in a subset (4-28%) of HCCs. The presence of K19 expression in HCCs has important clinical implications, as K19-positive HCCs have been associated with aggressive tumor biology and poor prognosis. Histomorphologically, K19-positive HCCs demonstrate a more infiltrative appearance, poor histological differentiation, more frequent vascular invasion, and more intratumoral fibrous stroma than K19-negative conventional HCCs. From the molecular aspect, K19-positive HCCs have been matched with various gene signatures that have been associated with stemness and poor prognosis, including the G1-3 groups, S2 class, cluster A, proliferation signature, and vascular invasion signature. K19-positive HCCs also show upregulated signatures related to transforming growth factor-β pathway and epithelial-to-mesenchymal transition. The main regulators of K19 expression include hepatocyte growth factor-MET paracrine signaling by cancer-associated fibroblast, epidermal growth factor-epidermal growth factor receptor signaling, laminin, and DNA methylation. Clinically, higher serum alpha-fetoprotein levels, frequent association with chronic hepatitis B, more invasive growth, and lymph node metastasis have been shown to be characteristics of K19-positive HCCs. Radiologic features including atypical enhancement patterns, absence of tumor capsules, and irregular tumor margins can be a clue for K19-positive HCCs. From a therapeutic standpoint, K19-positive HCCs have been associated with poor outcomes after curative resection or liver transplantation, and resistance to systemic chemotherapy and locoregional treatment, including transarterial chemoembolization and radiofrequency ablation. In this review, we summarize the currently available knowledge on the clinico-radio-pathological and molecular features of K19-expressing HCCs, including a detailed discussion on the regulation mechanism of these tumors.

The cellular origins of cancer with particular reference to the gastrointestinal tract

Stem cells or their closely related committed progenitor cells are the likely founder cells of most neoplasms. In the continually renewing and hierarchically organized epithelia of the oesophagus, stomach and intestine, homeostatic stem cells are located at the beginning of the cell flux, in the basal layer of the oesophagus, the isthmic region of gastric oxyntic glands and at the bottom of gastric pyloric-antral glands and colonic crypts. The introduction of mutant oncogenes such as KrasG12D or loss of Tp53 or Apc to specific cell types expressing the likes of Lgr5 and Mist1 can be readily accomplished in genetically engineered mouse models to initiate tumorigenesis. Other origins of cancer are discussed including 'reserve' stem cells that may be activated by damage or through disruption of morphogen gradients along the crypt axis. In the liver and pancreas, with little cell turnover and no obvious stem cell markers, the importance of regenerative hyperplasia associated with chronic inflammation to tumour initiation is vividly apparent, though inflammatory conditions in the renewing populations are also permissive for tumour induction. In the liver, hepatocytes, biliary epithelial cells and hepatic progenitor cells are embryologically related, and all can give rise to hepatocellular carcinoma and cholangiocarcinoma. In the exocrine pancreas, both acinar and ductal cells can give rise to pancreatic ductal adenocarcinoma (PDAC), although the preceding preneoplastic states are quite different: acinar-ductal metaplasia gives rise to pancreatic intraepithelial neoplasia culminating in PDAC, while ducts give rise to PDAC via. mucinous cell metaplasia that may have a polyclonal origin.

Distinct Mechanisms Are Responsible for Nrf2-Keap1 Pathway Activation at Different Stages of Rat Hepatocarcinogenesis

Activation of the Nrf2-Keap1 pathway, the main intracellular defense against environmental stress, has been observed in several human cancers, including hepatocellular carcinoma (HCC). Here, we assessed whether distinct mechanisms of activation may be involved at different stages of hepatocarcinogenesis. We adopted an experimental model consisting of treatment with diethylnitrosamine (DENA) followed by a choline-devoid methionine-deficient (CMD) diet for 4 months. The CMD diet was then replaced with a basal diet, and the animals were killed at 6, 10 or 13 months after DENA injection. Nrf2 activation occurred at early steps of hepatocarcinogenesis and persisted throughout the tumorigenic process. While Nrf2 mutations were extremely frequent at early steps (90%), their incidence diminished with the progression to malignancy (25%). Conversely, while p62 was almost undetectable in early nodules, its accumulation occurred in HCCs, suggesting that Nrf2 pathway activation at late stages is mainly due to Keap1 sequestration by p62. We demonstrate that, in a model of hepatocarcinogenesis resembling human non-alcoholic fatty liver disease, Nrf2 mutations are the earliest molecular changes responsible for the activation of the Nrf2-Keap1 pathway. The progressive loss of mutations associated with a concomitant p62 accumulation implies that distinct mechanisms are responsible for Nrf2-Keap1 pathway activation at different stages of hepatocarcinogenesis.

Ring1 promotes the transformation of hepatic progenitor cells into cancer stem cells through the Wnt/β-catenin signaling pathway

The proliferation of hepatic progenitor cells (HPCs) is observed in reactive conditions of the liver and primary liver cancers. Ring1 as a member of polycomb-group proteins which play vital roles in carcinogenesis and stem cell self-renewal was increased in HCC patients and promoted proliferation and survival of cancer cell by degrading p53. However, the mechanisms of Ring1 driving the progression of hepatocarcinogenesis have not been elucidated. In this study, forced expression Ring1 and Ring1 siRNA lentiviral vectors were utilized to stably overexpression and silence Ring1 in HPC cell line (WB-F344), respectively. Our finding indicated that overexpression of Ring1 in HPCs promoted colony formation, cell multiplication, and invasion in vitro, conversely depletion of Ring1 repressed the biological functions of HPCs relative to controls. The expression of β-catenin was upregulated in the HPCs with overexpression of Ring1, and the correlation analysis also showed that β-catenin and Ring1 had a significant correlation in the liver cancer tissues and adjacent tissues. The activation of the Wnt/β-catenin signaling pathway significantly increased the expression of liver cancer stem cells related (LCSCs)-related molecular markers CD90 and EpCAM, which led to the transformation of HPCs into LCSCs. Most importantly, the injection of HPCs with overexpressed Ring1 into the subcutaneous of nude mice leads to the formation of poorly differentiated HCC neoplasm. Our findings elucidate that overexpression of Ring1 the activated Wnt/β-catenin signaling pathway and drove the transformation of HPCs into cancer stem cell-like cells, suggesting Ring1 has extraordinary potential in early diagnosis of HCC.

Combined Hepatocellular-Cholangiocarcinoma: Changes in the 2019 World Health Organization Histological Classification System and Potential Impact on Imaging-Based Diagnosis

Combined hepatocellular-cholangiocarcinoma (cHCC-CCA) is a primary liver cancer (PLC) with both hepatocytic and cholangiocytic phenotypes. Recently, the World Health Organization (WHO) updated its histological classification system for cHCC-CCA. Compared to the previous WHO histological classification system, the new version no longer recognizes subtypes of cHCC-CCA with stem cell features. Furthermore, some of these cHCC-CCA subtypes with stem cell features have been recategorized as either hepatocellular carcinomas (HCCs) or intrahepatic cholangiocarcinomas (ICCs). Additionally, distinctive diagnostic terms for intermediate cell carcinomas and cholangiolocarcinomas (previous cholangiolocellular carcinoma subtype) are now recommended. It is important for radiologists to understand these changes because of its potential impact on the imaging-based diagnosis of HCC, particularly because cHCC-CCAs frequently manifest as HCC mimickers, ICC mimickers, or as indeterminate on imaging studies. Therefore, in this review, we introduce the 2019 WHO classification system for cHCC-CCA, illustrate important imaging features characteristic of its subtypes, discuss the impact on imaging-based diagnosis of HCC, and address other important considerations.

