Hepatic progenitor cells in human liver tumor development

Apigenin inhibits lipid metabolism of hepatocellular carcinoma cells by targeting the histone demethylase KDM1A

BACKGROUND

The development of cancer is accompanied by metabolic reprogramming, and the liver serves as a central hub for lipid transportation. Apigenin, a plant-derived flavonoid, demonstrates potent anticancer properties across various cancer types and exhibits promising potential as a therapeutic agent for cancer treatment. However, there are limited studies focusing on the downstream targets of apigenin. Moreover, there are few reports on the impact of apigenin in lipid metabolism within liver cancer cells.

PURPOSE

The objective is to elucidate the metabolic mechanism underlying the inhibitory effect of apigenin on liver cancer progression, search for downstream targets and provide reliable data support for the clinical trials of apigenin.

METHODS

Anticancer effects of apigenin were detected at cellular and molecular levels in vitro, and downstream targets of apigenin, especially metabolic pathway genes, were analyzed by transcriptome. Next, the downstream target of apigenin was verified and the biological function of the downstream target was examined. Finally, the downstream target of apigenin was further verified by restoring target gene expression.

RESULTS

Cellular molecular experiments showed that Apigenin inhibited the proliferation, migration, invasion and lipid metabolism of hepatocellular carcinoma (HCC) cells. Transcriptome analysis showed apigenin widely regulates histone demethylase, particularly histone H3K4 lysine demethylase 1A (KDM1A). Apigenin treatment inhibited the expression of KDM1A protein and mRNA levels in liver cancer cells, molecular docking predicted the interaction between apigenin and KDM1A. Furthermore, downregulation KDM1A inhibited the proliferation and lipid metabolism of HCC cells, in the same way, overexpressing KDM1A promoted proliferation of HCC cells. Finally, restoring KDM1A expression partially attenuated the effects of apigenin on lipid metabolism in HCC cells.

CONCLUSION

In conclusion, our study provides compelling evidence that apigenin inhibits liver cancer progression and elucidates its mechanism of action in regulating lipid metabolism. Specifically, we find that apigenin suppresses the progression of HCC cells by downregulating genes involved in lipid metabolism. Additionally, our results indicate that KDM1A acts as a downstream target of apigenin in the inhibition of lipid metabolism in HCC. These findings offer experimental support for the potential use of apigenin as a therapeutic agent for liver cancer, highlighting its relevance in future clinical applications.

Radio-pathologic correlation of biphenotypic primary liver cancer (combined hepatocellular cholangiocarcinoma): changes in the 2019 WHO classification and impact on LI-RADS classification at liver MRI

OBJECTIVES

To explain the new changes in pathologic diagnoses of biphenotypic primary liver cancer (PLC) according to the updated 2019 World Health Organization (WHO) classification and how it impacts Liver Imaging Reporting and Data System (LI-RADS) classification using gadoxetic acid-enhanced MRI (Gd-EOB-MRI).

METHODS

We retrospectively included 209 patients with pathologically proven biphenotypic PLCs according to the 2010 WHO classification who had undergone preoperative Gd-EOB-MRI between January 2009 and December 2018. Imaging analysis including LI-RADS classification and pathologic review including the proportion of tumor components were performed. Frequencies of each diagnosis and subtype according to the 2010 and 2019 WHO classifications were compared, and changes in LI-RADS classification were evaluated. Univariable and multivariable analysis were performed to determine significant tumor component for LI-RADS classification.

RESULTS

Of the 209 biphenotypic PLCs of the 2010 WHO classification, 177 (84.7%) were diagnosed as bipheonotypic PLCs, 25 (12.0%) as hepatocellular carcinomas (HCCs), and 7 (3.3%) as cholangiocarcinomas (CCAs) using the 2019 WHO classification. Of the 177 biphenotypic PLCs, LR-M, LR-4, and LR-5 were assigned in 77 (43.5%), 21 (11.9%), and 63 (35.5%), respectively. There were no significant differences in the proportion of LR-5 and LR-M categories between the WHO 2010 and 2019 classifications (p = 0.941). Proportion of HCC component was the only independent factor for LI-RADS classification (adjusted odds ratio, 1.02; p < 0.001).

CONCLUSION

According to the 2019 WHO classification, 15% of biphenotypic PLCs from the 2010 WHO classification were re-diagnosed as HCCs or CCAs, and a substantial proportion of biphenotypic PLCs of the 2019 WHO classification could be categorized as LR-4 or LR-5 on Gd-EOB-MRI.

KEY POINTS

• Among 209 diagnosed biphenotypic PLCs according to the 2010 WHO classification, 177 (84.7%) lesions were reclassified as bipheonotypic PLCs, 25 (12.0%) as HCCs, and 7 (3.3%) as CCAs using the 2019 WHO classification. • Of the 177 biphenotypic PLCs at the 2019 WHO classification, LR-M, LR-4, and LR-5 were assigned in 77 (43.5%), 21 (11.9%), and 63 (35.5%), respectively. • LI-RADS classification relied on the proportion of HCC component (adjusted odds ratio,1.02; p < 0.001).

Intrahepatic Cholangiocarcinoma Cells Promote Epithelial-mesenchymal Transition of Hepatocellular Carcinoma Cells by Secreting LAMC2

Hepatocellular carcinoma and intrahepatic cholangiocarcinoma cells are common primary hepatic tumor cells in the liver. Combined hepatocellular cholangiocarcinoma (CHC) contains both hepatocellular carcinoma cells and intrahepatic cholangiocarcinoma cells in one tumor lesion and these tumors show poor prognosis. Here we examined the potential interaction between hepatocellular carcinoma cells and intrahepatic cholangiocarcinoma cells using cell culture studies. The results showed that culture supernatant from intrahepatic cholangiocarcinoma cells induced endothelial-mesenchymal transition and facilitated the migration and invasion of hepatocellular carcinoma cells, although it did not accelerate the proliferation of hepatocellular carcinoma cells. Furthermore, culture supernatant from intrahepatic cholangiocarcinoma cells increased the chemoresistance of hepatocellular carcinoma cells. Laminin subunit gamma 2 (LAMC2) was detected in the culture supernatant of intrahepatic cholangiocarcinoma cells but not in that of hepatocellular carcinoma cells. Using established LAMC2 knockout intrahepatic cholangiocarcinoma cells, our results demonstrated that intrahepatic cholangiocarcinoma cells promoted the epithelial-mesenchymal transition of hepatocellular carcinoma cells through secreting LAMC2. Our results have revealed a novel mechanism of interaction between intrahepatic cholangiocarcinoma cells and hepatocellular carcinoma cells, which may provide new insight into developing effective treatments for CHC.

