Functional genomic studies: insights into the pathogenesis of liver cancer

ViroISDC: a method for calling integration sites of hepatitis B virus based on feature encoding

BACKGROUND

Hepatitis B virus (HBV) integrates into human chromosomes and can lead to genomic instability and hepatocarcinogenesis. Current tools for HBV integration site detection lack accuracy and stability.

RESULTS

This study proposes a deep learning-based method, named ViroISDC, for detecting integration sites. ViroISDC generates corresponding grammar rules and encodes the characteristics of the language data to predict integration sites accurately. Compared with Lumpy, Pindel, Seeksv, and SurVirus, ViroISDC exhibits better overall performance and is less sensitive to sequencing depth and integration sequence length, displaying good reliability, stability, and generality. Further downstream analysis of integrated sites detected by ViroISDC reveals the integration patterns and features of HBV. It is observed that HBV integration exhibits specific chromosomal preferences and tends to integrate into cancerous tissue. Moreover, HBV integration frequency was higher in males than females, and high-frequency integration sites were more likely to be present on hepatocarcinogenesis- and anti-cancer-related genes, validating the reliability of the ViroISDC.

CONCLUSIONS

ViroISDC pipeline exhibits superior precision, stability, and reliability across various datasets when compared to similar software. It is invaluable in exploring HBV infection in the human body, holding significant implications for the diagnosis, treatment, and prognosis assessment of HCC.

Genetic dominance of transforming growth factor-β1 polymorphisms in chronic liver disease

Chronic liver disease (CLD) is an extremely common clinical condition accompanied by sustained inflammatory response leading to tissue damage. Transforming growth factor-β1 (TGF-β1) is known as a master immune regulator in CLDs, but the association between TGF-β1 polymorphisms and CLD risk is controversial and inconclusive, and the genetic dominance of CLDs remains unknown. In this study, the relationship between TGF-β1 polymorphisms and CLD susceptibility is systematically analyzed based on 35 eligible studies. Individuals with the TGF-β1-509 allele (TT or CT) or codon 10 allele (Pro/Pro) show an increased risk of CLDs. Subgroup analyses indicate TGF-β1-509C/T has a significant correlation with cirrhosis and chronic hepatitis C, codon 10 is associated with chronic hepatitis B occurrence, and codon 25 exhibits a relationship with autoimmune hepatitis risk. Missense mutations in G29E, A105S, D191N, and F321L of TGF-β1 are the genetic factors of HCC susceptibility. Furthermore, the TGF-β1 gene expression is significantly elevated in CLD patients, and the TGF-β1 codon 263 is located close to the region where the TGF-β1 dimerization interacts, indicating the TGF-β1 codon 263 variant may affect the secretion of TGF-β1 by altering its dimerization. Together, our findings provide new insights into the immune regulator gene TGF-β1 polymorphisms as susceptibility factors for CLD occurrence and regulators for TGF-β1 expression, which have implications for the regulation of immune factors during CLD development.

Long Noncoding RNA XIST Promotes Resistance to Lenvatinib in Hepatocellular Carcinoma Cells via Epigenetic Inhibition of NOD2

Background. Hepatocellular carcinoma (HCC) is a severe global health issue that still lacks of effective treatments. Lenvatinib is a novel tyrosine kinase inhibitor (TKI) that has been approved for the treatment of HCC. However, drug resistance is inevitable and limits the clinical application of lenvatinib. Till now, there is still little knowledge about the mechanisms under the resistance to lenvatinib in HCC. Long noncoding RNA (lncRNA) is a group of noncoding RNAs that play essential roles in various physiological activities including the chemoresistance. In the present study, through RNA sequencing, we discovered that lncRNA XIST was upregulated in HCC cells that was insensitive to lenvatinib. Mechanically, we found that lncXIST promotes lenvatinib resistance via activation of EZH2-NOD2-ERK axis in HCC cells. Our data suggest that targeting lncXIST/EZH2/NOD2/ERK axis might be a promising strategy to enhance the efficacy of lenvatinib against HCC cells.

Long noncoding RNA matrilineal expression gene 3 inhibits hepatocellular carcinoma progression by targeting microRNA-5195-3p and regulating the expression of forkhead box O1

We investigated the effect of the long noncoding RNA (lncRNA) maternally expressed gene 3 (MEG3) on hepatocellular carcinoma (HCC) tumorigenesis and progression by targeting miR-5195-3p and transcription factor forkhead box O1 (FOXO1) to identify a novel target for HCC treatment. HCC clinical samples were collected, and cell counting kit-8 (CCK-8), and transwell migration and invasion assays were performed. Furthermore, interaction was detected via double luciferase reporter and RNA pull-down assays. MEG3, miR-5195-3p, and FOXO1 expression was determined by quantitative real-time polymerase chain reaction (RT-qPCR) and Western blotting. Xenograft tumor models were established to investigate the effect of MEG3 in vivo. Compared with normal tissues, MEG3 expression was significantly downregulated in HCC tissues. MEG3 overexpression inhibited the viability and migration of HCC cells. Double luciferase reporter and RNA pull-down assays confirmed the binding between MEG3 and miR-5195-3p as well as between miR-5195-3p and FOXO1. RT-qPCR and Western blotting results showed that MEG3 inhibited the expression of miR-5195-3p and promoted that of FOXO1. Additionally, MEG3 overexpression inhibited HCC tumorigenesis and progression in xenograft tumor models while depletion of MEG3 exerted the opposite way. Therefore, the lncRNA MEG3 inhibits HCC tumorigenesis and progression through the miR-5195-3p/FOXO1 signaling axis.