CK19-positive Hepatocellular Carcinoma is a Characteristic Subtype

The heterogeneity of hepatocellular carcinoma (HCC) commonly leads to therapeutic failure of HCC. Cytokeratin 19 (CK19) is well acknowledged as a biliary/progenitor cell marker and a marker of tumor stem cell. CK19-positive HCCs demonstrate aggressive behaviors and poor outcomes which including worse overall survival and early tumor recurrence after hepatectomy and liver transplantation. CK19-positive HCCs are resistant to chemotherapies as well as local treatment. This subset of HCC is thought to derive from liver progenitor cells and can be induced by extracellular stimulation such as hypoxia. Besides being a stemness marker, CK19 plays an important role in promoting malignant property of HCC. The regulatory network associated with CK19 expression has been summarized that extracellular stimulations which transmit into cytoplasm through signal transduction pathways (TGF-β, MAKP/JNK and MEK-ERK1/2), further induce important nuclear transcriptional factors (SALL4, AP1, SP1) to activate CK19 promoter. Novel noncoding RNAs are also involved in the regulation of CK19 expression. TGFβR1 becomes a therapeutic target for CK19-positive HCC. In conclusion, CK19 can be a potential biomarker for predicting poor prognosis after surgical and adjuvant therapies. CK19-pisitive HCCs exhibit distinctive molecular profiling, should be diagnosed and treated as a separate subtype of HCCs.

A novel model of liver cancer stem cells developed from induced pluripotent stem cells

Background

Liver cancer is the second most common cause of cancer-related death. Every type of tumours including liver cancer contains cancer stem cells (CSCs). To date, the molecular mechanism regulating the development of liver CSCs remains unknown.

Methods

In this study, we tried to generate a new model of liver CSCs by converting mouse induced pluripotent stem cells (miPSCs) with hepatocellular carcinoma (HCC) cell line Huh7 cells conditioned medium (CM). miPSCs treated with CM were injected into the liver of BALB/c nude mice. The developed tumours were then excised and analysed.

Results

The primary cultured cells from the malignant tumour possessed self-renewal capacity, differentiation potential and tumorigenicity in vivo, which were found rich in liver cancer-associated markers as well as CSC markers.

Conclusions

We established a model of liver CSCs converting from miPS and showed different stages of stemness during conversion process. Our CSC model will be important to assess the molecular mechanisms necessary to develop liver CSCs and could help in defeating liver cancer.

Overexpression of Epcam and CD133 Correlates with Poor Prognosis in Dual-phenotype Hepatocellular Carcinoma

Background: Dual-phenotype hepatocellular carcinoma (DPHCC) is associated with high rate of post-operative recurrence and low rate of survival, which may reflect the post-operative persistence of cancer stem cells (CSCs). Here we explored the potential correlation between DPHCC and expression of CSCs markers. Methods: In this retrospective study, we included 19 patients with DPHCC and 61 patients with non-DPHCC treated in 2015 by liver resection. Paraffin-embedded tumor tissue specimens were analyzed using immunohistochemistry as well as immunofluorescence double-staining. Rates of recurrence-free survival and overall survival were compared between the two groups using the Kaplan-Meier method, and expression of the CSC markers CD133, CD90, and EpCAM were compared using real-time quantitative PCR and western blotting. Results: Overall survival rates were significantly lower for patients with DPHCC than patients with non-DPHCC at 1 year (78.9% vs 93.4%), 2 years (52.6% vs 72.1%), and 3 years (42.1% vs 67.2%) (P = 0.019). Multivariate Cox proportional hazard modeling identified CK19 positivity (P = 0.016) and multiple nodules (P = 0.023) as independent predictors of poor recurrence-free survival. Independent predictors of poor overall survival were CK19 positivity (P = 0.032), Barcelona Clinic Liver Cancer stage C (P = 0.025) and carbohydrate antigen 19-9 (CA19-9) >37 ng/ml (P = 0.016). Expression of CD133 and EpCAM mRNA and protein were significantly higher in DPHCC tissue than non-DPHCC tissue, while CD90 expression was similar between the groups. Conclusions: These results suggest that DPHCC is associated with significantly lower overall survival than non-DPHCC, and that the poor prognosis among DPHCC patients may be related to the presence of CSCs expressing CD133 and EpCAM.

Optimizing curative management of hepatocellular carcinoma

The goal of curative management of hepatocellular carcinoma is to provide the best chance of remission. However, recurrence rates for both local and distant relapse are high. Patient subgroups at higher risk of these events can be identified based on histological patterns that are closely linked to specific molecular subtypes. Patient outcome has improved with more effective therapeutic strategies thanks to technological advances in surgical techniques and percutaneous ablation. The main goal of controlling the cause of liver disease is to decrease distant/late recurrence and prevent deterioration of hepatic function. Ongoing trials testing the combination of neoadjuvant and/or adjuvant regimens with these procedures as well as routine tumour molecular analysis may modify therapeutic algorithms for hepatocellular carcinoma in the future.

A radiomics-based biomarker for cytokeratin 19 status of hepatocellular carcinoma with gadoxetic acid-enhanced MRI

OBJECTIVES

We aimed to develop a radiomics-based model derived from gadoxetic acid-enhanced MR images to preoperatively identify cytokeratin (CK) 19 status of hepatocellular carcinoma (HCC).

METHODS

A cohort of 227 patients with single HCC was classified into a training set (n = 159) and a time-independent validated set (n = 68). A total of 647 radiomic features were extracted from multi-sequence MR images. The least absolute shrinkage and selection operator regression and decision tree methods were utilized for feature selection and radiomics signature construction. A multivariable logistic regression model incorporating clinico-radiological features and the fusion radiomics signature was built for prediction of CK19 status by evaluating area under curve (AUC).

RESULTS

In the whole cohort, 57 patients were CK19 positive and 170 patients were CK19 negative. By combining 11 and 6 radiomic features extracted in arterial phase and hepatobiliary phase images, respectively, a fusion radiomics signature achieved AUCs of 0.951 and 0.822 in training and validation datasets. The final combined model integrated a-fetoprotein levels, arterial rim enhancement pattern, irregular tumor margin, and the fusion radiomics signature, with a sensitivity of 0.818 and specificity of 0.974 in the training cohort and that of 0.769 and 0.818 in the validated cohort. The nomogram based on the combined model showed satisfactory prediction performance in training (C-index 0.959) and validation (C-index 0.846) dataset.

