Genetic alterations in hepatoblastoma and hepatocellular carcinoma: common and distinctive aspects

Characterisation of Aberrant Metabolic Pathways in Hepatoblastoma Using Liquid Chromatography and Tandem Mass Spectrometry (LC-MS/MS)

Hepatoblastoma (HB) is a rare childhood tumour with an evolving molecular landscape. We present the first comprehensive metabolomic analysis using untargeted and targeted liquid chromatography coupled to high-resolution tandem mass spectrometry (LC-MS/MS) of paired tumour and non-tumour surgical samples in HB patients (n = 8 pairs). This study demonstrates that the metabolomic landscape of HB is distinct from that of non-tumour (NT) liver tissue, with 35 differentially abundant metabolites mapping onto pathways such as fatty acid transport, glycolysis, the tricarboxylic acid (TCA) cycle, branched-chain amino acid degradation and glutathione synthesis. Targeted metabolomics demonstrated reduced short-chain acylcarnitines and a relative accumulation of branched-chain amino acids. Medium- and long-chain acylcarnitines in HB were similar to those in NT. The metabolomic changes reported are consistent with previously reported transcriptomic data from tumour and non-tumour samples (49 out of 54 targets) as well as metabolomic data obtained using other techniques. Gene set enrichment analysis (GSEA) from RNAseq data (n = 32 paired HB and NT samples) demonstrated a downregulation of the carnitine metabolome and immunohistochemistry showed a reduction in CPT1a (n = 15 pairs), which transports fatty acids into the mitochondria, suggesting a lack of utilisation of long-chain fatty acids in HB. Thus, our findings suggest a reduced metabolic flux in HB which is corroborated at the gene expression and protein levels. Further work could yield novel insights and new therapeutic targets.

Two Cases of Hepatoblastoma in Adults

Adult hepatoblastoma is a rare tumor whose etiology and mechanisms of development are still incompletely understood. Imaging and biological tests such as AFP and liver enzymes are non-specific. Histologically, there are 2 histological variants: pure epithelial with 5 types (pure fetal, embryonal, small cell undifferentiated, cholangioblastic, and macrotrabecular), a mixed epithelial and a mesenchymal variant with or without a teratoid contingent. The main differential diagnosis concerns hepatocellular carcinoma. The treatment of hepatoblastoma in adults is not yet standardized and surgery remains the mainstay of treatment. In this report we aim to describe the clinical, pathological, and immunohistochemical features of this rare entity in adult patients and discuss the elements allowing its distinction from hepatocellular carcinoma (HCC).

Metabolic Contributions of Wnt Signaling: More Than Controlling Flight

The canonical Wnt signaling pathway is ubiquitous throughout the body and influences a diverse array of physiological processes. Following the initial discovery of the Wnt signaling pathway during wing development in Drosophila melanogaster, it is now widely appreciated that active Wnt signaling in mammals is necessary for the development and growth of various tissues involved in whole-body metabolism, such as brain, liver, pancreas, muscle, and adipose. Moreover, elegant gain- and loss-of-function studies have dissected the tissue-specific roles of various downstream effector molecules in the regulation of energy homeostasis. This review attempts to highlight and summarize the contributions of the Wnt signaling pathway and its downstream effectors on whole-body metabolism and their influence on the development of metabolic diseases, such as diabetes and obesity. A better understanding of the Wnt signaling pathway in these tissues may aid in guiding the development of future therapeutics to treat metabolic diseases.

Pediatric Hepatocellular Carcinoma

PURPOSE

Pediatric hepatocellular carcinoma is rarely seen in childhood. It constitutes approximately 1% of childhood solid organ malignancies. Pediatric hepatocellular carcinoma is the second most common malignant liver tumor after hepatoblastoma in children. In this review, we aimed to review the diagnosis and treatment of pediatric hepatocellular carcinoma in the light of the latest literature.

METHODS

We reviewed the literature in terms of the diagnosis and treatment of pediatric hepatocellular carcinoma.

RESULTS

Hepatocellular carcinoma (HCC) and hepatoblastoma constitute 0.5-1.5% of all childhood malignant tumors. HCC is responsible for 27% of all liver tumors and 4% of all pediatric liver transplantations. While 99.6% of HCC is seen in adults, only 0.4% of it is seen in pediatric patients. Etiological predisposition and biological behavior are different from adults. In a child with cirrhosis or liver disease, HCC should be suspected in the presence of a high level of AFP and an abnormal nodule on ultrasonography. Hepatoblastoma should be considered first in the differential diagnosis.

CONCLUSION

Treatment of pediatric HCC is challenging. Complete surgical resection is essential for the cure. To this end, different neoadjuvant chemotherapy protocols have been designed to convert non-resectable tumors into resectable tumors. For tumors that cannot be resected, liver transplantation for each patient with childhood HCC should be decided individually.

Challenges of applying multicellular tumor spheroids in preclinical phase

The three-dimensional (3D) multicellular tumor spheroids (MCTs) model is becoming an essential tool in cancer research as it expresses an intermediate complexity between 2D monolayer models and in vivo solid tumors. MCTs closely resemble in vivo solid tumors in many aspects, such as the heterogeneous architecture, internal gradients of signaling factors, nutrients, and oxygenation. MCTs have growth kinetics similar to those of in vivo tumors, and the cells in spheroid mimic the physical interaction of the tumors, such as cell-to-cell and cell-to-extracellular matrix interactions. These similarities provide great potential for studying the biological properties of tumors and a promising platform for drug screening and therapeutic efficacy evaluation. However, MCTs are not well adopted as preclinical tools for studying tumor behavior and therapeutic efficacy up to now. In this review, we addressed the challenges with MCTs application and discussed various efforts to overcome the challenges.

Hepatoblastoma and Pediatric Hepatocellular Carcinoma: An Update

Hepatoblastomas (HBs) and pediatric hepatocellular carcinomas (HCCs) together account for almost 80% of primary malignant liver tumors in children and adolescents/young adults. Children's Hepatic International Collaboration (CHIC), Children's Oncology Group (COG), SociétéInternationale d'Oncologie Pédiatrique (SIOP), and International Childhood Liver Tumors Strategy Group trials have contributed to define prognostic factors and risk stratification in these tumors. The recently proposed histologic International Consensus classification of HB and HCC in children based on retrospective analysis from CHIC cases represents the base to define entities with homogeneous clinicopathologic and molecular features. This review will provide a morphologic guide for the upcoming International Liver Tumor treatment trial (Pediatric Hepatic International Tumour Trial) to be conducted through several continents. There will be an emphasis on molecular features and immunohistochemical markers for the definition of the individual histologic subtypes of HB and to better characterize the group of liver tumors in the provisional category of hepatocellular neoplasm-not otherwise specified. A brief overview of HCC in children will also be provided.