Liver progenitor cell-driven liver regeneration

The liver is a highly regenerative organ, but its regenerative capacity is compromised in severe liver diseases. Hepatocyte-driven liver regeneration that involves the proliferation of preexisting hepatocytes is a primary regeneration mode. On the other hand, liver progenitor cell (LPC)-driven liver regeneration that involves dedifferentiation of biliary epithelial cells or hepatocytes into LPCs, LPC proliferation, and subsequent differentiation of LPCs into hepatocytes is a secondary mode. This secondary mode plays a significant role in liver regeneration when the primary mode does not effectively work, as observed in severe liver injury settings. Thus, promoting LPC-driven liver regeneration may be clinically beneficial to patients with severe liver diseases. In this review, we describe the current understanding of LPC-driven liver regeneration by exploring current knowledge on the activation, origin, and roles of LPCs during regeneration. We also describe animal models used to study LPC-driven liver regeneration, given their potential to further deepen our understanding of the regeneration process. This understanding will eventually contribute to developing strategies to promote LPC-driven liver regeneration in patients with severe liver diseases.

New Perspectives in Liver Transplantation: From Regeneration to Bioengineering

Advanced liver diseases have very high morbidity and mortality due to associated complications, and liver transplantation represents the only current therapeutic option. However, due to worldwide donor shortages, new alternative approaches are mandatory for such patients. Regenerative medicine could be the more appropriate answer to this need. Advances in knowledge of physiology of liver regeneration, stem cells, and 3D scaffolds for tissue engineering have accelerated the race towards efficient therapies for liver failure. In this review, we propose an update on liver regeneration, cell-based regenerative medicine and bioengineering alternatives to liver transplantation.

Combined hepatocellular-cholangiocarcinoma: An analysis of clinicopathological characteristics after surgery

Combined hepatocellular-cholangiocarcinoma (CHCC) is a rare type of primary liver cancer (PLC). The aim of this study was to investigate the disease characteristics in CHCC patients and compare them with those in hepatocellular carcinoma (HCC) or intrahepatic cholangiocarcinoma (ICC).The perioperative and follow-up data of CHCC patients (n = 15), HCC patients (n = 577), and ICC patients (n = 61) were retrospectively analyzed, and the clinicopathological characteristics were compared among these 3 groups.In the CHCC group, the serum level of AFP was significantly higher than that of the ICC group (P = .002), and the CA19-9 level was higher than that of the HCC group (P = .011). The positive rates of CK7 and CK19 expression were higher in CHCC group than in HCC group (both P < .001), while the positive rates of Glypican-3 and Hepatocyte expression were higher in CHCC group than in ICC group (both P < .001). Meanwhile, the CHCC patients were likely to have undergone more MJH/LT than the HCC patients (P = .037) and the ICC patients (P = .011). Macrovascular invasion and lymph node metastasis in the CHCC group were significantly higher but satellite lesions were similar, compared to the HCC group. Both the 1-year disease-free survival (DFS) and the 1-year overall survival (OS) for the CHCC patients were worse than those for the HCC patients. AFP ≥ 400 ng/ml, tumor size ≥5 cm, tumor number ≥2, macro- and microvascular invasion, distant metastasis and positive margin were risk factors for both DFS and OS for the PLC patients. Multivariate analysis also confirmed that ICC and lymph node metastasis were risk factors for DFS and MJH/LT was risk factor for OS.CHCC patients appear to have intermediate clinical characteristics in comparison with the HCC and ICC patients, and the 1-year DFS and OS for the CHCC patients was worse than the HCC patients, but similar to the ICC patients.

Human Liver Regeneration: An Etiology Dependent Process

Regeneration of the liver has been an interesting and well-investigated topic for many decades. This etiology and time-dependent mechanism has proven to be extremely challenging to investigate, certainly in human diseases. A reason for this challenge is found in the numerous interactions of different cell components, of which some are even only temporarily present (e.g., inflammatory cells). To orchestrate regeneration of the epithelial cells, their interaction with the non-epithelial components is of utmost importance. Hepatocytes, cholangiocytes, liver progenitor cells, and peribiliary glands have proven to be compartments of regeneration. The ductular reaction is a common denominator in virtually all liver diseases; however, it is predominantly found in late-stage hepatic and biliary diseases. Ductular reaction is an intriguing example of interplay between epithelial and non-epithelial cells and encompasses bipotential liver progenitor cells which are able to compensate for the loss of the exhausted hepatocytes and cholangiocytes in biliary and hepatocytic liver diseases. In this manuscript, we focus on the etiology-specific damage that is observed in different human diseases and how the liver regulates the regenerative response in an acute and chronic setting. Furthermore, we describe the importance of morphological keynotes in different etiologies and how spatial information is of relevance for every basic and translational research of liver regeneration.

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.

Acquisition of Cholangiocarcinoma Traits during Advanced Hepatocellular Carcinoma Development in Mice

Past studies have identified hepatic tumors with mixed hepatocellular carcinoma (HCC) and cholangiocarcinoma (CC) characteristics that have a more aggressive behavior and a poorer prognosis than classic HCC. Whether this pathologic heterogeneity is due to a cell of origin of bipotent liver progenitors or the plasticity of cellular constituents comprising these tumors remains debated. In this study, we investigated the potential acquisition of CC-like traits during advanced development of HCC in mice. Primary and rare high-grade HCC developed in a genetic mouse model. A mouse model of highly efficient HCC invasion and metastasis by orthotopic transplantation of liver cancer organoids propagated from primary tumors in the genetic model was further developed. Invasive/metastatic tumors developed in both models closely recapitulated advanced human HCC and displayed a striking acquisition of CC-related pathologic and molecular features, which was absent in the primary HCC tumors. Our study directly demonstrates the pathologic evolution of HCC during advanced tumor development, providing the first evidence that tumors with mixed HCC and CC features, or at least a subset of these tumors, represent a more advanced developmental stage of HCC. Finally, liver cancer organoid-generated high-grade tumors exhibited significantly increased extracellular vesicle secretion, suggesting that identifying tumor-specific extracellular vesicle proteins in plasma may be a promising tool for liver cancer detection.

The progenitor cell dilemma: Cellular and functional heterogeneity in assistance or escalation of liver injury

Liver progenitor cells (LPCs) are quiescent cells that are activated during liver injury and thought to give rise to hepatocytes and cholangiocytes in order to support liver regeneration and tissue restitution. While hepatocytes are capable of self-renewal, during most chronic injuries the proliferative capacity of hepatocytes is inhibited, thus LPCs provide main source for regeneration. Despite extensive lineage tracing studies, their role and involvement in these processes are often controversial. Additionally, increasing evidence suggests that the LPC compartment consists of heterogeneous cell populations that are actively involved in cellular interactions with myeloid and lymphoid cells during regeneration. On the other hand, LPC expansion has been associated with an increased fibrogenic response, raising concerns about the therapeutic use of these cells. This review aims to summarize the current understanding of the identity, the cellular interactions and the key pathways affecting the biology of LPCs. Understanding the regulatory circuits and the specific role of LPCs is especially important as it could provide novel therapeutic platforms for the treatment of liver inflammation, fibrosis and regeneration.

