Molecular classification of hepatocellular carcinoma

Construction of a prognostic prediction model in liver cancer based on genes involved in integrin cell surface interactions pathway by multi-omics screening

Background: Liver cancer is a common malignant tumor with an increasing incidence in recent years. We aimed to develop a model by integrating clinical information and multi-omics profiles of genes to predict survival of patients with liver cancer. Methods: The multi-omics data were integrated to identify liver cancer survival-associated signal pathways. Then, a prognostic risk score model was established based on key genes in a specific pathway, followed by the analysis of the relationship between the risk score and clinical features as well as molecular and immunologic characterization of the key genes included in the prediction model. The function experiments were performed to further elucidate the undergoing molecular mechanism. Results: Totally, 4 pathways associated with liver cancer patients' survival were identified. In the pathway of integrin cell surface interactions, low expression of COMP and SPP1, and low CNVs level of COL4A2 and ITGAV were significantly related to prognosis. Based on above 4 genes, the risk score model for prognosis was established. Risk score, ITGAV and SPP1 were the most significantly positively related to activated dendritic cell. COL4A2 and COMP were the most significantly positively associated with Type 1 T helper cell and regulatory T cell, respectively. The nomogram (involved T stage and risk score) may better predict short-term survival. The cell assay showed that overexpression of ITGAV promoted tumorigenesis. Conclusion: The risk score model constructed with four genes (COMP, SPP1, COL4A2, and ITGAV) may be used to predict survival in liver cancer patients.

mTOR up-regulation of SNRPA1 contributes to hepatocellular carcinoma development

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related death worldwide. Recent studies showed that snRNPs were implicated in human cancer development. The role of SNRPA1, which is a member of U2 snRNPs, in HCC, remains undocumented. Here, we found that SNRPA1 was highly expressed in HCC tissue compared with normal adjacent liver tissues. Up-regulation of SNRPA1 was correlated with the clinical stage of HCC and the overall survival of HCC patients. In vitro and in vivo results showed that knockdown of SNPRA1 inhibited the cell proliferation, colony formation and xenografted tumorigenesis of HCC cells. Apoptosis was induced by SNPRA1 down-regulation. Mechanistically, SNPRA1 was stimulated by mTOR activation. In addition, whole-genome microarray analysis identified that 262 genes were up-regulated and 462 genes were down-regulated by SNPRA1 knockdown in HCC cells. qPCR analysis suggested that the fibroblast growth factor-2 (FGF2), Alpha-fetoprotein (AFP), β-catenin, Ki-67 and cyclin B1 were down-regulated and caspase 3, p53 as well as p21 were up-regulated after SNRPA1 knockdown. Taken together, our findings implicate that SNPRA1 functions as an oncogene in HCC.

The mRNA Distribution of Cancer Stem Cell Marker CD90/Thy-1 Is Comparable in Hepatocellular Carcinoma of Eastern and Western Populations

Epidemiology of hepatocellular carcinoma (HCC) showed a correlation between incidence and geographical-relevant risk factors. This study aims to compare the distributions of cancer stem cells (CSC) in two distant populations in Asia and Europe. We analyzed 52 and 43 selected HCC patients undergoing hepatectomy in Ho Chi Minh City (Vietnam) and Trieste (Italy). Each patient sample consisted of HCC, peri-HCC, and non-tumoral (distal) tissue. Demographic data were recorded together with clinical findings. The protocol for the collection of tissue samples and RNA was standardized in both laboratories and gene expression analysis was performed in a single laboratory with identical PCR conditions. Baseline data showed comparable laboratory findings between the two cohorts. mRNA distribution showed a comparable pattern of all CSC markers analyzed with the expression of CD90 progressively increasing from distal and peri-HCC to be highest in HCC (p < 0.001), confirmed by immunofluorescence data. CD90 mRNA distribution was related to HBV-related HCC and a tumor diameter less than 5 cm. Patients with high tumoral CD90 mRNA had a shorter time (p < 0.05) to tumor recurrence compared to patients with lower CD90. This comparative study showed that CD90 mRNA expressions are comparable between Eastern and Western HCC cases.

Activation of extracellular signal-regulated kinase is associated with hepatocellular carcinoma with aggressive phenotypes

AIM

Sorafenib inhibits multiple kinase signaling pathways, including the rat sarcoma virus (Ras)/rapidly accelerated fibrosarcoma (Raf)/mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway, and is a promising therapy for hepatocellular carcinoma (HCC). However, the role of ERK activation in HCC remains unclear. This study was designed to investigate the potential link between ERK activation and aggressive HCC phenotypes.

METHODS

We evaluated nuclear ERK expression by immunohistochemistry in 154 resected HCC nodules from 136 patients. We then investigated the associations of ERK expression with the clinicopathological characteristics of HCC, c-MET expression, and the molecular subclass biomarkers Ki-67, keratin 19 (KRT19, CK19, or K19), and sal-like protein 4. Multivariate Cox regression analysis was carried out to determine independent prognostic factors for overall survival and recurrence-free survival. The effects of ERK activation by hepatocyte growth factor (HGF) on eight HCC cell lines were further examined.

RESULTS

High-level nuclear expression of ERK was observed in 20 (13%) of 154 nodules and was significantly associated with higher serum alpha-fetoprotein levels (P = 0.034), poorer differentiation (P = 0.003), a higher Ki-67 index (P < 0.001), high-level expression of c-MET (P = 0.008), KRT19 (P = 0.002), or sal-like protein 4 (P < 0.001), and shorter overall survival (multivariate hazard ratio 3.448; P = 0.028) and recurrence-free survival (multivariate hazard ratio 2.755; P = 0.004). HCC cells treated with hepatocyte growth factor showed enhanced cell proliferation together with ERK activation and upregulated KRT19 expression, both of which were inhibited by sorafenib.

CONCLUSIONS

High-level ERK activation is associated with a KRT19-positive highly proliferative subtype of HCC with a dismal prognosis. These findings support the key role of the hepatocyte growth factor/c-MET/ERK axis in HCC progression.

Targeting Jak/Stat pathway as a therapeutic strategy against SP/CD44+ tumorigenic cells in Akt/β-catenin-driven hepatocellular carcinoma

BACKGROUND & AIMS

Hepatic resection and liver transplantation with adjuvant chemo- and radiotherapy are the mainstay of hepatocellular carcinoma (HCC) treatment, but the 5-year survival rate remains poor because of frequent recurrence and intrahepatic metastasis. Only sorafenib and lenvatinib are currently approved for the first-line treatment of advanced, unresected HCC, but they yield modest survival benefits. Thus, there is a need to identify new therapeutic targets to improve current HCC treatment modalities.

METHODS

The HCC tumor model was generated by hydrodynamic transfection of AKT1 and β-catenin (CTNNB1) oncogenes. Cancer cells with stemness properties were characterized following isolation using side population (SP) and CD44 surface markers by flow cytometry. The effect of Jak/Stat inhibitors was analyzed in vitro by using tumorsphere culture and in vivo using an allograft mouse model.

RESULTS

Co-activation of both Wnt/β-catenin and Akt/mTOR pathways was found in 14.4% of our HCC patient cohort. More importantly, these patients showed poorer survival than those with either Wnt/β-catenin or Akt/mTOR pathway activation alone, demonstrating the clinical relevance of our study. In addition, we observed that Akt/β-catenin tumors contained a subpopulation of cells with stem/progenitor-like characteristics identified through SP analysis and expression of the cancer stem cell-like marker CD44, which may contribute to tumor self-renewal and drug resistance. Consequently, we identified small molecule inhibitors of the Jak/Stat pathway that demonstrated efficacy in mitigating tumor proliferation and formation in Akt/β-catenin-driven HCC.

CONCLUSIONS

In conclusion, we have shown that Akt/β-catenin tumors contain a subpopulation of tumor-initiating cells with stem/progenitor-like characteristics which can be effectively targeted with inhibitors of the Jak/Stat pathway, demonstrating that inhibition of the Jak/Stat pathway could be an alternative method to overcome drug resistance and effectively treat Akt/β-catenin-driven HCC tumors.