Analysis of β-catenin gene mutations and gene expression in liver tumours of C57BL/10J mice produced by chronic administration of sodium phenobarbital

In this study liver tumours produced in male and female mice of the low spontaneous liver tumour incidence C57BL/10J strain treated for 99 weeks with 1000 ppm in the diet with the model constitutive androstane receptor (CAR) activator sodium phenobarbital (NaPB) were analysed for β-catenin mutations by Western immunoblotting and DNA/RNA analysis. Some gene array analysis was also performed to identify genes involved in CAR activation and in β-catenin and Hras gene mutations. Analysis of 8 male and 2 female NaPB-induced liver tumour samples (comprising 2 adenomas, 6 carcinomas and 2 samples containing separate adenomas and carcinomas) revealed truncated β-catenin forms in just 4 male liver tumour samples, with the presence of the truncated β-catenin forms being confirmed by β-catenin exon 1-3 mutation analysis. Microarray gene expression analysis was performed with three of the NaPB-induced male mouse liver tumour samples where β-catenin mutations had not been identified by Western immunoblotting and DNA/RNA analysis and with three liver samples from both NaPB-induced non-tumour tissue and control animals. Treatment with NaPB resulted in induction of Cyp2b subfamily gene expression in both NaPB-induced mouse liver tumours and in NaPB-treated non-tumour tissue. In addition, the gene expression analysis demonstrated that the β-catenin and Hras pathways were not modified in NaPB-induced mouse liver tumours not exhibiting truncated β-catenin forms. Overall, while chronic administration of the model CAR activator NaPB results in both hepatocellular adenoma and carcinoma in the low spontaneous liver tumour incidence C57BL/10J mouse strain, only 40 % of the liver tumours evaluated in this study had β-catenin mutations. These results are in agreement with previous studies with the CAR activator oxazepam and demonstrate that mouse liver tumours induced by nongenotoxic CAR activators in the absence of initiation with a genotoxic agent are due to a number of mechanisms, including those largely independent of either the Wnt/β-catenin signalling pathway or Hras oncogene mutations.

Wnt/β-catenin signaling as a useful therapeutic target in hepatoblastoma

Hepatoblastoma is a malignant tumor in the liver of children that generally occurs at the age of 2–3 years. There have been ample evidence from the preclinical as well as clinical studies suggesting the activation of Wnt/β-catenin signaling in hepatoblastoma, which is mainly attributed to the somatic mutations in the exon 3 of β-catenin gene. There is increased translocation of β-catenin protein from the cell surface to cytoplasm and nucleus and intracellular accumulation is directly linked to the severity of the cancer. Accordingly, the alterations in β-catenin and its target genes may be used as markers in the diagnosis and prognosis of pediatric live tumors. Furthermore, scientists have reported the therapeutic usefulness of inhibition of Wnt/β-catenin signaling in hepatoblastoma and this inhibition of signaling has been done using different methods including short interfering RNA (siRNA), miRNA and pharmacological agents. Wnt/β-catenin works in association with other signaling pathways to induce the development of hepatoblastoma including Yes-associated protein (YAP)1 (YAP-1), mammalian target of rapamycin (mTOR) 1 (mTOR-1), SLC38A1, glypican 3 (GPC3), nuclear factor κ-light-chain-enhancer of activated B cells (NF-kB), epidermal growth factor receptor, ERK1/2, tumor necrosis factor-α (TNF-α), regenerating islet-derived 1 and 3 α (REG1A and 3A), substance P (SP)/neurokinin-1 receptor and PARP-1. The present review describes the key role of Wnt/β-catenin signaling in the development of hepatoblastoma. Moreover, the role of other signaling pathways in hepatoblastoma in association with Wnt/β-catenin has also been described.

New insights into the association between AXIN2 148 C/T, 1365 C/T, and rs4791171 A/G variants and cancer risk

BACKGROUND

Many epidemiological studies have investigated association of AXIN2 variants on overall cancer risks; however, the available results remain inconsistent.

METHODS

An updated analysis was conducted to ascertain a more accurate estimation of the correlation between AXIN2 148 C/T, 1365 C/T, and rs4791171 A/G polymorphisms and cancer risk. We also used in silico tools to assess the effect of AXIN2 expression on cancer susceptibility and overall survival time.

RESULTS

A total of 4281 cases and 3955 control participants were studied. The overall results indicated that AXIN2 148 C/T variant was associated with cancer risk (allelic contrast: OR = 0.88, 95% CI 0.77-0.99, P heterogeneity = 0.004; dominant model: OR = 0.82, 95% CI 0.69-0.96, P heterogeneity = 0.022), especially for lung and prostate adenocarcinoma. Similar results were observed in 1365 C/T polymorphism (OR = 0.71, 95% CI 0.61-0.98, P heterogeneity = 0.873; dominant model: OR = 0.66, 95% CI 0.47-0.94, P heterogeneity = 0.775). Moreover, in subgroup analysis by ethnicity, similar findings were obtained for Asian and Caucasian populations. Results from in silico tools suggested that AXIN2 expressions in lung adenocarcinoma were lower than that in normal group.

CONCLUSIONS

Our findings indicated that AXIN2 148 C/T and 1365 C/T variants may be associated with decreased cancer susceptibility.

Utilizing ethacrynic acid and ciclopirox olamine in liver cancer

Once aberrantly activated, the Wnt/β-catenin pathway may result in uncontrolled proliferation and eventually cancer. Efforts to counter and inhibit this pathway are mainly directed against β-catenin, as it serves a role on the cytoplasm and the nucleus. In addition, specially-generated lymphocytes are recruited for the purpose of treating liver cancer. Peripheral blood mononuclear lymphocytes are expanded by the timely addition of interferon γ, interleukin (IL)-1β, IL-2 and anti-cluster of differentiation 3 antibody. The resulting cells are called cytokine-induced killer (CIK) cells. The present study utilised these cells and combine them with drugs inhibiting the Wnt pathway in order to examine whether this resulted in an improvement in the killing ability of CIK cells against liver cancer cells. Drugs including ethacrynic acid (EA) and ciclopirox olamine (CPX) were determined to be suitable candidates, as determined by previous studies. Drugs were administered on their own and combined with CIK cells and then a cell viability assay was performed. These results suggest that EA-treated cells demonstrated apoptosis and were significantly affected compared with untreated cells. Unlike EA, CPX killed normal and cancerous cells even at low concentrations. Subsequent to combining EA with CIK cells, the potency of killing was increased and a greater number of cells died, which proves a synergistic action. In summary, EA may be used as an anti-hepatocellular carcinoma drug, while CPX possesses a high toxicity to cancerous as well as to normal cells. It was proposed that EA should be integrated into present therapeutic methods for cancer.

Patient-derived multicellular tumor spheroids towards optimized treatment for patients with hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide and has poor prognosis. Specially, patients with HCC usually have poor tolerance of systemic chemotherapy, because HCCs develop from chronically damaged tissue that contains considerable inflammation, fibrosis, and cirrhosis. Since HCC exhibits highly heterogeneous molecular characteristics, a proper in vitro system is required for the study of HCC pathogenesis. To this end, we have established two new hepatitis B virus (HBV) DNA-secreting HCC cell lines from infected patients.