Androgen Receptors Act as a Tumor Suppressor Gene to Suppress Hepatocellular Carcinoma Cells Progression via miR-122-5p/RABL6 Signaling

Hepatocellular carcinoma (HCC) is a malignant tumor with a high degree of malignancy and a poor prognosis. Androgen receptor (AR) has been reported to play important roles in the regulation of the progression of HCC, but the underlying mechanisms of how AR regulates HCC initiation, progression, metastasis, and chemotherapy resistance still need further study. Our study found that AR could act as a tumor suppression gene to suppress HCC cells invasion and migration capacities via miR-122-5p/RABL6 signaling, and the mechanism study further confirmed that miR-122-5p could suppress the expression of RABL6 to influence HCC cells progression by directly targeting the 3'UTR of the mRNA of RABL6. The preclinical study using an in vivo mouse model with orthotopic xenografts of HCC cells confirmed the in vitro data, and the clinical data gotten from online databases based on TCGA samples also confirmed the linkage of AR/miR-122-5p/RABL6 signaling to the HCC progression. Together, these findings suggest that AR could suppress HCC invasion and migration capacities via miR-122-5p/RABL6 signaling, and targeting this newly explored signaling may help us find new therapeutic targets for better treatment of HCC.

MT1JP-mediated miR-24-3p/BCL2L2 axis promotes Lenvatinib resistance in hepatocellular carcinoma cells by inhibiting apoptosis

PURPOSE

Lenvatinib is a long-awaited alternative to Sorafenib for first-line targeted therapy of patients with advanced hepatocellular carcinoma (HCC). However, resistance to Lenvatinib results in tumor progression and has become a major obstacle to improving the prognosis of HCC patients. Exploring the mechanisms underlying Lenvatinib resistance is considered essential for the treatment of advanced HCC.

METHODS

Lenvatinib resistant HCC (LR-HCC) cells were generated and potential long non-coding RNAs (Lnc-RNAs) upregulated in LR-HCC cells were identified by RNA sequencing. The effects of upregulated Lnc-RNAs were evaluated in vitro in cell models and in vivo in experimental animals using quantitative cell viability and apoptosis assays.

RESULTS

We found that Lnc-RNA MT1JP (MT1JP) was upregulated in LR-HCC cells and inhibited the apoptosis signaling pathway. In addition, we found that sponging of microRNA-24-3p by MT1JP released Bcl-2 like 2 (BCL2L2), an anti-apoptotic protein, thereby forming a positive-feedback loop. The role of this feedback loop was validated using rescue assays. Additionally, we found that upregulation of MT1JP and BCL2L2 impaired the sensitivity of HCC cells to Lenvatinib both vitro and vivo.

CONCLUSIONS

Our results suggest a novel molecular feedback loop between MT1JP and apoptosis signaling in Lenvatinib sensitive HCC cells.

M2 macrophage-derived extracellular vesicles facilitate CD8+T cell exhaustion in hepatocellular carcinoma via the miR-21-5p/YOD1/YAP/β-catenin pathway

Hepatocellular carcinoma (HCC) is a common malignancy. CD8⁺ T cell-mediated immune response is critical for the inhibition of HCC progression. M2 macrophages participate in HCC progression. This study set out to investigate the effect of M2 macrophage-derived extracellular vesicles (EVs) on CD8⁺ T cell exhaustion in HCC. M2 macrophage-derived EVs were isolated and identified. The murine model of primary HCC was established through DEN/CCl₄ induction, and model mice were injected with EVs. Peripheral blood mononuclear cells (PBMCs) were isolated from the mouse liver and CD8⁺ T cells were sorted. The expressions of immune checkpoint inhibitory receptors and effector cytokines on CD8⁺ T cells were detected, followed by the evaluation of CD8⁺ T cell proliferation and killing function. miR-21-5p expression in M2 macrophage-derived EVs was detected. The binding relationship between miR-21-5p and YOD1 was verified. The activation of the YAP/β-catenin pathway was detected. Consequently, M2 macrophage-derived EVs promoted CD8⁺ T cell exhaustion in HCC mice. miR-21-5p expression was upregulated in M2 macrophage-derived EVs, and EVs carried miR-21-5p into HCC tissues. miR-21-5p targeted YOD1. Inhibition of miR-21-5p or overexpression of YOD1 annulled the promoting effect of EVs on CD8⁺ T cell exhaustion. YOD1 inactivated the YAP/β-catenin pathway. In conclusion, M2 macrophage-derived EVs facilitated CD8⁺ T cell exhaustion via the miR-21-5p/YOD1/YAP/β-catenin axis. This study may confer novel insights into the immunotherapy of HCC.

BZW2/5MP1 acts as a promising target in hepatocellular carcinoma

Basic leucine zipper and W2 domain 2 (BZW2), also known as 5MP1, is a protein related to translation regulation. Evidence from previous studies indicates that BZW2 is involved in tumorigenesis in several cancers. However, little is known about the role of BZW2 in hepatocellular carcinoma (HCC). In this study, we first analyzed the gene expression profile of BZW2 in multiple HCC datasets. Next, we explored the biological effects of BZW2 in HCC cell lines. BZW2 was overexpressed in different HCC cohorts. Multivariate analysis confirmed that increased BZW2 expression is an independent prognostic indicator of shorter overall survival. BZW2 coexpressed genes were mainly enriched in the biological processes of ribonucleoprotein complex biogenesis, rRNA metabolism, translational initiation, and negative regulation of metabolic processes. BZW2 depletion reduced proliferation, clonality, and invasion and increased apoptosis in MHCC97-H cells. Furthermore, BZW2 overexpression or knockdown enhanced or impaired c-Myc expression, respectively. Overall, these findings identified BZW2 as a biomarker of HCC and provided novel insight that the effect of BZW2 on the translatome is a potential mechanism that promotes HCC progression via the c-Myc pathway.