Claudins-4 and -7 might be valuable markers to distinguish hepatocellular carcinoma from cholangiocarcinoma

The claudin family members are the functional components of tight junctions. Expression and localization of claudins vary among organs and tumor types. In this study, we examined expression and localization of tight junction proteins (TJP) in human liver tumors, to estimate their usefulness as differential diagnostic markers. The materials used for immunohistochemical analysis were 47 liver tumor specimens including 29 cases of hepatocellular carcinoma (HCC), 15 cases of cholangiocarcinoma (CC), 3 cases of combined HCC and CC (CHC), and 3 cases of cholangiolocellular carcinoma (CoCC). Samples were examined using semiquantitative and statistical analysis of immunoreactivity. In HCC, claudin-1, occludin, tricellulin, and JAM-A were expressed on the cell membrane as well as in hepatocytes. In CC, claudins-1, -4, and -7, tricellulin, and JAM-A were expressed on the cell membrane and occludin was predominantly expressed in the apicalmost areas of the cell membrane. Significant differences in the immunohistochemical scores of claudin-4 and claudin-7 were observed when comparing HCC and CC. CHC was positive for all of the TJPs examined in this study. The expression pattern of CoCC was found to be similar to that of CC. There were differences in the distribution of intensity scores of claudins-4 and -7 and occludin between CoCC and HCC. In addition, CHC was positive for Glypican-3 and CK-19. CoCC was positive for only CK-19. The results suggest that claudins-4 and -7 might be valuable markers for distinguishing HCC and CC and that CoCC might arise from hepatic ductal cells.

Human ductal plate and its derivatives express antigens of cholangiocellular, hepatocellular, hepatic stellate/progenitor cell, stem cell, and neuroendocrine lineages, and proliferative antigens

Molecular mechanisms of human ductal plate (DP) development and differentiation (DD) are unclear. The author immunohistochemically investigated expressions of cholangiocellular antigens (CEA, CA19-9, EMA, MUC1, MUC2, MUC5AC, MUC6, mucins, CK7, and CK19), hepatocellular antigens (HepPar1, AFP, CK8, and CK18), hepatic stellate/progenitor cell (HSC) antigens or stem cell (SC) antigens (C-erbB2, CD56, chromogranin, synaptophysin, bcl2, NSE, NCAM, KIT, and PDGFRA), and proliferating antigen (Ki67) in 32 human fetal livers (HFL). The DD of human intrahepatic bile duct (IBD) could be categorized into four stages: DP, remodeling DP, remodeled DP, and immature IBD. All the molecules examined were expressed in the DP and DP derivatives. These results suggest that human DP or DP derivatives have capacities to differentiate into cholangiocellular, hepatocellular, HSC, SC, and neuroendocrine lineages. The data also suggest that NCAM, KIT/SC factor-signaling, NSE, HGF/MET signaling, PDGFa/PDGFRA signaling, chromogranin, synaptophysin, and CD56 play important roles in DD of DP and biliary cells of HFL. DP, DP derivatives, and IBD in HFL have proliferative capacity.

Keratin 19 protein expression is an independent predictor of survival in human hepatocellular carcinoma

AIM

We aimed to assess the clinicopathological relevance and prognostic significance of expression of the hepatic progenitor cell markers keratin 19 (K19), epithelial cell adhesion molecule (EpCAM) and CD117 (c-KIT) in a White series of hepatocellular carcinoma (HCC).

METHODS

We evaluated the immunohistochemical expression of K19, EpCAM and CD117 in 89 surgical specimens of HCC from Greek patients (mean age 66.7±11.3 years, male 75.2%) followed up for 39.6±25.3 months.

RESULTS

K19, EpCAM and CD117 expression was detected in tumour cells of 10.11, 15.38 and 3.7% HCCs, respectively. Female sex was correlated with EpCAM immunohistochemical expression (P=0.035), whereas no other significant relationship with clinicopathological parameters was observed. K19 positivity tended to be correlated with microvascular invasion (P=0.054). In univariate analysis, K19 positivity and microvascular invasion were found to be associated with decreased recurrence-free survival (P<0.001 and P=0.004, respectively) and overall survival (P=0.002 and P=0.029, respectively). EpCAM and CD117 positivity was not correlated with patient survival. In multivariate analysis, K19 positivity emerged as an independent predictor of recurrence-free survival (odds ratio=7.84, 95% confidence interval=2.658-22.912, P<0.001) and overall survival (odds ratio=3.845, 95% confidence interval=1.401-10.549, P=0.009).

CONCLUSION

Our study confirms the prognostic significance of K19 expression in Caucasian patients with HCCs, providing further evidence that it may be used to stratify HCC according to tumour aggressiveness.

The adverse outcome pathway for rodent liver tumor promotion by sustained activation of the aryl hydrocarbon receptor

An Adverse Outcome Pathway (AOP) represents the existing knowledge of a biological pathway leading from initial molecular interactions of a toxicant and progressing through a series of key events (KEs), culminating with an apical adverse outcome (AO) that has to be of regulatory relevance. An AOP based on the mode of action (MOA) of rodent liver tumor promotion by dioxin-like compounds (DLCs) has been developed and the weight of evidence (WoE) of key event relationships (KERs) evaluated using evolved Bradford Hill considerations. Dioxins and DLCs are potent aryl hydrocarbon receptor (AHR) ligands that cause a range of species-specific adverse outcomes. The occurrence of KEs is necessary for inducing downstream biological responses and KEs may occur at the molecular, cellular, tissue and organ levels. The common convention is that an AOP begins with the toxicant interaction with a biological response element; for this AOP, this initial event is binding of a DLC ligand to the AHR. Data from mechanistic studies, lifetime bioassays and approximately thirty initiation-promotion studies have established dioxin and DLCs as rat liver tumor promoters. Such studies clearly show that sustained AHR activation, weeks or months in duration, is necessary to induce rodent liver tumor promotion--hence, sustained AHR activation is deemed the molecular initiating event (MIE). After this MIE, subsequent KEs are 1) changes in cellular growth homeostasis likely associated with expression changes in a number of genes and observed as development of hepatic foci and decreases in apoptosis within foci; 2) extensive liver toxicity observed as the constellation of effects called toxic hepatopathy; 3) cellular proliferation and hyperplasia in several hepatic cell types. This progression of KEs culminates in the AO, the development of hepatocellular adenomas and carcinomas and cholangiolar carcinomas. A rich data set provides both qualitative and quantitative knowledge of the progression of this AOP through KEs and the KERs. Thus, the WoE for this AOP is judged to be strong. Species-specific effects of dioxins and DLCs are well known--humans are less responsive than rodents and rodent species differ in sensitivity between strains. Consequently, application of this AOP to evaluate potential human health risks must take these differences into account.

Cancer stem cells in primary liver cancers: pathological concepts and imaging findings

There is accumulating evidence that cancer stem cells (CSCs) play an integral role in the initiation of hepatocarcinogenesis and the maintaining of tumor growth. Liver CSCs derived from hepatic stem/progenitor cells have the potential to differentiate into either hepatocytes or cholangiocytes. Primary liver cancers originating from CSCs constitute a heterogeneous histopathologic spectrum, including hepatocellular carcinoma, combined hepatocellular-cholangiocarcinoma, and intrahepatic cholangiocarcinoma with various radiologic manifestations. In this article, we reviewed the recent concepts of CSCs in the development of primary liver cancers, focusing on their pathological and radiological findings. Awareness of the pathological concepts and imaging findings of primary liver cancers with features of CSCs is critical for accurate diagnosis, prediction of outcome, and appropriate treatment options for patients.