CONCLUSIONS

The combined model based on a fusion radiomics signature derived from arterial and hepatobiliary phase images of gadoxetic acid-enhanced MRI can be a reliable biomarker for CK19 status of HCC.

KEY POINTS

• Arterial rim enhancement pattern and irregular tumor margin on hepatobiliary phase on gadoxetic acid-enhanced MRI can be useful for evaluating CK19 status of HCC. • A radiomics-based model performed better than the clinico-radiological model both in training and validation datasets for predicting CK19 status of HCC. • The nomogram based on the fusion radiomics signature can be easily used for CK19 stratification of HCC.

Hepatocellular carcinoma in non-alcoholic fatty liver disease (NAFLD) - pathological evidence for a predominance of steatohepatitic inflammatory non-proliferative subtype

OBJECTIVES

This study evaluated clinical and pathological aspects of patients with hepatocellular carcinoma (HCC) secondary to non-alcoholic fatty liver disease (NAFLD) and related these factors to immunohistochemical markers representative of the proliferative class.

METHODS

We evaluated 35 HCC nodules from 21 patients diagnosed with NAFLD undergoing liver resection (n=12) or liver transplantation (n=8) or both (n=1). Demographic, clinical and biochemical data were compared to histological features and to immunohistochemical reactivity for K19 and Ki-67.

RESULTS

Cirrhosis was present in 58% of patients. Ages ranged from 50 to 77 years. Sixteen patients (76%) were male and had type 2 diabetes mellitus, 81% had arterial hypertension, and 90% had BMI above 25 kg/m². Alpha-fetoprotein levels were normal in 62% of patients. Twenty-five (70%) nodules were diagnosed as "steatohepatitic HCC". Only 32% of the nodules presented high levels of Ki-67 (>10%) and/or K19 (>5%), although 63% were poorly differentiated (G.3/G.4) according to Edmondson & Steiner grading system. K19 positivity (>5%) was associated with higher degree of intratumoral inflammation (G.2/G.3), and with fibrosis, both at the center of the tumor and at the tumor front, whereas Ki-67 positivity (>10%) was associated with ballooning of neoplastic cells and occurred in more than 70% in non-cirrhotic patients.

CONCLUSION

NAFLD-related HCC was found in non-cirrhotic patients in 42% of cases, alpha-fetoprotein level was normal in 63% and "steatohepatitic HCC" was the predominant histological type. Immunoexpression of K19 and/or Ki-67 occurred in 32% of the nodules and were associated with intratumoral inflammation and ballooning, suggesting that HCC in MtS may be preferentially "an inflammatory, non-proliferative subtype of HCC".

Overview of organic anion transporters and organic anion transporter polypeptides and their roles in the liver

Organic anion transporters (OATs) and organic anion transporter polypeptides (OATPs) are classified within two SLC superfamilies, namely, the SLC22A superfamily and the SLCO superfamily (formerly the SLC21A family), respectively. They are expressed in many tissues, such as the liver and kidney, and mediate the absorption and excretion of many endogenous and exogenous substances, including various drugs. Most are composed of 12 transmembrane polypeptide chains with the C-terminus and the N-terminus located in the cell cytoplasm. OATs and OATPs are abundantly expressed in the liver, where they mainly promote the uptake of various endogenous substrates such as bile acids and various exogenous drugs such as antifibrotic and anticancer drugs. However, differences in the locations of glycosylation sites, phosphorylation sites, and amino acids in the OAT and OATP structures lead to different substrates being transported to the liver, which ultimately results in their different roles in the liver. To date, few articles have addressed these aspects of OAT and OATP structures, and we study further the similarities and differences in their structures, tissue distribution, substrates, and roles in liver diseases.

Molecular and histological correlations in liver cancer

Hepatocellular carcinoma (HCC) is a highly heterogeneous cancer, both at the molecular and histological level. High-throughput sequencing and gene expression profiling have identified distinct transcriptomic subclasses and numerous recurrent genetic alterations; several HCC subtypes characterised by histological features have also been identified. HCC phenotype appears to be closely related to particular gene mutations, tumour subgroups and/or oncogenic pathways. Non-proliferative tumours display a well-differentiated phenotype. Among this molecular subgroup, CTNNB1-mutated HCCs constitute a homogeneous subtype, exhibiting cholestasis and microtrabecular and pseudoglandular architectural patterns. Another non-proliferative subtype has a gene expression pattern similar to that of mature hepatocytes (G4) and displays a steatohepatitic phenotype. In contrast, proliferative HCCs are most often poorly differentiated, and notably include tumours with progenitor features. A novel morphological variant of proliferative HCC - designated "macrotrabecular-massive" - was recently shown to be associated with angiogenesis activation and poor prognosis. Altogether, these findings may help to translate our knowledge of HCC biology into clinical practice, resulting in improved precision medicine for patients with this highly aggressive malignancy. This manuscript reviews the most recent data in this exciting field, discussing future directions and challenges.

Identification of hedgehog signaling as a potential oncogenic driver in an aggressive subclass of human hepatocellular carcinoma: A reanalysis of the TCGA cohort

Hepatocellular carcinoma (HCC) is a heterogeneous disease and the second most common cause of cancer-related death worldwide. Marked developments in genomic technologies helped scientists to understand the heterogeneity of HCC and identified multiple HCC-related molecular subclasses. An integrative analysis of genomic datasets including 196 patients from The Cancer Genome Atlas (TCGA) group has recently reported a new HCC subclass, which contains three subgroups (iCluster1, iCluster2, and iCluster3). However, the transcriptional molecular characteristics underlying the iClusters have not been thoroughly investigated. Herein, we identified a more aggressive subset of HCC patients in the iCluster1, and re-clustered the TCGA samples into novel HCC subclasses referred to as aggressive (Ag), moderate-aggressive (M-Ag), and less-aggressive (L-Ag) subclasses. The Ag subclass had a greater predictive power than the TCGA iCluster1, and a higher level of alpha fetoprotein, microscopic vascular invasion, immune infiltration, isocitrate dehydrogenase 1/2 mutation status, and a worse survival than M-Ag and L-Ag subclasses. Global transcriptomic analysis showed that activation of hedgehog signaling in the Ag subclass may play key roles in tumor development of aggressive HCC. GLI1, a key transcriptional regulator of hedgehog signaling upregulated in the Ag subclass, was correlated with poor prognosis of HCC, and may be a potential prognostic biomarker and therapeutic target for Ag subclass HCC patients.