Methods

Based on these two new HCC cell lines, we have developed chemosensitivity assays for patient-derived multicellular tumor spheroids (MCTSs) in order to select optimized anti-cancer drugs to provide more informative data for clinical drug application. To monitor the effect of the interaction of cancer cells and stromal cells in MCTS, we used a 3D co-culture model with patient-derived HCC cells and stromal cells from human hepatic stellate cells, human fibroblasts, and human umbilical vein endothelial cells to facilitate screening for optimized cancer therapy.

Results

To validate our system, we performed a comparison of chemosensitivity of the three culture systems, which are monolayer culture system, tumor spheroids, and MCTSs of patient-derived cells, to sorafenib, 5-fluorouracil, and cisplatin, as these compounds are typically standard therapy for advanced HCC in South Korea.

Conclusion

In summary, these findings suggest that the MCTS culture system is the best methodology for screening for optimized treatment for each patients with HCC, because tumor spheroids not only mirror the 3D cellular context of the tumors but also exhibit therapeutically relevant pathophysiological gradients and heterogeneity of in vivo tumors.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0752-0) contains supplementary material, which is available to authorized users.

Βeta-catenin N-terminal domain: An enigmatic region prone to cancer causing mutations

The Wnt/β-catenin is a highly conserved signaling pathway involved in cell fate decisions during various stages of development. Dysregulation of canonical Wnt/β-catenin signaling has been associated with various diseases including cancer. β-Catenin, the central component of canonical Wnt signaling pathway, is a multi-functional protein playing both structural and signaling roles. β-Catenin is composed of three distinct domains: N-terminal domain, C-terminal domain and a central armadillo repeat domain. N-terminal domain of β-catenin harbours almost all of the cancer causing mutations, thus deciphering its critical structural and functional roles offers great potential in cancer detection and therapy. Here, in this review, we have collected information from pharmacological analysis, bio-physical and structural studies, molecular modeling, in-vivo and in-vitro assays, and transgenic animal experiments employing various N-terminal domain variants of β-catenin to discuss the interaction of β-catenin with its binding partners that specifically interact with this domain and the implications of these interactions on signaling, cell fate determination, and in tumorigenesis. A thorough understanding of interactions between β-catenin and its binding partners will enable us to more effectively understand how β-catenin switches between its multiple roles, and will lead to the development of specific assays for the identification of small molecules as chemotherapeutic agents to treat diseases, including cancer and neurological disorders, where Wnt/β-catenin signaling is dysregulated.

Pediatric hepatocellular carcinoma: challenges and solutions

Hepatocellular carcinoma (HCC) is a very rare entity in children, making it nearly impossible to orchestrate Phase II/III studies even as multinational cooperative trials. In contrast to adults, nearly 50% of the children have a response (α-fetoprotein decline and/or tumor shrinkage) to chemotherapeutic agents such as cisplatin and doxorubicin (PLADO), demonstrating that HCC in childhood can be chemotherapy sensitive. As a result, the main treatment options in pediatric HCC focus on systemic drug therapies and resection as the central therapy. In nonmetastatic patients with complete resection upfront, the 5-year event-free survival and overall survival has reached 80%–90%. In almost all reported studies, children received adjuvant chemotherapy (mostly PLADO), but it has never been proven that postoperative chemotherapy is superior to observation. No data are available for the effects of sorafenib. The 3-year survival is <20% in children with unresectable HCC independent of the chemotherapy given preoperatively. Currently, PLADO in combination with sorafenib is recommended with the goal of achieving operability status. Alternatively, data are promising for the combination of sorafenib with gemcitabine and oxaliplatin. For children with nonresectable and nonmetastastic liver tumors, it has been shown that the Milan criteria regarding liver transplantation are not applicable – individual decisions have to be made. Transarterial chemoembolization could be offered to patients with chemotherapy-resistant liver tumors for palliative care or potentially to achieve surgical resectability, and therefore cure. Information about the feasibility or effects of new agents or approaches as discussed in adult HCC patients is not available for childhood HCC. Research has to be done for characterizing the molecular and genomic mechanisms of pediatric HCC to support the development of novel therapeutic approaches and the implementation of personalized medicine.

Induction of apoptosis by IGFBP3 overexpression in hepatocellular carcinoma cells

BACKGROUND

The insulin-like growth factor (IGF) system comprises a group of proteins that play key roles in regulating cell growth, differentiation, and apoptosis in a variety of cellular systems. The aim of this study was to investigate the role of insulin-like growth factor binding protein 3 (IGFBP3) in hepatocellular carcinoma.

MATERIALS AND METHODS

Expression of IGF2, IGFBP3, and PTEN was analyzed by qRT-PCR. Lentivirus vectors were used to overexpress IGFBP3 in hepatocellular carcinoma cell (HCC) lines. The effect of IGFBP3 on proliferation was investigated by MTT and colony formation assays.

RESULTS

Expression of IGF2, IGFBP3, and PTEN in several HCC cell lines was lower than in normal cell lines. After 5-aza-2'-deoxycytidine/trichostatin A treatment, significant demethylation of the promoter region of IGFBP3 was observed in HCC cells. Overexpression of IGFBP3 induced apoptosis and reduced colony formation in HUH7 cells.

CONCLUSIONS

Expression of IGF2, IGFBP3, and PTEN in several HCC cell lines was lower than in normal cell lines. After 5-aza-2'-deoxycytidine/ trichostatin A treatment, significant demethylation of the promoter region of IGFBP3 was observed in HCC cells. Overexpression of IGFBP3 induced apoptosis and reduced colony formation in HUH7 cells.

The genomic landscape of hepatoblastoma and their progenies with HCC-like features

BACKGROUND & AIMS

Hepatoblastoma (HB) is the most common childhood liver cancer and occasionally presents with histological and clinical features reminiscent of hepatocellular carcinoma (HCC). Identification of molecular mechanisms that drive the neoplastic continuation towards more aggressive HCC phenotypes may help to guide the new stage of targeted therapies.

METHODS

We performed comprehensive studies on genetic and chromosomal alterations as well as candidate gene function and their clinical relevance.

RESULTS

Whole-exome sequencing identified HB as a genetically very simple tumour (2.9 mutations per tumour) with recurrent mutations in ß-catenin (CTNNB1) (12/15 cases) and the transcription factor NFE2L2 (2/15 cases). Their HCC-like progenies share the common CTNNB1 mutation, but additionally exhibit a significantly increased mutation number and chromosomal instability due to deletions of the genome guardians RAD17 and TP53, accompanied by telomerase reverse-transcriptase (TERT) promoter mutations. Targeted genotyping of 33 primary tumours and cell lines revealed CTNNB1, NFE2L2, and TERT mutations in 72.5%, 9.8%, and 5.9% of cases, respectively. All NFE2L2 mutations affected residues of the NFE2L2 protein that are recognized by the KEAP1/CUL3 complex for proteasomal degradation. Consequently, cells transfected with mutant NFE2L2 were insensitive to KEAP1-mediated downregulation of NFE2L2 signalling. Clinically, overexpression of the NFE2L2 target gene NQO1 in tumours was significantly associated with metastasis, vascular invasion, the adverse prognostic C2 gene signature, as well as poor outcome.