LAY SUMMARY

The prognosis for patients with hepatocellular carcinoma is poor, partly because of the lack of effective treatment options for those with more advanced disease. In this study, we identified a subpopulation of cancer cells with stem cell-like properties that were critical for tumor maintenance and growth in a mouse model of hepatocellular carcinoma. Through further experiments, we demonstrated that the Jak/Stat pathway is a promising therapeutic target in hepatocellular carcinoma.

Suppression of Hepatocellular Carcinoma by Mycophenolic Acid in Experimental Models and in Patients

BACKGROUND

Tumor recurrence is a major complication following liver transplantation (LT) as treatment for hepatocellular carcinoma (HCC). Immunosuppression is an important risk factor for HCC recurrence, but conceivably may depend on the type of immunosuppressive medication. Mycophenolic acid (MPA) is a currently widely used immunosuppressant. This study investigated the effects of MPA on HCC.

METHODS

Three human HCC cell lines and organoids from mouse primary liver tumor were used as experimental models. MTT, Alamar Blue assay, cell cycle analysis, colony formation, and [3H]-thymidine assays were performed. An LT database was used for retrospective analysis of the effect of mycophenolate mofetil, the prodrug of MPA, on HCC recurrence.

RESULTS

With clinically achievable concentrations, MPA effectively inhibited HCC cell proliferation and single-cell colony-forming unit. In short-term experiments, MPA effectively elicited S phase arrest in HCC cell lines. In addition, the initiation and growth of liver tumor organoids were effectively inhibited by MPA. Most importantly, the use of mycophenolate mofetil in patients with HCC-related LT was significantly associated with less tumor recurrence and improved patient survival.

CONCLUSIONS

MPA can specifically counteract HCC growth in vitro and tumor recurrence in LT patients. These results warrant prospective clinical trials into the role of MPA-mediated immunosuppression following LT of patients with HCC.

Genomic Perspective on Mouse Liver Cancer Models

Selecting the most appropriate mouse model that best recapitulates human hepatocellular carcinoma (HCC) allows translation of preclinical mouse studies into clinical studies. In the era of cancer genomics, comprehensive and integrative analysis of the human HCC genome has allowed categorization of HCC according to molecular subtypes. Despite the variety of mouse models that are available for preclinical research, there is a lack of evidence for mouse models that closely resemble human HCC. Therefore, it is necessary to identify the accurate mouse models that represent human HCC based on molecular subtype as well as histologic aggressiveness. In this review, we summarize the mouse models integrated with human HCC genomic data to provide information regarding the models that recapitulates the distinct aspect of HCC biology and prognosis based on molecular subtypes.

Epigenetic alterations caused by aflatoxin b1: a public health risk in the induction of hepatocellular carcinoma

Aflatoxin B1 (AFB1) is currently the most commonly studied mycotoxin due to its great toxicity, its distribution in a wide variety of foods such as grains and cereals and its involvement in the development of + (hepatocellular carcinoma; HCC). HCC is one of the main types of liver cancer, and has become a serious public health problem, due to its high incidence mainly in Southeast Asia and Africa. Studies show that AFB1 acts in synergy with other risk factors such as hepatitis B and C virus leading to the development of HCC through genetic and epigenetic modifications. The genetic modifications begin in the liver through the biomorphic AFB1, the AFB1-exo-8.9-Epoxy active, which interacts with DNA to form adducts of AFB1-DNA. These adducts induce mutation in codon 249, mediated by a transversion of G-T in the p53 tumor suppressor gene, causing HCC. Thus, this review provides an overview of the evidence for AFB1-induced epigenetic alterations and the potential mechanisms involved in the development of HCC, focusing on a critical analysis of the importance of severe legislation in the detection of aflatoxins.

Selecting patients with hepatocellular carcinoma for liver transplantation: incorporating tumor biology criteria

Liver transplantation (LT) is the optimal therapeutic option for patients with liver cirrhosis and hepatocellular carcinoma (HCC). Due to universal donor shortage, only the patients with limited tumor burden (under the so-called Milan criteria) are considered as potential candidates for LT in most institutions. It is expected that in the near future, more liver grafts will be available for patients with HCC due to the implementation of new direct antivirals against hepatitis C, leaving a prone scenario to consider expanding Milan criteria. A moderate expansion of Milan criteria could be implemented without increasing the risk of tumor recurrence if patients with favorable biological behavior are carefully selected. Incorporating information regarding tumor biology in the decision-making algorithm would result in a more rational use of LT in patients with HCC. In the present review, surrogate markers of tumor biology are critically evaluated as potential tools to be combined with existing radiological criteria. In addition, the current state of liquid biopsy is discussed, as this cutting-edge technology may reshape the management of HCC in the upcoming years.

High Keratin 8/18 Ratio Predicts Aggressive Hepatocellular Cancer Phenotype

BACKGROUND & AIMS: Steatohepatitis (SH) and SH-associated hepatocellular carcinoma (HCC) are of considerable clinical significance. SH is morphologically characterized by steatosis, liver cell ballooning, cytoplasmic aggregates termed Mallory-Denk bodies (MDBs), inflammation, and fibrosis at late stage. Disturbance of the keratin cytoskeleton and aggregation of keratins (KRTs) are essential for MDB formation. METHODS: We analyzed livers of aged Krt18^−/− mice that spontaneously developed in the majority of cases SH-associated HCC independent of sex. Interestingly, the hepatic lipid profile in Krt18^−/− mice, which accumulate KRT8, closely resembles human SH lipid profiles and shows that the excess of KRT8 over KRT18 determines the likelihood to develop SH-associated HCC linked with enhanced lipogenesis. RESULTS: Our analysis of the genetic profile of Krt18^−/− mice with 26 human hepatoma cell lines and with data sets of >300 patients with HCC, where Krt18^−/− gene signatures matched human HCC. Interestingly, a high KRT8/18 ratio is associated with an aggressive HCC phenotype. CONCLUSIONS: We can prove that intermediate filaments and their binding partners are tightly linked to hepatic lipid metabolism and to hepatocarcinogenesis. We suggest KRT8/18 ratio as a novel HCC biomarker for HCC.

MicroRNA-199 suppresses cell proliferation, migration and invasion by downregulating RGS17 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), the most common primary tumor of the liver, has a poor prognosis and shows rapid progression. MicroRNAs (miRNAs) play important roles in carcinogenesis and tumor progression. Regulators of G-protein signaling (RGS) are critical for defining G-protein-dependent signal fidelity. RGS17 plays an important role in the regulation of cancer cell proliferation, migration and invasion. Here, we showed that miR-199 was downregulated in a hepatocarcinoma cell line. Overexpression of miR-199 significantly suppressed HCC cell proliferation, migration, and invasion in vitro. RGS17 overexpression promoted HCC cell proliferation, migration, and invasion, and reversed the miR-199 mediated inhibition of proliferation, migration, and invasion. Dual-fluorescence reporter experiments confirmed that miR-199 downregulated RGS17 by direct interaction with the 3'-UTR of RGS17 mRNA. In vivo studies showed that miR-199 overexpression significantly inhibited the growth of tumors. Taken together, the results suggested that miR-199 inhibited tumor growth and metastasis by targeting RGS17.

Deletion of sphingosine kinase 1 inhibits liver tumorigenesis in diethylnitrosamine-treated mice

Primary liver cancer is the 3rd leading cause of cancer deaths worldwide with very few effective treatments. Sphingosine kinase 1 (SphK1), a key regulator of sphingolipid metabolites, is over-expressed in human hepatocellular carcinoma (HCC) and our previous studies have shown that SphK1 is important in liver injury. We aimed to explore the role of SphK1 specifically in liver tumorigenesis using the SphK1 knockout (SphK1^-/-) mouse. SphK1 deletion significantly reduced the number and the size of DEN-induced liver cancers in mice. Mechanistically, fewer proliferating but more apoptotic and senescent cells were detected in SphK1 deficient tumors compared to WT tumors. There was an increase in sphingosine rather than a decrease in sphingosine 1-phosphate (S1P) in SphK1 deficient tumors. Furthermore, the STAT3-S1PR pathway that has been reported previously to mediate the effect of SphK1 on colorectal cancers was not altered by SphK1 deletion in liver cancer. Instead, c-Myc protein expression was down-regulated by SphK1 deletion. In conclusion, this is the first in vivo evidence that SphK1 contributes to hepatocarcinogenesis. However, the downstream signaling pathways impacting on the development of HCC via SphK1 are organ specific providing further evidence that simply transferring known oncogenic molecular pathway targeting into HCC is not always valid.