A Point-based Histologic Scoring System for Hepatocellular Carcinoma Can Stratify Risk of Posttransplant Tumor Recurrence

Eligibility for liver transplant is most commonly decided by measuring tumor size and number on radiographic imaging. However, this method often underestimates the extent of disease. Evaluation of tumor histology has been shown to improve risk stratification when compared with imaging-based transplant criteria, but the World Health Organization (WHO) guidelines for grading hepatocellular carcinoma (HCC) are imprecise and require subjective interpretation by the pathologist. We performed a retrospective analysis of 190 explanted livers containing HCC and correlated histologic features with posttransplant recurrence to formulate a three-tiered, point-based scoring system that categorizes tumors as having a low, intermediate, or high risk of recurrence. Our Recurrence Risk Assessment Score (RRAS) evaluates tumor architecture and specific cytologic features-nuclear pleomorphism, cytoplasmic amphophilia, and nuclear-to-cytoplasmic ratio-showing superior stratification of HCC recurrence risk compared with imaging criteria and grade assigned by WHO methodology. Stratifying tumors using RRAS criteria, the rate of recurrence after transplant was 0% among low-risk tumors (compared with 3% of well-differentiated tumors), 12% among intermediate-risk tumors (compared with 15% of moderately differentiated tumors), and 54% among high-risk tumors (compared with 29% of poorly differentiated tumors). Receiver operating characteristic analysis shows significantly improved performance of RRAS criteria in predicting HCC recurrence compared with WHO grade (area under curve of 0.841 and 0.671, respectively; P=0.0061). Our results indicate that evaluation of tumor histology offers superior prediction of recurrence risk following liver transplantation compared with radiographic criteria, and that the RRAS system better stratifies recurrence risk compared with HCC grading by WHO methodology.

Heterogeneity of Epigenetic and Epithelial Mesenchymal Transition Marks in Hepatocellular Carcinoma with Keratin 19 Proficiency

OBJECTIVE

Keratin 19 (K19) expression is a potential predictor of poor prognosis in patients with hepatocellular carcinoma (HCC). To clarify the feature of K19-proficient HCC, we traced epigenetic footprints in cultured cells and clinical materials.

PATIENTS AND METHODS

In vitro, KRT19 promoter methylation was analyzed and 5-aza-2'-deoxycytidine with trichostatin A (TSA) treatment was performed. Among 564 surgically resected HCCs, the clinicopathological relevance of K19-proficent HCCs was performed in comparison with hepatocytic (HepPar-1 and arginase-1), epithelial-mesenchymal transition (E-cadherin and vimentin), biliary differentiation-associated (K7 and NOTCH-1) markers, and epigenetic markers (KRT19 promoter/long interspersed nucleotide element-1 [LINE-1] methylation status).

RESULTS

KRT19 promoter methylation was clearly associated with K19 deficiency and 5-aza-2'-deoxycytidine with TSA treatment-stimulated K19 re-expression, implicating DNA methylation as a potential epigenetic process for K19 expression. After excluding HCCs with recurrence, TNM stage as IIIB or greater, preoperative therapy, transplantation, and combined hepatocellular cholangiocarcinoma, we assessed 125 of 564 HCC cases. In this cohort, K19 expression was found in 29 HCCs (23.2%) and corresponded with poor survival following surgery (p = 0.025) and extrahepatic recurrence-free survival (p = 0.017). Compared with K19-deficient HCCs, lower KRT19 promoter methylation level was observed in K19-proficient HCCs (p < 0.0001). Conversely, HCC with genome-wide LINE-1 hypermethylation was frequently observed in K19-proficient HCCs (p = 0.0079). Additionally, K19 proficiency was associated with K7 proficiency (p = 0.043), and reduced E-cadherin and HepPar-1 expression (p = 0.043 and p < 0.0001, respectively).

CONCLUSIONS

K19-proficient HCC exhibited poor prognosis owing to extrahepatic recurrence, with molecular signatures differing from those in conventional cancer stem cells, providing novel insights of the heterogeneity underlying tumor development.

Magnetic resonance texture analysis for the identification of cytokeratin 19-positive hepatocellular carcinoma

PURPOSE

To investigate potential findings associated with cytokeratin 19 (CK19)-positive HCC, with special emphasis on MR texture analysis.

MATERIALS AND METHODS

Forty-eight patients with CK19-negative HCC and 38 patients with CK19-positive were retrospectively evaluated by texture analysis based on conventional MRI. Clinicalpathological characteristics, conventional MR imaging findings, and the MR texture analysis contained of 2415 texture features in the seven conventional sequences were compared. Significant features for differentiating were identified by univariate and multivariate analyses. Receiver operating characteristic analyses of the significant findings were performed and compared to evaluate their diagnostic performance.

RESULTS

There was no significant difference between the top1 texture feature (three-dimensional standard deviation separation of intensity on T2-weighted original images, abbreviated as: StdSeparation 3D) and the combined top1-6 feature in identifying CK19-positive HCC(P = 0.660). Univariate and multivariate analyses indicated that serum alpha-fetoprotein (AFP) level ≥400 ng/mL(P = 0.013), arterial rim enhancement(P = 0.005), and StdSeparation 3D texture character(P = 0.002) were independent variables associated with CK19-positive HCCs. The combination of the three indices showed a better performance than AFP level(P = 0.0028), arterial rim enhancement(P < 0.0001), and their combination(P = 0.0098); while no significantly better than the StdSeparation 3D texture character alone(P = 0.0788). An acceptable discrimination(AUC = 0.765) with both sensitivity and specificity greater than 75% was achieved for StdSeparation 3D texture character.

CONCLUSION

Serum AFP level ≥400 ng/mL, arterial rim enhancement, and the StdSeparation 3D texture character were independently associated with CK19-positive HCC. The StdSeparation 3D texture character may be a reliable imaging biomarker which can improve the diagnostic performance.

Update on hepatocellular carcinoma: Pathologists’ review

Histopathologic diversity and several distinct histologic subtypes of hepatocellular carcinoma (HCC) are well-recognized. Recent advances in molecular pathology and growing knowledge about the biology associated with distinct histologic features and immuno-profile in HCC allowed pathologists to update classifications. Improving sub-classification will allow for more clinically relevant diagnoses and may allow for stratification into biologically meaningful subgroups. Therefore, immuno-histochemical and molecular testing are not only diagnostically useful, but also are being incorporated as crucial components in predicting prognosis of the patients with HCC. Possibilities of targeted therapy are being explored in HCC, and it will be important for pathologists to provide any data that may be valuable from a theranostic perspective. Herein, we review and provide updates regarding the pathologic sub-classification of HCC. Pathologic diagnostic approach and the role of biomarkers as prognosticators are reviewed. Further, the histopathology of four particular subtypes of HCC: Steatohepatitic, clear cell, fibrolamellar and scirrhous - and their clinical relevance, and the recent consensus on combined HCC-cholangiocarcinoma is summarized. Finally, emerging novel biomarkers and new approaches to HCC stratification are reviewed.

Prognostic Implications of Arginase and Cytokeratin 19 Expression in Hepatocellular Carcinoma After Curative Hepatectomy: Correlation With Recurrence-Free Survival

BACKGROUND

The prognostic value of arginase expression in hepatocellular carcinoma (HCC) has been evaluated previously. However, no clear distinction exists yet on the role of arginase-1 as a predictor of recurrence in HCC. Cytokeratin 19 (CK19), a cholangiocytic marker, is occasionally expressed in HCC, but the combination of arginase-1 and CK19 expression has never been evaluated. The aim of the study was to investigate the usefulness of arginase-1 and CK19 expression alone and in combination for prognosticating HCC tumor recurrence after surgical resection.

