A TGF-β-dominant chemoresistant phenotype of hepatoblastoma associated with aflatoxin exposure in children

BACKGROUND AND AIMS

Hepatoblastoma (HB) is the most common liver cancer in children, posing a serious threat to children's health. Chemoresistance is the leading cause of mortality in patients with HB. A more explicit definition of the features of chemotherapy resistance in HB represents a fundamental urgent need.

APPROACH AND RESULTS

We performed an integrative analysis including single-cell RNA sequencing, whole-exome sequencing, and bulk RNA sequencing in 180 HB samples, to reveal genomic features, transcriptomic profiles, and the immune microenvironment of HB. Multicolor immunohistochemistry staining and in vitro experiments were performed for validation. Here, we reported four HB transcriptional subtypes primarily defined by differential expression of transcription factors. Among them, the S2A subtype, characterized by strong expression of progenitor ( MYCN , MIXL1 ) and mesenchymal transcription factors ( TWIST1 , TBX5 ), was defined as a new chemoresistant subtype. The S2A subtype showed increased TGF-β cancer-associated fibroblast and an immunosuppressive microenvironment induced by the upregulated TGF-β of HB. Interestingly, the S2A subtype enriched SBS24 signature and significantly higher serum aflatoxin B1-albumin (AFB1-ALB) level in comparison with other subtypes. Functional assays indicated that aflatoxin promotes HB to upregulate TGF-β. Furthermore, clinical prognostic analysis showed that serum AFB1-ALB is a potential indicator of HB chemoresistance and prognosis.

CONCLUSIONS

Our studies offer new insights into the relationship between aflatoxin and HB chemoresistance and provide important implications for its diagnosis and treatment.

Intratumoral CXCR4hi neutrophils display ferroptotic and immunosuppressive signatures in hepatoblastoma

Pediatric hepatoblastoma (HB) is the most common primary liver malignancy in infants and children. With great diversity and plasticity, tumor-infiltrating neutrophils were one of the most determining factors for poor prognosis in many malignant tumors. In this study, through bulk RNA sequencing for sorted blood and tumor-infiltrated neutrophils and comparison of neutrophils in tumor and para-tumor tissue by single-cell sequencing, we found that intratumoral neutrophils were composed of heterogenous functional populations at different development stages. Our study showed that terminally differentiated neutrophils with active ferroptosis prevailed in tumor tissue, whereas, in para-tumor, pre-fate naïve neutrophils were dominant and ferroptotic neutrophils dispersed in a broad spectrum of cell maturation. Gene profiling and in vitro T-cell coculture experiment confirmed that one of main functional intratumoral neutrophils was mainly immunosuppressive, which relied on the activation of ferroptosis. Combining the bulk RNA-seq, scRNA-seq data, and immunochemistry staining of tumor samples, CXCL12/CXCR4 chemotaxis pathway was suggested to mediate the migration of neutrophils in tumors as CXCR4 highly expressed by intratumoral neutrophils and its ligand CXCL12 expressed much higher level in tumor than that in para-tumor. Moreover, our study pinpointed that infiltrated CXCR4hi neutrophils, regardless of their differential distribution of cell maturation status in HB tumor and para-tumor regions, were the genuine perpetrators for immune suppression. Our data characterized the ferroptosis-dependent immunosuppression energized by intratumoral CXCR4 expression neutrophils and suggest a potential cell target for cancer immunotherapies.

Cellular origin and molecular mechanisms of lung metastases in patients with aggressive hepatoblastoma

BACKGROUND AND AIMS

Lung metastases are the most threatening signs for patients with aggressive hepatoblastoma (HBL). Despite intensive studies, the cellular origin and molecular mechanisms of lung metastases in patients with aggressive HBL are not known. The aims of these studies were to identify metastasis-initiating cells in primary liver tumors and to determine if these cells are secreted in the blood, reach the lung, and form lung metastases.

APPROACH

We have examined mechanisms of activation of key oncogenes in primary liver tumors and lung metastases and the role of these mechanisms in the appearance of metastasis-initiating cells in patients with aggressive HBL by RNA-Seq, immunostaining, chromatin immunoprecipitation, Real-Time Quantitative Reverse Transcription PCR and western blot approaches. Using a protocol that mimics the exit of metastasis-initiating cells from tumors, we generated 16 cell lines from liver tumors and 2 lines from lung metastases of patients with HBL.

RESULTS

We found that primary HBL liver tumors have a dramatic elevation of neuron-like cells and cancer-associated fibroblasts and that these cells are released into the bloodstream of patients with HBL and found in lung metastases. In the primary liver tumors, the ph-S675-β-catenin pathway activates the expression of markers of cancer-associated fibroblasts; while the ZBTB3-SRCAP pathway activates the expression of markers of neurons via cancer-enhancing genomic regions/aggressive liver cancer domains leading to a dramatic increase of cancer-associated fibroblasts and neuron-like cells. Studies of generated metastasis-initiating cells showed that these cells proliferate rapidly, engage in intense cell-cell interactions, and form tumor clusters. The inhibition of β-catenin in HBL/lung metastases-released cells suppresses the formation of tumor clusters.

CONCLUSIONS

The inhibition of the β-catenin-cancer-enhancing genomic regions/aggressive liver cancer domains axis could be considered as a therapeutic approach to treat/prevent lung metastases in patients with HBL.

Identification and experimental validation of druggable epigenetic targets in hepatoblastoma

BACKGROUND & AIMS

Hepatoblastoma (HB) is the most frequent childhood liver cancer. Patients with aggressive tumors have limited therapeutic options; therefore, a better understanding of HB pathogenesis is needed to improve treatment. HBs have a very low mutational burden; however, epigenetic alterations are increasingly recognized. We aimed to identify epigenetic regulators consistently dysregulated in HB and to evaluate the therapeutic efficacy of their targeting in clinically relevant models.

METHODS

We performed a comprehensive transcriptomic analysis of 180 epigenetic genes. Data from fetal, pediatric, adult, peritumoral (n = 72) and tumoral (n = 91) tissues were integrated. Selected epigenetic drugs were tested in HB cells. The most relevant epigenetic target identified was validated in primary HB cells, HB organoids, a patient-derived xenograft model, and a genetic mouse model. Transcriptomic, proteomic and metabolomic mechanistic analyses were performed.

RESULTS

Altered expression of genes regulating DNA methylation and histone modifications was consistently observed in association with molecular and clinical features of poor prognosis. The histone methyltransferase G9a was markedly upregulated in tumors with epigenetic and transcriptomic traits of increased malignancy. Pharmacological targeting of G9a significantly inhibited growth of HB cells, organoids and patient-derived xenografts. Development of HB induced by oncogenic forms of β-catenin and YAP1 was ablated in mice with hepatocyte-specific deletion of G9a. We observed that HBs undergo significant transcriptional rewiring in genes involved in amino acid metabolism and ribosomal biogenesis. G9a inhibition counteracted these pro-tumorigenic adaptations. Mechanistically, G9a targeting potently repressed the expression of c-MYC and ATF4, master regulators of HB metabolic reprogramming.

CONCLUSIONS

HBs display a profound dysregulation of the epigenetic machinery. Pharmacological targeting of key epigenetic effectors exposes metabolic vulnerabilities that can be leveraged to improve the treatment of these patients.

IMPACT AND IMPLICATIONS

In spite of recent advances in the management of hepatoblastoma (HB), treatment resistance and drug toxicity are still major concerns. This systematic study reveals the remarkable dysregulation in the expression of epigenetic genes in HB tissues. Through pharmacological and genetic experimental approaches, we demonstrate that the histone-lysine-methyltransferase G9a is an excellent drug target in HB, which can also be harnessed to enhance the efficacy of chemotherapy. Furthermore, our study highlights the profound pro-tumorigenic metabolic rewiring of HB cells orchestrated by G9a in coordination with the c-MYC oncogene. From a broader perspective, our findings suggest that anti-G9a therapies may also be effective in other c-MYC-dependent tumors.

A developmentally prometastatic niche to hepatoblastoma in neonatal liver mediated by the Cxcl1/Cxcr2 axis

BACKGROUND AND AIMS

Hepatoblastoma (HB) is the most common pediatric liver cancer. Its predominant occurrence in very young children led us to investigate whether the neonatal liver provides a protumorigenic niche to HB development.

APPROACH AND RESULTS

HB development was compared between orthotopic transplantation models established in postnatal day 5 (P5) and 60 (P60) mice (P5Tx and P60Tx models). Single-cell RNA-sequencing (sc-RNAseq) was performed using tumor and liver tissues from both models and the top candidate cell types and genes identified are investigated for their roles in HB cell growth, migration, and survival.