The significance of intertumor and intratumor heterogeneity in liver cancer

Genomic analyses of primary liver cancer samples reveal a complex mutational landscape with vast intertumor and intratumor heterogeneity. Different primary liver tumors and subclones within each tumor display striking molecular and biological variations. Consequently, tumor molecular heterogeneity contributes to drug resistance and tumor relapse following therapy, which poses a substantial obstruction to improving outcomes of patients with liver cancer. There is an urgent need to the compositional and functional understanding of tumor heterogeneity. In this review, we summarize genomic and non-genomic diversities, which include stemness and microenvironmental causes of the functional heterogeneity of the primary liver cancer ecosystem. We discuss the importance and intricacy of intratumor heterogeneity in the context of cancer cell evolution. We also discuss methodologies applicable to determine intratumor heterogeneity and highlight the best-fit patient-derived in vivo and in vitro models to recapture the functional heterogeneity of primary liver cancer with the aim to improve future therapeutic strategies.

miR-29a-3p suppresses cell proliferation and migration by downregulating IGF1R in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), the most common primary tumor of the liver, has a poor prognosis and rapid progression. MicroRNAs (miRNAs) play important roles in carcinogenesis and tumor progression. Insulin-like growth factor 1 receptor (IGF1R) is a transmembrane heterotetrameric protein that has been reported to promote transformation to malignancy and cancer cell proliferation and survival. In this study, we found that the expression of miR-29a-3p was downregulated in HCC patients, resulting in poor survival rates. Contrastingly, the overexpression of miR-29a-3p significantly inhibited proliferation and migration in HepG2 cells. miR-29a-3p directly targeted IGF1R and down-regulated its expression. Moreover, knockdown of IGF1R led to the increased production of chemokine ligand 5 (CCL5). In tumor lesions, the local expression of CCL5 negatively affected the expression of IGF1R. Transwell analysis showed that CCL5 was important for the chemotactic movement of CD8⁺ T lymphocytes. The expression of CCL5 in HCC tissues positively correlated with the expression of CD8⁺ T lymphocyte surface marker, CD8. Patients with high CCL5 expression exhibited better survival. Our results revealed that miR-29a-3p is a tumor suppressor gene that acts by directly repressing the oncogene IGF1R, which takes part in immunoregulation in tumor microenvironments in HCC, implying that miR-29a-3p could be a potential target for HCC treatment.

MicroRNA-424 inhibits Akt3/E2F3 axis and tumor growth in hepatocellular carcinoma

By comparing the expression profiles of miRNAs in different subtypes of HCC, we identified miR-424 as a HCC related miRNA. We found that the expression of miR-424 was significantly decreased in HCC tissues and six liver cancer cell lines. Significantly, its expression levels were correlated with tumor size, multiple nodules, vein invasion, TNM stage and overall survival of HCC. We showed that up-regulated miR-424 suppressed HCC cell proliferation in vivo and in vitro. Multi-pathway reporter arrays suggested that miR-424 suppressed the pRb-E2F pathway. Consistently, Akt3 and E2F3 were identified as the targets of miR-424 as evidenced by that ectopic miR-424 expression suppressed Akt3 and E2F3 expressions. Silencing Akt3 and E2F3 by siRNA pheno-copied the effect of ectopic miR-424 on HCC growth. Whereas, overexpression of Akt3 and E2F3 attenuated the effect of miR-424 on HCC growth. Together, our data demonstrated a tumor suppressor role for miR-424 in HCC development and progression with therapeutic implications. The strong correlation of miR-424 expression with HCC patient survival suggests that miR-424 could be a valuable biomarker for HCC prognosis.

Identification and Validation of HCC-specific Gene Transcriptional Signature for Tumor Antigen Discovery

A novel two-step bioinformatics strategy was applied for identification of signatures with therapeutic implications in hepatitis-associated HCC. Transcriptional profiles from HBV- and HCV-associated HCC samples were compared with non-tumor liver controls. Resulting HCC modulated genes were subsequently compared with different non-tumor tissue samples. Two related signatures were identified, namely “HCC-associated” and “HCC-specific”. Expression data were validated by RNA-Seq analysis carried out on unrelated HCC samples and protein expression was confirmed according to The Human Protein Atlas" (http://proteinatlas.org/), a public repository of immunohistochemistry data. Among all, aldo-keto reductase family 1 member B10, and IGF2 mRNA-binding protein 3 were found strictly HCC-specific with no expression in 18/20 normal tissues. Target peptides for vaccine design were predicted for both proteins associated with the most prevalent HLA-class I and II alleles. The described novel strategy showed to be feasible for identification of HCC-specific proteins as highly potential target for HCC immunotherapy.

Circulating tumor DNA in hepatocellular carcinoma: trends and challenges

Molecular characterization of individual patients’ tumor cells is becoming increasingly important in offering effective treatment for patients in clinical practice. Recent advances in the field have indicated that circulating tumor DNA (ctDNA) has huge potential to serve as a biomarker for early detection and precision treatment as well as prognosis of hepatocellular carcinoma (HCC). As ctDNA in HCC patients harbors the molecular characteristics of HCC tumor cells, ctDNA analysis in the blood may be sufficient for convenient, non-invasive and accurate detection, providing information for HCC diagnosis, treatment and prognosis. In this review, we will summarize and discuss current trends and challenges of ctDNA application in HCC.

Application of next-generation sequencing in gastrointestinal and liver tumors

Malignant transformation of normal cells is associated with the evolution of genomic alterations. This concept has led to the development of molecular testing platforms to identify genomic alterations that can be targeted with novel therapies. Next generation sequencing (NGS) has heralded a new era in precision medicine in which tumor genes can be studied efficiently. Recent developments in NGS have allowed investigators to identify genomic predictive makers and hereditary mutations to guide treatment decision. The application of NGS in gastrointestinal cancers is being extensively studied but continues to face substantial challenges. In our review, we discuss various NGS platforms and highlight their role in identifying familial mutations and markers of response or resistance to cancer therapy. We also provide a balanced discussion of the challenges that limit the routine use of NGS in clinical practice.

Characterization of copy number alterations in a mouse model of fibrosis-associated hepatocellular carcinoma reveals concordance with human disease

Hepatocellular carcinoma (HCC) is a prevalent human cancer with rising incidence worldwide. Human HCC is frequently associated with chronic liver inflammation and cirrhosis, pathophysiological processes that are a consequence of chronic viral infection, disturbances in metabolism, or exposure to chemical toxicants. To better characterize the pathogenesis of HCC, we used a human disease‐relevant mouse model of fibrosis‐associated hepatocarcinogenesis. In this model, marked liver tumor response caused by the promutagenic chemical N‐nitrosodiethylamine in the presence of liver fibrosis was associated with epigenetic events indicative of genomic instability. Therefore, we hypothesized that DNA copy number alterations (CNAs), a feature of genomic instability and a common characteristic of cancer, are concordant between human HCC and mouse models of fibrosis‐associated hepatocarcinogenesis. We evaluated DNA CNAs and changes in gene expression in the mouse liver (normal, tumor, and nontumor fibrotic tissues). Additionally, we compared our findings to DNA CNAs in human HCC cases (tumor and nontumor cirrhotic/fibrotic tissues) using publicly available data from The Cancer Genome Atlas (TCGA). We observed that while fibrotic liver tissue is largely devoid of DNA CNAs, highly frequently occurring DNA CNAs are found in mouse tumors, which is indicative of a profound increase in chromosomal instability in HCC. The cross‐species gene‐level comparison of CNAs identified shared regions of CNAs between human fibrosis‐ and cirrhosis‐associated liver tumors and mouse fibrosis‐associated HCC. Our results suggest that CNAs most commonly arise in neoplastic tissue rather than in fibrotic or cirrhotic liver, and demonstrate the utility of this mouse model in replicating the molecular features of human HCC.