METHODS

Tissue sections from 112 HCCs were immunostained using an automated method and the mouse monoclonal arginase-1 and mouse monoclonal CK19 antibodies. The clinicopathologic variables, including alpha-fetoprotein levels, viral hepatitis, cirrhosis, tumor size, grade and number, vascular invasion, tumor-node-metastasis (TNM) stage, and tumor recurrence and survival, were obtained from each patient's medical records. The variables were assessed for correlation with the immunochemical results. Comparisons of recurrence-free and overall survival were performed using univariate and multivariate regression analyses. A P-value of ≤ 0.05 was considered statistically significant.

RESULTS

High arginase-1 expression was detected in the HCCs of 93 patients (83%), whereas CK19 was positive in the HCCs of only 19 patients (17%). In the univariate analyses, CK19 positivity in HCC was associated with decreased recurrence-free survival compared with CK19-negative HCC (P = 0.0002). Arginase-1 expression was associated with decreased recurrence-free survival when patients were stratified over advanced TNM stage and presence of vascular invasion. The combination of arginase-1 and CK19 expression was a better predictor of decreased recurrence-free survival (P = 0.00008). Arginase-1/CK19 expressions when combined with multiple tumors, TNM stage and vascular invasion were also associated with decreased recurrence-free survival. In the multivariate analysis, tumor grade, CK19 and arginase-1/CK19 expressions were identified as independent prognostic indicators for decreased recurrence-free survival.

CONCLUSION

Arginase-1 and CK19 combination immunoreactivity is a potential biomarker of adverse prognosis in HCC, correlating with the presence of multiple tumors, vascular invasion and advanced stage.

Diverse perspectives to address for the future treatment of heterogeneous hepatocellular carcinoma

Hepatocellular carcinomas (HCCs), which often arise from chronic liver damage, have poor conditional 5-year survival and are recognized as heterogeneous tumors. Considering the heterogeneity of HCCs, diverse perspectives need to be addressed for treating such tumors, besides the findings of conventional imaging modalities and tumor markers. Data from the latest technologies, such as liquid biopsy, and the detection of the presence of cancer cells with stem/progenitor cell markers, gene mutations and diverse pathways, crosstalk with immune cells and cancer-associated fibroblasts, and mechanisms of epithelial–mesenchymal transition provide diverse lines of information. Integration of these data with clinical data might be necessary to develop effective therapies for precision medicine. Here, we review several aspects of dealing with the complexity of heterogeneous HCCs.

YAP and TAZ Heterogeneity in Primary Liver Cancer: An Analysis of Its Prognostic and Diagnostic Role

Primary liver cancer comprises a diverse group of liver tumors. The heterogeneity of these tumors is seen as one of the obstacles to finding an effective therapy. The Hippo pathway, with its downstream transcriptional co-activator Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ), has a decisive role in the carcinogenesis of primary liver cancer. Therefore, we examined the expression pattern of YAP and TAZ in 141 patients with hepatocellular carcinoma keratin 19 positive (HCC K19⁺), hepatocellular carcinoma keratin 19 negative (HCC K19⁻), combined hepatocellular–cholangiocarcinoma carcinoma (cHCC-CCA), or cholangiocarcinoma (CCA). All cHCC-CCA and CCA patients showed high expression levels for YAP and TAZ, while only some patients of the HCC group were positive. Notably, we found that a histoscore of both markers is useful in the challenging diagnosis of cHCC-CCA. In addition, positivity for YAP and TAZ was observed in the hepatocellular and cholangiocellular components of cHCC-CCA, which suggests a single cell origin in cHCC-CCA. Within the K19⁻ HCC group, our results demonstrate that the expression of YAP is a statistically significant predictor of poor prognosis when observed in the cytoplasm. Nuclear expression of TAZ is an even more specific and independent predictor of poor disease-free survival and overall survival of K19⁻ HCC patients. Our results thus identify different levels of YAP/TAZ expression in various liver cancers that can be used for diagnostics.

Hepatitis B virus X reduces hepatocyte apoptosis and promotes cell cycle progression through the Akt/mTOR pathway in vivo

Hepatitis B virus X (HBx), a viral onco-protein encoded by HBV, can promote oncogenesis of HCC. However, the mechanism of HBx in hepatocarcinogenesis is still unclear. In this study, we establish a new mouse model with normal immune system to investigate the role of HBx and its functional mechanisms under normal immune function. The animal model was established by injecting HBx-EGFP-14-19 cells into the hepatic portal vein of KM mice. To verify the mouse model, the expression of HBx in the liver tissue of mice was detected by qRT-PCR, western blotting and immunohistochemistry. The apoptosis index was calculated using the terminal deoxynucleotidyl transferase-dUTP nick-end labeling (TUNEL) assay, and the expression levels of apoptosis-related and cell cycle-related factors were measured. Moreover, expression of proteins in the protein kinase B/mammalian target of rapamycin (Akt/mTOR) signaling pathway was detected in HBx-EGFP-14-19 mice with and without use of an Akt inhibitor. The results showed the HBx was successfully overexpressed in liver of KM mice. After overexpressing HBx, the apoptosis index was downregulated in HBx-EGFP-14-19 liver tissue, and the expression levels of caspase-9 and Bad were reduced, but Bcl-xl was increased in HBx-EGFP-14-19 liver tissue. Overexpression of HBx increased the expression of the cyclin-dependent kinase 2 (CDK2), cyclinD1 and cyclinE. Moreover, compared with the low-level HBx group, p-Akt and p-mTOR were increased in the livers of mice with high levels of HBx. However, inactivation of apoptosis by overexpression of HBx was abolished by the treatment with an Akt inhibitor. These results indicate that HBx can induce anti-apoptosis mechanisms in hepatocytes in vivo, which is mediated by the Akt/mTOR signaling pathway.

MRC-5 Cancer-associated Fibroblasts Influence Production of Cancer Stem Cell Markers and Inflammation-associated Cell Surface Molecules, in Liver Cancer Cell Lines