CONCLUSIONS

Our study demonstrates the importance of CTNNB1 mutations and NFE2L2-KEAP1 pathway activation in HB development and defines loss of genomic stability and TERT promoter mutations as prominent characteristics of aggressive HB with HCC features.

Exome sequencing of hepatoblastoma reveals novel mutations and cancer genes in the Wnt pathway and ubiquitin ligase complex

Hepatoblastoma (HB) is the most common primary liver tumor in children. Mutations in the β-catenin gene that lead to constitutive activation of the Wnt pathway have been detected in a large proportion of HB tumors. To identify novel mutations in HB, we performed whole-exome sequencing of six paired HB tumors and their corresponding lymphocytes. This identified 24 somatic nonsynonymous mutations in 21 genes, many of which were novel, including three novel mutations targeting the CTNNB1 (G512V) and CAPRIN2 (R968H/S969C) genes in the Wnt pathway, and genes previously shown to be involved in the ubiquitin ligase complex (SPOP, KLHL22, TRPC4AP, and RNF169). Functionally, both the CTNNB1 (G512V) and CAPRIN2 (R968H/S969C) were observed to be gain-of-functional mutations, and the CAPRIN2 (R968H/S969C) was also shown to activate the Wnt pathway in HB cells. These findings suggested the activation of the Wnt pathway in HB, which was confirmed by immunohistochemical staining of the β-catenin in 42 HB tumors. We further used short hairpin RNA (shRNA)-mediated interference to assess the effect of 21 mutated genes on HB cell survival. The results suggested that one novel oncogene (CAPRIN2) and three tumor suppressors (SPOP, OR5I1, and CDC20B) influence HB cell growth. Moreover, we found that SPOP S119N is a loss-of-function mutation in HB cells. We finally demonstrated that one of the mechanisms by which SPOP inhibits HB cell proliferation is through regulating CDKN2B expression.

CONCLUSION

These results extend the landscape of genetic alterations in HB and highlight the dysregulation of Wnt and ubiquitin pathways in HB tumorigenesis.

Frequent losses of heterozygosity in the mitofusin 2 gene in hepatocellular carcinoma: their relationship to clinicopathological features

BACKGROUND

The aim of the study was to determine the features of loss of heterozygosity in the mitofusin 2 gene and their association with clinicopathological characteristics of hepatocellular carcinoma.

METHODOLOGY

Loss of heterozygosity of four microsatellite loci were detected in tumors and their adjacent normal tissues of 29 surgically resected hepatocellular carcinomas using an ABI3130xl automated sequencer.

RESULTS

The results showed the incidences of loss of heterozygosity on microsatellite loci D1S2667, D1S2740, D1S434, and D1S228 were 21%, 23%, 21%, and 22%, respectively. Loss of heterozygosity in the mitofusin 2 gene was closely correlated with age, degree of differentiation, capsule integrity, and tumor size (P <0.05) but was not correlated with gender, thrombosis, liver cirrhosis, or alpha-fetoprotein levels (P >0.05).

CONCLUSIONS

Frequent loss of heterozygosity in the mitofusin 2 gene exists in hepatocellular carcinoma. Loss of heterozygosity, which represents a tumor suppressor gene pathway, may play a critical role in the occurrence and development of hepatocellular carcinoma.

Epigallocatechin-3-gallate inhibits hepatoblastoma growth by reactivating the Wnt inhibitor SFRP1

Activation of Wnt signaling plays a central role in the formation of hepatoblastoma (HB), the most common pediatric liver cancer. Blocking this pathway with specific inhibitors is currently the target of various research endeavours. This study provides evidence that the naturally occurring flavonoid epigallocatechin-3-gallate (EGCG) is highly effective against HB growth through inhibition of Wnt signaling. We demonstrate that EGCG has a strong cytotoxic effect on HB cells in a time- and dose-dependent manner by impinging on cell viability, while leaving normal fibroblasts unaffected. Apoptotic features, including morphological changes, caspase 3 activity, and proteolytic cleavage of poly(ADP-ribose) polymerase, were frequently found in EGCG-treated HB cells, thereby suggesting involvement of the mitochondrial intrinsic apoptotic pathway. We furthermore show that EGCG effectively inhibits Wnt signaling, as evidenced by down-regulation of Wnt-responsive reporter gene activity and expression of the Wnt target genes MYC and CCND1. Interestingly, EGCG induced reexpression of the tumor suppressor gene SFRP1, which is transcriptionally silenced in HB cells and known to down-regulate Wnt signaling. Considering the lack of toxic effects on normal cells, EGCG should be preclinically validated as an adjuvant therapy in vivo with the ultimate goal of determining its efficacy in human trials.

Multifocal hepatic neoplasia in 3 children with APC gene mutation

Hepatoblastoma (HB), the most common hepatic neoplasm in children is associated with germline mutations in adenomatous polyposis coli tumor-suppressor gene that cause familial adenomatous polyposis syndrome. Individuals with familial adenomatous polyposis have a 750 to 7500× the risk of developing HB. We report 3 children with APC gene mutation, who underwent resection or liver transplant for HB. In addition to HB, all 3 patients had multiple independent adenoma-like nodules lacking qualities of intrahepatic metastases. Twenty-five nodules were subjected to immunohistochemical analysis using a panel of antibodies including glypican-3 (GPC3), β-catenin, cytokeratin AE1/AE3, CD34, Ki-67, glutamine synthetase (GS), and fatty acid binding protein. The nodules were round, ranged in size from 0.2 to 1.5 cm, and paler than the background liver. All lacked the chemotherapy effect. The nodules were circumscribed but nonencapsulated and composed of well-differentiated hepatocytes with occasional minor atypical features and absent or rare portal tracts. One lesion displayed a "nodule-within-nodule" pattern. The nodules demonstrated diffuse GS overexpression. Nine (36%) nodules were focally reactive for GPC3, and 1 (4%) displayed focal nuclear β-catenin expression. The associated HB showed diffuse expression of GS, GPC3, and β-catenin nuclear staining. We interpret these nodules as neoplastic with most being adenomas (GPC3 negative) that show features of independent origin and represent early stages of carcinogenesis, implying potential to progress to HB or hepatocellular carcinoma. To our knowledge, this is the first report of multifocal neoplasms in patients with HB and APC gene mutation.