STK33 promotes hepatocellular carcinoma through binding to c-Myc

OBJECTIVE

STK33 has been reported to play an important role in cancer cell proliferation. We investigated the role of STK33 in hepatocellular carcinoma (HCC) and its underlying mechanisms.

DESIGN

251 patients with HCC were analysed for association between STK33 expression and clinical stage and survival rate. Tamoxifen (TAM)-inducible, hepatocyte-specific STK33 transgenic and knockout mice models were used to study the role of STK33 in liver tumorigenesis. HCC cell lines were used to study the role of STK33 in cell proliferation in vitro and in vivo.

RESULTS

STK33 expression was found to be frequently upregulated in patients with HCC. Significant associations were found between increased expression of STK33 and advanced HCC staging and shorter disease-free survival of patients. Overexpression of STK33 increased HCC cell proliferation both in vitro and in vivo, whereas suppression of STK33 inhibited this effect. Using a TAM-inducible, hepatocyte-specific STK33 transgenic mouse model, we found that overexpression of STK33 resulted in increased hepatocyte proliferation, leading to tumour cell burst. Using a TAM-inducible, hepatocyte-specific STK33 knockout mouse model, we found that, when subjected to the diethylnitrosamine (DEN) liver cancer bioassay, STK33KO(flox/flox, Alb-ERT2-Cre) mice exhibited a markedly lower incidence of tumour formation compared with control mice. The underlying mechanism may be that STK33 binds directly to c-Myc and increases its transcriptional activity. In particular, the C-terminus of STK33 blocks STK33/c-Myc association, downregulates HCC cell proliferation, and reduces DEN-induced liver tumour cell number and tumour size.

CONCLUSIONS

STK33 plays an essential role in hepatocellular proliferation and liver tumorigenesis. The C-terminus of STK33 could be a potential therapeutic target in the treatment of patients with STK33-overexpressed HCC.

Immunohistochemical molecular analysis indicates hepatocellular carcinoma subgroups that reflect tumor aggressiveness

Histopathologic parameters and molecular markers are widely accepted as useful predictors of tumor aggressiveness in hepatocellular carcinoma (HCC). However, few studies have analyzed immunohistochemical profiles comprehensively in one series, a fact that has resulted in fragmentation of information that could be applied in clinical practice. We conducted immunohistochemical expression analysis of biliary/stem cell markers (cytokeratin 19, sal-like protein 4, epithelial cell adhesion molecule, and CD133), Wnt/β-catenin signaling-related molecules (β-catenin and glutamine synthetase), p53, and cell proliferation markers (Ki-67 and mitosis) in 162 HCCs surgically resected from 142 patients and analyzed the results with respect to clinicopathological features. Immunohistochemical analysis broadly identified 3 groups: the biliary/stem cell marker-positive group, the Wnt/β-catenin signaling-related marker-positive group, and the biliary/stem cell marker-negative and Wnt/β-catenin signaling-related marker-negative group. p53 was frequently positive in the biliary/stem cell marker-positive group, but it was rarely positive in the Wnt/β-catenin signaling-related marker-positive group. The biliary/stem cell marker-positive group exhibited poor tumor differentiation, increased frequency of portal vein invasion and/or intrahepatic metastasis, and highly proliferative activity. In contrast, the biliary/stem cell marker-negative and Wnt/β-catenin signaling-related marker-negative group exhibited better tumor differentiation, a decreased frequency of portal vein invasion and/or intrahepatic metastasis, and less proliferative activity. The Wnt/β-catenin signaling-related marker-positive group showed neither tendency. The biliary/stem cell marker-positive group had the shortest time to recurrence among the 3 groups. Immunohistochemical profiling of HCC reflects tumor aggressiveness and suggests the potential efficacy of immunohistochemistry-based subclassification of HCC.

Evaluation of CTNNB1 and TP53 variability in patients with hepatocellular carcinoma and occult hepatitis B virus infection

Hepatitis B virus (HBV) infection plays a major role in hepatocellular carcinoma (HCC) development. Much evidence suggests that HBV also maintains its pro-oncogenic properties in cases of occult HBV infection (OBI). Mutations of the beta-catenin and p53 genes (CTNNB1 and TP53, respectively) may be associated with HCC occurrence in patients with overt HBV infection, whereas such genetic mutations have not been investigated in HCC patients with OBI thus far. We investigated the genetic heterogeneity of CTNNB1 exon 3 and all of the TP53 exons in tumor DNA extracts from a unique cohort of 61 HCC patients (all previously tested for HBV DNA and for its integration into the host's genome), including 34 OBI-positive, 20 HBV surface antigen (HBsAg)/OBI-negative, and 7 HBsAg-positive cases. No CTNNB1 exon 3 mutations or TP53 mutations were detected in any case. The homo- or heterozygous TP53 R72P polymorphism was found in 18 of 61 cases (29.5%), although no differences in its prevalence between OBI and non-OBI cases as well as between cases with and without viral integration were revealed. In conclusion, CTNNB1 and TP53 somatic mutations seem to be a rare event in patients with HCC in our area and in cases with either overt or occult HBV infection.

Next Generation of Preclinical Liver Cancer Models

Because of its heterogeneity, lack of prognostic markers, tumor-escape mechanisms, and frequent relapse upon surgical intervention, treatment of hepatocellular carcinoma (HCC) remains challenging. In this issue of Clinical Cancer Research, Groß and colleagues characterize a rodent model that might help identify novel drugs for combinatorial sorafenib-based therapies for HCC.

Evaluation of the medicinal herb Graptopetalum paraguayense as a treatment for liver cancer

Background

Hepatocellular carcinoma (HCC) is the fifth most common malignancy and the third most common cause of cancer-related death worldwide. Sorafenib is the only drug for patients with advanced-stage hepatocellular carcinoma (HCC) that has been shown to confer a survival benefit to patients with HCC; however, it has many side effects. Thus, alternate therapeutic strategies with improved safety and therapeutic efficacy for the management of HCC should be developed.

Methods and Findings

We demonstrate that an extract of Graptopetalum paraguayense (GP) down-regulated the expression levels of several onco-proteins, including AURKA, AURKB, and FLJ10540, in HCC cells. To isolate the active components in the GP extracts, we prepared extracts fractions and assessed their effects on the expression of onco-proteins in HCC cells. The fraction designated HH-F3 was enriched in active ingredients, exhibited cytotoxic effects, and suppressed the expression of the onco-proteins in HCC cells. The structure of the main active compound in HH-F3 was found to be similar to that of the proanthocyanidin compounds derived from Rhodiola rosea. In addition, a distinct new compound rich in 3, 4, 5-trihydroxy benzylic moieties was identified in the HH-F3 preparations. Mechanistic studies indicated that HH-F3 induced apoptosis in HCC cells by promoting the loss of mitochondrial membrane potential and the production of reactive oxygen species. HH-F3 also enhanced PTEN expression and decreased AKT phosphorylation at Ser473 in a concentration-dependent manner in HCC cells. Moreover combination of GP or HH-F3 and sorafenib synergistically inhibits the proliferation of Huh7 cells. The treatment of a rat model with diethylnitrosamine (DEN)-induced liver cancer with extracts of GP and HH-F3 decreased hepatic collagen contents and inhibited tumor growth.

Conclusions

These results indicate that GP extracts and HH-F3 can protect the liver by suppressing tumor growth; consequently, these compounds could be considered for the treatment of HCC.

TP53 R72P polymorphism modulates DNA methylation in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is characterized by widespread epidemiological and molecular heterogeneity. Previous work showed that in the western part of North Africa, a region of low incidence of HCC, mutations are scarce for this tumor type. As epigenetic changes are considered possible surrogates to mutations in human cancers, we decided, thus, to characterize DNA methylation in HCC from North-African patients.

METHODS

A set of 11 loci was investigated in a series of 45 tumor specimens using methylation-specific and combined-bisulfite restriction assay PCR. Results obtained on clinical samples were subsequently validated in liver cancer cell lines.