Differential Mutation Detection Capability Through Capture-Based Targeted Sequencing in Plasma Samples in Hepatocellular Carcinoma

Circulating tumor DNA (ctDNA) is a promising biomarker for accurate monitoring and less invasive assessment of tumor burden and treatment response. Here, targeted next-generation sequencing (NGS) with a designed gene panel of 176 cancer-relevant genes was used to assess mutations in 90 ctDNA samples from 90 patients with multiple types of liver disease and 10 healthy donor samples for control. Using our ctDNA detection panel, we identified mutations in 98.89% (89/90) of patient plasma biopsy samples, and 19 coding variants located in 10 cancer-related genes [ACVR2A, PCLO, TBCK, adhesion G protein-coupled receptor (ADGRV1), COL1A1, GABBR1, MUC16, MAGEC1, FASLG, and JAK1] were identified in 96.7% of patients (87/90). The 10 top mutated genes were tumor protein p53 (TP53), ACVR2A, ADGRV1, MUC16, TBCK, PCLO, COL11A1, titin (TTN), DNAH9, and GABBR1. TTN and TP53 and TTN and DNAH9 mutations tended to occur together in hepatocellular carcinoma samples. Most importantly, we found that most of those variants were insertions (frameshift insertions) and deletions (frameshift deletions and in-frame deletions), such as insertion variants in ACVR2A, PCLO, and TBCK; such mutations were detected in almost 95% of patients. Our study demonstrated that the targeted NGS-based ctDNA mutation profiling was a useful tool for hepatocellular carcinoma (HCC) monitoring and could potentially be used to guide treatment decisions in HCC.

Farnesoid X receptor via Notch1 directs asymmetric cell division of Sox9+ cells to prevent the development of liver cancer in a mouse model

Background

Asymmetrical cell division (ACD) maintains the proper number of stem cells to ensure self-renewal. The rate of symmetric division increases as more cancer stem cells (CSCs) become malignant; however, the signaling pathway network involved in CSC division remains elusive. FXR (Farnesoid X receptor), a ligand-activated transcription factor, has several anti-tumor effects and has been shown to target CSCs. Here, we aimed at evaluating the role of FXR in the regulation of the cell division of CSCs.

Methods

The FXR target gene and downstream molecular mechanisms were confirmed by qRT-PCR, Western blot, luciferase reporter assay, EMAS, Chip, and IF analyses. Pulse-chase BrdU labeling and paired-cell experiments were used to detect the cell division of liver CSCs. Gain- and loss-of-function experiments in Huh7 cells and mouse models were performed to support findings and elucidate the function and underlying mechanisms of FXR-Notch1 in liver CSC division.

Results

We demonstrated that activation of Notch1 was significantly elevated in the livers of hepatocellular carcinoma (HCC) in Farnesoid X receptor-knockout (FXR-KO) mice and that FXR expression negatively correlated with Notch1 level during chronic liver injury. Activation of FXR induced the asymmetric divisions of Sox9⁺ liver CSCs and ameliorated liver injury. Mechanistically, FXR directs Sox9⁺ liver CSCs from symmetry to asymmetry via inhibition of Notch1 expression and activity. Deletion of FXR signaling or over-expression of Notch1 greatly increased Notch1 expression and activity along with ACD reduction. FXR inhibited Notch1 expression by directly binding to its promoter FXRE. FXR also positively regulated Numb expression, contributing to a feedback circuit, which decreased Notch1 activity and directed ACD.

Conclusion

Our findings suggest that FXR represses Notch1 expression and directs ACD of Sox9⁺ cells to prevent the development of liver cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02298-6.

Inhibition of HMGB1 Suppresses Hepatocellular Carcinoma Progression via HIPK2-Mediated Autophagic Degradation of ZEB1

Autophagy is a conserved catabolic process maintaining cellular homeostasis and reportedly plays a critical role in tumor progression. Accumulating data show that autophagic activity is inhibited in hepatocellular carcinoma. However, the underlying molecular basis of impaired autophagy in HCC remains unclear. In this study, we revealed that autophagic activity was suppressed by HMGB1 in a HIPK2-dependent way. Targeting HMGB1 could inhibit the degradation of HIPK2, as a result of which, autophagic degradation of ZEB1 was enhanced by reprogramming glucose metabolism/AMPK/mTOR axis. Moreover, we demonstrated that selectively degradation of ZEB1 was responsible for HCC growth inhibition in HMGB1 deficient cells. Lastly, we found the combination therapy of HMGB1 inhibitor and rapamycin achieved a better anti-HCC effect. These results demonstrate that impaired autophagy is controlled by HMGB1 and targeting HMGB1 could suppress HCC progression via HIPK2-mediated autophagic degradation of ZEB1.

Direct targeting of β-catenin in the Wnt signaling pathway: Current progress and perspectives

Aberrant activation of the Wnt/β-catenin signaling circuit is associated with cancer recurrence and relapse, cancer invasion and metastasis, and cancer immune evasion. Direct targeting of β-catenin, the central hub in this signaling pathway, is a promising strategy to suppress the hyperactive β-catenin signaling but has proven to be highly challenging. Substantial efforts have been made to discover compounds that bind with β-catenin, block β-catenin-mediated protein-protein interactions, and suppress β-catenin signaling. Herein, we characterize potential small-molecule binding sites in β-catenin, summarize bioactive small molecules that directly target β-catenin, and review structure-based inhibitor optimization, structure-activity relationship, and biological activities of reported inhibitors. This knowledge will benefit future inhibitor development and β-catenin-related drug discovery.

Nod2 protects mice from inflammation and obesity-dependent liver cancer

Nod2 is a pattern recognition receptor that modulates host innate immune responses and protects from inflammation, steatosis, and obesity. Obesity and inflammation are risk factors for hepatocellular carcinoma, however, the role of Nod2 in obesity-dependent hepatic tumorigenesis is not known. Here we tested the hypothesis that Nod2 protects from high fat diet (HFD)-dependent hepatic cancer. We used an obesity-dependent hepatic tumor model. WT and Nod2^−/− mice were treated with the carcinogen dimethylbenz[a]anthracene (DMBA) and maintained on HFD. Nod2^−/− mice treated with DMBA and maintained on HFD gain significantly more weight and develop more liver tumors than similarly treated WT mice. Livers of Nod2^−/− tumorigenic mice had increased expression of genes involved in cell proliferation, immune responses, and cholesterol biosynthesis, increased infiltration of neutrophils, inflammatory monocytes, and T cells, and increased activation of STAT3 and ERK during the later stages of tumorigenesis. Bioinformatic analyses of genes with differential expression predicted an increase in cancer, immune, and cholesterol biosynthesis pathways. In summary, we have identified a novel role for Nod2 and demonstrate that Nod2 protects from HFD-dependent liver malignancy and this protection is accompanied by decreased cell proliferation, inflammation, steroid biosynthesis, neutrophils and macrophages infiltration, and STAT3 and MAPK signaling in the liver.