Clinicopathologic implication of hepatic progenitor cell marker expression in hepatoblastoma

Hepatic progenitor cells (HPCs) are thought to play a role in hepatoblastoma, as hepatoblastomas are characterized by an immature histology and a wide variety of cell lineages. We aimed to investigate the extent of expression of HPCs marker and its clinical implication in hepatoblastoma. We collected 61 hepatoblastomas and 9 childhood hepatocellular carcinomas (HCCs) and performed immunohistochemistry for HPC markers, including cytokeratin 19 (CK19), octamer-binding transcription factor 3/4 (Oct-3/4), epithelial cell adhesion molecule (EpCAM), and delta-like 1 homolog (DLK1). Of the hepatoblastoma samples, 27/61 (44.3%), 21/61 (34.4%), 51/61 (83.6%) and 56/61 (91.8%) exhibited positivity for CK19, Oct-3/4, EpCAM and DLK-1, respectively. For HCCs, the rates of expression were 22.2% (CK19), 77.8% (EpCAM) and 77.8% (DLK-1). Oct-3/4 was not expressed in HCC cells. Hepatoblastomas with a poorly differentiated epithelial component had a higher incidence of CK19 and Oct-3/4 expression than those with a well differentiated epithelial component (p=0.005 and 0.037, respectively). Higher disease stage of hepatoblastoma was correlated with CK19 expression (p=0.043). Oct-3/4-positive hepatoblastomas were associated with short disease-free survival (p=0.035). Both hepatoblastomas and childhood HCCs, therefore, exhibit characteristics of HPCs, and the poor prognosis of patients with Oct-3/4-positive hepatoblastoma suggests that stem-like properties affect hepatoblastoma pathogenicity.

Pharmacological inhibition of beta-catenin in hepatoblastoma cells

PURPOSE

The proto-oncogene beta-catenin is linked to an abnormal activation of the Wnt/beta-catenin-pathway and shows mutations in 50-90 % of hepatoblastoma (HB). Corresponding, the recently published murine orthotopic HB model differs from the former subcutaneous model by nuclear beta-catenin distribution. As the nuclear localization of beta-catenin is considered to reflect a more aggressive tumor growth, the influence of beta-catenin inhibition on cell viability and drug-efficiency in HB cells was analyzed.

METHODS

Beta-catenin distribution in HB cells was analyzed by immunofluorescence. The influence of beta-catenin inhibitors Celecoxib, Etodolac, ICG001, and MET kinase inhibitor (SU11274) alone and in combination with cisplatin (CDDP) on HB cell lines (HuH6, HepT1) was evaluated by cell viability assays and BrdU incorporation.

RESULTS

Celecoxib and ICG001 reduced dose-dependently HB cell viability and decreased nuclear beta-catenin in cultivated HB cells. Etodolac was without influence at concentrations up to 100 μM. Combinations of Celecoxib or ICG001 with MET kinase inhibitor or CDDP resulted in additive reduction of cell viability.

CONCLUSION

Pharmaceutical beta-catenin inhibitors can modulate the nuclear localization of beta-catenin and reduce cell viability of HB cells in vitro. These promising effects might optimize the outcome of high-risk HB. The orthotopic HB model is a suitable basis for further in vivo studies.

Evaluating the effect of high-intensity focused ultrasound therapy on liver tumors using multislice CT perfusion

The aim of this study was to investigate the changes of the multislice computed tomography (MSCT) perfusion parameters and histopathology of the liver in rabbits with VX2 tumors before and after high-intensity focused ultrasound (HIFU) therapy. VX2 carcinoma cells were implanted into the livers of eight New Zealand white rabbits 3 weeks prior to the treatment. MSCT perfusion was performed one week before and one and six weeks after the treatment. These CT perfusion (CTP) data, including hepatic blood flow (HBF), hepatic blood volume (HBV), mean transit time (MTT) and permeability-surface area product (PS), were analyzed semi-quantitatively and qualitatively. Furthermore, the histopathological features of the liver tissues were also assessed semi-quantitatively before and after the treatment. Six weeks after HIFU therapy, MTT increased noticeably from 5.45±0.27 to 10.38±2.22 sec (P<0.05) and PS decreased significantly from 79.03±3.41 to 68.13±0.21 ml/100 g/min (P<0.05), while no significant differences in HBF and HBV were found. Furthermore, more CD3⁺ T cells were observed at the rim and center of the liver tumors six weeks after treatment. Therefore, HIFU therapy may be a simple and effective method for the treatment of liver tumors. CTP, as an effective method to obtain functional information about HBF, is able to quantify tumor vascularity and angiogenesis in liver tumors.

Current concepts in pediatric liver tumors

Liver tumors in children can be classified into benign or malignant; some of the benign lesions can have the potential of malignant transformation, and therefore the therapeutic approach may change. These neoplasms account for nearly 1-2% of all pediatric tumors and they have gained significant attention in the last decades due to data suggesting that the incidence may be increasing 5% annually. We know that with new and improved imaging modalities some of these lesions may be detected more often than before. Recent studies showed that liver cancer represented 2% of malignancies in infants by 1980s and this was doubled in incidence to 4% in the following 10 yr. In this review our aim is to discuss all primary liver tumors in children with attention to their clinicopathological and immunohistochemical features followed by the current standard of care.

β-Catenin mutations in 2 nested stromal epithelial tumors of the liver--a neoplasia with defective mesenchymal-epithelial transition

Nested stromal epithelial tumor of the liver is a rare neoplasm of early childhood and adolescence with a characteristic nested morphology of spindle and epithelioid cells. Histogenesis and pathogenesis of this neoplasm are, however, still unclear. Because the characteristic nested morphology with spindle mesenchymal and epithelioid cells is suggestive of altered mesenchymal-epithelial transition and β-catenin mutations are rather common in other liver tumors such as hepatoblastomas, we investigated the β-catenin gene in 2 nested stromal epithelial tumors of the liver and analyzed additional factors involved in mesenchymal-epithelial transition, such as E-cadherin, vimentin, c-Met, TWIST, SNAIL, and SLUG by molecular genetic and immunohistochemical methods. Mutation analysis of both cases revealed large deletions in exon 3 of the β-catenin gene (155 and 228 base pairs), resulting in an accumulation of β-catenin in the cytoplasm and nuclei of tumor cells, as evidenced by immunohistochemistry. The expression of the mesenchymal-epithelial transition factors SNAIL, SLUG, TWIST, c-Met, vimentin, and β-catenin was generally increased, whereas E-cadherin was decreased. Morphological and immunohistochemical analysis, however, showed a variable expression pattern of various epithelial and mesenchymal markers both in the spindle and epithelioid cell compartments of the tumors, thus illustrating the transitional status of the tumor cells. In conclusion, our data clearly identify protein stabilizing mutations of the β-catenin gene as a common feature of nested stromal epithelial tumors of the liver, similarly as in hepatoblastomas. Therefore, nested stromal epithelial tumors of the liver may be regarded as a variant of hepatoblastoma, despite differing from it in clinical and morphological aspects. The characteristic epithelioid-spindle morphology along with the incomplete epithelial differentiation proposes impaired mesenchymal-epithelial transition as a possible pathogenetic mechanism of this rare tumor. However, because only 2 cases were studied, this hypothesis awaits further validation.

Sorafenib and cisplatin/doxorubicin (PLADO) in pediatric hepatocellular carcinoma

PURPOSE

Overall survival is poor in children with primary unresectable hepatocellular carcinoma. Sorafenib has been shown to significantly improve progression-free survival in adult hepatocellular carcinoma (HCC) patients. We evaluated the experience of PLADO (cisplatin 80 mg/m(2) /day, doxorubicin 2 × 30 mg/m(2) /day) in combination with sorafenib in pediatric HCC patients.

PATIENTS AND METHODS

Clinical data of 12 patients (7-16 years), 7 with unresectable tumor, were retrospectively assessed.