RESULTS

DNA methylation at tumor suppressor loci is significantly higher in samples displaying chromosome instability. More importantly, DNA methylation was significantly higher in Arg/Arg when compared to Pro/Pro genotype carriers at codon 72 rs1042522 of TP53 (65% vs 20% methylated loci, p = 0.0006), a polymorphism already known to affect somatic mutation rate in human carcinomas. In vitro experiments in cell lines indicated that enzymes controlling DNA methylation were differentially regulated by codon 72 Arg or Pro isoforms of p53. Furthermore, the Arg72-carrying version of p53 was shown to re-methylate DNA more rapidly than the pro-harboring isoform. Finally, Pro-carrying cell lines were shown to be significantly more resistant to decitabine treatment (two-fold, p = 0.005).

CONCLUSIONS

Our data suggest that Arg72Pro polymorphism in a WT p53 context may act as a primary driver of epigenetic changes in HCC. It suggests, in addition, that rs1042522 genotype may predict sensitivity to epigenetic-targeted therapy. This model of liver tumorigenesis that associates low penetrance genetic predisposition to epigenetic changes emerges from a region of low HCC incidence and it may, therefore, apply essentially to population living in similar areas. Surveys on populations submitted to highly mutagenic conditions as perinatally-acquired chronic hepatitis B or aflatoxin B1 exposure remained to be conducted to validate our observations as a general model.

The direct and indirect roles of HBV in liver cancer: prospective markers for HCC screening and potential therapeutic targets

Chronic hepatitis B virus (HBV) infection remains the number one risk factor for hepatocellular carcinoma (HCC), accounting for more than 600 000 deaths/year. Despite highly effective antiviral treatment options, chronic hepatitis B (CHB), subsequent end-stage liver disease and HCC development remain a major challenge worldwide. In CHB, liver damage is mainly caused by the influx of immune cells and destruction of infected hepatocytes, causing necro-inflammation. Treatment with nucleoside/nucleotide analogues can effectively suppress HBV replication in patients with CHB and thus decrease the risk for HCC development. Nevertheless, the risk of HCC in treated patients showing sufficient suppression of HBV DNA replication is significantly higher than in patients with inactive CHB, regardless of the presence of baseline liver cirrhosis, suggesting direct, long-lasting, predisposing effects of HBV. Direct oncogenic effects of HBV include integration in the host genome, leading to deletions, cis/trans-activation, translocations, the production of fusion transcripts and generalized genomic instability, as well as pleiotropic effects of viral transcripts (HBsAg and HBx). Analysis of these viral factors in active surveillance may allow early identification of high-risk patients, and their integration into a molecular classification of HCC subtypes might help in the development of novel therapeutic approaches.

Modeling human liver cancer heterogeneity: virally induced transgenic models and mouse genetic models of chronic liver inflammation

In addition to being the most common primary liver cancer, hepatocellular carcinoma (HCC) is the second most common cause of cancer-related death in humans. Treatment options are limited for this chemoresistant cancer, with liver transplantation and surgical intervention in early stages being the most successful treatments. Drug development over the past 15 years has focused on generating mouse models that mimic the human pathology for HCC. This has enabled the laboratory testing of potentially new human therapeutics. Described in this unit are the classification of HCC and an overview of hepatitis virus-related transgenic and genetically engineered mouse models (GEMMs) that are employed for elucidating the mechanism(s) responsible for the development of HCC, with particular emphasis on genetic, dietary, and environmental factors.

OATP1B3 expression is strongly associated with Wnt/β-catenin signalling and represents the transporter of gadoxetic acid in hepatocellular carcinoma

BACKGROUND & AIMS

In the current era of emerging molecular targeted drugs, it is necessary to identify before treatment the specific subclass to which a tumour belongs. Gadoxetic acid is a liver-specific contrast agent that is preferentially taken up by hepatocytes. Therefore, gadoxetic acid-enhanced magnetic resonance imaging (EOB-MRI) should provide precise molecular information about hepatocellular carcinomas (HCCs). The aim of this study was to investigate the transporters of gadoxetic acid in HCC comprehensively and to analyse the molecular regulatory mechanism of such transporters.

METHODS

Expression levels of transporters, transcriptional factors and Wnt target genes in clinical samples were examined by quantitative real-time reverse transcription polymerase chain reaction and immunohistochemistry. LiCl treatment of the HCC cell line KYN-2 was conducted in vitro to assess the effects of Wnt signalling activity.

RESULTS

Comprehensive analyses of transporter mRNAs and protein expressions revealed that the organic anion transporting polypeptide 1B3 (OATP1B3) had the strongest correlation with tumour enhancement in hepatobiliary-phase images of EOB-MRI. Association analysis with OATP1B3 expression revealed significant correlation with the expression of Wnt/β-catenin target genes. Further, LiCl treatment induced OATP1B3 mRNA expression in KYN-2 cells, indicating a strong association between OATP1B3 expression and Wnt/β-catenin signalling. The sensitivity and specificity to predict Wnt/β-catenin-activated HCC using tumour enhancement in EOB-MRI were 78.9% and 81.7%, respectively.

CONCLUSIONS

OATP1B3 was confirmed as the most important transporter mediating HCC enhancement in EOB-MRI. OATP1B3 expression showed a strong association with the expression of Wnt/β-catenin target genes, therefore, OATP1B3-upregulated HCC likely represents a specific subclass of Wnt/β-catenin-activated HCC.

The DEN and CCl4 -Induced Mouse Model of Fibrosis and Inflammation-Associated Hepatocellular Carcinoma

Human hepatocellular carcinoma (HCC) develops most often as a complication of fibrosis or cirrhosis. While most human studies of HCC provide crucial insights into the molecular signatures of HCC, seldom do they address the etiology of HCC. Mouse models are essential tools for investigating the pathogenesis of HCC; however, the overwhelming majority of cancer models in rodents do not feature liver fibrosis. Detailed in this unit is a protocol for an experimental mouse model of HCC that arises in association with advanced liver fibrosis. The disease model is induced by a single injection of N-nitrosodiethylamine (DEN) followed by repeated administration of carbon tetrachloride (CCl4 ). A dramatic potentiation of liver tumor incidence is observed following administration of DEN and CCl4 , with 100% of mice developing liver tumors at 5 months of age. This model can be employed for studying the molecular mechanisms of fibrogenesis and HCC development, and in cancer hazard/chemotherapy testing of drug candidates.

Deregulation of RB1 expression by loss of imprinting in human hepatocellular carcinoma

The tumour suppressor gene RB1 is frequently silenced in many different types of human cancer, including hepatocellular carcinoma (HCC). However, mutations of the RB1 gene are relatively rare in HCC. A systematic screen for the identification of imprinted genes deregulated in human HCC revealed that RB1 shows imprint abnormalities in a high proportion of primary patient samples. Altogether, 40% of the HCC specimens (16/40) showed hyper- or hypomethylation at the CpG island in intron 2 of the RB1 gene. Re-analysis of publicly available genome-wide DNA methylation data confirmed these findings in two independent HCC cohorts. Loss of correct DNA methylation patterns at the RB1 locus leads to the aberrant expression of an alternative RB1-E2B transcript, as measured by quantitative real-time PCR. Demethylation at the intron 2 CpG island by DNMT1 knock-down or aza-deoxycytidine (DAC) treatment stimulated expression of the RB1-E2B transcript, accompanied by diminished RB1 main transcript expression. No aberrant DNA methylation was found at the RB1 locus in hepatocellular adenoma (HCA, n = 10), focal nodular hyperplasia (FNH, n = 5) and their corresponding adjacent liver tissue specimens. Deregulated RB1 expression due to hyper- or hypomethylation in intron 2 of the RB1 gene is found in tumours without loss of heterozygosity and is associated with a decrease in overall survival (p = 0.032) if caused by hypermethylation of CpG85. This unequivocally demonstrates that loss of imprinting represents an important additional mechanism for RB1 pathway inactivation in human HCC, complementing well-described molecular defects.