CONCLUSIONS

We found that various HB cell lines including HepG2 cells were consistently and considerably more tumorigenic and metastatic in the P5Tx model than in the P60Tx models. Sc-RNAseq of the P5Tx and P60Tx HepG2 models revealed that the P5Tx tumor was more hypoxic and had a larger number of activated hepatic stellate cells (aHSCs) in the tumor-surrounding liver that express significantly higher levels of Cxcl1 than those from the P60Tx model. We found these differences were developmentally present in normal P5 and P60 liver. We showed that the Cxcl1/Cxcr2 axis mediated HB cell migration and was critical to HB cell survival under hypoxia. Treating HepG2 P60Tx model with recombinant CXCL1 protein induced intrahepatic and pulmonary metastasis and CXCR2 knockout (KO) in HepG2 cells abolished their metastatic potential in the P5Tx model. Lastly, we showed that in tumors from patients with metastatic HB, there was a similar larger population of aHSCs in the tumor-surrounding liver than in localized tumors, and tumor hypoxia was uniquely associated with prognosis of patients with HB among pediatric cancers. We demonstrated that the neonatal liver provides a prometastatic niche to HB development through the Cxcl1/Cxcr2 axis.

Hepatoblastomas with carcinoma features represent a biological spectrum of aggressive neoplasms in children and young adults

BACKGROUND & AIMS

Hepatoblastoma (HB) and hepatocellular carcinoma (HCC) are the predominant liver cancers in children, though their respective treatment options and associated outcomes differ dramatically. Risk stratification using a combination of clinical, histological, and molecular parameters can improve treatment selection, but it is particularly challenging for tumors with mixed histological features, including those in the recently created hepatocellular neoplasm not otherwise specified (HCN NOS) provisional category. We aimed to perform the first molecular characterization of clinically annotated cases of HCN NOS.

METHODS

We tested whether these histological features are associated with genetic alterations, cancer gene dysregulation, and outcomes. Namely, we compared the molecular features of HCN NOS, including copy number alterations, mutations, and gene expression profiles, with those in other pediatric hepatocellular neoplasms, including HBs and HCCs, as well as HBs demonstrating focal atypia or pleomorphism (HB FPAs), and HBs diagnosed in older children (>8).

RESULTS

Molecular profiles of HCN NOS and HB FPAs revealed common underlying biological features that were previously observed in HCCs. Consequently, we designated these tumor types collectively as HBs with HCC features (HBCs). These tumors were associated with high mutation rates (∼3 somatic mutations/Mb) and were enriched with mutations and alterations in key cancer genes and pathways. In addition, recurrent large-scale chromosomal gains, including gains of chromosomal arms 2q (80%), 6p (70%), and 20p (70%), were observed. Overall, HBCs were associated with poor clinical outcomes.

CONCLUSIONS

Our study indicates that histological features seen in HBCs are associated with combined molecular features of HB and HCC, that HBCs are associated with poor outcomes irrespective of patient age, and that transplanted patients are more likely to have good outcomes than those treated with chemotherapy and surgery alone. These findings highlight the importance of molecular testing and early therapeutic intervention for aggressive childhood hepatocellular neoplasms.

LAY SUMMARY

We molecularly characterized a class of histologically aggressive childhood liver cancers and showed that these tumors are clinically aggressive and that their observed histological features are associated with underlying recurrent molecular features. We proposed a diagnostic algorithm to identify these cancers using a combination of histological and molecular features, and our analysis suggested that these cancers may benefit from specialized treatment strategies that may differ from treatment guidelines for other childhood liver cancers.

Deleting the β-catenin degradation domain in mouse hepatocytes drives hepatocellular carcinoma or hepatoblastoma-like tumor growth

BACKGROUND & AIMS

One-third of hepatocellular carcinomas (HCCs) harbor mutations activating the β-catenin pathway, predominantly via mutations in the CTNNB1 gene itself. Mouse models of Apc loss-of-function are widely used to mimic β-catenin-dependent tumorigenesis. Given the low prevalence of APC mutations in human HCCs, we aimed to generate liver tumors through CTNNB1 exon 3 deletion (βcat^Δex3). We then compared βcat^Δex3 liver tumors with liver tumors generated via frameshift in exon 15 of Apc (Apc^fs-ex15).

METHODS

We used hepatocyte-specific and inducible mouse models generated through either a Cre-Lox or a CRISPR/Cas9 approach using adeno-associated virus vectors. Tumors generated by the Cre-Lox models were phenotypically analyzed using immunohistochemistry and were selected for transcriptomic analysis by RNA-sequencing (RNAseq). Mouse RNAseq data were compared to human RNAseq data (8 normal tissues, 48 HCCs, 9 hepatoblastomas) in an integrative analysis. Tumors generated via CRISPR were analyzed using DNA sequencing and immuno-histochemistry.

RESULTS

Mice with CTNNB1 exon 3 deletion in hepatocytes developed liver tumors indistinguishable from Apc^fs-ex15 liver tumors. Both Apc^fs-ex15 and βcat^Δex3 mouse models induced growth of phenotypically distinct tumors (differentiated or undifferentiated). Integrative analysis of human and mouse tumors showed that differentiated mouse tumors cluster with well-differentiated human CTNNB1-mutated tumors. Conversely, undifferentiated mouse tumors cluster with human mesenchymal hepatoblastomas and harbor activated YAP signaling.

CONCLUSION

Apc^fs-ex15 and βcat^Δex3 mouse models both induce growth of tumors that are transcriptionally similar to either well-differentiated and β-catenin-activated human HCCs or mesenchymal hepatoblastomas.

LAY SUMMARY

New and easy-to-use transgenic mouse models of primary liver cancers have been generated, with mutations in the gene encoding beta-catenin, which are frequent in both adult and pediatric primary liver cancers. The mice develop both types of cancer, constituting a strong preclinical model.

Comparison of the Impact of Xanthohumol and Phenethyl Isothiocyanate and Their Combination on Nrf2 and NF-κB Pathways in HepG2 Cells In Vitro and Tumor Burden In Vivo

Background: Increasing evidence suggests that combinations of phytochemicals are more efficient than single components in the modulation of signaling pathways involved in cancer development. In this study, the impact of phenethyl isothiocyanate (PEITC), indole-3-carbinol (I3C), xanthohumol, (X), and resveratrol (RES) and their combinations on the activation and expression of Nrf2 and NF-κB in human hepatocytes and HCC cells were evaluated. Methods: THLE-2 and HepG2 cells were exposed to single phytochemicals and their combinations for 24 h. The activation of Nrf2 and NF-κB, expression of their target genes, and effect on cells survival were assessed. The tumor burden was evaluated in mice carrying xenografts. Results: All phytochemicals enhanced the activation and expression of Nrf2 and its target genes SOD and NQO1 in HepG2 cells. The increased expression of NQO1 (~90%) was associated with increased ROS generation. X + PEITC downregulated NF-κB activation reducing binding of its active subunits to DNA resulting in diminished COX-2 expression. In contrast to single phytochemicals, X + PEITC induced apoptosis. Moderate reduction of tumor burden in mice carrying xenografts following X and PEITC or their combination was observed. Conclusions: Since Nrf2 is overexpressed in HCC its reduced activation together with diminished level of NF-κB by X + PEITC may be considered as a strategy to support conventional HCC therapy.

Hepatoblastoma: glutamine depletion hinders cell viability in the embryonal subtype but high GLUL expression is associated with better overall survival

Purpose

Glutamine plays an important role in cell viability and growth of various tumors. For the fetal subtype of hepatoblastoma, growth inhibition through glutamine depletion was shown. We studied glutamine depletion in embryonal cell lines of hepatoblastoma carrying different mutations. Since asparagine synthetase was identified as a prognostic factor and potential therapeutic target in adult hepatocellular carcinoma, we investigated the expression of its gene ASNS and of the gene GLUL, encoding for glutamine synthetase, in hepatoblastoma specimens and cell lines and investigated the correlation with overall survival.

Methods

We correlated GLUL and ASNS expression with overall survival using publicly available microarray and clinical data. We examined GLUL and ASNS expression by RT-qPCR and by Western blot analysis in the embryonal cell lines Huh-6 and HepT1, and in five hepatoblastoma specimens. In the same cell lines, we investigated the effects of glutamine depletion. Hepatoblastoma biopsies were examined for histology and CTNNB1 mutations.

Results

High GLUL expression was associated with a higher median survival time. Independent of mutations and histology, hepatoblastoma samples showed strong GLUL expression and glutamine synthesis. Glutamine depletion resulted in the inhibition of proliferation and of cell viability in both embryonal hepatoblastoma cell lines. ASNS expression did not correlate with overall survival.

Conclusion

Growth inhibition resulting from glutamine depletion, as described for the hepatoblastoma fetal subtype, is also detected in established embryonal hepatoblastoma cell lines carrying different mutations. At variance with adult hepatocellular carcinoma, in hepatoblastoma asparagine synthetase has no prognostic significance.

YTHDC1 gene polymorphisms and hepatoblastoma susceptibility in Chinese children: A seven-center case-control study

BACKGROUND

Hepatoblastoma is a commonly occurring embryonal tumors in children. N6-methyladenosine (m⁶ A) plays a critical role in gene expression, thus contributing to the occurrence and progression of cancer. RNA splicing is regulated by the nuclear m⁶ A reader YTHDC1, yet the roles of YTHDC1 polymorphisms in hepatoblastoma remain unclear.

METHODS

We conducted a seven-center case-control study to determine the association between YTHDC1 gene polymorphisms (rs2293596 T>C, rs2293595 T>C and rs3813832 T>C) and hepatoblastoma susceptibility. We recruited 313 hepatoblastoma patients and 1446 healthy controls.