RESULTS

In total 6/12 (50%) patients are in complete remission after a median follow-up of 20 months (4 with PLADO/sorafenib/resection, 2 with liver transplantation after local relapse). Of the seven patients with unresectable tumor, PLADO/sorafenib resulted in partial response (PR) in four, stable disease (SD) in two, and progression in one. Three are alive in CR after complete resection after 12 (alternative therapy after two cycles PLADO/sorafenib), 12 and 18 months (six cycles PLADO/sorafenib), respectively. All four patients with elevated alpha-fetoprotein levels had a marked drop after two cycles. Of the five patients with primary complete tumor resection one is alive disease-free at 27 months. Four had local or metastatic relapses (13, 7, 12, and 13 months), two of whom were rescued by liver transplantation (CR after 25 and 32 months). The main toxicity attributable to sorafenib was a hand-foot skin reaction (HFSR) in seven patients.

CONCLUSION

Sorafenib in combination with PLADO may be a promising approach in pediatric HCC; HFSR was the most important toxicity. Data based on prospective studies are needed to evaluate pharmacokinetics, resectability rates, and survival in pediatric HCC treated with sorafenib.

Genetics and imaging of hepatocellular adenomas: 2011 update

Hepatocellular adenomas are benign liver neoplasms with specific but varied histopathologic findings and tumor biology. The results from recent studies of the pathologic and genetic basis of hepatocellular adenomas provide important insights into the pathogenesis and molecular changes, as well as the putative oncologic pathways used by diverse adenoma subtypes. On the basis of the genetic and pathologic features, hepatocellular adenomas are categorized into three distinct subtypes: (a) inflammatory hepatocellular adenomas, (b) hepatocyte nuclear factor 1 α-mutated hepatocellular adenomas, and (c) β-catenin-mutated hepatocellular adenomas. Different subtypes show variable clinical behavior, imaging findings, and natural history, and thus the options for treatment and surveillance may vary. Cross-sectional imaging plays an important role in the diagnosis, subtype characterization, identification of complications, and surveillance of hepatocellular adenomas. New schemas for genotype-phenotype classification of hepatic adenomas, as well as management triage of patients with specific subtypes of adenomas, are being proposed in an attempt to improve clinical outcomes.

Deregulation of Hippo kinase signalling in human hepatic malignancies

BACKGROUND/AIMS

Hepatocellular carcinoma (HCC), cholangiocarcinoma (CC) and hepatoblastoma (HB) are the main hepatic malignancies with limited treatment options and high mortality. Recent studies have implicated Hippo kinase pathway in cancer development, but detailed analysis of Hippo kinase signalling in human hepatic malignancies, especially CC and HB, is lacking.

METHODS

We investigated Hippo kinase signalling in HCC, CC and HB using cells and patient samples.

RESULTS

Increased expression of yes-associated protein (Yap), the downstream effector of the Hippo kinase pathway, was observed in HCC cells, and siRNA-mediated knockdown of Yap resulted in decreased survival of HCC cells. The density-dependent activation of Hippo kinase pathway characteristic of normal cells was not observed in HCC cells and CCLP cells, a cholangiocarcinoma cell line. Immunohistochemistry of Yap in HCC, CC and HB tissues indicated extensive nuclear localization of Yap in majority of tissues. Western blot analysis performed using total cell extracts from patient samples and normal livers showed extensive activation of Yap. Marked induction of Glypican-3, CTGF and Survivin, the three Yap target genes was observed in the tumour samples. Further analysis revealed significant decrease in expression and activity of Lats kinase, the main upstream regulator of Yap. However, no change in activation of Mst-2 kinase, the upstream regulator of Lats kinase was observed.

CONCLUSIONS

These data show that Yap induction mediated by inactivation of Lats is observed in hepatic malignancies. These studies highlight Hippo kinase pathway as a novel therapeutic target for hepatic malignancies.

HGF/c-Met related activation of β-catenin in hepatoblastoma

Background

Activation of beta-catenin is a hallmark of hepatoblastoma (HB) and appears to play a crucial role in its pathogenesis. While aberrant accumulation of the beta-catenin is a common event in HB, mutations or deletions in CTNNB1 (beta-catenin gene) do not always account for the high frequency of protein expression. In this study we have investigated alternative activation of beta-catenin by HGF/c-Met signaling in a large cohort of 98 HB patients enrolled in the SIOPEL-3 clinical trial.

Methods

We performed immunohistochemistry, using antibodies to total beta-catenin and tyrosine654-phosphorylated beta-catenin, which is a good surrogate marker of HGF/c-Met activation. CTNNB1 mutation analysis was also carried out on all samples. We also investigated beta-catenin pathway activation in two liver cancer cell lines, HuH-6 and HuH-7.

Results

Aberrant beta-catenin expression was seen in the cytoplasm and/or nucleus of 87% of tumour samples. Our results also revealed a large subset of HB, 83%, with cytoplasmic expression of tyrosine654-phosphorylated beta-catenin and 30% showing additional nuclear accumulation. Sequence analysis revealed mutations in 15% of our cohort. Statistical analysis showed an association between nuclear expression of c-Met-activated beta-catenin and wild type CTNNB1 (P-value = 0.015). Analysis of total beta-catenin and Y654-beta-catenin in response to HGF activation in the cell lines, mirrors that observed in our HB tumour cohort.

Results

We identified a significant subset of hepatoblastoma patients for whom targeting of the c-Met pathway may be a treatment option and also demonstrate distinct mechanisms of beta-catenin activation in HB.

Block of proliferation 1 (BOP1) plays an oncogenic role in hepatocellular carcinoma by promoting epithelial-to-mesenchymal transition

Genomic amplification of regional chromosome 8q24 is a common event in human cancers. In hepatocellular carcinoma (HCC), a highly aggressive malignancy that is rapidly fatal, recurrent 8q24 gains can be detected in >50% of cases. In this study, attempts to resolve the 8q24 region by way of array comparative genomic hybridization for affected genes in HCC revealed distinctive gains of block of proliferation 1 (BOP1). Gene expression evaluation in an independent cohort of primary HCC (n = 65) revealed frequent BOP1 up-regulation in tumors compared with adjacent nontumoral liver (84.6%; P < 0.0001). Significant associations could also be drawn between increased expressions of BOP1 and advance HCC staging (P = 0.004), microvascular invasion (P = 0.006), and shorter disease-free survival of patients (P = 0.02). Examination of expression of C-MYC, a well-known oncogene located in proximity to BOP1, in the same series of primary HCC cases did not suggest strong clinicopathologic associations. Functional investigations by small interfering RNA-mediated suppression of BOP1 in HCC cell lines indicated significant inhibition on cell invasion (P < 0.005) and migration (P < 0.05). Overexpression of BOP1 in the immortalized hepatocyte cell line L02 showed increase cellular invasiveness and cell migratory rate (P < 0.0001). In both gene knockdown and ectopic expression assays, BOP1 did not exert an effect on cell viability and proliferation. Evident regression of the epithelial-mesenchymal transition (EMT) phenotype was readily identified in BOP1 knockdown cells, whereas up-regulation of epithelial markers (E-cadherin, cytokeratin 18, and γ-catenin) and down-regulation of mesenchymal markers (fibronectin and vimentin) were seen. A corresponding augmentation of EMT was indicated from the ectopic expression of BOP1 in L02. In addition, BOP1 could stimulate actin stress fiber assembly and RhoA activation.