Genetic and epigenetic changes in fibrosis-associated hepatocarcinogenesis in mice

Hepatocellular carcinoma (HCC) is one of the most prevalent cancers and is rising in incidence worldwide. The molecular mechanisms leading to the development of HCC are complex and include both genetic and epigenetic events. To determine the relative contribution of these alterations in liver tumorigenesis, we evaluated epigenetic modifications at both global and gene specific levels, as well as the mutational profile of genes commonly altered in liver tumors. A mouse model of fibrosis-associated liver cancer that was designed to emulate cirrhotic liver, a prevailing disease state observed in most humans with HCC, was used. Tumor and nontumor liver samples from B6C3F1 mice treated with N-nitrosodiethylamine (DEN; a single ip injection of 1 mg/kg at 14 days of age) and carbon tetrachloride (CCl4; 0.2 ml/kg, 2 times/week ip starting at 8 weeks of age for 14 weeks), as well as corresponding vehicle control animals, were analyzed for genetic and epigenetic alterations. H-ras, Ctnnb1 and Hnf1α genes were not mutated in tumors in mice treated with DEN+CCl4 . In contrast, the increased tumor incidence in mice treated with DEN+CCl4 was associated with marked epigenetic changes in liver tumors and nontumor liver tissue, including demethylation of genomic DNA and repetitive elements, a decrease in histone 3 lysine 9 trimethylation (H3K9me3) and promoter hypermethylation and functional downregulation of Riz1, a histone lysine methyltransferase tumor suppressor gene. Additionally, the reduction in H3K9me3 was accompanied by increased expression of long interspersed nucleotide elements 1 and short interspersed nucleotide elements B2, which is an indication of genomic instability. In summary, our results suggest that epigenetic events, rather than mutations in known cancer-related genes, play a prominent role in increased incidence of liver tumors in this mouse model of fibrosis-associated liver cancer.

High cytoplasmic expression of Krüppel-like factor 4 is an independent prognostic factor of better survival in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related mortality in the world. Hepatocarcinogenesis is complex, with an extraordinary molecular heterogeneity. Krüppel-like factor 4 (KLF4) plays an important role in cell proliferation and differentiation, and it can function as a tumor suppressor or an oncoprotein, depending on tissue type. The role of KLF4 in HCC remains controversial. The aim of this study was to explore the clinical significance of KLF4 expression in HCC. The study included 205 patients with surgical resection. We performed immunostaining for KLF4 and Ki-67 to investigate the correlations of the clinicopathological parameters of HCC and to examine the proliferative index. KLF4 staining was observed in the cytoplasm of non-tumorous hepatocytes and tumor cells. We subdivided the immunohistological staining results for KLF4 into low expression (Staining 0 and 1+) and high expression (Staining 2+ and 3+) subgroups. The expression of KLF4 was significantly correlated with tumor differentiation (p = 0.001). The Ki-67 proliferative index was significantly lower in well-differentiated HCCs (0.781% ± 1.02% vs. 2.16% ± 3.14%, p = 0.012), but not significantly different between low-KLF4 expression and high-KLF4 expression (1.87% ± 2.93% vs. 2.51% ± 3.28%, p = 0.32). Kaplan-Meier analysis showed that a high expression of KLF4 was significantly correlated with a longer disease-specific survival (p = 0.019). Univariate and multivariate analyses showed that high KLF4 expression was an independent predictor of a better disease-specific survival (p = 0.017; hazard ratio = 0.398; 95% confidence interval: 0.19-0.85). High cytoplasmic expression of KLF4 was associated with better disease-specific survival and was an independently favorable prognostic factor in hepatocellular carcinoma. These promising results suggest that KLF4 may play an anti-oncogenic role in hepatocarcinogenesis.

MicroRNA-424 is down-regulated in hepatocellular carcinoma and suppresses cell migration and invasion through c-Myb

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related mortality worldwide. MicroRNAs (miRNAs) are important regulators of multiple cellular processes, and the aberrant miRNAs expressions have been observed in different types of cancer including HCC. Their pathysiologic role and their relevance to tumorigenesis are still largely unknown. In this study, we demonstrated the down-regulation of miR-424 in HCC cell lines and tissues by quantitative RT-PCR analyses. Overexpression of miR-424 reduced the HCC cell prolifetation, migration, and invasion. Conversely, inhibiton of miR-424 expression significantly accelerated the cell proliferation, migration, and invasion. In addition, we further identified c-Myb as a functional downstream target of miR-424 by directly targeting the 3'UTR of c-Myb. Furthermore, overexpression of c-Myb impaired miR-424-induced inhibition of proliferation and invasion in HCC cells. Our results demonstrated that miR-424 was involved in tumorigenesis of HCC at least in part by suppression of c-Myb.

Rationale of personalized immunosuppressive medication for hepatocellular carcinoma patients after liver transplantation

Liver transplantation is the only potentially curative treatment for hepatocellular carcinoma (HCC) that is not eligible for surgical resection. However, disease recurrence is the main challenge to the success of this treatment. Immunosuppressants that are universally used after transplantation to prevent graft rejection could potentially have a significant impact on HCC recurrence. Nevertheless, current research is exclusively focused on mammalian target of rapamycin inhibitors, which are thought to be the only class of immunosuppressive agents that can reduce HCC recurrence. In fact, substantial evidence from the bench to the bedside indicates that other classes of immunosuppressants may also exert diverse effects; for example, inosine monophosphate dehydrogenase inhibitors potentially have antitumor effects. In this article, we aim to provide a comprehensive overview of the potential effects of different types of immunosuppressants on HCC recurrence and their mechanisms of action from both experimental and clinical perspectives. To ultimately improve the outcomes of HCC patients after transplantation, we propose a concept and approaches for developing personalized immunosuppressive medication to be used either as immunosuppression maintenance or during the prevention/treatment of HCC recurrence.

[microRNA: new diagnostic and therapeutic tools in liver disease?]

microRNA are small non coding RNA, which negatively regulate the expression of their targets. Due to their various targets, miRNAs play a key role in number of physiological processes and in oncogenesis. The identification of specific miRNA signatures in various types of tumours, including hepatocellular carcinoma (HCC), highlights the dual role of miRNA, both oncogenes and tumour suppressors. Here, we review the current knowledge concerning the deregulation of miRNA expression in liver disease. All studies focusing on miRNAs argue for their possible use as diagnostic, prognostic and therapeutic markers. Here, we preferentially discuss the promising therapeutic strategies based on miRNAs that have been tested in HCC.

Decreased apoptosis in advanced-stage/high-grade hepatocellular carcinoma complicating chronic hepatitis C is mediated through the downregulation of p21 ras

OBJECTIVE AND BACKGROUND

Although p21 ras has been reported to be upregulated in hepatocellular carcinoma complicating chronic hepatitis C type I, p21 ras has a different role in advanced stages, as it has been found to be downregulated. The goal of this study was to investigate the status of p21 ras in early-stage/low-grade and late-stage/high-grade hepatocellular carcinoma and its possible link to apoptosis.

MATERIAL AND METHODS

Thirty-five cases each of chronic HCV hepatitis type 4 (group I) and cirrhosis with hepatocellular carcinoma (HCC) complicating chronic HCV hepatitis (groups II and III) were immunohistochemically evaluated using a p21 ras polyclonal antibody. The apoptotic index was determined in histologic sections using the terminal deoxynucleotidyl transferase-mediated d-UTP biotin nick end labeling (TUNEL) assay.

RESULTS

Significant differences (P=0.001) were detected in p21 ras protein expression between the three groups. A near 2-fold increase in p21 ras staining was observed in the cirrhotic cases compared to the hepatitis cases, and p21 ras expression was decreased in the HCC group. p21 ras expression correlated with stage (r=0.64, P=0.001) and grade (r=(-)0.65, P=0.001) in the HCC group and grade in the HCV group (r=0.44, P=0.008). Both p21 ras expression and TUNEL-LI were significantly lower in large HCCs compared to small HCCs (P=0.01 each). The TUNEL values were negatively correlated with stage in the HCC group (r=(-)0.85, P=0.001). The TUNEL values were also negatively correlated with grade in both the HCV and HCC groups (r=0.89, P=0.001 and r=(-)0.53, P=0.001, respectively). The p21 ras scores were significantly correlated with the TUNEL-LI values in the HCC group (r=0.63, P=0.001) and HCV group (r=0.88, P=0.001).