RESULTS

There was no significant association between all of these polymorphisms and hepatoblastoma susceptibility in single locus or combined analysis. Stratification analysis revealed that rs2293596 TC/CC genotype carriers had a higher risk of developing hepatoblastoma in the subgroup of clinical stages III + IV [adjusted odds ratio (OR) = 1.80, 95% confidence interval (CI) = 1.18-2.76, p = 0.007]. In addition, 3 risk genotype carriers are more likely to develop hepatoblastoma in the subgroup of clinical stages III + IV (adjusted OR = 1.80, 95% CI = 1.18-2.76, p = 0.007). Furthermore, false-positive probability analysis was used to notarize our findings. Haplotype analysis indicated that there was no significant association between inferred haplotypes of YTHDC1 gene based on observed genotypes and hepatoblastoma risk.

CONCLUSIONS

In conclusion, our findings suggest that the rs2293596 T>C polymorphism may contribute to hepatoblastoma susceptibly and YTHDC1 gene polymorphisms may have a cumulative effect on hepatoblastoma risk.

Insights into the Chemical Biology of Childhood Embryonal Solid Tumors by NMR-Based Metabolomics

Most childhood cancers occur as isolated cases and show very different biological behavior when compared with cancers in adults. There are some solid tumors that occur almost exclusively in children among which stand out the embryonal solid tumors. These cancers main types are neuroblastoma, nephroblastoma (Wilms tumors), retinoblastoma and hepatoblastomas and tumors of the central nervous system (CNS). Embryonal solid tumors represent a heterogeneous group of cancers supposedly derived from undifferentiated cells, with histological features that resemble tissues of origin during embryogenesis. This key observation suggests that tumorigenesis might begin during early fetal or child life due to the errors in growth or pathways differentiation. There are not many literature data on genomic, transcriptomic, epigenetic, proteomic, or metabolomic differences in these types of cancers when compared to the omics- used in adult cancer research. Still, metabolomics by nuclear magnetic resonance (NMR) in childhood embryonal solid tumors research can contribute greatly to understand better metabolic pathways alterations and biology of the embryonal solid tumors and potential to be used in clinical applications. Different types of samples, such as tissues, cells, biofluids, mostly blood plasma and serum, can be analyzed by NMR to detect and identify cancer metabolic signatures and validated biomarkers using enlarged group of samples. The literature search for biomarkers points to around 20-30 compounds that could be associated with pediatric cancer as well as metastasis.

STAT3-Activated Long Non-Coding RNA Lung Cancer Associated Transcript 1 Drives Cell Proliferation, Migration, and Invasion in Hepatoblastoma Through Regulation of the miR-301b/STAT3 Axis

Hepatoblastoma (HB) usually occurs in infants and toddlers. Although long non-coding RNAs (lncRNAs) in various human cancers have been widely studied, the role of lncRNAs in HB remains unclear. This study aimed to investigate the biological role of the lncRNA lung cancer associated transcript 1 (LUCAT1) in HB. Analysis of data from The Cancer Genome Atlas indicated that upregulation of lncRNA LUCAT1 was closely associated with poor overall survival of HB patients. Quantitative reverse transcription polymerase chain reaction analysis showed that LUCAT1 was highly expressed in both HB tissues and cell lines. Loss-of function assays to identify the biological function of LUCAT1 in HB showed that LUCAT1 knockdown inhibited cell proliferation, migration, and invasion but reversed epithelial-mesenchymal transition. Luciferase assays indicated that STAT3 was a transcription activator of LUCAT1 and that LUCAT1 could increase STAT3 expression by competitively binding to miR-301b. In conclusion, it was found that LUCAT1 was activated by STAT3 and promoted cell proliferation, migration, and invasion in HB through modulation of the miR-301b/STAT3 axis.

p53, stem cell biology and childhood blastomas

PURPOSE OF REVIEW

Childhood blastomas, unlike adult cancers, originate from developing organs in which molecular and cellular features exhibit differentiation arrest and embryonic characteristics. Conventional cancer therapies, which rely on the generalized cytotoxic effect on rapidly dividing cells, may damage delicate organs in young children, leading to multiple late effects. Deep understanding of the biology of embryonal cancers is crucial in reshaping the cancer treatment paradigm for children.

RECENT FINDINGS

p53 plays a major physiological role in embryonic development, by controlling cell proliferation, differentiation and responses to cellular stress. Tumor suppressor function of p53 is commonly lost in adult cancers through genetic alterations. However, both somatic and germline p53 mutations are rare in childhood blastomas, suggesting that in these cancers, p53 may be inactivated through other mechanisms than mutation. In this review, we summarize current knowledge about p53 pathway inactivation in childhood blastomas (specifically neuroblastoma, retinoblastoma and Wilms' tumor) through various upstream mechanisms. Laboratory evidence and clinical trials of targeted therapies specific to exploiting p53 upstream regulators are discussed.

SUMMARY

Despite the low rate of inherent TP53 mutations, p53 pathway inactivation is a common denominator in childhood blastomas. Exploiting p53 and its regulators is likely to translate into more effective targeted therapies with minimal late effects for children. (see Video Abstract, Supplemental Digital Content 1, http://links.lww.com/COON/A23).

Comprehensive Proteomics Identification of IFN-λ3-regulated Antiviral Proteins in HBV-transfected Cells

Interferon lambda (IFN-λ) is a relatively unexplored, yet promising antiviral agent. IFN-λ has recently been tested in clinical trials of chronic hepatitis B virus infection (CHB), with the advantage that side effects may be limited compared with IFN-α, as IFN-λ receptors are found only in epithelial cells. To date, IFN-λ's downstream signaling pathway remains largely unelucidated, particularly via proteomics methods. Here, we report that IFN-λ3 inhibits HBV replication in HepG2.2.15 cells, reducing levels of both HBV transcripts and intracellular HBV DNA. Quantitative proteomic analysis of HBV-transfected cells was performed following 24-hour IFN-λ3 treatment, with parallel IFN-α2a and PBS treatments for comparison using a dimethyl labeling method. The depth of the study allowed us to map the induction of antiviral proteins to multiple points of the viral life cycle, as well as facilitating the identification of antiviral proteins not previously known to be elicited upon HBV infection (e.g. IFITM3, XRN2, and NT5C3A). This study also shows up-regulation of many effectors involved in antigen processing/presentation indicating that this cytokine exerted immunomodulatory effects through several essential molecules for these processes. Interestingly, the 2 subunits of the immunoproteasome cap (PSME1 and PSME2) were up-regulated whereas cap components of the constitutive proteasome were down-regulated upon both IFN treatments, suggesting coordinated modulation toward the antigen processing/presentation mode. Furthermore, in addition to confirming canonical activation of interferon-stimulated gene (ISG) transcription through the JAK-STAT pathway, we reveal that IFN-λ3 restored levels of RIG-I and RIG-G, proteins known to be suppressed by HBV. Enrichment analysis demonstrated that several biological processes including RNA metabolism, translation, and ER-targeting were differentially regulated upon treatment with IFN-λ3 versus IFN-α2a. Our proteomic data suggests that IFN-λ3 regulates an array of cellular processes to control HBV replication.

Evaluation of Aflatoxin M1 Effects on the Metabolomic and Cytokinomic Profiling of a Hepatoblastoma Cell Line

Hepatoblastoma incidence has been associated with different environmental factors even if no data are reported about a correlation between aflatoxin exposure and hepatoblastoma initiation. Considering that hepatoblastoma develops in infants and children and aflatoxin M1 (AFM1), the aflatoxin B1 (AFB1) hydroxylated metabolite, can be present in mothers' milk and in marketed milk products, in this study we decided to test the effects of AFM1 on a hepatoblastoma cell line (HepG2). Firstly, we evaluated the effects of AFM1 on the cell viability, apoptosis, cell cycle, and metabolomic and cytokinomic profile of HepG2 cells after treatment. AFM1 induced: (1) a decrease of HepG2 cell viability, reaching IC50 at 9 µM; (2) the blocking of the cell cycle in the G0/G1 phase; (3) the decrease of formiate levels and incremented level of some amino acids and metabolites in HepG2 cells after treatment; and (4) the increase of the concentration of three pro-inflammatory cytokines, IL-6, IL-8, and TNF-α, and the decrease of the anti-inflammatory interleukin, IL-4. Our results show that AFM1 inhibited the growth of HepG2 cells, inducing both a modulation of the lipidic, glycolytic, and amino acid metabolism and an increase of the inflammatory status of these cells.

Gankyrin Promotes Tumor-Suppressor Protein Degradation to Drive Hepatocyte Proliferation

Background & Aims

Uncontrolled liver proliferation is a key characteristic of liver cancer; however, the mechanisms by which this occurs are not well understood. Elucidation of these mechanisms is necessary for the development of better therapy. The oncogene Gankyrin (Gank) is overexpressed in both hepatocellular carcinoma and hepatoblastoma. The aim of this work was to determine the role of Gank in liver proliferation and elucidate the mechanism by which Gank promotes liver proliferation.

Methods

We generated Gank liver-specific knock-out (GLKO) mice and examined liver biology and proliferation after surgical resection and liver injury.