Low HOXC10 expression in liver cancer regulates proliferation via a mechanism involving miR-221 and the MAPK signaling pathway

Homeodomain-containing gene 10 (HOXC10) is associated with the progression of a variety of different types of human cancer; however, the role of HOXC10 in liver cancer is not completely understood. The present study aimed to investigate the mechanisms underlying the effects of HOXC10 on liver cancer tumorigenesis. Quantitative PCR and western blotting were used to detect the expression patterns of HOXC10 in cancer and adjacent healthy tissues. EdU, Cell Counting Kit-8 and colony formation assays were used to determine the functions of HOXC10 in liver cancer cell lines. ENCORI, TargetScan and miRTarBase were used to identify microRNAs that target HOXC10. The verification of the interaction between HOXC10 and microRNA-221 was determined by a luciferase assay. Compared with adjacent non-cancerous tissues, the expression of HOXC10 was markedly decreased in liver cancer tissues. A HOXC10 small interfering (si)RNA significantly attenuated HOXC10 expression at the mRNA and protein levels, and enhanced cell proliferation compared with the siRNA-negative control group. In addition, the luciferase reporter assay indicated that microRNA-221 directly bound to the 3'-untranslated region of HOXC10, and interfered with the inhibitory effect of HOXC10 on proliferation. In addition, HOXC10 knockdown elevated the expression levels of mitogen-activated protein kinase signaling pathway markers compared with the siRNA-negative control group. Therefore, the results of the present study may aid with the development of novel therapeutic regimens and diagnostic markers of liver cancer.

LncRNA SNAI3-AS1 promotes PEG10-mediated proliferation and metastasis via decoying of miR-27a-3p and miR-34a-5p in hepatocellular carcinoma

During recent years, long noncoding RNAs (lncRNAs) have received focal attention due to their important function in cancer regulation. Though the relation between lncRNA SNAI3-AS1 and the development of hepatocellular carcinoma (HCC) has been described in our previous study, the role and the exact mechanism of SNAI3-AS1 are still unclear. In this study, qRT-PCR analysis revealed that the expression of SNAI3-AS1 was elevated and was correlated with the levels of PEG10 in HCC tissues. Through functional experiments, we determined that knockdown of SNAI3-AS1 and PEG10 inhibited the proliferation and metastasis, whereas overexpression of SNAI3-AS1 and PEG10 promoted the proliferation and metastasis of HCC cells. In addition, rescue experiments confirmed that upregulation of PEG10 partially restored cell function inhibition induced by SNAI3-AS1 knockdown. Therefore, we hypothesized that PEG10 may be regulated by SNAI3-AS1, which in turn mediates the malignant biological processes of HCC cells regulated by PEG10. Further bioinformatics analysis and mechanistic experiments showed that SNAI3-AS1 functions as a competing endogenous RNA (ceRNA) to activate PEG10 by acting as a sponge for miR-27-3p and miR-34a-5p. In summary, our study revealed that SNAI3-AS1 is a tumor regulator of PEG10 in the progression of HCC, and may contribute to the improvement of HCC diagnosis and therapy.

Emodin succinyl ester inhibits malignant proliferation and migration of hepatocellular carcinoma by suppressing the interaction of AR and EZH2

Emodin is a promising anti-cancer reagent. To improve the physicochemical and anti-cancer property, we modified its structure and get a derivative called emodin succinyl ester (ESE). Here, we investigated the effect of ESE on the suppression of hepatocellular carcinoma (HCC) and the underlying mechanism. Our results showed that ESE strongly inhibited HCC cell proliferation and migration in vitro. Further study revealed that ESE treatment decreased transcription level and protein expression of androgen receptor (AR) and enhancer of zeste homolog 2 (EZH2), two key factors interacting to promote aggressive HCC development. Conversely, overexpression of AR attenuated the inhibitory effect of ESE on EZH2 expression, and vice versa. Importantly, overexpression of AR or EZH2 could counteract ESE-suppressed cell proliferation and migration. The association of ESE-targeted AR and EZH2 with the suppression of tumorigenicity was further confirmed in xenograft and diethylnitrosamine (DEN)-induced HCC mouse models. These findings validate the therapeutic effect of ESE on HCC aggression by targeting the interaction of AR and EZH2, suggesting ESE may be a potent drug in the clinical treatment of HCC.

Vital and Distinct Roles of H2A.Z Isoforms in Hepatocellular Carcinoma

Purpose

H2A.Z is an oncogenic histone variant that is overexpressed in cancers. Two isoforms of H2A.Z, H2AFZ and H2AFV, are identical except for a three-amino acid difference. However, their isoform-specific functions remain unclear in cancer development. Thereby, this study aimed to investigate whether the two isoforms play distinct functions in hepatocarcinogenesis.

Materials and Methods

Expressions of H2A.Z isoforms in 116 paired hepatocellular cancerous and para-cancerous tissues were detected by employing qPCR. GEO and TCGA databases were used to probe expressions and prognostic value of the two H2A.Z isoforms. A comprehensive meta-analysis was conducted. Furthermore, co-expressed analysis of H2AFZ and H2AFV was performed by using cBioPortal database. H2A.Z binding genes from Chip-seq were intersected with H2A.Z isoforms co-expressed genes to perform functional annotations. Cell proliferation experiments from H2AFZ knockout HepG2 and BEL-7402 cells were implemented. Finally, RNA-seq was applied to analyse alternative splicing in H2AFZ knockout and wild-type cells.

Results

H2AFZ and H2AFV were both significantly upregulated (P < 0.01) in hepatocellular carcinoma and related to poor prognosis (P < 0.01). The two H2A.Z isoforms played vital roles in cell proliferation. It is also predicted that unique functions of H2AFV contain spindle midzone and microtubule, while H2AFZ is especially associated with RNA export and spliceosome. Further, devoid H2AFZ may restrain liver cancer cell proliferation and cause many alternative splicing events.