CONCLUSIONS

p21 ras acts as an initiator in HCC complicating type 4 chronic HCV and is downregulated with HCC progression, which most likely promotes tumor cell survival because it facilitates the downregulation of apoptosis with tumor progression.

Direct effects of hepatitis B virus-encoded proteins and chronic infection in liver cancer development

Hepatocellular carcinoma (HCC) ranks as the third leading cause of cancer-related death worldwide with currently limited treatment options. Chronic hepatitis B virus (HBV) infection accounts for HCC development in more than 50% of cases. The lifetime risk of HBV carriers to develop cirrhosis, liver failure or HCC is estimated to be as high as 15-40%. Although several pathways and triggers contributing to HCC development have been described, many features of hepatocellular carcinogenesis and the attributed direct role of viral factors remain elusive. Host genetic factors, the geographic area and epidemiologic factors, as well as the direct risk related to chronic HBV and hepatitis C virus (HCV) infections, account for geographical and gender differences of HCC prevalence. There is growing evidence that hepatocarcinogenesis is a multistep process. Human HCC is typically preceded by chronic inflammation and apoptotic and nonapoptotic cell death with compensatory liver proliferation. However, we still lack a thorough understanding of the common underlying molecular mechanisms. High levels of HBV replication and chronicity of inflammation are known to independently increase the risk for HCC. A direct carcinogenic role of viral factors is very likely to contribute to liver cancer since HCC is known to also occur in noncirrhotic livers of individuals with an inactive chronic or even with occult HBV infection with no significant histological signs of inflammation or cytopathic effects. Furthermore, synergistic or independent viral risk factors for primary liver cancer development have been described, such as HBV genotype, integration of viral DNA into the host genome and direct effects of viral proteins. A broader understanding of these viral factors in hepatocarcinogenesis might give rise to new diagnostic and therapeutic means in the future. We review the current state of research in liver cancer development and focus on the role of direct viral factors in HBV infection.

Complex disease interventions from a network model for type 2 diabetes

There is accumulating evidence that the proteins encoded by the genes associated with a common disorder interact with each other, participate in similar pathways and share GO terms. It has been anticipated that the functional modules in a disease related functional linkage network are informative to reveal significant metabolic processes and disease's associations with other complex disorders. In the current study, Type 2 diabetes associated functional linkage network (T2DFN) containing 2770 proteins and 15041 linkages was constructed. The functional modules in this network were scored and evaluated in terms of shared pathways, co-localization, co-expression and associations with similar diseases. The assembly of top scoring overlapping members in the functional modules revealed that, along with the well known biological pathways, circadian rhythm, diverse actions of nuclear receptors in steroid and retinoic acid metabolisms have significant occurrence in the pathophysiology of the disease. The disease's association with other metabolic and neuromuscular disorders was established through shared proteins. Nuclear receptor NRIP1 has a pivotal role in lipid and carbohydrate metabolism, indicating the need to investigate subsequent effects of NRIP1 on Type 2 diabetes. Our study also revealed that CREB binding protein (CREBBP) and cardiotrophin-1 (CTF1) have suggestive roles in linking Type 2 diabetes and neuromuscular diseases.

Akt and mTORC1 have different roles during liver tumorigenesis in mice

BACKGROUND & AIMS

Phosphatidylinositide 3-kinase (PI3K) is deregulated in many human tumor types, including primary liver malignancies. The kinase v-akt murine thymoma viral oncogene homolog 1 (Akt) and mammalian target of rapamycin complex (mTORC1) are effectors of PI3K that promote cell growth and survival, but their individual roles in tumorigenesis are not well defined.

METHODS

In livers of albumin (Alb)-Cre mice, we selectively deleted tuberous sclerosis (Tsc)1, a negative regulator of Ras homolog enriched in brain and mTORC1, along with Phosphatase and tensin homolog (Pten), a negative regulator of PI3K. Tumor tissues were characterized by histologic and biochemical analyses.

RESULTS

The Tsc1fl/fl;AlbCre, Ptenfl/fl;AlbCre, and Tsc1fl/fl;Ptenfl/fl;AlbCre mice developed liver tumors that differed in size, number, and histologic features. Livers of Tsc1fl/fl;AlbCre mice did not develop steatosis; tumors arose later than in the other strains of mice and were predominantly hepatocellular carcinomas. Livers of the Ptenfl/fl;AlbCre mice developed steatosis and most of the tumors that formed were intrahepatic cholangiocarcinomas. Livers of Tsc1fl/fl;Ptenfl/fl;AlbCre formed large numbers of tumors, of mixed histologies, with the earliest onset of any strain, indicating that loss of Tsc1 and Pten have synergistic effects on tumorigenesis. In these mice, the combination of rapamycin and MK2206 was more effective in reducing liver cell proliferation and inducing cell death than either reagent alone. Tumor differentiation correlated with Akt and mTORC1 activities; the ratio of Akt:mTORC1 activity was high throughout the course of intrahepatic cholangiocarcinomas development and low during hepatocellular carcinoma development. Compared with surrounding nontumor liver tissue, tumors from all 3 strains had increased activities of Akt, mTORC1, and mitogen-activated protein kinase and overexpressed fibroblast growth factor receptor 1. Inhibition of fibroblast growth factor receptor 1 in Tsc1-null mice suppressed Akt and mitogen-activated protein kinase activities in tumor cells.

CONCLUSIONS

Based on analyses of knockout mice, mTORC1 and Akt have different yet synergistic effects during the development of liver tumors in mice.

Impact of genetic targets on cancer therapy: hepatocellular cancer

Understanding cancer at the genetic level had gained significant attention over the last decade since the human genome was first sequenced in 2001. For hepatocellular carcinoma (HCC) a number of genome-wide profiling studies have been published. These studies have provided us with gene sets, based on which we can now classify tumors and have an idea about the likely clinical outcomes. In addition to that, genomic profiling for HCC has provided us a better understanding of the carcinogenesis process and identifies key steps at multiple levels (i.e. Genetics, molecular pathways) that can be potential targets for treatment and prevention. Although still an incurable disease, unresectable HCC has one proven systemic therapy, sorafenib, and many under active investigation. With advancement in technology and understanding of hepatocarcinogenesis, scientists hope to provide true personalized treatment for this disease in the near future. In this review article we discuss advances in understanding genetics and pathogenesis of HCC and the currently available and ongoing trials for targeted therapies. These emerging therapies may guide the development of more effective treatments or possibly a cure for HCC.

New genetic associations in thiopurine-related bone marrow toxicity among inflammatory bowel disease patients

Background: The toxicity related to thiopurine drug therapy for inflammatory bowel disease (IBD) varies widely among patients. Almost 15–30% of patients with IBD develop side effects during treatment, often bone marrow suppression. Several factors have been implicated in determining this toxicity, mainly individual genetic variation related to formation of active thiopurine metabolites. The aim was to identify genes involved in thiopurine-related myelosuppression. Materials & methods: A two-stage investigation of 19,217 coding SNPs (cSNPs) was performed in a Spanish (Inflammatory Bowel Disease Group of Galicia [EIGA]) cohort of 173 IBD patients, 15 with bone marrow suppression. The top 20 cSNPs identified in the first stage with p < 10-3 for allelic test association and SNPs that define the common TPMT alleles were replicated in a different Spanish (ENEIDA) cohort (87 patients, 29 with bone marrow suppression). Results: Several cSNPs showed a significant p-value in the allelic joint analysis (p-Cochran–Mantel–Haenszel test ≤2.55 × 10-3) despite no cSNP passing correction for multiple testing in the first cohort. Of note is rs3729961 in the gene IL6ST, a transducer signal chain shared by many cytokines including IL6 (p-value combined = 2.36 × 10-4, odds ratio [95% CI]: 3.41 [1.71–6.78]). In addition, we detected association with rs3749598 in the FSTL5 gene that appears to interact with metalloproteases at the extracellular matrix level (p-value combined = 4.89 × 10-4), odds ratio (95% CI): 3.67 (1.68–8.01). Conclusion: We have identified IL6ST and FSLT5 as new bone marrow suppression susceptibility candidate genes after thiopurine treatment in IBD patients. This is the first report of variants associated with thiopurine-related myelosuppression that was identified by a genome-wide association study. Its validation awaits functional analyses and replication in additional studies.