Results

Global profiling of gene expression in GLKO mice showed significant changes in pathways involved in liver cancer and proliferation. Investigations of liver proliferation after partial hepatectomy and CCl4 treatment showed that GLKO mice have dramatically inhibited proliferation of hepatocytes at early stages after surgery and injury. In control LoxP mice, liver proliferation was characterized by Gank-mediated reduction of tumor-suppressor proteins (TSPs). The failure of GLKO hepatocytes to proliferate is associated with a lack of down-regulation of these proteins. Surprisingly, we found that hepatic progenitor cells of GLKO mice start proliferation at later stages and restore the original size of the liver at 14 days after partial hepatectomy. To examine the proliferative activities of Gank in cancer cells, we used a small molecule, cjoc42, to inhibit interactions of Gank with the 26S proteasome. These studies showed that Gank triggers degradation of TSPs and that cjoc42-mediated inhibition of Gank increases levels of TSPs and inhibits proliferation of cancer cells.

Conclusions

These studies show that Gank promotes hepatocyte proliferation by elimination of TSPs. This work provides background for the development of Gank-mediated therapy for the treatment of liver cancer. RNA sequencing data can be accessed in the NCBI Gene Expression Omnibus: GSE104395.

Control the intracellular NF-κB activity by a sensor consisting of miRNA and decoy

Many diseases are associated with the abnormal activation of NF-κB and its signaling pathway. NF-κB has become an important target for disease treatment and development of new drugs. Many various NF-κB inhibitors were therefore developed; however, they have difficulties to become clinical drugs due to their adverse side effects resulted from the affected normal physiological functions of this transcription factor. To overcome this limitation, this study construct a transgenic vector that can express an artificial miRNA targeting NF-κB RelA under the control of a NF-κB-specific promoter. The promoter consists of a NF-κB decoy and a minimal promoter. The vector was named as decoy minimal promoter-artificial microRNA (DMP-amiRNA). This study verified that this vector can sense and control the intracellular NF-κB activity upon transfection. Working of the vector forms a perfect feedback loop that realizes the NF-κB self-control. With the vector in cells, the higher NF-κB activity, the higher DMP transcriptional activity, and the more amiR533 expression. DMP-amiRNA can moderately inhibit the intracellular NF-κB activity but exert no significant effect on cell viability. This study therefore develops a new strategy for inhibiting over activity of NF-κB, which should has great potential in clinical application.

Differentiation Effects by the Combination of Spheroid Formation and Sodium Butyrate Treatment in Human Hepatoblastoma Cell Line (Hep G2): A Possible Cell Source for Hybrid Artificial Liver

The aim of this study was to investigate the feasibility of human hepatoblastoma cell line (Hep G2), which differentiates by spheroid formation, and treatment with sodium butyrate (SB) as a cell source for hybrid artificial liver (HAL). Hep G2 spontaneously formed spheroids in polyurethane foam (PUF) within 3 days of culture and restored weak ammonia removal activity. Treatment with SB, which is a histone deacetylase inhibitor, further increased the ammonia removal activity of Hep G2 spheroids in a concentration-dependent manner. The activation of ornithine transcarbamylase—a urea cycle enzyme—was significantly related to the upregulation of ammonia removal by spheroid formation, but scarcely contributed to the further upregulation following SB treatment. In contrast with ammonia removal, treatment with SB reduced the albumin secretion of Hep G2 spheroids in a concentration-dependent manner. In the PUF-HAL module in a circulation culture, the ammonia removal rate and albumin secretion rate (per unit volume of the module) of Hep G2 spheroids treated with 5 mM SB were almost the same as those of primary porcine hepatocyte spheroids. These results suggest that simultaneous use of spheroid formation and SB treatment in Hep G2 is beneficial in enhancing the functions of human hepatocytes with potential applications in regenerative medicine and drug screening.

Design, microfabrication, and characterization of a moulded PDMS/SU-8 inkjet dispenser for a Lab-on-a-Printer platform technology with disposable microfluidic chip

In this paper, we present a disposable inkjet dispenser platform technology and demonstrate the Lab-on-a-Printer concept, an extension of the ubiquitous Lab-on-a-Chip concept, whereby microfluidic modules are directly integrated into the printhead. The concept is demonstrated here through the integration of an inkjet dispenser and a microfluidic mixer enabling control over droplet composition from a single nozzle in real-time during printing. The inkjet dispenser is based on a modular design platform that enables the low-cost microfluidic component and the more expensive actuation unit to be easily separated, allowing for the optional disposal of the former and reuse of the latter. To limit satellite droplet formation, a hydrophobic-coated and tapered micronozzle was microfabricated and integrated with the fluidics to realize the dispenser. The microfabricated devices generated droplets with diameters ranging from 150-220 μm, depending mainly on the orifice diameter, with printing rates up to 8000 droplets per second. The inkjet dispenser is capable of dispensing materials with a viscosity up to ∼19 mPa s. As a demonstration of the inkjet dispenser function and application, we have printed type I collagen seeded with human liver carcinoma cells (cell line HepG2), to form patterned biological structures.

Momordin Ic couples apoptosis with autophagy in human hepatoblastoma cancer cells by reactive oxygen species (ROS)-mediated PI3K/Akt and MAPK signaling pathways

Momordin Ic is a principal saponin constituent of Fructus Kochiae, which acts as an edible and pharmaceutical product more than 2000 years in China. Our previous research found momordin Ic induced apoptosis by PI3K/Akt and MAPK signaling pathways in HepG2 cells. While the role of autophagy in momordin Ic induced cell death has not been discussed, and the connection between the apoptosis and autophagy is not clear yet. In this work, we reported momordin Ic promoted the formation of autophagic vacuole and expression of Beclin 1 and LC-3 in a dose- and time-dependent manner. Compared with momordin Ic treatment alone, the autophagy inhibitor 3-methyladenine (3-MA) also can inhibit apoptosis, while autophagy activator rapamycin (RAP) has the opposite effect, and the apoptosis inhibitor ZVAD-fmk also inhibited autophagy induced by momordin Ic. Momordin Ic simultaneously induces autophagy and apoptosis by suppressing the ROS-mediated PI3K/Akt and activating the ROS-related JNK and P38 pathways. Additionally, momordin Ic induces apoptosis by suppressing PI3K/Akt-dependent NF-κB pathways and promotes autophagy by ROS-mediated Erk signaling pathway. Those results suggest that momordin Ic has great potential as a nutritional preventive strategy in cancer therapy.

Lin28b is sufficient to drive liver cancer and necessary for its maintenance in murine models

Lin28a/b are RNA-binding proteins that influence stem cell maintenance, metabolism, and oncogenesis. Poorly differentiated, aggressive cancers often overexpress Lin28, but its role in tumor initiation or maintenance has not been definitively addressed. We report that LIN28B overexpression is sufficient to initiate hepatoblastoma and hepatocellular carcinoma in murine models. We also detected Lin28b overexpression in MYC-driven hepatoblastomas, and liver-specific deletion of Lin28a/b reduced tumor burden, extended latency, and prolonged survival. Both intravenous siRNA against Lin28b and conditional Lin28b deletion reduced tumor burden and prolonged survival. Igf2bp proteins are upregulated, and Igf2bp3 is required in the context of LIN28B overexpression to promote growth. Therefore, multiple murine models demonstrate that Lin28b is both sufficient to initiate liver cancer and necessary for its maintenance.

[Inhibitory effect of norcantharidin combined with evodiamine on the growth of human hepatic carcinoma cell line HepG2 in vitro]

OBJECTIVE

To investigate the combined effect of evodiamine (EVO) and norcantharidin (NCTD) on HepG2 cells.

METHODS

HepG2 cells were treated with EVO or/and NCTD at different concentrations in vitro, with blank culture medium as the negative control. The inhibitory effect of EVO or/and NCTD was determined by MTT assay. Cell cycle and cell apoptosis were assessed by flow cytometry (FCM) combined with PI staining and annexin V-FITC/PI, respectively. The expressions of Bax and Bcl-2 were examined by Western blotting. RESULTS MTT assay showed that NCTD and EVO had restraining effect on the growth of HepG2 cells. The combination of NCTD and EVO had significant synergistic inhibition effect (CI<1). The arrest rate of G2/M phase was (36.13±1.63)% in the EVO induced group and (10.67±0.89)% in the NCTD induced group, and the combination of EVO and NCTD up-regulated the rate to (73.42±1.92)% (P<0.05). In addition, the apoptosis rate of HepG2 cells treated by two-drug combination increased significantly from (15.78 ± 3.08)% in the EVO group and (11.47 ± 1.60)% in the NCTD group to (21.86±2.70)% in the EVO combined with NCTD group (P<0.05). Western blotting demonstrated that the expression level of Bax protein went up significantly (P<0.05), meanwhile Bcl-2 protein dropped significantly (P<0.05) in the combined induced group.

CONCLUSION

EVO combined with NCTD showed synergetic effect on anti-proliferation and pro-apoptosis in HepG2 cells.