Conclusion

Both H2A.Z isoforms play vital and distinct roles in the occurrence and progression of liver cancer, which may pave a way for novel therapeutic applications for cancers in the future.

Health risk from aflatoxins in processed meat products in Riyadh, KSA

This study investigated the health risks associated with aflatoxins (AFs) in processed meat products (PMP) sold in Riyadh, Kingdom of Saudi Arabia. The occurrence and levels of AFs were assessed using high-performance liquid chromatography with fluorescence detection (HPLC-FD), whereas the cancer risk attributed to the consumption of meat products containing AFs was estimated by means of margin of exposure (MOE) on a scale of 100-600, representing high and low exposure, respectively. The results indicated that 37.5% of the samples were contaminated, with concentrations ranging from 0.30 to 52.93 μg/kg, at an average of 6.4 ± 12.58 μg/kg. The percentage contamination levels with total AFs higher than the permissible Saudi limit of 20 μg/kg were 4% of samples analysed and 10% of contaminated samples. AFB1 and AFG1 were the most prevalent toxins, followed by AFB2; AFG2 was not detected in any sample. The MOE was found to be 175 and 311 for total AFs in processed beef meat and poultry meat products, respectively. These results showed that the daily intake of AF-contaminated PMP may constitute a public health concern. To our knowledge, this is the first study to report the health risk associated with PMP contaminated with AFs.

Leucine-rich repeat and sterile alpha motif containing 1 promotes the oncogenic growth of human hepatocellular carcinoma cells

Background

Hepatocellular carcinoma (HCC), the most common primary cancer of the liver, is one of the most common malignancies and the leading cause of cancer-related death worldwide. Leucine-rich repeat and sterile alpha motif containing 1 (LRSAM1) is an E3 ubiquitin ligase involved in diverse cellular activities, including the regulation of cargo sorting, cell adhesion and antibacterial autophagy. The role of LRSAM1 in HCC remains unknown.

Methods

In this study, we reviewed the TCGA database and then performed gain-of-function and loss-of-function analyses of LRSAM1 in HCC cell lines.

Results

We found that the mRNA expression level of LRSAM1 was significantly increased in clinical HCC tissues in the TCGA database. Transient LRSAM1 knockdown in several human HCC cell lines led to reduced growth in conventional culture conditions. Stable LRSAM1 knockdown in HepG2 cells led to impaired anchorage-independent growth whereas its stable ectopic overexpression yielded the opposite effects. LRSAM1 overexpression in HepG2 cells enhanced in vivo tumorigenicity, whereas LRSAM1 knockdown in this cell line significantly impaired tumor growth.

Conclusions

Our data suggest that LRSAM1 promotes the oncogenic growth of human HCC cells, although the underlying mechanisms remain to be explored.

Dissecting the expression landscape of cytochromes P450 in hepatocellular carcinoma: towards novel molecular biomarkers

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related deaths around the world. Recent advances in genomic technologies have allowed the identification of various molecular signatures in HCC tissues. For instance, differential gene expression levels of various cytochrome P450 genes (CYP450) have been reported in studies performed on limited numbers of HCC tissue samples, or focused on a small subset on CYP450s. In the present study, we monitored the expression landscape of all the members of the CYP450 family (57 genes) in more than 200 HCC tissues using RNA-Seq data from The Cancer Genome Atlas. Using stringent statistical filters and data from paired tissues, we identified significantly dysregulated CYP450 genes in HCC. Moreover, the expression level of selected CYP450s was validated by qPCR on cDNA samples from an independent cohort. Threshold values (sensitivity and specificity) based on dysregulated gene expression were also determined to allow for confident identification of HCC tissues. Finally, a global look at expression levels of the 57 members of the CYP450 family across ten different cancer types revealed specific expression signatures. Overall, this study provides useful information on the transcriptomic landscape of CYP450 genes in HCC and on new potential HCC biomarkers.

Gene amplification derived a cancer-testis long noncoding RNA PCAT6 regulates cell proliferation and migration in hepatocellular carcinoma

Our previous work demonstrated cancer-testis (CT) genes as a new source of candidate driver of cancer. Recently, mounting evidence indicates that long noncoding RNAs (lncRNAs) with CT expression pattern could play a pivotal role in cancer biology. Here, we characterized a conserved CT long noncoding RNA (CT-lncRNA), PCAT6, which is expressed exclusively in the testis and is reactivated in liver hepatocellular carcinoma (LIHC) tissues due to the highly frequent amplification. The expression in LIHC was correlated with clinical prognosis in TCGA data. Knockdown of PCAT6 could inhibit cell proliferation and migration in hepatocellular carcinoma (LIHC) cells. Gene set enrichment analysis (GSEA) based on coexpression network revealed that PCAT6 was involved in similar cilium-related pathways in the testis and LIHC tissues. However, PCAT6 was mainly positively correlated with gametogenesis-related pathways in the testis but was coexpressed with mitotic cell cycle genes in LIHC. Together, our data demonstrated that CT-lncRNA PCAT6 represents the similarity and difference between tumorigenesis and gametogenesis. The CT expression pattern and important role in LIHC oncogenesis make PCAT6 an ideal target for LIHC diagnosis and therapy.

Identification and Therapeutic Intervention of Coactivated Anaplastic Lymphoma Kinase, Fibroblast Growth Factor Receptor 2, and Ephrin Type-A Receptor 5 Kinases in Hepatocellular Carcinoma

Though kinase inhibitors have been heavily investigated in the clinic to combat advanced hepatocellular carcinoma (HCC), clinical outcomes have been disappointing overall, which may be due to the absence of kinase-addicted subsets in HCC patients. Recently, strategies that simultaneously inhibit multiple kinases are increasingly appreciated in HCC treatment, yet they are challenged by the dynamic nature of the kinase networks. This study aims to identify clustered kinases that may cooperate to drive the malignant growth of HCC. We show that anaplastic lymphoma kinase, fibroblast growth factor receptor 2, and ephrin type-A receptor 5 are the essential kinases that assemble into a functional cluster to sustain the viability of HCC cells through downstream protein kinase B-dependent, extracellular signal-regulated kinase-dependent, and p38-dependent signaling pathways. Their coactivation is associated with poor prognosis for overall survival in about 13% of HCC patients. Moreover, their activities are tightly regulated by heat shock protein 90 (Hsp90). Thereby Combined kinase inhibition or targeting of heat shock protein 90 led to significant therapeutic responses both in vitro and in vivo. Conclusion: Our findings established a paradigm that highlights the cooperation of anaplastic lymphoma kinase, fibroblast growth factor receptor 2, and ephrin type-A receptor 5 kinases in governing the growth advantage of HCC cells, which might offer a conceptual "combined therapeutic target" for diagnosis and subsequent intervention in a subgroup of HCC patients.