Original submitted 14 September 2012; Revision submitted 13 February 2013

Conditional disruption of Axin1 leads to development of liver tumors in mice

BACKGROUND & AIMS

Mutations in components of the Wnt signaling pathway, including β-catenin and AXIN1, are found in more than 50% of human hepatocellular carcinomas (HCCs). Disruption of Axin1 causes embryonic lethality in mice. We generated mice with conditional disruption of Axin1 to study its function specifically in adult liver.

METHODS

Mice with a LoxP-flanked allele of Axin1 were generated by homologous recombination. Mice homozygous for the Axin1fl/fl allele were crossed with AhCre mice; in offspring, Axin1 was disrupted in liver following injection of β-naphthoflavone (Axin1fl/fl/Cre mice). Liver tissues were collected and analyzed by quantitative real-time polymerase chain reaction and immunoprecipitation, histology, and immunoblot assays.

RESULTS

Deletion of Axin1 from livers of adult mice resulted in an acute and persistent increase in hepatocyte cell volume, proliferation, and transcription of genes that induce the G(2)/M transition in the cell cycle and cytokinesis. A subset of Wnt target genes was activated, including Axin2, c-Myc, and cyclin D1. However, loss of Axin1 did not increase nuclear levels of β-catenin or cause changes in liver zonation that have been associated with loss of the adenomatous polyposis coli (APC) or constitutive activation of β-catenin. After 1 year, 5 of 9 Axin1fl/fl/Cre mice developed liver tumors with histologic features of HCC.

CONCLUSIONS

Hepatocytes from adult mice with conditional disruption of Axin1 in liver have a transcriptional profile that differs from that associated with loss of APC or constitutive activation of β-catenin. It might be similar to a proliferation profile observed in a subset of human HCCs with mutations in AXIN1. Axin1fl/fl mice could be a useful model of AXIN1-associated tumorigenesis and HCC.

[MicroRNAs in hepatocarcinogenesis]

The details of molecular alterations occurring during hepatocarcinogenesis have not been revealed yet. Nevertheless, it is known that microRNAs (miRNA), these short RNA molecules regulating gene expression mainly in a negative way, are also involved in this process. Altered miRNA expression levels are present in liver diseases when compared with normal liver tissue, and the observed alterations depend mainly on which is more advantegous for the disease: activation or inhibition of the genes (e.g. oncogenes or tumor suppressor genes) regulated by the altered miRNAs. The miRNA expression pattern described in hepatocellular carcinoma seems to differ the most from that found in the normal liver; however, remarkable alterations at miRNA levels have been published in early stages of hepatic tumor progression such as fibrosis and chronic hepatitis. For example, the expression of miR-21, miR-221, miR-222 and miR-199a showing characteristic alterations in hepatocellular carcinoma also displayed deregulated expressions in these two early stages. The liver characteristic miRNA, miR-122, usually exhibits a decreased expression level upon liver injury as well as miR-122 expression tends to decrease as hepatic carcinogenesis progresses. Besides, miR-122 enhances the replication of hepatitis C virus and the initial low or high level of miR-122 seems to influence the efficiency of interferon therapy. Recently, statistically significant differences have been detected in the expression of several miRNAs being present in the serum of patients with chronic hepatitis, chirrhosis and hepatocellular carcinoma when compared with normal controls. It suggests that serum miRNAs could be potential biomarkers. In this article, the major and recent alterations of microRNA expression patterns in stages of hepatocarcinogenesis such as fibrosis, viral infections (hepatitis), cirrhosis and hepatocellular carcinoma are summarized.

Primovist, Eovist: what to expect?

Gadolinium ethoxybenzyl dimeglumine (Gd-EOB-DTPA, Primovist in Europe and Eovist in the USA) is a liver-specific magnetic resonance imaging contrast agent that has up to 50% hepatobiliary excretion in the normal liver. After intravenous injection, Gd-EOB-DTPA distributes into the vascular and extravascular spaces during the arterial, portal venous and late dynamic phases, and progressively into the hepatocytes and bile ducts during the hepatobiliary phase. The hepatocyte uptake of Gd-EOB-DTPA mainly occurs via the organic anion transporter polypeptides OATP1B1 and B3 located at the sinusoidal membrane and biliary excretion via the multidrug resistance-associated proteins MRP2 at the canalicular membrane. Because of these characteristics, Gd-EOB-DTPA behaves similarly to non-specific gadolinium chelates during the dynamic phases, and adds substantial information during the hepatobiliary phase, improving the detection and characterization of focal liver lesions and diffuse liver disease. This information is particularly relevant for the detection of metastases, and for the detection and characterization of nodular lesions in liver cirrhosis, including early hepatocellular carcinomas. Finally, GD-EOB-DTPA-enhanced magnetic resonance imaging may provide quantitative assessment regarding liver perfusion and hepatocyte function in diffuse liver diseases. The full potential of GD-EOB-DTPA-enhanced magnetic resonance imaging has to be established further. It is already clear that GD-EOB-DTPA-enhanced magnetic resonance imaging provides anatomic and functional information in the setting of focal and diffuse liver disease that is unattainable with magnetic resonance imaging enhanced with non-specific contrast agents.

Functional genomic studies: insights into the pathogenesis of liver cancer

Liver cancer is the sixth-most-common cancer overall but the third-most-frequent cause of cancer death. Among primary liver cancers, hepatocellular carcinoma (HCC), the major histological subtype, is associated with multiple risk factors, including hepatitis B and C virus infection, alcohol consumption, obesity, and diet contamination. Although previous studies have revealed that certain genetic and epigenetic changes, such as TP53 and β-catenin mutations, occur in HCC cells, the pathogenesis of this cancer remains obscure. Functional genomic approaches-including genome-wide association studies, whole-genome and whole-exome sequencing, array-based comparative genomic hybridization, global DNA methylome mapping, and gene or noncoding RNA expression profiling-have recently been applied to HCC patients with different clinical features to uncover the genetic risk factors and underlying molecular mechanisms involved in this cancer's initiation and progression. The genome-wide analysis of germline and somatic genetic and epigenetic events facilitates understanding of the pathogenesis and molecular classification of liver cancer as well as the identification of novel diagnostic biomarkers and therapeutic targets for cancer.

Hepatocellular carcinoma: focus on different aspects of management

Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third cause of cancer-related mortality worldwide. Its incidence is clearly arising comprised by the prevalence of major risk factors mainly hepatitis B and hepatitis C. The population at risk is composed of chronic liver patients at the stage of extensive fibrosis or cirrhosis. The monitoring programs of this population have allowed early detection of disease management to promote a radical therapy. Understanding the carcinogenic process and the mastery of the staging systems remain essential keys in diagnosis and treatment of HCC. Recent advances in diagnosis and new treatments have made important impacts on the disease by increasing survival rates and improving quality of life for HCC patients. This paper outlines the different management aspects of HCC which include epidemiology, prevention, carcinogenesis, staging systems, diagnosis, surveillance, and the treatment.

Translational medicine in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a highly complex disease that is generally resistant to commonly used chemotherapy and radiotherapy. Consequently, there is an urgent need for the development of new treatment strategies for this devastating disease. In the past decade, tremendous progress has been achieved in the molecular stratification of HCCs for diagnosis, prognosis, and therapeutic decision-making. To date, the molecular classification of HCCs has been carried out through transcriptomic, genetic and epigenetic profiling of tumors. Such research has led to identification of several potential molecular targets in HCC, and subsequently, development of novel systemic agents for the treatment of HCC has begun in earnest. In this article, we review the current knowledge of the molecular pathogenesis of HCC and outline potential areas for application of this knowledge in a clinical setting. As a typical virus and inflammation-associated cancer, both host immune response and tumor microenvironment have crucial roles in HCC pathogenesis. In addition, we examine the potential of immunotherapy and strategies targeting various components of the tumor microenvironment, as well as novel molecular and cellular targets in HCC such as cancer stem cells.