Background: Current opinion suggests that expansion of cancer stem cells (CSCs) and activation of pro-tumoral inflammation cascade correlate with cancer progression. Materials and methods: We explored the possible contributions of MRC-5 cancer-associated fibroblasts to the expression profiles of CSC markers and inflammation-associated cell surface molecules. The liver cancer cell lines Bel-7402, SMMC-7721, MHCC-LM3, and HepG2 cultured in conditioned medium (CM) from MRC-5 served as test groups, whereas the liver cancer cell lines cultured in normal medium served as control groups. Results: Flow cytometry revealed that the proportions of CD90⁺ cells were significantly higher in MHCC-LM3-(MRC-5)-CM and HepG2-(MRC-5)-CM cells, and moderately higher in Bel-7402-(MRC-5)-CM and SMMC-7721-(MRC-5)-CM cells, than in controls. The CD90⁺/CD45^- proportions were elevated in Bel-7402-(MRC-5)-CM and MHCC-LM3-(MRC-5)-CM cells, but reduced in HepG2-(MRC-5)-CM and SMMC-7721-(MRC-5)-CM cells, as compared to controls. Western blotting indicated that Nanog was downregulated in MHCC-LM3-(MRC-5)-CM and HepG2-(MRC-5)-CM cells, compared to controls; that POU5F1 (OCT4/3) was downregulated in MHCC-LM3-(MRC-5)-CM, but upregulated in Bel-7402-(MRC-5)-CM and HepG2-(MRC-5)-CM cells, compared to controls, and that CK19 was upregulated in Bel-7402-(MRC-5)-CM and MHCC-LM3-(MRC-5)-CM cells, compared to controls. Proportions of cells expressing Toll-like receptor-1⁺ (TLR1) and TLR4 were significantly higher in MHCC-LM3-(MRC-5)-CM cells, and moderately higher in HepG2-(MRC-5)-CM cells, than controls. However, the TLR1⁺ and TLR4⁺ proportions were lower in Bel-7402-(MRC-5)-CM and SMMC-7721-(MRC-5)-CM cells than controls. Proportions of CD25⁺ cells were reduced in HepG2-(MRC-5)-CM and SMMC-7721-(MRC-5)-CM cells, but elevated in MHCC-LM3-(MRC-5)-CM and Bel-7402-(MRC-5)-CM cells, compared to controls. Proportion of CD61⁺ cells was higher in liver cancer cells cultured in MRC-5-CM than in controls. Proportion of CD14⁺ cells was lower in HCC cells cultured in MRC-5-CM than in controls. Conclusion: MRC-5 extensively affected the production of CSC markers and inflammation-associated cell surface molecules. Tumor-targeting molecular therapies should consider these findings.

EpCAM- and/or NCAM-Expressing Hepatocellular Carcinoma in Which Behavior of Hepatic Progenitor Cell Marker-Positive Cells Are Followed

Hepatic progenitor cell (HPC) marker-positive hepatocellular carcinomas (HCCs) have recently been extensively analyzed, and their prognosis has been reported as poor compared to HPC marker-negative HCCs. However, previous studies have analyzed the existence of HPC marker-positive cancer cells only in primary lesions, as well as the recurrence rate and prognosis of such tumors. Here, we are the first to report the behavior of HPC marker-positive cancer cells during vascular invasion and metastasis of an HCC. We concurrently analyzed EpCAM- and/or NCAM-expressing cancer cells in the primary, vascular invasion, and metastatic lesions of an HCC. An HCC which includes EpCAM- and/or NCAM-expressing cancer cells has not been previously reported. EpCAM- and/or NCAM-positive cancer cells invaded the vessels and formed heterogeneous populations of these HPC marker-positive cancer cells with HPC marker-negative cancer cells. The frequency of HPC marker-positive cancer colonies and cells in vessels was higher than that in the primary HCC. In the metastatic lesions, EpCAM-positive cancer cells were more frequently detected than NCAM-positive cancer cells, indicating that EpCAM may be more important than NCAM for cancer cell settlement in the metastatic lesions. Furthermore, bigger metastatic tumors tended to include HPC marker-positive cancer cells, suggesting that HPC marker-positive cancer cells have a growth advantage in the metastatic lesions. These results showed that HPC marker-positive cancer cells would be important for vascular invasion and metastasis and suggested that HPC marker-positive cancer cells are an important target in HCC treatment.

HBV induces different responses of the hepatocytes and oval cells during HBV-related hepatic cirrhosis

Although hepatitis B virus (HBV)-related cirrhosis and hepatocellular carcinoma (HCC) cause a sever health problem worldwide, the underlying mechanisms are still elusive. This study aimed to investigate the responses of different cell types isolated from HBV transgenic mice. A cross-sectional set of hepatocytes and oval cells were obtained from HBV transgenic and control mice. Flow cytometry, immunohistochemistry and microarray were applied to investigate the cell biology of the hepatocytes and oval cells. Our results showed that HBV induced the proliferation of both cell oval cells and hepatocytes, and induced cell death of HBV hepatocytes while had minimal effects on oval cells. Further molecular and pathways analysis identified some genes and signaling pathways may be responsible for the different responses between oval cells and hepatocytes. In addition, analyses of selectively ten genes by IHC staining in human samples were consistent with microarray data. In summary, HBV transgenic mice is a useful model for studying the biological behaviors of oval cells affected by HBV and HBV-cirrhosis. Also, our results help better understand the mechanisms of HBV induced cirrhosis, and provide novel progenitor markers or prognostic/therapeutic markers.

Subclassification and Detection of New Markers for the Discrimination of Primary Liver Tumors by Gene Expression Analysis Using Oligonucleotide Arrays

Background/Aims

The failure to correctly differentiate between intrahepatic cholangiocarcinoma (CC) and hepatocellular carcinoma (HCC) is a significant clinical problem, particularly in terms of the different treatment goals for both cancers. In this study a specific gene expression profile to discriminate these two subgroups of liver cancer was established and potential diagnostic markers for clinical use were analyzed.

Methods

To evaluate the gene expression profiles of HCC and intrahepatic CC, Oligonucleotide arrays (AffymetrixU133A) were used. Overexpressed genes were checked for their potential use as new markers for discrimination and their expression values were validated by reverse transcription polymerase chain reaction and immunohistochemistry analyses.

Results

695 genes/expressed sequence tags (ESTs) in HCC (245 up-/450 down-regulated) and 552 genes/ESTs in CC (221 up-/331 down-regulated) were significantly dysregulated (p＜0.05, fold change >2, ≥70%). Using a supervised learning method, and one-way analysis of variance a specific 270-gene expression profile that enabled rapid, reproducible differentiation between both tumors and nonmalignant liver tissues was established. A panel of 12 genes (e.g., HSP90β, ERG1, GPC3, TKT, ACLY, and NME1 for HCC; SPT2, T4S3, CNX43, TTD1, HBD01 for CC) were detected and partly described for the first time as potential discrimination markers.

Conclusions

A specific gene expression profile for discrimination of primary liver cancer was identified and potential marker genes with feasible clinical impact were described.

Update on the pathology of liver neoplasms

Many advances have developed in the pathology of liver tumors in the recent decade. Examples of these advances include the use of glutamine synthetase in the diagnosis of focal nodular hyperplasia, subtyping of hepatocellular adenomas using molecular and immunohistochemical methods, the unraveling of the fusion transcript between the DNAJB1 gene and the PRKACA gene in fibrolamellar carcinoma, and the more unified classification and terminology in intrahepatic bile duct tumors and their precursor lesions. Nevertheless, challenges still remain, e.g., the differential diagnosis between well-differentiated hepatocellular carcinoma and hepatocellular adenoma; distinction among poorly differentiated hepatocellular carcinoma, cholangiocarcinoma and metastatic neoplasm; terminology of the combined hepatocellular carcinoma-cholangiocarcinoma, etc. This review aims to address updates in the pathologic diagnosis and clinical relevance of tumors of the liver and intrahepatic bile ducts in adults and their differential diagnosis and diagnostic pitfalls.