CONCLUSION

Our findings underline an important role for BOP1 in HCC invasiveness and metastasis potentials through inducing EMT and promoting actin cytoskeleton remodeling.

Hepatocellular adenomas: current update on genetics, taxonomy, and management

Hepatocellular adenomas (HCAs) are uncommon, benign hepatocellular neoplasms that commonly occur in young women. Recent advances in pathology and cytogenetics have thrown fresh light on the pathogenesis of HCAs leading to classification of HCAs into 3 distinct subtypes, each with a characteristic epidemiology, histopathology, oncogenesis, and imaging findings. The aim of the article was to provide a comprehensive review of contemporary taxonomy of HCAs, with an emphasis on cross-sectional imaging findings and management.

Hepatoblastoma in association with bilateral polycystic kidneys

We describe the first known case of hepatoblastoma associated with bilateral autosomal recessive polycystic kidney disease in a preterm twin boy. The diagnostic and therapeutic considerations are addressed. The patient survived after primary hepatectomy operation and administration of modified adjuvant chemotherapy.

Equine Primary Liver Tumors: A Case Series and Review of the Literature

Hepatoblastoma (HB) is an uncommon pediatric liver tumor in humans and horses. In humans, HB is most frequently diagnosed in fetuses, neonates, and young children, whereas hepatocellular carcinoma (HCC) affects juvenile and adult humans. Hepatoblastoma in the horse is rare, with only 9 reported cases. Affected horses ranged in age from late-term aborted fetuses to 3 years. The current study describes 3 new cases of primary liver tumors in horses and reviews findings in relation to other reports on this condition. Tumors classified as HB were identified in a male Standardbred aborted fetus and in a 4-year-old Thoroughbred filly. Hepatocellular carcinoma was diagnosed in a 15-month-old Paint filly. In the Standardbred fetus, the tumor was only present in the liver. In the Thoroughbred and Paint fillies, primary tumors were in the right liver lobe and at the hilus, respectively, and there were metastases to other lobes (HB) and mesenteric lymph nodes (HCC). Tumors were sharply demarcated from adjacent tissue, nonencapsulated, compressive, and invasive. Consisting of cords and nests, or disorganized sheets of epithelial cells, tumors had variable stromal and vascular components. The fetal tumor contained areas of smaller, less differentiated cells with a pronounced mesenchymal component interpreted to be embryonal hepatic tissue. Diagnoses were based on tumor histomorphologic features, resemblance to hepatocyte developmental stages, age of the animal, and patterns of metastasis. Tumors classified as HB were α-fetoprotein immunoreactive. Primary hepatic tumors in the horse are diverse in morphology and include subtypes compatible with classification criteria applied to human tumors.

Occurrence of hepatocellular carcinoma after hepatoblastoma resection in an adult with hepatitis C virus

Hepatoblastoma is a rare malignancy in adults. It is often diagnosed after the appearance of symptoms, therefore, the tumor size tends to be larger. In patients with no indication for a hepatic resection, the prognosis of adult hepatoblastoma is quite poor. A 54-year-old man with hepatitis C virus-associated liver cirrhosis was initially treated with a hepatic resection for a hepatic tumor, 3 cm in diameter. The tumor consisted of osteoid-like and cartilaginous foci, myxomatous stroma, and poorly differentiated hepatocellular carcinomatous cells and was diagnosed as a mixed epithelial and mesenchymal hepatoblastoma. Two years after the first operation, multicentric hepatocellular carcinomas developed in the remnant liver and were successfully treated with a secondary hepatic resection combined with radio-frequency ablation. The patient is now alive with no recurrence at 5 years after the initial hepatectomy. To the best of our knowledge, the primary hepatoblastoma was the smallest such tumor reported and this is the first report of a metachronous hepatoblastoma and hepatocellular carcinoma in an adult hepatitis patient.

[Clinical characteristics and survival of children with hepatoblastoma--single centre experience]

INTRODUCTION

Hepatoblastoma is the most frequent malignant liver tumour of childhood and it accounts for 1% of all paediatric cancers. The outcome is significantly improved by introducing intensive chemotherapy regimens followed by complete surgical tumour resection. The long-term survival is 75-95% at present.

OBJECTIVE

To summarize clinical characteristics and treatment results in children with hepatoblastoma.

METHOD

The patients diagnosed with hepatoblastoma and treated at the Department of Haematology of the University Children's Hospital in Belgrade, between January 1995 and December 2007 were retrospectively analysed. We analysed mode of therapy, surgical management and patients' survival according to Kaplan Mayer statistical test.

RESULTS

Eleven patients were treated (ten boys and one girl), aged from 6 months to 13 years, mean 32 months, median 12 months. The most frequent presenting sign was abdominal distension. Routine laboratory examination showed elevated alpha-fetoprotein (AFP), range 147 to 44880 ng/ml, mean 8667 ng/ml.Ten patients (91%) had elevated platelet count, range 450 to 909 x 10(9)/l. Initial lung metastasis developed in 3 patients (27%).The diagnosis was established by an open surgical biopsy in 6 patients and after complete tumour resection in 4 patients, namely 2 patients after preoperative chemotherapy and in 2 patients with no previous chemotherapy. Histopathology verified hepatoblastoma in 10 patients: in 7 patients with epithelial type and in 3 patients with mixed epithelial-mesenchyme type. Six patients were in continuous remission with mean follow up of 58 months. One patient was lost to follow up. Four patients died; three patients due to disease progression and one patient due to sepsis after the first cycle of chemotherapy.

CONCLUSION

Combined preoperative chemotherapy with complete tumour resection followed by postoperative chemotherapy results in a high percentage of definitive cures.

Wnt/beta-catenin pathway in hepatocellular carcinoma pathogenesis and liver physiology

The Wnt/beta-catenin pathway is a key developmental pathway for which alterations have been described in various human cancers. The aberrant activation of this pathway is a major event in human hepatocellular carcinoma. Several laboratories have shown that the Wnt/beta-catenin pathway plays an essential role in all phases of liver development and maturation, and is required for the metabolic function of this organ. In this review, we summarize current knowledge regarding the role of the Wnt/beta-catenin pathway in hepatocellular carcinoma pathogenesis and liver biology, and the possibilities for developing new therapeutic interventions based on this knowledge.