Multidrug resistance and cancer stem cells in neuroblastoma and hepatoblastoma

Chemotherapy is one of the major modalities in treating cancers. However, its effectiveness is limited by the acquisition of multidrug resistance (MDR). Several mechanisms could explain the up-regulation of MDR genes/proteins in cancer after chemotherapy. It is known that cancer stem cells (CSCs) play a role as master regulators. Therefore, understanding the mechanisms that regulate some traits of CSCs may help design efficient strategies to overcome chemoresistance. Different CSC phenotypes have been identified, including those found in some pediatric malignancies. As solid tumors in children significantly differ from those observed in adults, this review aims at providing an overview of the mechanistic relationship between MDR and CSCs in common solid tumors, and, in particular, focuses on clinical as well as experimental evidence of the relations between CSCs and MDR in neuroblastoma and hepatoblastoma. Finally, some novel approaches, such as concomitant targeting of multiple key transcription factors governing the stemness of CSCs, as well as nanoparticle-based approaches will also be briefly addressed.

[Glypican 3 expression in hepatoblastoma and its diagnostic implication]

OBJECTIVE

To explore the expression and diagnostic significance of glypican-3 (GPC3) in hepatoblastoma.

METHODS

Five tissue microarray paraffin blocks were constructed to include 54 cases of hepatoblastoma. The tumor tissue samples were obtained from 3 surgical biopsies, 33 needle biopsies, 5 stage I resection tumors, and 13 stage II resection tumors after transcatheter arterial chemoembolization. Ten samples of non-neoplastic hepatic tissue adjacent to tumor were used as control. Immunohistochemical staining of GPC3 (clone 1G12) was performed. Among the 54 cases of hepatoblastoma, 22 cases were fetal subtype, 24 cases were mixed fetal and embryonal subtype and 8 cases were mixed epithelial and mesenchymal type.

RESULTS

GPC3 was positive in fetal epithelial cells (54/54, 100%), but negative or weakly positive in embryonic epithelial cells in all cases of hepatoblastoma. Undifferentiated small cells and all mesenchymal components were negative for the expression. Non-neoplastic hepatocytes adjacent to tumor were negative for GPC3 expression (0/10) .

CONCLUSIONS

Fetal epithelial components of hepatoblastoma express GPC3 protein detectable by immunohistochemistry. Normal hepatocytes after birth, small cell undifferentiated and embryonic epithelial components of hepatoblastoma do not or weakly express GPC3 protein. Therefore, GPC3 immunohistochemistry offers a valuable aid to the diagnosis of hepatoblastoma in infants and children.

Crosstalk between beta-catenin and snail in the induction of epithelial to mesenchymal transition in hepatocarcinoma: role of the ERK1/2 pathway

Epithelial to mesenchymal transition (EMT) is an integral process in the progression of many epithelial tumors. It involves a coordinated series of events, leading to the loss of epithelial features and the acquisition of a mesenchymal phenotype, resulting in invasion and metastasis. The EMT of hepatocellular carcinoma (HCC) cells is thought to be a key event in intrahepatic dissemination and distal metastasis. In this study, we used 12-O-tet-radecanoylphorbol-13-acetate (TPA) to dissect the signaling pathways involved in the EMT of HepG2 hepatocarcinoma cells. The spectacular change in phenotype induced by TPA, leading to a pronounced spindle-shaped fibroblast-like cell morphology, required ERK1/2 activation. This ERK1/2-dependent EMT process was characterized by a loss of E-cadherin function, modification of the cytoskeleton, the acquisition of mesenchymal markers and profound changes to extracellular matrix composition and mobility. Snail was essential for E-cadherin repression, but was not sufficient for full commitment of the TPA-triggered EMT. We found that TPA triggered the formation of a complex between Snail and β-catenin that activated the Wnt pathway. This study thus provides the first evidence for the existence of a complex network governed by the ERK1/2 signaling pathway, converging on the coregulation of Snail and the Wnt/β-catenin pathway and responsible for the onset and the progression of EMT in hepatocellular carcinoma cells.

Resveratrol as a pan-HDAC inhibitor alters the acetylation status of histone [corrected] proteins in human-derived hepatoblastoma cells

The polyphenolic alcohol resveratrol has demonstrated promising activities for the prevention and treatment of cancer. Different modes of action have been described for resveratrol including the activation of sirtuins, which represent the class III histone deacetylases (HDACs). However, little is known about the activity of resveratrol on the classical HDACs of class I, II and IV, although these classes are involved in cancer development or progression and inhibitors of HDACs (HDACi) are currently under investigation as promising novel anticancer drugs. We could show by in silico docking studies that resveratrol has the chemical structure to inhibit the activity of different human HDAC enzymes. In vitro analyses of overall HDAC inhibition and a detailed HDAC profiling showed that resveratrol inhibited all eleven human HDACs of class I, II and IV in a dose-dependent manner. Transferring this molecular mechanism into cancer therapy strategies, resveratrol treatment was analyzed on solid tumor cell lines. Despite the fact that hepatocellular carcinoma (HCC) is known to be particularly resistant against conventional chemotherapeutics, treatment of HCC with established HDACi already has shown promising results. Testing of resveratrol on hepatoma cell lines HepG2, Hep3B and HuH7 revealed a dose-dependent antiproliferative effect on all cell lines. Interestingly, only for HepG2 cells a specific inhibition of HDACs and in turn a histone hyperacetylation caused by resveratrol was detected. Additional testing of human blood samples demonstrated a HDACi activity by resveratrol ex vivo. Concluding toxicity studies showed that primary human hepatocytes tolerated resveratrol, whereas in vivo chicken embryotoxicity assays demonstrated severe toxicity at high concentrations. Taken together, this novel pan-HDACi activity opens up a new perspective of resveratrol for cancer therapy alone or in combination with other chemotherapeutics. Moreover, resveratrol may serve as a lead structure for chemical optimization of bioavailability, pharmacology or HDAC inhibition.

Nrf2-induced antiapoptotic Bcl-xL protein enhances cell survival and drug resistance

Nuclear transcription factor Nrf2 binds with the antioxidant-response element (ARE) in the promoter regions of cytoprotective genes, leading to their increased expression and cellular protection. In this study, we investigated the role of Nrf2 in the regulation of antiapoptotic Bcl-xL protein and its effect on cellular apoptosis. Treatment of mouse Hepa-1 cells with the antioxidant tert-butylhydroquinone led to the induction of Bcl-xL gene expression. Promoter mutagenesis, transfection, and chromatin immunoprecipitation assays identified an ARE between nucleotides -608 and -600 in the forward strand of the proximal Bcl-xL promoter that bound to Nrf2 and led to increased Bcl-xL gene expression. In addition, short interfering RNA (siRNA) inhibition and overexpression of Nrf2 led to a respective decrease and increase in Bcl-xL gene expression. These results implicated Nrf2 in the regulation of expression and induction of Bcl-xL protein. Nrf2-mediated expression of Bcl-xL protein downregulated Bax and decreased caspase 3/7 activity. SiRNA inhibition of both Nrf2 and Bcl-xL increased the susceptibility of cancer cells to etoposide-mediated cell death and reduced cell survival. Moreover, dysfunctional/mutant INrf2 (inhibitor of Nrf2) in human lung cancer cells failed to degrade Nrf2, resulting in increased Bcl-xL levels and increased cell survival. These data provide the first evidence of Nrf2 in the control of Bcl-xL expression and apoptotic cell death with implications for antioxidant protection, survival of cancer cells, and drug resistance.

Antioxidative effects of Alisma orientale extract in palmitate-induced cellular injury

CONTEXT

Alisma orientale (Sam.) Juzepczuk (Alismataceae) is an indigenous medicinal herb that has been traditionally used for diuretic, hypolipidemic, anti-inflammatory, and antidiabetic proposes in northern and eastern Asia.

OBJECTIVE

This study examined the mechanisms underlying the cytoprotective effect of an aqueous extract of A. orientale (AEAO) against long-chain saturated fatty acid-induced cellular injury.

MATERIALS AND METHODS

HepG2 cells were treated with 0.5 mM palmitate to generate a cellular model of nonalcoholic fatty liver disease (NAFLD). Using this cellular model, the cytoprotective effect of AEAO (100 µg/mL) against long-chain saturated fatty acid-induced cellular injury was evaluated by measuring the steatosis, ROS accumulation, and apoptosis.

RESULTS

AEAO significantly attenuated palmitate-induced intracellular steatosis and cellular damage up to 54 and 33%, respectively. Palmitate-induced intracellular levels of reactive oxygen species (ROS) and reactive aldehydes were significantly reduced in the presence of AEAO to 40 and 75%, respectively, suggesting that oxidative stress plays a role in the palmitate-induced damage. AEAO inhibited the palmitate-mediated activation of c-Jun NH(2)-terminal kinase (JNK), a kinase that is correlated with NAFLD. Inhibition of JNK by SP600125 or addition of AEAO significantly reduced palmitate-induced steatosis, ROS accumulation, and apoptosis, indicating that the protective effects of AEAO against palmitate-induced cellular damage result from blocking ROS-activated JNK signaling.

DISCUSSION AND CONCLUSION

The combined properties of AEAO in cellular steatosis and ROS production are beneficial for treating NAFLD, which includes complex metabolic changes, such that modulation of a single target is often not sufficient to achieve the desired therapeutic effect.