Sorafenib inhibits caspase-1 expression through suppressing TLR4/stat3/SUMO1 pathway in hepatocellular carcinoma

Sorafenib has been demonstrated to be a beneficial treatment for advanced hepatocellular carcinoma (HCC). Emerging evidence indicates that caspase-1 activation plays a crucial role in HCC progression. However, the relationship between caspase-1 and sorafenib has rarely been reported. In this study, we showed that caspase-1 was essential for lipopolysaccharide (LPS)-induced epithelial-mesenchymal transition (EMT). Moreover, sorafenib treatment could inhibit LPS-stimulated caspase-1 overexpression through restricting the nuclear transport of p65, which contributed to inactivation of NF-κB. Co-immunoprecipitation (Co-IP) experiments and immunoblot analysis indicated that sorafenib treatment decreased the SUMOylation of p65 via inhibiting TLR4/stat3/SUMO1 signaling cascades. In conclusion, the results of this study suggest that sorafenib inhibits caspase-1 expression through suppressing the nuclear translocation of p65 and provide new insights into the mechanisms of sorafenib treatment in HCC.

Amplification of Glyceronephosphate O-Acyltransferase and Recruitment of USP30 Stabilize DRP1 to Promote Hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death worldwide, and the underlying pathophysiology of HCC is highly complex. In this study, we report that, in a bioinformatic screen of 2,783 genes encoding metabolic enzymes, GNPAT, which encodes the enzyme glyceronephosphate O-acyltransferase, is amplified, upregulated, and highly correlated with poor clinical outcome in human patients with HCC. High GNPAT expression in HCC was due to its amplification and transcriptional activation by the c-Myc/KDM1A complex. GNPAT compensated the oncogenic phenotypes in c-Myc-depleted HCC cells. Mechanistically, GNPAT recruited the enzyme USP30, which deubiquitylated and stabilized dynamin-related protein 1 (DRP1), thereby facilitating regulation of mitochondrial morphology, lipid metabolism, and hepatocarcinogenesis. Inhibition of GNPAT and DRP1 dramatically attenuated lipid metabolism and hepatocarcinogenesis. Furthermore, DRP1 mediated the oncogenic phenotypes driven by GNPAT. Taken together, these results indicate that GNPAT and USP30-mediated stabilization of DRP1 play a critical role in the development of HCC.Significance: This study identifies and establishes the role of the enzyme GNPAT in liver cancer progression, which may serve as a potential therapeutic target for liver cancer. Cancer Res; 78(20); 5808-19. ©2018 AACR.

Androgen receptor drives hepatocellular carcinogenesis by activating enhancer of zeste homolog 2-mediated Wnt/β-catenin signaling

Background

Androgen receptor (AR) plays a crucial role as a transcription factor in promoting the development of hepatocellular carcinoma (HCC) which is prone to aberrant chromatin modifications. However, the regulatory effects of AR on epigenetic mediators in HCC remain ill-defined. Enhancer of zeste homolog 2 (EZH2), an oncogene responsible for the tri-methylation of histone H3 at lysine 27 (H3K27me3), was identified to be overexpressed in approximate 70–90% of HCC cases, which prompted us to investigate whether or how AR regulates EZH2 expression.

Methods

Colony formation, soft agar assay, xenograft and orthotopic mouse models were used to determine cell proliferation and tumorigenicity of gene-manipulated HCC cells. Gene regulation was assessed by chromatin immunoprecipitation, luciferase reporter assay, quantitative RT-PCR and immunoblotting. Clinical relevance of candidate proteins in patient specimens was examined in terms of pathological parameters and postsurgical survival rates.

Findings

In this study, we found that AR upregulated EZH2 expression by binding to EZH2 promoter and stimulating its transcriptional activity. EZH2 overexpression increased H3K27me3 levels and thereby silenced the expression of Wnt signal inhibitors, resulting in activation of Wnt/β-catenin signaling and subsequently induction of cell proliferation and tumorigenesis. In a cohort of human HCC patients, concordant overexpression of AR, EZH2, H3K27me3 and active β-catenin was observed in tumor tissues compared with paired non-tumor tissues, which correlated with tumor progression and poor prognosis. These findings demonstrate a novel working model in which EZH2 mediates AR-induced Wnt/β-catenin signaling activation through epigenetic modification, and support the application of EZH2-targeted reagents for treating HCC patients.

PRAF2 expression indicates unfavorable clinical outcome in hepatocellular carcinoma

Introduction

Prenylated Rab acceptor 1 domain family member 2 (PRAF2), a novel oncogene, has been shown to be essential for the development of several human cancers; however, its role in hepatocellular carcinoma (HCC) remains unclear.

Materials and methods

PRAF2 mRNA and protein expressions were examined in fresh tissues by quantitative reverse transcription-polymerase chain reaction and Western blot, respectively, and in 518 paraffin-embedded HCC samples by immunohistochemistry. The correlation of PRAF2 expression and clinical outcomes was determined by the Student's t-test, Kaplan-Meier test, and multivariate Cox regression analysis. The role of PRAF2 in HCC was investigated by cell viability, colony formation, and migration assays in vitro and with a nude mouse model in vivo.