Genes involved in viral carcinogenesis and tumor initiation in hepatitis C virus-induced hepatocellular carcinoma

The role of chronic hepatitis C virus (HCV) in the pathogenesis of HCV-associated hepatocellular carcinoma (HCC) remains controversial. To understand the transition from benign to malignant, we studied the gene expression patterns in liver tissues at different stages, including normal, cirrhosis, and different HCC stages. We studied 108 liver tissue samples obtained from 88 distinct patients (41 HCV-cirrhotic tissues, 17 HCV-cirrhotic tissues from patients with HCC, and 47 HCV-HCC tissues). Differentially expressed genes (DEG) were studied by use of high-density oligonucleotide arrays. Among probe sets identified as differentially expressed via the F test, all pairwise comparisons were performed. Cirrhotic tissues with and without concomitant HCC were further evaluated, and a classifier was used to predict whether the tissue type was associated with HCC. Differential expression profiles were analyzed using Interaction Networks and Functional Analysis. Characteristic gene signatures were identified when normal tissue was compared with cirrhosis, cirrhosis with early HCC, and normal with HCC. Pathway analysis classified the cellular and biological functions of the DEG as related to cellular growth and proliferation, cell death and inflammatory disease in cirrhosis; cell death, cell cycle, DNA replication, and immune response in early HCCs; and cell death, cell growth and proliferation, cell cycle, and DNA repair in advanced HCCs. Characteristic gene signatures were identified at different stages of HCV-HCC progression. A set of genes were identified to predict whether the cirrhotic tissue was associated with HCC.

p19Arf inhibits the invasion of hepatocellular carcinoma cells by binding to C-terminal binding protein

The INK4A/ARF tumor suppressor locus is frequently inactivated in hepatocellular carcinoma (HCC), yet the consequences of this remain unknown. We recently described a HCC mouse model in which loss of the Ink4a/Arf locus accelerates the development of metastasis and enhances tumor cell migration and invasion in cell culture assays. We show here that knockdown of p19Arf in an HCC cell line increases invasion in cell culture assays. Furthermore, reintroduction of p19(Arf) into HCC cell lines lacking Ink4a/Arf inhibits tumor cell invasion, without affecting cell proliferation, or cell transformation as measured by soft agar colony formation. Inhibition of cell invasion by p19(Arf) was dependent on its C-terminal binding protein (CtBP) interaction domain but independent of Mdm2 binding and nucleolar localization. Indeed, RNA interference-mediated knockdown of CtBP1 or CtBP2 decreased cell invasion, and ectopic expression of CtBP2 enhanced tumor cell migration and invasion. Thus, our data indicate a novel role for the Arf tumor suppressor protein in regulating phenotypes associated with tumor progression and metastasis in HCC cells.

Sporadic childhood hepatoblastomas show activation of beta-catenin, mismatch repair defects and p53 mutations

Hepatoblastoma, a rare embryonic tumor that may arise sporadically or in the context of hereditary syndromes (familial adenomatous polyposis and Beckwith-Wiedemann's) is the most frequent liver cancer of childhood. Deregulation of the APC/beta-catenin pathway occurs in a consistent fraction of hepatoblastomas, with mutations in the APC and beta-catenin genes implicated in familial adenomatous polyposis-associated and sporadic hepatoblastomas, respectively. Alterations in other cancer-related molecular pathways have not been reported. We investigated a series of 21 sporadic paraffin-embedded hepatoblastoma cases for mutations in the p53 (exons 5-8) and beta-catenin (exon 3) genes, loss of heterozygosity at APC, microsatellite instability and immunohistochemical expression of beta-catenin and of the two main mismatch repair proteins, MLH1 and MSH2. No loss of heterozygosity at APC was detected. We found mutations in beta-catenin and p53 in 4/21 (19%) and 5/21 (24%) cases respectively, beta-catenin protein accumulation in 14/21 cases (67%), microsatellite instability in 17/21 cases (81%), of which eight resulted positive for high-level of microsatellite instability (in four cases associated with loss of MLH1/MSH2 immunostaining). No correlations between involved molecular pathway(s) and hepatoblastoma histotype(s) emerged. This study confirms that beta-catenin deregulation is involved in sporadic hepatoblastoma and also suggests that mismatch repair defects and p53 mutations contribute to this rare liver cancer. Sporadic hepatoblastoma appears to be molecularly and phenotypically heterogeneous and may reflect different pathways of liver carcinogenesis.

Malignant hepatic tumor occurring 10 yrs after a histocompatible sibling donor bone marrow transplantation for severe aplastic anemia

A 13-yr-old boy developed post-transplant liver tumor. At three yrs of age, this patient underwent a histocompatible sibling donor BMT for severe aplastic anemia, after a conditioning with antithymocyte globulin and cyclophosphamide. He became a HBV carrier after BMT. Stable mixed chimerism and mild thrombocytopenia, but no active hepatitis continued. At age 13, abdominal pain was a sign of massive tumor. Extremely high levels of alpha-fetoprotein indicated the clinical diagnosis of hepatoblastoma that might be the first report as post-BMT malignancy. The necropsy specimens revealed that the tumor was recipient cell-origin and showed the histopathological features of both hepatoblastoma and hepatocellular carcinoma. Prolonged mixed chimerism and hepatitis virus infection might induce a rare oncogenesis after non-irradiated conditioning.

Tumour suppressors in liver carcinogenesis

The circuitous cell signalling pathways of hepatocytes comprise several factors that operate to downgrade or even interrupt the transmission of a given signal. These down-regulating influences are essential to keep cell proliferation and cell survival in check and if impaired, can alter a delicate balance in favour of cell proliferation. Each signalling pathway that has been implicated in carcinogenesis is influenced by both oncogenic factors that promote tumour growth when activated as well as tumour suppressor proteins that have to be impaired to favour tumour growth. This summary of the Tumour Suppressors in Liver Carcinogenesis Symposium held at the 2007 EASL Annual Meeting discusses four pathways with pre-eminent tumour suppressor activity, each involved in hepatocarcinogenesis: p53, mTOR, beta-catenin and hedgehog.

Pediatric liver tumors: initial presentation, image finding and outcome

BACKGROUND

Few reports have been carried out on the characteristics of pediatric liver tumors.

METHODS

A retrospective study of 57 patients diagnosed with liver tumors from 1989 through 2004 was conducted. They were classified into groups; 10 benign, 33 primary malignant and 14 metastatic liver tumors. Their demographics, initial presentations, laboratory data, image findings and outcomes were investigated and compared.

RESULTS

Hepatocellular carcinoma (HCC) with 91% hepatitis B virus-related, constituted 23 of 33 primary malignant liver tumors and had the poorest survival rate. Initially, 70% of patients with primary malignant liver tumors were at disseminated stages. All of HCC and 88% of hepatoblastoma had elevated serum levels of aphal-fetoprotein. However, abnormal liver function tests as alanine aminotransferase, total bilirubin, albumin and alkaline phosphatase were uncommon in patients with pediatric liver tumors. Metastatic liver tumors compared with primary malignant liver tumors showed hypo-echogenicity in abdominal ultrasound (US) exam and a lesser presence of vessel invasion and contrast enhancement in computed tomography studies (P < 0.01).

CONCLUSIONS

It is important to diagnose primary malignant liver tumors before their clinical symptoms and signs develop. Children with chronic hepatitis B virus infection must be followed every 6 months by serum aphal-fetoprotein and abdominal US even when their liver function tests are normal. Image studies with abdominal US and computed tomography scan can differentiate between primary and metastatic liver tumors.