Membranes for biohybrid liver support: the behaviour of C3A hepatoblastoma cells is dependent on the composition of acrylonitrile copolymers

Co-polymers based on acrylonitrile, N-vinylpyrrolidone, aminoethylmethacrylate and sodium methallylsulfonate were used to prepare flat membranes by phase inversion. The surface properties of membranes were characterised by water contact angle measurements, atomic force microscopy and X-ray photoelectron spectroscopy (XPS). Membrane permeability was estimated by porosity measurements with water as test liquid. Human C3A hepatoblastoma cells were plated on these materials. Cell-material interaction was characterised by overall cell morphology, formation of focal adhesion contacts and intercellular junctions. Furthermore, cell proliferation was measured and compared with the functional activity of cells as indicated by 7-ethoxycoumarin-O-deethylation. More hydrophilic materials reduced spreading of cells, formation of focal adhesion and subsequent proliferation while homotypic cell adhesion was facilitated in correlation with stronger expressions of intercellular junctions and improved functional activity. In contrast, membranes with stronger adhesivity enhanced cell proliferation but reduced the functional activity of cells. It was concluded that the co-polymerisation of acrylonitrile with hydrophilic co-monomers, such as N-vinylpyrrolidone, could be used to tailor membrane materials for the application in biohybrid liver support systems.

Proteasome inhibition overcomes TRAIL resistance in human hepatoblastoma cells

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is responsible for cell death in many cancer cells while being non-toxic for most normal cells. In this study, we investigated the role of TRAIL in human hepatoblastoma (HB) cells and analyzed different approaches to reverse TRAIL resistance in these tumors. Death receptors DR4 and DR5 expression was found on all analyzed primary HB samples and on the cell lines HuH6 and HepT1 by immunofluorescence staining. Recombinant TRAIL alone did not induce in vitro cytotoxicity. Decoy receptor blocking by antibodies led to moderate effects in HepT1 but not in HUH6 cells, whereas FLIP knock-down using siRNA rendered HUH6 cells but not HepT1 cells sensible to TRAIL. Bcl-2 inhibition with ABT-737 enhanced TRAIL-mediated apoptosis in all HB cells. Strongest cytotoxic TRAIL effects were seen in HB cell lines with synchronous proteasome inhibition using bortezomib. FLIP and Bcl-2 contributed to the TRAIL resistance in HB. Overcoming TRAIL resistance in HB by proteasome inhibitors has been identified a possible additive to improve treatment results in HB patients with drug resistant tumors.

Hepatitis C virus Core protein stimulates cell growth by down-regulating p16 expression via DNA methylation

Hepatitis C virus Core plays a vital role in the development of hepatocellular carcinoma; however, its action mechanism is still controversial. Here, we showed that Core down-regulated levels of p16, resulting in inactivation of Rb and subsequent activation of E2F1, which lead to growth stimulation of hepatocytes. For this effect, Core inhibited p16 expression by inducing promoter hypermethylation via up-regulation of DNA methyltransferase 1 (DNMT1) and DNMT3b. The growth stimulatory effect of Core was abolished when levels of p16 were restored by either exogenous complementation or treatment with 5-Aza-2'dC, indicating that the effect is critical for the stimulation of cell growth by Core.

The role of microRNAs in the biology of rare diseases

Rare diseases (RD) are characterized by low prevalence and affect not more than five individuals per 10,000 in the European population; they are a large and heterogeneous group of disorders including more than 7,000 conditions and often involve all organs and tissues, with several clinical subtypes within the same disease. Very often information concerning either diagnosis and/or prognosis on many RD is insufficient. microRNAs are a class of small non-coding RNAs that regulate gene expression at the posttranscriptional level by either degrading or blocking translation of messenger RNA targets. Recently, microRNA expression patterns of body fluids underscored their potential as noninvasive biomarkers for various diseases. The role of microRNAs as potential biomarkers has become particularly attractive. The identification of disease-related microRNAs is essential for understanding the pathogenesis of diseases at the molecular level, and is critical for designing specific molecular tools for diagnosis, treatment and prevention. Computational analysis of microRNA-disease associations is an important complementary means for prioritizing microRNAs for further experimental examination. In this article, we explored the added value of miRs as biomarkers in a selected panel of RD hitting different tissues/systems at different life stages, but sharing the need of better biomarkers for diagnostic and prognostic purposes.

Nuclear receptor mRNA expression by HBV in human hepatoblastoma cell lines

Recent studies have implicated nuclear receptors (NRs) in the development of hepatocarcinogenesis. We assumed that hepatitis B virus (HBV) alters the expression of NRs and coregulators, and compared the gene expression profiling for 84 NRs and related genes between HpeG2.2.15, which secretes complete HBV virion, and HepG2 by real-time RT-PCR with SyBr green. Forty (47.6%) genes were upregulated 2-fold or greater, and only 5 (5.9%) were downregulated 2-fold or more, in HepG2.2.15 compared to HepG2. These results suggest that HBV affects NRs and their related signal transduction, and that they play important roles in viral replication and HBV-related hepatocarcinogenesis.

Sodium valproate induces mitochondria-dependent apoptosis in human hepatoblastoma cells

BACKGROUND

Sodium valproate inhibits proliferation in neuroblastoma and glioma cells, and inhibits proliferation and induces apoptosis in hepatoblastoma cells. Information describing the molecular pathways of the antitumor effects of sodium valproate is limited; therefore, we explored the mechanisms of action of sodium valproate in the human hepatoblastoma cell line, HepG2.

METHODS

The effects of sodium valproate on the proliferation of HepG2 cells were evaluated by the Walsh-schema transform and colony formation assays. Sodium valproate-induced apoptosis in HepG2 cells was investigated with fluorescence microscopy to detect morphological changes; by flow cytometry to calculate DNA ploidy and apoptotic cell percentages; with Western blotting analyses to determine c-Jun N-terminal kinases (JNK), p-JNK, Bcl-2, Bax, and caspase-3 and -9 protein expression levels; and using JC-1 fluorescence microscopy to detect the membrane potential of mitochondria. Statistical analyses were performed using one-way analysis of variance by SPSS 13.0 software.

RESULTS

Our results indicated that sodium valproate treatment inhibited the proliferation of HepG2 cells in a dose-dependent manner. Sodium valproate induced apoptosis in HepG2 cells as it: caused morphologic changes associated with apoptosis, including condensed and fragmented chromatin; increased the percentage of hypodiploid cells in a dose-dependent manner; increased the percentage of annexin V-positive/propidium iodide-negative cells from 9.52% to 74.87%; decreased JNK and increased phosphate-JNK protein expression levels; reduced the membrane potential of mitochondria; decreased the ratio of Bcl-2/Bax; and activated caspases-3 and -9.

CONCLUSION

Sodium valproate inhibited the proliferation of HepG2 cells, triggered mitochondria-dependent HepG2 cell apoptosis and activated JNK.

Evaluation of hydro-alcoholic extract of Eclipta alba for its anticancer potential: an in vitro study

ETHNOPHARMACOLOGICAL RELEVANCE

Eclipta alba is traditionally used as hepatoprotective agent. The study was designed to explore its antiproliferative activity on liver and other related cancer.

AIM OF THE STUDY

The present study was designed to assess and establish the role of Eclipta alba as anti-cancer agent using HepG2, C6 glioma and A498 cell lines as model system.

MATERIALS AND METHODS

Antiproliferative and cytotoxic effects of the Eclipta alba hydroalcoholic extract (EAE) was determined using MTT assay. The expression level of NF-kB was analysed by western blotting and RT PCR. Gelatin zymography was done for gelatinase matrix metalloproteinases (MMP-2 and 9) analysis.

RESULTS

EAE inhibited the cell proliferation in dose dependent manner in HepG2, A498 and C6 glioma cell lines with an IC50 of 22±2.9, 25±3.6 and 50±8.7 μg/ml, respectively. The expression of MMP (2 and 9) was down-regulated with EAE treatment. DNA damage was observed following 72h of extract treatment, leading to apoptosis. Additionally, the expression level of NF-kB was evaluated with western blotting and RT-PCR and was found to be down-regulated/inactivated.

CONCLUSIONS

The data establish the existence of anti-proliferative, DNA damaging and anti-metastasis properties in EAE which is yet unexplored and hold high therapeutic impact.

Aqueous extract of Tribulus terrestris Linn induces cell growth arrest and apoptosis by down-regulating NF-κB signaling in liver cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

A medicinal herb Tribulus terrestris Linn has been used to treat various diseases including hepatocellular carcinoma. The aim of the present study was to investigate the anticancer activity of Tribulus terrestris Linn (TT) in liver cancer cells.

MATERIALS AND METHODS

The antitumor activity of aqueous TT extract was analyzed by testing the cytotoxicity and the effect on clonogenecity in HepG2 cells. Apoptosis and cell cycle arrest induced by TT were dissected by flow cytometry and its inhibitory effect on NF-κB activity was determined by analyzing the expression levels of NF-κB/IκB subunit proteins. The suppression of NF-κB-regulated gene expression by TT was assessed by RT-PCR.