Human fetal ductal plate revisited. I. ductal plate expresses NCAM, KIT, MET, PDGFRA, and neuroendocrine antigens (NSE, chromogranin, synaptophysin, and CD56)

BACKGROUND

The molecular mechanisms of ductal plate (DP) development and differentiation (DD) in human fetal livers (HFLs) are unclear.

MATERIALS AND METHODS

The author immunohistochemically investigated expressions of NCAM, KIT, KIT, PDGFRA, and neuroendocrine antigens in 32 HFLs.

RESULTS

The processes of human intrahepatic bile duct (IBD) DD could be categorized into four stages: DP, remodeling DP, remodeled DP, and mature IBD. NCAM was always expressed in DP and remodeling DP, but not in remodeled DP and mature IBD. The biliary elements were positive for cytokeratin (CK)7, 8, 18, and 19. The hepatoblasts were positive for CK8 and CD18, but negative for CK7 and CK19; however, periportal hepatoblasts showed biliary-type CKs (CK7 and CK19). NCAM was always expressed in DP and remodeling DP, but not in remodeled DP and mature IBD. KIT was occasionally (12/32 cases) expressed in DP and remodeling DP, but not in remodeled DP and mature IBD. NCAM expression was also seen in some hepatoblasts and hematopoietic cells and neurons. KIT was also expressed in some hepatoblasts, hematopoietic cells, and mast cells. MET and PDGFRA were strongly expressed in DP, remodeling DP, remodeled DP, and mature IBD. MET and PDGFRA were also strongly expressed in hepatoblasts and hematopoietic cells. MET and PDGFRA were not expressed in portal mesenchyme, portal veins, sinusoids, and hepatic veins. DP showed immunoreactive chromogranin, synaptophysin, neuron-specific enolase (NSE), and CD56. Expressions of chromogranin and CD56 were infrequently seen in remodeling DP. No expressions of these four neuroendocrine antigens were seen in remodeled DP and mature IBD. The nerve fibers were consistently positive for chromogranin, synaptophysin, NSE, and CD56 in the portal mesenchyme in the stages of remodeling DP, remodeled DP, and mature IBDs.

CONCLUSIONS

The data suggest that NCAM, KIT/stem cell factor-signaling, NSE, hepatocyte growth factor/MET signaling, PDGFα/PDGFRA signaling, chromogranin, synaptophysin, and CD56 play important roles in DD of biliary cells of HFL. They also suggest that the DP cells having neuroendocrine molecules give rise to hepatic stem/progenitor cells.

Classification of primary hepatic tumours in the cat

Hepatic tumours in dogs have recently been re-classified to follow a revised human classification system that takes account of identified hepatic progenitor cells. This study investigated the presence and relative frequency of morphological types of feline primary hepatic neoplasms and aimed to determine whether a similar new classification scheme could be applied in cats. Feline primary liver tumours (n = 61) were examined histologically and with a series of immunohistochemical markers. Six cases of nodular hyperplasia and 21 tumours of hepatocellular origin were diagnosed. The latter were subdivided into hepatocellular tumours that were well differentiated and had no evidence of metastases (n = 18) and tumours that showed poorly differentiated areas with marked cellular and nuclear pleomorphism and had intrahepatic and, or, distant metastases (n = 3). These malignant feline hepatocellular tumours maintained their hepatocellular characteristics (HepPar-1, MRP2, pCEA positive) and were negative, or only <5% positive, for K19. Twenty-five cholangiocellular tumours were diagnosed and all had intrahepatic and, or, distant metastases. Eight NSE positive small cell carcinomas (carcinoids) were diagnosed and subdivided into small cell carcinomas with HPC characteristics (K19 positive) and neuroendocrine carcinomas (K19 negative). In addition, one squamous cell carcinoma originating from the distal part of the choledochal duct was recognised. Feline primary hepatic neoplasms can be sub-divided into benign and malignant hepatocellular tumours, cholangiocellular carcinomas, small cell carcinomas with HPC characteristics, neuroendocrine carcinomas and squamous cell carcinomas. The marked species difference justifies a specific classification for feline primary hepatic neoplasms.

Side population cell fractions from hepatocellular carcinoma cell lines increased with tumor dedifferentiation, but lack characteristic features of cancer stem cells

BACKGROUND AND AIM

Cancer stem cells (CSCs), a minority population with stem cell-like characteristics, play important roles in cancer development and progression. Putative CSC markers, such as CD13, CD90, CD133, and epithelial cell adhesion molecule (EpCAM), and side population (SP) technique are generally used in an attempt to isolate CSCs. We aimed to clarify the relationship between CSCs and clonal dedifferentiation in hepatocellular carcinoma (HCC).

METHODS

We used a well-differentiated HCC cell line (HAK-1A) and a poorly differentiated HCC cell line (HAK-1B) established from a single nodule with histological heterogeneity. HAK-1B arose because of clonal dedifferentiation of HAK-1A. The SP cells and non-SP (NSP) cells were isolated from the two cell lines with a FACSAria II and used for the analyses.

RESULTS

The SP cell fractions in HAK-1A and HAK-1B were 0.2% and 0.9%, respectively. CD90 or EpCAM was not expressed in either HAK-1A or HAK-1B, while CD13 and CD133 were expressed in HAK-1B alone. Although sphere forming ability, tumorigenicity, growth rate, and CD13 expression were higher in HAK-1B SP cells than HAK-1B NSP cells, there were no differences in drug resistance, colony forming ability, or cell cycle rates between HAK-1B SP and NSP cells, suggesting HAK-1B SP cells do not fulfill CSC criteria.

CONCLUSIONS

Our findings suggested a possible relationship between the expression of CSC markers and clonal dedifferentiation. However, the complete features of CSC could not be identified in SP cells, and the concept of SP cells as a universal marker for CSC may not apply to HAK-1A and HAK-1B.

Improved Serum Alpha-Fetoprotein Levels after Iron Reduction Therapy in HCV Patients

Background and Aims. To examine the changes in serum alpha-fetoprotein (AFP) levels after iron reduction by therapeutic phlebotomy in chronic hepatitis C patients. Methods. This retrospective study included 26 chronic hepatitis C patients. The patients were developed iron depletion by repeated therapeutic phlebotomies. Results. Iron reduction therapy significantly reduced the median level of serum AFP from 13 to 7 ng/mL, ALT from 96 to 50 IU/L, gamma-glutamyl transpeptidase (GGT) from 55 to 28 IU/L, and ferritin from 191 to 10 ng/mL (P < 0.001 for each). The rate of decline in the AFP level correlated positively only with that in GGT (r = 0.695, P = 0.001), although a spurious correlation was observed between the rates of decline for AFP and ALT. The AFP level normalized (<10 ng/mL) posttreatment in eight (50%) of 16 patients who had elevated pretreatment AFP levels. Normalized post-treatment ALT and GGT levels were seen in 12% (3 of 26) and 39% (7 of 18) of the patients, respectively. Multivariate analysis identified a post-treatment GGT level of <30 IU/L as an independent factor associated with post-treatment AFP normalization (odds ratio, 21; 95% confidence interval, 1.5-293; P = 0.024). Conclusions. Iron reduction by therapeutic phlebotomy can reduce serum AFP and GGT levels in chronic hepatitis C patients.