1α,25-Dihydroxyvitamin D3 inhibits aflatoxin B1-induced proliferation and dedifferentiation of hepatic progenitor cells by regulating PI3K/Akt and Hippo pathways

Hepatic progenitor cells (HPCs) might be the origin of hepatocellular carcinoma. 1α,25-Dihydroxyvitamin D3 (1,25(OH)₂D₃) (VD3) has been documented as an anticancer agent for various cancers. However, the potential effect of VD3 on the proliferation and malignant transformation of HPCs induced by aflatoxin B1 (AFB1) has not been determined. In this study, we found that AFB1 exhibited the stimulative effects on the proliferation, dedifferentiation and invasion of HPCs via activating AKT pathway but turning off Hippo pathway, which were terminated when VD3 was used in combination with AFB1. Furthermore, in AFB1-induced liver damage mouse model, VD3 also showed protective effect by reducing HPCs population. Together, these preclinical data not only provide a newly identified mechanism by which AFB1 affects HPCs but also strengthen the idea of developing VD3 as an anticancer agent.

Primary Liver Cancers-Part 1: Histopathology, Differential Diagnoses, and Risk Stratification

Hepatocellular carcinoma (HCC) and cholangiocarcinoma (CC) are the 2 most common primary malignant liver tumors, with hepatocellular and bile ductular differentiation, respectively. This article reviews the key histopathological findings of these 2 primary liver cancers and includes a review of the role of ancillary testing for differential diagnosis, risk stratification according to the American Joint Committee on Cancer (AJCC) staging recommendation, and a review of precancerous lesions. A literature review was conducted to identify articles with information relevant to precancerous precursors, current histopathological classification, ancillary testing, and risk stratification of primary malignant liver tumors. The histomorphology of normal liver, preinvasive precursors, primary malignancies, and morphological variants, and the utilization of ancillary tests for the pathological diagnosis are described. Dysplastic nodules are the preinvasive precursors of HCC, and intraductal papillary neoplasms of bile ducts and biliary intraepithelial neoplasia are the preinvasive precursors of CC. Benign liver nodules including focal nodular hyperplasia and adenomas are included in this review, since some forms of adenomas progress to HCC and often they have to be differentiated from well-differentiated HCC. A number of morphological variants of HCC have been described in the literature, and it is necessary to be aware of them in order to render the correct diagnosis. Risk stratification is still dependent on the AJCC staging system. The diagnosis of primary liver carcinomas is usually straightforward. Application of the appropriate ancillary studies aids in the differential diagnosis of difficult cases. The understanding of the carcinogenesis of these malignancies has improved with the standardization of the pathological classification of preinvasive precursors and studies of the molecular pathogenesis. Risk stratification still depends on pathological staging.

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).

Clinical outcome of hepatocellular carcinoma can be predicted by the expression of hepatic progenitor cell markers and serum tumour markers

The high heterogeneity of hepatocellular carcinomas (HCCs) complicates stratification of HCC patients for treatment. Therefore, it is necessary to establish a comprehensive panel of HCC biomarkers related to tumour behaviour and cancer prognosis. Resected HCCs from 251 patients were stained for hepatic progenitor cell (HPC) markers epithelial cell adhesion molecule (EpCAM), neural cell adhesion molecule (NCAM), delta-like 1 homolog (DLK1), and cytokeratin 19 (CK19). Staining patterns were analysed for their prognostic association with relapse-free survival and overall survival. α-Fetoprotein (AFP), lectin-reactive α-fetoprotein (AFP-L3), and des-γ-carboxy prothrombin (DCP) were assessed as indicators of HPC protein expression. Expression pattern of HPC markers correlated with tumour malignancy indicated by high AFP/AFP-L3 serum levels, more frequent vascular invasion, and poorer tumour differentiation. EpCAM expression, DCP ≥300 mAU/ml, age ≥60, and Child-Pugh score grade B or C were independent prognostic factors of poor outcome and were used in a new scoring system for HCC prognosis after operation. Expression of two or more HPC markers was a significant predictor of poor HCC outcome and serum levels of AFP/AFP-L3 correlated with the expression of HPC proteins. Our study paved the way for further elucidation of the association among HPC markers, serum tumour markers, and HCC clinical outcome for precision medicine.

Keratin 19 Expression in Hepatocellular Carcinoma Is Regulated by Fibroblast-Derived HGF via a MET-ERK1/2-AP1 and SP1 Axis

Keratin (KRT) 19 is a poor prognostic marker for hepatocellular carcinoma (HCC); however, regulatory mechanisms underlying its expression remain unclear. We have previously reported the presence of fibrous tumor stroma in KRT19-positive HCC, suggesting that cross-talk between cancer-associated fibroblasts (CAF) and tumor epithelial cells could regulate KRT19 expression. This was investigated in this study using an in vitro model of paracrine interaction between HCC cell lines (HepG2, SNU423) and hepatic stellate cells (HSC), a major source of hepatic myofibroblasts. HSCs upregulated transcription and translation of KRT19 in HCC cells via paracrine interactions. Mechanistically, hepatocyte growth factor (HGF) from HSCs activated c-MET and the MEK-ERK1/2 pathway, which upregulated KRT19 expression in HCC cells. Furthermore, AP1 (JUN/FOSL1) and SP1, downstream transcriptional activators of ERK1/2, activated KRT19 expression in HCC cells. In clinical specimens of human HCC (n = 339), HGF and KRT19 protein expression correlated with CAF levels. In addition, HGF or MET protein expression was associated with FOSL1 and KRT19 expression and was found to be a poor prognostic factor. Analysis of data from The Cancer Genome Atlas also revealed KRT19 expression was closely associated with CAF and MET-mediated signaling activities. These results provide insights into the molecular background of KRT19-positive HCC that display an aggressive phenotype.Significance: These findings reveal KRT19 expression in hepatocellular carcinoma is regulated by cross-talk between cancer-associated fibroblasts and HCC cells, illuminating new therapeutic targets for this aggressive disease. Cancer Res; 78(7); 1619-31. ©2018 AACR.

CK7/CK19 index: A potential prognostic factor for postoperative intrahepatic cholangiocarcinoma patients

BACKGROUND AND OBJECTIVES

Frequently aberrant expression of cytokeratin 7 (CK7) and cytokeratin 19 (CK19) have been observed in several human cancers. In this retrospective study, we aimed at investigating the prognostic significance of CK7 and CK19 in intrahepatic cholangiocarcinoma (ICC).

METHODS

Immunohistochemistry was performed to assess CK7 and CK19 expression on tissue microarrays in training cohort enrolling 214 ICC patients and validation cohort comprising 108 ICC patients. Kaplan-Meier analysis, Cox's proportional hazards regression, and nomogram were applied to evaluate the prognostic significance of both CKs.