RESULTS

TT extract repressed clonogenecity and proliferation, induced apoptosis, and enhanced accumulation in the G0/G1 phase of liver cancer cells. It also turned out that TT extract inhibited NF-κB-dependent reporter gene expression and NF-κB subunit p50 expression, while it enhanced the cellular level of IκBα by inhibiting the phosphorylation and degradation of IκBα. In addition, IKK activity was inhibited in a dose-dependent manner. Furthermore, TT extract suppressed the transcription of genes associated with cell cycle regulation, anti-apoptosis, and invasion.

CONCLUSION

These data showed that TT extract blocks proliferation and induces apoptosis in human liver cancer cells through the inhibition of NF-κB signaling. Aqueous TT extract can be used as an anticancer drug for hepatocellular carcinoma patients.

In vitro assessment of poly-iodinated triglyceride reconstituted low-density lipoprotein: initial steps toward CT molecular imaging

RATIONALE AND OBJECTIVES

Targeted molecular probes offer the potential for greater specificity in cancer imaging with contrast-enhanced computed tomography (CT). We investigate a low-density lipoprotein (LDL) nanoparticle loaded with poly-iodinated triglyceride (ITG) in a proof of concept study of targeted x-ray imaging. LDLs are targeted to the LDL cell surface receptor (LDLR), which is overexpressed in several tumor types. The LDL-LDLR pathway presents a high-capacity and self-renewing transport system for molecular imaging in CT.

MATERIALS AND METHODS

ITG was synthesized and loaded into the core of LDL particles to form a reconstituted nanoparticle, hereafter referred to as (rITG)LDL. Particle size was measured by dynamic light scattering. The x-ray attenuation of the (rITG)LDL solution was measured with CT imaging and signal enhancement was calibrated for equivalent iodine concentration. Cultured human hepatoblastoma G2 (HepG2) cells, which overexpress LDLR, were incubated with (rITG)LDL with or without native LDL. The cells were imaged with CT to characterize particle sequestration.

RESULTS

Reconstitution of LDL with ITG was successful and did not compromise the targeting function of the particle. Measurement of the x-ray attenuation properties of the (rITG)LDL solution revealed an effective iodine concentration of 0.78 mg/mL. In vitro studies of HepG2 cells demonstrated a significant increase in CT image intensity over control cells when incubated with (rITG)LDL.

CONCLUSION

The in vitro results of this study suggest that (rITG)LDL can provide adequate image enhancement for CT molecular imaging. Potential applications include breast imaging and small animal imaging at low x-ray energies. In vivo experiments will be required to verify that tumor uptake of (rITG)LDL is sufficient for enhanced detection. Use at higher x-ray energies, as used in conventional CT, will require a further increase in iodine loading.

The effect of differentiating and apoptotic agents on notch signalling pathway in hepatoblastoma

BACKGROUND/AIMS

Notch expression is not yet determined in hepatoblastoma. In this study the effect of chemotherapeutics (cisplatin, doxorubicin, cytosin arabinoside); differentiating agent (13 cis-retinoic acid) and apoptotic agents (5-aza-2'-deoxycytidine, arsenic trioxide) on notch expression in hepatoblastoma were evaluated.

METHODOLOGY

After HepG2 cell line was cultured and the agents and their combinations were applied for 24 hour in pre-optimized 50% lethal doses, RNA isolation and cDNA converting, expression of 84 custom array genes of notch signaling pathway (SABiosciences, PAT059F-24) was determined by Real Time PCR. The methylation status of 6 genes that showed more than 5 fold changes compared with control group were explored by Methylation qPCR Assay. High expressed genes are HDAC1, NFKB1, CHUK, CDKN1A, and CBL. Low expressed genes are DLL1, CD44, FZD2, GLI1, IL17B, LMO2, NOTCH1, LOR, PAX5, PT-CRA, SH2D1A, and WISP1. The genes searched for methylation (DLL1, HEY1, DTX1, HDAC1, NOTCH2 and JAG1) were not found to be related with methylation.

RESULTS

The high expressed genes are related with cell proliferation. The main signaling genes that are closed to notch in signaling pathway are low expressed in hepatoblastoma. The agents do not show prominent effect of gene expression in many genes and methylation is not the reason of expression changes. The use of retinoic acid in the control of minimal residual disease of hepatoblastoma should be discussed. 5 aza "cytidin" the demethylating agent is not advised in treatment according to our results.

CONCLUSION

Cisplatin as main chemotherapeutic agent treatment is shown to change gene expression levels in notch signalling pathway in hepatoblastoma.

6-dehydrogingerdione sensitizes human hepatoblastoma Hep G2 cells to TRAIL-induced apoptosis via reactive oxygen species-mediated increase of DR5

The anticancer effects of 6-dehydrogingerdione (6-DG), a compound isolated from the rhizomes of Zingiber officinale , and its mechanisms of sensitization to TRAIL-induced apoptosis were studied using human hepatoblastoma Hep G2 cells. This study demonstrates for the first time that 6-DG-induced apoptosis might be executed via mitochondrial- and Fas receptor-mediated pathways. Further studies also demonstrated that 6-DG could sensitize Hep G2 cells to TRAIL-induced apoptosis. 6-DG also up-regulated Ser-15 phosphorylation and evoked p53 nuclear translocation. Abrogation of p53 expression by p53 small interfering RNA significantly attenuated 6-DG-induced DR5 expression, thus rendering these cells resistant to TRAIL-induced apoptosis. DR5 expression after 6-DG treatment was accompanied by provoking intracellular reactive oxygen species (ROS) generation. Pretreatment with N-acetyl-l-cysteine (NAC) attenuated 6-DG-induced DR5 expression and inhibited TRAIL-induced apoptosis. In contrast to Hep G2 cells, DR5 up-regulation and sensitization to TRAIL-induced apoptosis instigated by 6-DG were not observed in normal MDCK cells. Taken together, these data suggested that in addition to the mitochondrial- and Fas receptor-mediated apoptotic pathways involved, ROS-dependent and p53-regulated DR5 expression was also demonstrated to play a pivotal role in the synergistic enhancement of TRAIL-induced apoptosis instigated by 6-DG in Hep G2 cells.

Selenium supplementation attenuates procollagen-1 and interleukin-8 production in fat-loaded human C3A hepatoblastoma cells treated with TGFbeta1

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is associated with obesity, insulin resistance and hepatic steatosis. Non-alcoholic steatohepatitis (NASH) is a serious consequence of NAFLD where chronic tissue damage and inflammation result in fibrosis which may progress to cirrhosis. Transforming growth factor beta1 (TGFbeta1), proinflammatory cytokines and oxidative stress are thought to play crucial roles in the pathogenesis of these conditions. The contributions of individual liver cell types to fibrogenesis remain controversial and the influence of selenium status has not been investigated.

METHODS

In this study we have used a cell culture model of fat-loading using oleate-treated human hepatoblastoma (C3A) cells to investigate how fat-loading and selenium status might influence the production of collagen in response to TGFbeta1. The secretion of inflammatory cytokines was also investigated, together with the epithelial character of the treated cells.

RESULTS

We found that in response to treatment with TGFbeta1, C3A cells produced mRNA encoding the pro-alphaI chain of procollagen I, secreted procollagen I peptide, up-regulated production of the proinflammatory cytokine interleukin-8 (IL-8) and the mesenchymal marker vimentin, and down-regulated albumin production. Most of these responses were considerably enhanced when cells were fat-loaded with oleate and were attenuated by selenium addition at a dose that optimised the expression of thioredoxin reductase and glutathione peroxidase.

CONCLUSIONS

Our data establish that both fat-loading and suboptimal selenium status enhance collagen and IL-8 production by C3A hepatocytes in response to TGFbeta1, possibly as part of an epithelial to mesenchymal transition.

GENERAL SIGNIFICANCE

These findings suggest that the hepatocyte may be an important contributor to the pathogenesis of fibrosis associated with NAFLD.

Molecular link(s) between hepatoblastoma pathogenesis and exposure to di-(2-ethylhexyl)phthalate: a hypothesis

Hepatoblastoma (HB) is the most important primary liver cancer in children, accounting for up to 1% of all paediatric malignancies. It affects mostly infants and young children between the age of 6 months and 3 years. Predisposing genetic factors for HB have been identified and scientific evidence clearly points out HB as a multi-factorial condition based on both genetic and environmental factors. Nevertheless, a clear understanding of the pathogenesis is yet lacking. The present review will focus on the impact of exposure to environmental chemicals, such as di-(2-ethylhexyl)phthalate (DEHP), and recognized risk factors, such as intrauterine growth retardation (IUGR), on HB establishment via altered signalling pathways (Wnt and IGF). The hypothesis linking the impairment of IGF2 foetal/adult switching and exposure to DEHP is discussed as a way forward to support HB prevention and early diagnosis.

[Inhibitory effects of Qushi Huayu Decoction on fatty deposition and tumor necrosis factor alpha secretion in HepG2 cells induced by free fatty acid]

OBJECTIVE

To study the effects of Qushi Huayu Decoction (QHD) contained serum on fatty deposition and tumor necrosis factor alpha (TNF-alpha) secretion of hepatic lipotoxicity model in vitro, for further investigating the mechanism of the decoction for preventing and treating fatty liver.