From hepatitis to hepatocellular carcinoma: a proposed model for cross-talk between inflammation and epigenetic mechanisms

Inflammation represents the body's natural response to tissue damage; however, chronic inflammation may activate cell proliferation and induce deregulation of cell death in affected tissues. Chronic inflammation is an important factor in the development of hepatocellular carcinoma (HCC), although the precise underlying mechanism remains unknown. Epigenetic events, which are considered key mechanisms in the regulation of gene activity states, are also commonly deregulated in HCC. Here, we review the evidence that chronic inflammation might deregulate epigenetic processes, thus promoting oncogenic transformation, and we propose a working hypothesis that epigenetic deregulation is an underlying mechanism by which inflammation might promote HCC development. In this scenario, different components of the inflammatory response might directly and indirectly induce changes in epigenetic machineries ('epigenetic switch'), including those involved in setting and propagating normal patterns of DNA methylation, histone modifications and non-coding RNAs in hepatocytes. We discuss the possibility that self-reinforcing cross-talk between inflammation and epigenetic mechanisms might amplify inflammatory signals and maintain a chronic state of inflammation culminating in cancer development. The potential role of inflammation-epigenome interactions in the emergence and maintenance of cancer stem cells is also discussed.

Epidemiological trends in incidence and mortality of hepatobiliary cancers in Germany

OBJECTIVE

While marked changes in the frequency of hepatobiliary malignancies, most notably hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC), have been observed in different populations, no such data have been reported for Germany. We aimed to provide epidemiological data on recent trends in liver-related mortality, specifically mortality from hepatobiliary malignancies, in Germany.

MATERIAL AND METHODS

We used incidence and mortality data to determine changes in the frequency of malignant and non-malignant liver disease in Germany over the past 30 years.

RESULTS

While overall liver disease mortality has slightly declined in Germany, deaths from hepatobiliary malignancies have declined in women, but remained constant in men. Among hepatobiliary malignancies, ICC stands out, because mortality has more than tripled both in men and women between 1998 and 2008. This is mirrored by a marked increase in new cases reported to local cancer registries, that is, incidence. Over the same time period, HCC and extrahepatic cholangiocarcinoma (ECC) have remained largely constant while gall bladder cancers (GBC) have declined twofold. The rapid rise in ICC is in line with finding from different regions worldwide, but in contrast to recent data from Denmark and France, two of Germany's direct neighbors.

CONCLUSIONS

The incidence of and mortality from ICC are rising markedly in Germany. The risk factors underlying this trend are as yet unclear.

Notch signaling inhibits hepatocellular carcinoma following inactivation of the RB pathway

Mice lacking all three Rb genes in the liver develop tumors resembling specific subgroups of human hepatocellular carcinomas, and Notch activity appears to suppress the growth and progression of these tumors.

Hepatocellular carcinoma (HCC) is the third cancer killer worldwide with >600,000 deaths every year. Although the major risk factors are known, therapeutic options in patients remain limited in part because of our incomplete understanding of the cellular and molecular mechanisms influencing HCC development. Evidence indicates that the retinoblastoma (RB) pathway is functionally inactivated in most cases of HCC by genetic, epigenetic, and/or viral mechanisms. To investigate the functional relevance of this observation, we inactivated the RB pathway in the liver of adult mice by deleting the three members of the Rb (Rb1) gene family: Rb, p107, and p130. Rb family triple knockout mice develop liver tumors with histopathological features and gene expression profiles similar to human HCC. In this mouse model, cancer initiation is associated with the specific expansion of populations of liver stem/progenitor cells, indicating that the RB pathway may prevent HCC development by maintaining the quiescence of adult liver progenitor cells. In addition, we show that during tumor progression, activation of the Notch pathway via E2F transcription factors serves as a negative feedback mechanism to slow HCC growth. The level of Notch activity is also able to predict survival of HCC patients, suggesting novel means to diagnose and treat HCC.

Clinicopathologic study on combined hepatocellular carcinoma and cholangiocarcinoma: with emphasis on the intermediate cell morphology

Combined hepatocellular carcinoma and cholangiocarcinoma (combined HCC-CC) is a rare subtype of primary liver cancer. We investigated the histopathologic features of transitional or intermediate areas in 21 combined HCC-CCs and immunophenotypes using different hepatic progenitor cell markers (CK7, CK19, c-kit, NCAM, and EpCAM). Major histologic findings of transitional or intermediate areas of 21 combined HCC-CCs included strands/trabeculae of small, uniform, oval-shaped cells with scant cytoplasm and hyperchromatic nuclei embedded within an abundant stroma, small cells with an antler-like anastomosing pattern, and solid nests of intermediate hepatocyte-like cells surrounded by small cells in periphery, in order of frequency. The intermediate area of one tumor was composed predominantly of spindle cells arranged in short fascicles. Immunophenotype of tumor cells with intermediate morphology suggested a progenitor cell origin for this tumor. Clinical findings of combined HCC-CC showed a closer resemblance with those of HCC than those of CC. In univariate analysis, tumor size, TNM stage, and serum alpha-fetoprotein levels showed a significant association with poor patient survival. Serum alpha-fetoprotein level was an independent prognostic indicator in multivariate analysis. In conclusion, an awareness of the clinicopathologic features, specifically the various morphologic features of intermediate areas in this tumor, is essential for prevention of potential misdiagnosis as another tumor.

Dysadherin can enhance tumorigenesis by conferring properties of stem-like cells to hepatocellular carcinoma cells

BACKGROUND & AIMS

Hepatocellular carcinoma (HCC) is associated with a high potential for metastasis and disease recurrence, even after surgical resection. The cancer stem cell (CSC) hypothesis proposes that CSCs are responsible for chemo-resistance, recurrence, and metastasis. Dysadherin is a prognostic indicator of metastasis and poor survival in many different cancer types. In this study, we investigated the possible link between dysadherin and CSC in HCC.

METHODS

We analyzed the functional implications of dysadherin on cancer stemness by modification of the dysadherin gene in HCC cell lines.

RESULTS

The transfection of dysadherin cDNA into the liver cancer cell line PLC/PRF/5 enhanced the properties of CSCs, including anti-apoptosis, their sphere-forming ability, side population phenotype, and tumor initiation ability in vivo. Furthermore, knockdown of dysadherin in the liver cancer cell line SK-Hep1 suppressed its stem cell-like properties.

CONCLUSIONS

These results show that dysadherin give rise to properties of CSC in HCC. Therefore, these findings suggest that dysadherin may be a potential molecular prognostic marker of HCC and may aid in the development of more effective therapies.