RESULTS

Both CK7 and CK19 expression were significantly up-regulated in ICC compared to their non-tumor counterparts, and positively correlated with aggressive tumor phenotypes, like lymph node metastasis and larger tumor size. Furthermore, high expression of either CK7 or CK19 predicted a significantly dismal postoperative survival. Integrated analysis of CK7 and CK19 expression was identified as a better indicator for survival probability. Notably, the nomogram integrating CK7/CK19 index had a perfect prognostic performance as compared with current staging systems. The results were further confirmed in the validation cohort.

CONCLUSIONS

CK7/CK19 index was an independent adverse prognostic factor for ICC patients' survival, and may be helpful to improve postoperative risk stratification and individualized treatment strategies.

Evaluating clinical and prognostic implications of Glypican-3 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most deadly cancers worldwide. In patients with HCC, histopathogical differentiation is an important indicator of prognosis; however, because determination of HCC differentiation is difficult, the recently described immunohistochemical (IHC) marker glypican3 (GPC3) might assist in HCC prognostication.The goal of our study was to investigate GPC3's IHC staining pattern and define the relationship between its expression and patients' clinicopathologic features and overall survival. We retrieved clinical parameters from 101 pathologically diagnosed HCC patients' medical records and classified these patients into 4 clinical score categories (0–3) based on increasing GPC3 staining intensity and the percentage of stained tumor cells in their resection and biopsy specimens. Histopathological samples were well, moderately, and poorly differentiated in 33, 22, and 12 patients, respectively, and the GPC3 expression rate was 63%, 86%, and 92%,respectively. The median overall survival was 49.9 months (confidence interval (CI): 35.3–64.6 months) for clinical scores 0–1 and 30.7 months (CI: 19.4–41.9 months) for clinical scores 2–3. This difference was not statistically significant (P = .06) but showed a strong trend. In conclusion, a greater GPC3 expression is associated with a worse HCC prognosis and may be a promising prognostic marker.

The Prognostic Value of Cytokeratin and Sal-Like Protein 4 Expression in Hepatocellular Carcinoma and Intra-Hepatic Cholangiocarcinoma in Taiwan

Background: We previously reported that modulation of cytokeratin18 induces pleomorphism of liver cells, higher cell motility, and higher drug sensitivity to sorafenib treatment of hepatoma cells. These relationships were established by in vitro experiments. The aim of this study was to determine the in vivo association between cytokeratin expression and tumor behavior, as well as cancer stem cells of hepatocellular carcinoma and intra-hepatic cholangiocarcinoma in Taiwan. Methods: Cytokeratins and sal-like protein 4 expression was determined in 83 hepatocellular carcinoma and 30 intra-hepatic cholangiocarcinoma specimens by immunohistochemistry. The relationship between cytokeratins and sal-like protein 4 expression with hepatitis virus infection, clinicopathologic factors, and survival was analyzed. Further, the correlation among cytokeratins and sal-like protein 4 expression was studied. Results: In addition to cytokeratin8/18, the expression of cytokeratin7/19 and sal-like protein 4 was noted in hepatocellular carcinoma; however, only cytokeratin19 expression had a significant correlation with poor overall survival and poor disease-free survival. The expression of cytokeratins and sal-like protein 4 was not correlated with hepatitis virus infection. The expression of cytokeratin19, but not 7, 8, and 18, was correlated with sal-like protein 4 expression in hepatocellular carcinoma. Cytokeratin7 expression was decreased and the sal-like protein 4 expression was absent in all 30 intra-hepatic cholangiocarcinoma cases. The expression of cytokeratins had not statistically significant correlation with overall and disease-free survival in patients with intra-hepatic cholangiocarcinoma. Conclusions: The expression of cytokeratin19 was associated with sal-like protein 4 expression, as well as poor overall and disease-free survival in hepatocellular carcinoma patients in Taiwan.

Surface markers of liver cancer stem cells and innovative targeted-therapy strategies for HCC

Liver cancer stem cells (LCSCs) have important roles in the occurrence, development, recurrence, therapy resistance and metastasis of hepatocellular carcinoma (HCC). Therefore, intensive studies are undergoing to identify the mechanisms by which LCSCs contribute to HCC invasion and metastasis, and to design more efficient treatments for this disease. With continuous efforts in LCSC research over the years, therapies targeting LCSCs are thought to have great potential for the clinical treatment and prognosis of liver cancer. Novel LCSC surface markers are continuously discovered and several have been used in targeted therapies to reduce HCC recurrence, metastasis, and drug resistance following tumor resection. The present review describes the surface markers characterizing LCSCs and the recent progress in therapies targeting these markers, including antibodies and polypeptides.

Imaging Features of Gadoxetic Acid-enhanced and Diffusion-weighted MR Imaging for Identifying Cytokeratin 19-positive Hepatocellular Carcinoma: A Retrospective Observational Study

Purpose To determine the preoperative magnetic resonance (MR) imaging findings potentially most useful for predicting cytokeratin 19 (CK19)-positive hepatocellular carcinoma (HCC) and to evaluate the prognosis after curative resection in patients with a single HCC lesion positive for CK19 compared with patients with HCC who are negative for CK19. Materials and Methods The institutional review board approved this study and waived the requirement for informed consent. Two hundred four patients with CK19-negative HCC and 38 with CK19-positive HCC who underwent curative resection after gadoxetic acid-enhanced and diffusion-weighted MR imaging were retrospectively evaluated in a single institution. Two radiologists evaluated preoperative findings at MR imaging. Significant findings for differentiating the two groups were identified at univariate and multivariate analyses. By using receiver operating characteristic analysis, the optimal cut-off values for quantitative variables were determined. Recurrence-free survival rates after surgery were also compared between groups. Results At multivariate analysis, irregular tumor margin (P = .024), arterial rim enhancement (P < .001), lower tumor-to-liver signal intensity (SI) ratio on hepatobiliary phase (HBP) images (≤0.522; P = .01), and lower tumor-to-liver apparent diffusion coefficient (ADC) ratio (≤0.820; P < .001) were independent significant factors to predict CK19-positive HCC. When three of these four criteria were combined, 63.2% (24 of 38; 95% confidence interval: 46.0%, 78.2%) of CK19-positive HCCs were identified with a specificity of 90.7% (185 of 204; 95% confidence interval: 46.0%, 78.2%). When all four criteria were satisfied, specificity was 99.5% (203 of 204; 95% confidence interval: 97.3%, 100%). Recurrence-free survival rates were significantly lower in patients with CK19-positive HCCs compared with those with CK19-negative HCCs after curative resection (63.9% vs 90.0% at 1 year, 63.9% vs 79.9% at 2 years, and 54.8% vs 70.2% at 3 years, P = .001 by log-rank test). Conclusion At gadoxetic acid-enhanced and diffusion-weighted MR imaging, irregular margin, arterial phase rim enhancement, lower tumor-to-liver ADC ratio, and lower tumor-to-liver SI ratio at HBP imaging may be helpful to predict CK19-positive HCC with early recurrence (<2 years) after curative resection. ^© RSNA, 2017 Online supplemental material is available for this article.