Results

In our study, the PRAF2 expression was noticeably increased in HCC tissues at both the mRNA and protein levels compared with that of the nontumorous tissues. Kaplan-Meier analysis indicated that high PRAF2 expression was correlated with worse overall survival in a cohort of 518 patients with HCC. The prognostic implication of PRAF2 was verified by stratified survival analysis. The multivariate Cox regression model revealed PRAF2 as an independent poor prognostic factor for overall survival (hazard ratio = 1.244, 95% CI: 1.039-1.498, P<0.017) in HCC. The in vitro data demonstrated that PRAF2 overexpression markedly enhanced cell viability, colony formation, and cell migration. Moreover, ectopic expression of PRAF2 promoted tumor growth and metastasis in vivo.

Conclusion

Collectively, we conclude that PRAF2 is increased in HCC and is a novel unfavorable biomarker for prognostic prediction for patients with HCC.

Transcriptome sequencing identified hub genes for hepatocellular carcinoma by weighted-gene co-expression analysis

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide, and it remains a challenge to understand the genetic mechanisms underlying hepatocarcinogenesis. A global gene network of differential expression profiles in HCC has yet to be fully characterized. In the present study, we performed transcriptome sequencing (mRNA and lncRNA) in liver cancer and cirrhotic tissues of nine HCC patients. We identified differentially expressed genes (DEGs) and constructed a weighted gene co-expression network for the DEGs. In total, 755 DEGs (747 mRNA and eight lncRNA) were identified, and several co-expression modules were significantly associated with HCC clinical traits, including tumor location, tumor grade, and the α-fetoprotein (AFP) level. Of note, we identified 15 hub genes in the module associated with AFP level, and three (SPX, AFP and ADGRE1) of four hub genes were validated in an independent HCC cohort (n=78). Identification of hub genes for HCC clinical traits has implications for further understanding of the molecular genetic basis of HCC.

Long Noncoding RNA FGFR3-AS1 Promotes Hepatocellular Carcinoma Carcinogenesis via Modulating the PI3K/AKT Pathway

Hepatocellular carcinoma (HCC) as one of the most refractory cancers leads to high mortality worldwide. Long noncoding RNAs have been widely acknowledged as important biomarkers and therapeutic targets in HCC. In this study, we investigated the effects of long noncoding RNA FGFR3-AS1 on tumor growth and metastasis in HCC. First, we found that the expression of FGFR3-AS1 was upregulated about threefold in HCC samples and cell lines. We knocked down FGFR3-AS1 in Huh7 and Hep3B cells and found that FGFR3-AS1 knockdown significantly inhibited cell proliferation but induced apoptosis. Moreover, FGFR3-AS1 knockdown led to more HCC cells arrested in the G₀ stage. FGFR3-AS1 knockdown significantly inhibited cell migration and invasion. Additionally, we found that FGFR3-AS1 silencing dramatically delayed tumor growth in vivo. We found that, mechanistically, FGFR3-AS1 silencing decreased the activation of the PI3K/AKT signaling pathway. Taken together, our data demonstrated the pro-oncogenic role of FGFR3-AS1 in HCC and suggested that FGFR3-AS1 may serve as a novel biomarker for the diagnosis and therapeutic target for HCC treatment.

Rage induces hepatocellular carcinoma proliferation and sorafenib resistance by modulating autophagy

The receptor for advanced glycation end products (Rage) is involved in the development of various tumors and acts as an oncogenic protein. Rage is overexpressed in tumors including hepatocellular carcinoma (HCC). However, the molecular mechanism of Rage in HCC progression and sorafenib resistance remains unclear. In this study, enhanced Rage expression is highly associated proliferation and contributes to sorafenib resistance. Rage deficiency contributed to autophagy induction through activating AMPK/mTOR signaling pathway, which is important for sorafenib response. Moreover, the interactions between Rage and Rage ligands such as high mobility group box 1 (HMGB1) and s100a4 positively increased Rage expression. Our data indicate that Rage may be a potential target for therapeutic intervention in HCC and biomarker for sorafenib resistance.

Molecular alterations in hepatocellular carcinoma associated with hepatitis B and hepatitis C infections

Chronic infections with hepatitis B (HBV) and hepatitis C viruses (HCV) are the leading cause of cirrhosis and hepatocellular carcinoma (HCC) worldwide. Both viruses encode multifunctional regulatory proteins activating several oncogenic pathways, which induce accumulation of multiple genetic alterations in the infected hepatocytes. Gene mutations in HBV- and HCV-induced HCCs frequently impair the TP53, Wnt/b-catenin, RAS/RAF/MAPK kinase and AKT/mTOR pathways, which represent important anti-cancer targets. In this review, we highlight the molecular mechanisms underlying the pathogenesis of primary liver cancer, with particular emphasis on the host genetic variations identified by high-throughput technologies. In addition, we discuss the importance of genetic alterations, such as mutations in the telomerase reverse transcriptase (TERT) promoter, for the diagnosis, prognosis, and tumor stratification for development of more effective treatment approaches.

Wnt Signaling in Stem Cells and Cancer Stem Cells: A Tale of Two Coactivators

Wnt signaling in stem cells plays critical roles in development, normal adult physiology, and disease. In this chapter, we focus on the role of the Wnt signaling pathway in somatic stem cell biology and its critical role in normal tissue homeostasis and cancer. Wnt signaling can both maintain potency and initiate differentiation in somatic stem cells, depending on the cellular and environmental context. Based principally on studies from our lab, we will explain the dichotomous behavior of this signaling pathway in determining stem cell fate decisions, placing special emphasis on the interaction of β-catenin with either of the two highly homologous Kat3 coactivator proteins, CBP and p300. We will also discuss our results, both preclinical and clinical, demonstrating that small molecule modulators of the β-catenin/Kat3 coactivator interaction can be safely utilized to shift the balance between maintenance of potency and initiation of differentiation.