Combined hepatocellular-cholangiocarcinoma in a lesser flamingo (Phoenicopterus minor)

A case of combined hepatocellular-cholangiocarcinoma (CHCC) in an adult male lesser flamingo (Phoenicopterus minor) that was part of a breeding programme at a private facility is reported. Grossly, the liver was markedly enlarged with multifocal, well-circumscribed, pinpoint to 2 cm diameter pale tan nodular masses. Histologically, the hepatic parenchyma was replaced by neoplastic cells that demonstrated hepatocellular and, less frequently, biliary epithelial cell differentiation. Positive pan-cytokeratin (AE1/AE3/PCK26) immunolabelling of the neoplastic cells forming bile ducts with the scattered immunoreactivity of cells forming glandular structures within the areas of hepatocellular differentiation supported the diagnosis. No metastases were detected. CHCC is a rare neoplasm in mammals and birds. This is the first report where gross, histological, and immunohistochemical characteristics of CHCC in a bird are described, and the first report of CHCC in a lesser flamingo.

The use of Cytokeratin 19 (CK19) immunohistochemistry in lesions of the pancreas, gastrointestinal tract, and liver

Cytokeratin immunostaining forms the bedrock of the immunohistochemical evaluation of tumors. Cytokeratin 19 (CK19) belongs to a family of keratins, which are normally expressed in the lining of the gastroenteropancreatic and hepatobiliary tracts. CK19 immunohistochemistry has been used successfully in thyroid tumors to recognize papillary carcinomas for some time. However, its use in the pancreas, liver, and gastrointestinal tract (GIT) has only recently come to the fore. The purpose of this review is to look at the use of CK19 immunohistochemistry in tumors occurring at these sites. CK19 has been shown to be an independent prognostic factor for pancreatic neuroendocrine tumors, especially the insulin-negative tumors. CK19 positive tumors are associated with poor outcome irrespective of the established pathologic parameters such as size, mitoses, lymphovascular invasion, and necrosis. It is recommended that CK19 be part of the immunohistochemical panel in the work-up of pancreatic endocrine tumors. CK19 is positive in the most of neuroendocrine tumors occurring in the rest of the GIT, except rectal tumors, which are negative. In the liver, CK19 is of prognostic value in hepatocellular carcinomas and is of use in distinguishing cholangiocarcinoma from hepatocellular carcinomas. It can also be used to highlight native ductules in the liver and helps separate conditions such as focal nodular hyperplasia from hepatic adenoma. The vast majority of adenocarcinomas in the GIT and pancreas are CK19 positive.

First report of ectopic ACTH syndrome and PTHrP-induced hypercalcemia due to a hepatoblastoma in a child

CONTEXT

Only occasionally, endocrine-active tumors develop directly from hepatic tissue, and may lead to paraneoplastic syndromes (PNS). PNS mostly accompany malignancy of adulthood and are exceedingly rare in children.

PATIENT

A girl aged 6 years and 9 months presented with a 2-month history of rapidly progressive weight gain, abdominal distension, and polyuria/pollakiuria accompanied by short episodes of abdominal pain. She showed the typical clinical features of Cushing's syndrome and a huge hepatic mass. An abdominal computed tomography (CT) scan revealed a large liver tumor. Blood glucose and serum calcium were greatly elevated.

DESIGN AND OBJECTIVE

Case report describing the causative relationship of the clinical findings.

METHODS

Physical examination; ultrasound of the abdomen; CT scan of the abdomen and the chest; conventional X-rays; routine hematology; blood chemistry and multiple parameters of calcium and phosphorus metabolism; multisteroid analysis in serum and urine; adrenocortical stimulation and suppression tests; histopathological assessment of the resected tumor; immunohistochemistry for ACTH, beta-endorphin, corticotrophin-releasing hormone (CRH), and PTH-related peptide (PTHrP); electron microscopy of tumor cells; ACTH and CRH extraction from the tumor tissue; and clinical follow-up for more than 20 years.

RESULTS

Giant hepatoblastoma (HB; approximately 1000 ml volume) of the right lobe of the liver with combined ectopic ACTH syndrome and PTHrP-induced tumor-associated hypercalcemia. Wide local excision and polychemotherapy led to complete reversal of the paraneoplastic phenotype.

CONCLUSIONS

This is the first report of an endocrine-active HB causing both Cushing's syndrome and PTHrP-related 'humoral hypercalcemia of malignancy'. This information should be added to the well-known beta-human chorionic gonadotropin-related paraneoplastic effects of HB in children.

Keratin 19 marks poor differentiation and a more aggressive behaviour in canine and human hepatocellular tumours

Background

The expression of Keratin 19 (K19) was reported in a subset of hepatocellular carcinomas (HCCs). K19 positive HCCs are associated with an increased malignancy compared to K19 negative HCCs. No suitable mouse models exist for this subtype of HCC, nor is the incidence of K19 expression in hepatocellular neoplasia in model animals known. Therefore, we compared the occurrence and tumour behaviour of K19 positive hepatocellular neoplasias in dog and man.

Results

The expression of hepatocellular differentiation (HepPar-1), biliary/progenitor cell (K7, K19), and malignancy (glypican-3) markers was semi-quantitatively assessed by immunohistochemistry. The histological grade of tumour differentiation was determined according to a modified classification of Edmondson and Steiner; the staging included intrahepatic, lymph node or distant metastases. Four of the 34 canine hepatocellular neoplasias showed K19 positivity (12%), of which two co-expressed K7. K19 positive tumours did not express HepPar-1, despite the histological evidence of a hepatocellular origin. Like in human HCC, all K19 positive hepatocellular neoplasias were glypican-3 positive and histologically poorly differentiated and revealed intra- or extrahepatic metastases whereas K19 negative hepatocellular neoplasias did not.

Conclusions

K19 positive hepatocellular neoplasias are highly comparable to man and occur in 12% of canine hepatocellular tumours and are associated with a poorly differentiated histology and aggressive tumour behaviour.

Retinoic acid signalling induces the differentiation of mouse fetal liver-derived hepatic progenitor cells

BACKGROUND

Hepatic progenitor cells (HPCs) can be isolated from fetal liver and extrahepatic tissues. Retinoic acid (RA) signalling plays an important role in development, although the role of RA signalling in liver-specific progenitors is poorly understood.

AIMS

We sought to determine the role of RA in regulating hepatic differentiation.

METHODS

RNA was isolated from liver tissues of various developmental stages. Liver marker expression was assessed by reverse transcriptase-polymerase chain reaction and immunofluorescence staining. Reversibly immortalized HPCs derived from mouse embryonic day 14.5 (E14.5) liver (aka, HP14.5) were established. Albumin promoter-driven reporter (Alb-GLuc) was used to monitor hepatic differentiation. Glycogen synthesis was assayed as a marker for terminal hepatic differentiation.

RESULTS

Retinoic acid receptor (RAR)-alpha, retinoid X receptor (RXR)-alpha and RXR-gamma expressed in E12.5 to postnatal day 28 liver samples. Expression of RAR-beta and RXR-beta was low perinatally, whereas RAR-gamma was undetectable in prenatal tissues and increased postnatally. Retinal dehydrogenase 1 and 2 (Raldh1 and Raldh2) were expressed in all tissues, while Raldh3 was weakly expressed in prenatal samples but was readily detected postnatally. Nuclear receptor corepressors were highly expressed in all tissues, while expression of nuclear co-activators decreased in perinatal tissues and increased after birth. HP14.5 cells expressed high levels of early liver stem cell markers. Expression of RA signalling components and coregulators was readily detected in HP14.5. RA was shown to induce Alb-GLuc activity and late hepatocyte markers. RA was further shown to induce glycogen synthesis in HP14.5 cells, an important function of mature hepatocytes.