METHODS

The steatosis with TNF-alpha secretion lipotoxic model of HepG2 induced by long-chain free fatty acid (FFA) was duplicated. Groups of normal, model cells and model cells treated with different concentrations of QHD contained serum were set up to test the content of TNF-alpha in culture supernate and triglyceride (TG) in cells, as well as to observe the ultrastructural change of cells by oil-red staining and the protein expression and gene expression of cellular TNF-alpha.

RESULTS

After being stimulated with FFA for 24 h, marked deposition of lipid with high content of TG presented in the cells of model group. Compared with the normal group, not only TNF-alpha content of culture supernate but also the protein expression and mRNA expression of intracellular TNF-alpha increased significantly. Contrast to the model group, the contents of TG in cells and TNF-alpha in supernate as well as the protein and mRNA expression of TNF-alpha in the model cell group treated with 10% QHD were lower significantly (all P < 0.01).

CONCLUSION

QHD could significantly inhibit the fatty deposition and TNF-alpha secretion in HepG2 cells induced by free fatty acid.

Oxidative stress induces p53-dependent apoptosis in hepatoblastoma cell through its nuclear translocation

Hepatoblastoma (HBL) is the most common malignant liver tumor in children. Since tumor suppressor p53 is rarely mutated in HBL, it remains unknown whether p53 could contribute to the hepatocarcinogenesis. In the present study, we have found for the first time that, like neuroblastoma (NBL), wild-type p53 was abnormally accumulated in the cytoplasm of the human HBL-derived Huh6 cells. In accordance with this notion, immunohistochemical analysis demonstrated that p53 is largely expressed in cytoplasm of human primary HBLs. In response to the oxidative stress, Huh6 cells underwent apoptotic cell death in association with the nuclear translocation of p53 and the transactivation of its target gene implicated in apoptotic cell death. siRNA-mediated knockdown of the endogenous p53 conferred the resistance of Huh6 cells to oxidative stress. Intriguingly, histone deacetylase inhibitor (nicotinamide) treatment strongly inhibited the oxidative stress-induced nuclear translocation of p53 as well as the p53-dependent apoptosis in Huh6 cells. In contrast to the previous observations, the cytoplasmic anchor protein for p53 termed Parc had undetectable effect on the cytoplasmic retention of p53. Collectively, our present results suggest that the abnormal cytoplasmic localization of p53 might contribute at least in part to the development of HBL.

NS5A protein of HCV enhances HBV replication and resistance to interferon response

HCV and HBV are the major causes of chronic liver diseases worldwide. Patients with both viruse's co-infection tend to develop severer liver diseases and are at high risk of liver-related death. NS5A protein of HCV plays key roles in HCV replication and inhibition of host immune responses. In this study, we described the establishment of HepG2-derived cell line that stably expresses NS5A protein and the application of a cellular system for HBV replication based on a recombinant adenovirus carrying HBV genome. Our results demonstrated that NS5A enhances the expression of S and E proteins of HBV, as well as the synthesis of viral DNA. Moreover, we showed that NS5A assists HBV to escape interferon responses. These data suggested that NS5A of HCV may employ multiple strategies contributing to the enhancement of HBV replication and interferon resistance during the co-infection of HCV and HBV.

Zinc deficiency depresses p21 gene expression: inhibition of cell cycle progression is independent of the decrease in p21 protein level in HepG2 cells

The influence of zinc status on p21 gene expression was examined in human hepatoblastoma (HepG2) cells. Cells were cultured for one passage in a basal medium depleted of zinc to induce severely zinc-deficient (ZD) cells or in basal medium supplemented with 0.4, 4.0, 16, or 32 μM zinc to represent mild zinc deficiency (ZD0.4), the amount of zinc in most normal media (ZN), the normal human plasma zinc level (zinc-adequate; ZA), or the high end of plasma zinc attainable by oral supplementation (ZS), respectively. In ZD and ZD0.4 cells, the nuclear p21 protein level, mRNA abundance, and promoter activity were reduced to 40, 70, and 65%, respectively, of ZN cells. However, p21 protein and mRNA levels, as well as p21 promoter activity, were not altered in ZA and ZS cells compared with ZN cells. Moreover, the amounts of acetylated histone-4 associated with the proximal and distal p21 promoter regions, as a measure of p21 promoter accessibility, were decreased in ZD (73 and 64%, respectively) and ZD0.4 (82 and 77%, respectively) cells compared with ZN cells (100 and 100%, respectively). Thus multiple lines of evidence indicate that the transcriptional process of p21 is downregulated by depressed zinc status in HepG2 cells. Furthermore, the transfection of 5 μg of plasmid cytomegalovirus-p21 plasmid, which constitutively expressed p21, was able to normalize the reduction in p21 protein level and cyclin D1-cdk4 complex activity but not the inhibition of cell growth and G1/S cell cycle progression in ZD cells.

A hierarchical approach employing metabolic and gene expression profiles to identify the pathways that confer cytotoxicity in HepG2 cells

BACKGROUND

Free fatty acids (FFA) and tumor necrosis factor alpha (TNF-alpha) have been implicated in the pathogenesis of many obesity-related metabolic disorders. When human hepatoblastoma cells (HepG2) were exposed to different types of FFA and TNF-alpha, saturated fatty acid was found to be cytotoxic and its toxicity was exacerbated by TNF-alpha. In order to identify the processes associated with the toxicity of saturated FFA and TNF-alpha, the metabolic and gene expression profiles were measured to characterize the cellular states. A computational model was developed to integrate these disparate data to reveal the underlying pathways and mechanisms involved in saturated fatty acid toxicity.

RESULTS

A hierarchical framework consisting of three stages was developed to identify the processes and genes that regulate the toxicity. First, discriminant analysis identified that fatty acid oxidation and intracellular triglyceride accumulation were the most relevant in differentiating the cytotoxic phenotype. Second, gene set enrichment analysis (GSEA) was applied to the cDNA microarray data to identify the transcriptionally altered pathways and processes. Finally, the genes and gene sets that regulate the metabolic responses identified in step 1 were identified by integrating the expression of the enriched gene sets and the metabolic profiles with a multi-block partial least squares (MBPLS) regression model.

CONCLUSION

The hierarchical approach suggested potential mechanisms involved in mediating the cytotoxic and cytoprotective pathways, as well as identified novel targets, such as NADH dehydrogenases, aldehyde dehydrogenases 1A1 (ALDH1A1) and endothelial membrane protein 3 (EMP3) as modulator of the toxic phenotypes. These predictions, as well as, some specific targets that were suggested by the analysis were experimentally validated.

FOXG1 is overexpressed in hepatoblastoma

Bacterial artificial chromosome array comparative genomic hybridization analysis of hepatoblastomas reveals a deletion in the 14q12 locus in 12 of 16 cases. A high frequency of copy gain is seen on chromosomes 1q, 2, 5p, 8, and 20. Frequent deletions are also seen at 6q, 17q, and 1p with less frequent gains on 4p, 6p, and 19p. 14q12 deletion locus analyses using quantitative real-time polymerase chain reaction reveals copy number gain/amplification in the region immediately telomeric to the deleted locus, including copy number gain (2- to 4-fold) of FOXG1 in 13 out of 16 tumors. This is associated with up-regulation (approximately 87-fold) of FOXG1 gene transcripts and increased protein expression. Immunostaining reveals an inverse relationship between FOXG1 expression and p21cip1 expression in all histologic subtypes. However, FOXG1 transcript levels were significantly higher (approximately 75-fold) in tumors with embryonal and small cell components when compared with pure fetal hepatoblastomas. FOXG1 has been implicated in the repression of transforming growth factor beta-induced expression of p21cip1 and cytostasis. Our findings are consistent with such a role for FOXG1. We propose that FOXG1 overexpression may contribute to the maintenance of the undifferentiated state in hepatoblastomas and could be a potential target for molecular therapeutics. This is the first report of a possible role for FOXG1 in hepatoblastoma and pediatric neoplasia.

Reciprocal expression of CCAAT/enhancer binding proteins alpha and beta in hepatoblastomas and its prognostic significance

Hepatoblastoma is one of the common pediatric solid tumors with frequent mutation of the beta-catenin gene which might be an early event of its carcinogenesis. However, the detailed molecular mechanism is still unknown. We studied the expression levels of CCAAT/enhancer binding protein alpha (C/EBPalpha) and C/EBPbeta, which regulate differentiation and growth of embryonic hepatocytes, to establish whether or not they were involved in affecting the clinical behavior of hepatoblastoma. The quantitative real-time reverse transcriptase-PCR revealed that expression of C/EBPalpha mRNA was significantly up-regulated in tumors 223% (p=0.013) as compared with that in adjacent normal livers, while expression of C/EBPbeta was down-regulated to 27% (p=0.002). Of interest, the immunohistochemical analysis showed that expression of C/EBPalpha was higher and that of C/EBPbeta lower in the poorly differentiated tumor cells than in the well-differentiated cells within the same tumor. Furthermore, high expression of C/EBPalpha (p=0.047) as well as low expression of C/EBPbeta (p=0.025) was significantly associated with poor prognosis of the patients. Cox hazard model suggested that expression of C/EBPalpha and that of C/EBPbeta were independent indicators to predict the prognosis from age but not from histology. Thus, expression of C/EBP proteins may play an important role in the genesis and clinical behavior of hepatoblastoma probably by inducing different stages of arrest of differentiation.