CONCLUSIONS

Our results strongly suggest that RA signalling may play an important role in regulating hepatic differentiation.

Expression and localization of aquaporin-1 in human cirrhotic liver

We investigated the expression and localization of aquaporin-1 (AQP-1) in hepatitis B virus (HBV)-associated cirrhotic human liver tissues. The expression of AQP-1 at the protein and mRNA levels was analyzed by immunohistochemistry, quantitative real-time polymerase chain reaction (qPCR) and Western blotting in normal and HBV-associated cirrhotic human liver tissues. The correlation with the expression of CK19, CK7 and AQP-1 was also compared. AQP-1 staining was strongly and uniformly positive in mature bile ducts, isolated hepatic progenitor cells (HPCs) and ductular reactions. Scattered intermediate hepatocyte-like cells expressed AQP-1, which are often intimately associated with CK7 positive hepatocytes. However, the number of AQP-1+ intermediate hepatocyte-like cells was lower than that of CK7+ cells, and such positivity was rarely seen on stains for CK19. When compared with normal liver tissues, AQP-1 was overexpressed at both the mRNA and protein levels in the cirrhotic liver tissues. AQP-1 was overexpressed in the cirrhotic liver tissues. AQP-1, similar to CK19, might be a more specific and more sensitive marker than CK7 for the identification of HPCs.

GABA's control of stem and cancer cell proliferation in adult neural and peripheral niches

Aside from traditional neurotransmission and regulation of secretion, gamma-amino butyric acid (GABA) through GABA(A) receptors negatively regulates proliferation of pluripotent and neural stem cells in embryonic and adult tissue. There has also been evidence that GABAergic signaling and its control over proliferation is not only limited to the nervous system, but is widespread through peripheral organs containing adult stem cells. GABA has emerged as a tumor signaling molecule in the periphery that controls the proliferation of tumor cells and perhaps tumor stem cells. Here, we will discuss GABA's presence as a near-universal signal that may be altered in tumor cells resulting in modified mitotic activity.

Viral hepatitis-associated intrahepatic cholangiocarcinoma shares common disease processes with hepatocellular carcinoma

Bile duct cells and hepatocytes differentiate from the same hepatic progenitor cells. To investigate the possible association of viral hepatitis B and C with intrahepatic cholangiocarcinoma (ICC), we conducted a retrospective case–control study using univariate and multivariate logistic analyses to identify risk factors for ICC. Besides hepatic lithiasis (25.6%; P<0.001), seropositivity for hepatitis B surface antigen (37.5% of all ICC patients; odds ratio (OR) =4.985, P<0.001) and seropositivity for hepatitis C antibodies (13.1%; OR=2.709; P=0.021) are the primary independent risk factors for ICC. Cirrhosis exerted synergic effects on the development of ICC. We compared the age distributions of viral-hepatitis associated ICC to that of viral hepatitis-associated hepatocellular carcinoma (HCC). The mean age of ICC patients with viral hepatitis B (56.4±11.1 years) were 9 years younger than that of ICC patients with viral hepatitis C (65.6±9.17 years), similar to that observed in HCC. The incidence ratio of HCC : ICC : CHC (combined hepatocellular cholangiocarcinoma) in our population was 233 : 17 : 1 consistent with the theoretic ratio of hepatocyte number to cholangiocyte number in the liver. Our findings indicated that both viral hepatitis-associated ICC and HCC shared common disease process for carcinogenesis and, possibly, both arose from the hepatic progenitor cells.

Relation between liver progenitor cell expansion and extracellular matrix deposition in a CDE-induced murine model of chronic liver injury

In chronic liver injury, liver progenitor cells (LPCs) proliferate in the periportal area, migrate inside the lobule, and undergo further differentiation. This process is associated with extracellular matrix (ECM) remodeling. We analyzed LPC expansion and matrix accumulation in a choline-deficient, ethionine-supplemented (CDE) model of LPC proliferation. After day 3, CDE induced collagen deposits in the periportal area. Expansion of LPCs as assessed by increased number of cytokeratin 19 (CK19)-positive cells was first observed at day 7, while ECM accumulated 10 times more than in controls. Thereafter, LPCs and ECM increased in parallel. Furthermore, ECM not only accumulates prior to the increase in number of LPCs, but is also found in front of LPCs along the porto-venous gradient of lobular invasion. Double immunostaining revealed that LPCs are embedded in ECM at all times. Moreover, LPCs infiltrating the liver parenchyma are chaperoned by alpha-smooth muscle actin (alpha-SMA)-positive cells. Gene expression analyses confirmed these observations. The expression of CK19, alpha-fetoprotein, E-cadherin, and CD49f messenger RNA (mRNA), largely overexpressed by LPCs, significantly increased between day 7 and day 10. By contrast, at day 3 there was a rapid burst in the expression of components of the ECM, collagen I and laminin, as well as in alpha-SMA and connective tissue growth factor expression.

CONCLUSION

Our data demonstrate that, in a CDE model, ECM deposition and activation of matrix-producing cells occurred as an initial phase, prior to LPC expansion, and in front of LPCs along the porto-venous gradient of lobular invasion. Those observations may reveal a fundamental role for the established hepatic microenvironment or niche during the process of activation and differentiation of liver progenitor cells.

Pathobiology of biliary epithelia and cholangiocarcinoma: proceedings of the Henry M. and Lillian Stratton Basic Research Single-Topic Conference

In June 2008, the American Association for the Study of Liver Diseases (AASLD) sponsored the Henry M. and Lillian Stratton Basic Research Single-Topic Conference on the Pathobiology of Biliary Epithelia and Cholangiocarcinoma, which was held in Atlanta, GA. Attendees from 12 different countries participated in this conference, making it a truly international scientific event. Both oral and poster presentations were given by multidisciplinary experts, who highlighted important areas of current basic and translational research on biliary epithelial cell biology and pathophysiology, and on the etiology, cellular and molecular pathogenesis, and target-based therapy of cholangiocarcinoma. The specific goals and objectives of the conference were: (1) to advance knowledge of basic and molecular mechanisms underlying developmental and proliferative disorders of the biliary tract; (2) to foster a better and more comprehensive understanding of mechanisms regulating biliary epithelial (cholangiocyte) growth and transport, signaling, cell survival, and abnormalities that result in disease; and (3) to understand basic mechanisms of cholangiocarcinoma development and progression, with the added goal of identifying and exploiting potentially critical molecular pathways that may be targeted therapeutically. A number of interrelated themes emerged from the oral and poster sessions that affected current understandings of the complex organization of transcriptional and signaling mechanisms that regulate bile duct development, hepatic progenitor cell expansion, cholangiocyte secretory functions and proliferation, and mechanisms of cholangiocarcinogenesis and malignant cholangiocyte progression. Most notable were the critical questions raised as to how best to exploit aberrant signaling pathways associated with biliary disease as potential targets for therapy.

Pathology of peripheral intrahepatic cholangiocarcinoma with reference to tumorigenesis

Cholangiocarcinomas (CCs) are neoplasms with cholangiocyte differentiation, and may arise from cholangiocytes of the biliary tree and possibly cholangiocyte progenitor cells. Intrahepatic CCs can be divided into the perihilar and peripheral types. Peripheral CCs present grossly as a mass forming tumor, and histologically as an adenocarcinoma of varying shapes and phenotypes. Some peripheral CCs (ductular type) are characterized by: (i) a histological resemblance to reactive bile ductules; (ii) the expression of neural cell adhesion molecule (NCAM) and vimentin. This type shows: (i) grossly, a blurred border; and (ii) histologically, carcinoma cells replacing the adjoining hepatocytes at the border of the tumor. It is frequently associated with neutrophilic infiltration and also with granulocyte and granulocyte macrophage colony-stimulating factors. We propose to call this type "ductular CC." The other peripheral CC (duct type) includes ordinary adenocarcinoma with well to moderately differentiated tubular and micropapillary patterns and is negative for NCAM but positive for mucin. This type can be called "duct CC," and shows a rather compressive growth. Interestingly, CC components of combined hepatocellular CC share the features of ductular CC, suggesting that hepatic progenitor cells may be involved in the tumorigenesis of ductular CC. The biological behavior of ductular CC and duct CC remains obscure, and follow-up and molecular studies on these tumors are required in order for these two CCs to be recognized as disease entities, and so as to evaluate their carcinogenesis.

Combined hepatocellular cholangiocarcinomas; analysis of a large database

Aim:

Combined hepatocellular cholangiocarcinoma (combined tumor) has been described as either a variant of hepatoma or a variant of cholangiocarcinoma. Prior studies evaluated fewer than 50 patients with combined tumors, precluding multivariate analyses. Posited was the notion that analysis of a large database would yield more definite answers.

Methods:

This study used SEER (Surveillance, Epidemiology, and End Results Program of the National Cancer Institute) to analyze 282 combined tumors, 2,035 intrahepatic cholangiocarcinomas, and 19,336 hepatomas between the years 1973–2003. Multinomial logit regression calculated point estimates and 95% confidence intervals (c.i.) for relative risk (rr). Cox regression calculated point estimates and 95% confidence intervals (c.i.) for hazard ratios (ĥ).

Results:

Men less often had cholangiocarcinomas than they had combined tumors (rr = 0.63, c.i. = 0.49–0.81). Hepatomas less often than combined tumors presented with distant spread (rr = 0.56, c.i. = 0.43–0.72). Men (rr = 1.50, c.i. = 1.17–1.93) and patients with a known Asian or Pacific birthplace (rr = 2.36, c.i. = 1.56–3.56) more often had hepatomas than they had combined tumors. Among patients not known to have an Asian/Pacific birthplace, a diagnosis of cholangiocarcinoma (ĥ = 0.72, c.i. = 0.63–0.82) or hepatoma (ĥ = 0.75, c.i. = 0.66–0.86) provided a better prognosis than did a diagnosis of combined tumor.

Conclusion:

Combined tumors differ from hepatomas and cholangiocarcinomas in terms of distribution and survival patterns in the population; they should be considered neither cholangiocarcinomas nor hepatomas.

Combined hepatocellular cholangiocarcinoma originating from hepatic progenitor cells: immunohistochemical and double-fluorescence immunostaining evidence

AIMS

Combined hepatocellular cholangiocarcinoma (CHC) is a rare form of primary liver cancer, showing a mixture of hepatocellular and biliary features. Data suggest that most CHC arise from hepatic progenitor cells (HPCs). The aim was to investigate the origin of CHC.

METHODS AND RESULTS

Twelve cases of CHC were studied by immunohistochemistry for hepatocytic (hepPar1, alpha-fetoprotein), cholangiocytic cytokeratin [(CK) 7, CK19], hepatic progenitor cell (OV-6), haematopoietic stem cell (c-kit, CD34), as well as CD45 and chromogranin-A markers. The combination of double-fluorescence immunostaining consisted of HepPar1 with CK19, and c-kit with OV-6. All 12 cases demonstrated more or less transitional areas, with strands/trabeculae of small, uniform, oval-shaped cells including scant cytoplasm and hyperchromatic nuclei embedded within a thick, desmoplastic stroma; however, two cases were found to consist entirely of such transitional areas. Simultaneous co-expression of hepPar1 and CK7, or CK19, was demonstrated in 10/12 (83.3%) cases of CHC. c-kit expression was noted in 10/12 (83.3%) cases, of which 7/10 (70%) showed co-expression of OV-6.

CONCLUSIONS

The results suggest that CHC are of HPC origin, supporting the concept that human hepatocarcinogenesis may originate from the transformation of HPCs.

JAK-STAT pathway in carcinogenesis: Is it relevant to cholangiocarcinoma progression

The features of JAK-STAT signaling in liver cells are discussed in the current review. The role of this signaling cascade in carcinogenesis is accentuated. The possible involvement of this pathway and alteration of its elements are compared for normal cholangiocytes, cholangiocarcinoma predisposition and development. Prolactin and interleukin-6 are described in detail as the best studied examples. In addition, the non-classical nuclear translocation of cytokine receptors is discussed in terms of its possible implication to cholangiocarcinoma development.

Adult stem cells in progression and therapy of hepatocellular carcinoma

Hepatocellular carcinoma is one of the most aggressive solid tumours associated with poor prognosis. Despite its significance, there is only an elemental understanding of the mechanisms that drive disease pathogenesis, and there are just limited therapy options. The medical community is currently experiencing a wave of enthusiasm for clinical trials, in which adult stem/progenitor cells are used for liver regeneration. This is based on promising results in animal models and encouraging reports from some initial clinical studies. On the other hand, several essential precautions are not being fully addressed. Stem cells may contribute to fibrosis or give rise to hepatic cancer stem cells as a source of hepatocellular carcinoma. This review outlines the current state of knowledge in progression of liver disease and highlights the function of adult stem cells in disease and therapy.

Expression of the novel protein PTPIP51 in rat liver: an immunohistochemical study

Expression of the novel protein tyrosine phosphatase interacting protein 51 (PTPIP51) was investigated on mRNA and protein level in the liver of adult Wistar rats. The presence of PTPIP51 mRNA was detected by Northern blotting. Immunostaining showed expression of PTPIP51 protein in distinct non-parenchymal cells. These cells were identified as Kupffer cells, stellate cells and natural killer cells by detection of cell-specific antigens. Whereas most endothelial cells lining large vessels reacted positive to the PTPIP51 antibody, sinusoidal endothelium showed no detectable amount of PTPIP51. Furthermore, PTPIP51 was also found to be expressed in cells forming the biliary tree. An additional subcellular analysis of the non-parenchymal cells by means of electron microscopy showed the presence of PTPIP51 protein in the cytoplasm and in the nuclei of non-parenchymal cells. Most of the hepatocytes did not show any immuno-detectable amount of PTPIP51, yet, some revealed PTPIP51 protein either in the cytoplasm or in the nucleus.