Targeted sequencing of cancer-associated genes in hepatocellular carcinoma using next-generation sequencing

Hepatocellular carcinoma (HCC) is the third leading cause of cancer mortality worldwide. Although the clinical success rate for the treatment of early-stage HCC has improved, the prognosis of advanced HCC remains poor owing to the high recurrence rate and the refractory nature of HCC for various anticancer drugs. A better understanding of the pathogenesis of HCC is therefore critically needed in order to treat HCC, including its genetic alterations. Next-generation sequencing (NGS) has provided an unbiased platform to systematically identify gene mutations and reveal the pathogenesis of various cancers. In the present study, a total of 118 samples (59 liver tissues including cancer and adjacent normal tissues) were sequenced using the AmpliSeq Hotspot Cancer Panel (version 2). The most common somatic mutations identified were tumor protein 53 (TP53; 35.6%) and β-catenin 1 (CTNNB1; 30.5%), and the most frequent variants of those genes were missense variants. In addition, somatic mutations including those in genes encoding colony-stimulating factor 1 receptor (5.1%), epidermal growth factor receptor (6.8%), RET proto-oncogene (3.4%), Erb-B2 receptor tyrosine kinase 4 (ERBB4; 1.7%) and serine/threonine kinase 11 (STK11, also known as liver kinase B1; 6.8%) were also identified at a low frequency in patients with HCC. A frameshift variant in STK11, a splice acceptor variant in TP53, a splice region variant in ERBB4 and a stop-gained variant in TP53 were also specifically determined. The most abundant alteration was a C:G>T:A transition (50%) and other transversions, i.e., C:G>G:C (19.6%), T:A>C:G (19.6%), C:G>A:T (12.5%), T:A>G:C (12.5%) and T:A>A:T (5.4%). This spectrum pattern differs from that in other solid tumors. TP53 mutations in the tumors at advanced stages were significantly more frequent compared with those in early-stage tumors. Additionally, age (<70 vs. ≥70 years) was significantly associated with CTNNB1 mutations. Using NGS, a number of novel gene mutations were identified in HCC, including established mutations and disproved mutations. The results of the present study offer new insight and improved understanding of the etiology and the development of HCC.

UGT1A polymorphisms as genetic biomarkers for hepatocellular carcinoma risk in Caucasian population

BACKGROUND & AIMS

The definition of new biomarkers of hepatocellular carcinoma (HCC) risk, especially in high-risk HBV/HCV-positive population, is urgently needed to improve HCC clinical management. This study focused on variants of UDP-glucuronosyltransferase 1A (UGT1A) enzymes that catalyse the reaction of glucuronidation, one of the most important chemical defence pathway of the body. The aim of this study was to elucidate the contribution of UGT1A polymorphisms in predicting HCC susceptibility in Caucasians.

METHODS

In this retrospective case-control analysis, 192 HCC liver transplanted patients represent the study group. Two age/sex-matched groups were used as control, one composed of 167 HBV- and/or HCV-infected individuals, and the other of 192 healthy subjects. All the cases were characterized for a panel of UGT1A1, UGT1A7 and UGT1A9 variants. The study end-point was the association between UGT1A markers and HCC onset.

RESULTS

UGT1A7*3 allele emerged as a protective marker for HCC development among both high-risk HBV/HCV-positive patients (OR=0.64, P=.0026), and healthy subjects (OR=0.47, P=.0051). UGT1A1*28 (OR=0.61, P=.0013) and UGT1A9*22 (OR=2.18, P=.0003) alleles were also associated to HCC occurrence, especially among healthy subjects. UGT1A haplotype, summarizing the UGT1A genetic alterations, confirmed the protective role against HCC development emerged for low-activity alleles. The observed associations could probably be linked to an increase of serum levels of health-beneficial molecules including free bilirubin.

CONCLUSION

A predictive effect of UGT1A polymorphisms on HCC risk was identified. If confirmed, these findings could contribute to improve the HCC surveillance, treatment tailoring and patients care.

ACYP2 polymorphisms are associated with the risk of liver cancer in a Han Chinese population

We explored the association between single nucleotide polymorphisms (SNPs) in ACYP2 and liver cancer risk. Thirteen SNPs were genotyped in 473 cases and 564 controls. Genetic model, linkage disequilibrium, and haplotype analyses were performed to evaluate the association between ACPY2 SNPs and liver cancer risk. We found that rs6713088 (G allele: odds ratio [OR] = 1.27, 95% confidence interval [CI]: 1.07-1.52, P = 0.007; GG vs. CC: OR = 1.49, 95% CI: 1.02-2.1, P = 0.038), rs843711 (T allele: OR = 1.29, 95% CI: 1.09-1.54, P = 0.004; TT vs. CC: OR = 1.62, 95% CI: 1.13-2.31, P = 0.008), rs843706 (A allele: OR = 1.30, 95% CI: 1.09-1.55, P = 0.003; AA vs. CC: OR = 1.62, 95% CI: 1.13-2.31, P = 0.008), and rs843645 (GG vs. AG: OR = 1.40, 95% CI: 1.07-1.82, P = 0.014) were associated with an increased risk of liver cancer. In contrast, rs1682111 (A allele: OR = 0.77, 95% CI: 0.640-0.94, P = 0.007; AT vs. TT: OR = 0.69, 95% CI: 0.53-0.91, P = 0.007), rs843720 (additive model: OR = 0.82, 95% CI: 0.68-1.00, P = 0.049), ATATCGCC and CG haplotypes (OR = 0.76, 95% CI: 0.62-0.92, P = 0.006; OR = 0.78, 95% CI: 0.65-0.93, P = 0.006, respectively) were significantly decreased liver cancer risk. Our results confirmed that rs6713088, rs843645, rs843711 and rs843706 were significantly increased liver cancer risk, but rs1682111, rs843720 and haplotypes (ATATCGCC and CG) were significantly decreased liver cancer risk in a Han Chinese population.

Histone deacetylases function as novel potential therapeutic targets for cancer

Diverse cellular functions, including tumor suppressor gene expression, DNA repair, cell proliferation and apoptosis, are regulated by histone acetylation and deacetylation. Histone deacetylases (HDACs) are enzymes involved in remodeling of chromatin by deacetylating the lysine residues. They play a pivotal role in epigenetic regulation of gene expression. Dysregulation of HDACs and aberrant chromatin acetylation and deacetylation have been implicated in the pathogenesis of various diseases, including cancer. Histone deacetylases have become a target for the development of drugs for treating cancer because of their major contribution to oncogenic cell transformation. Overexpression of HDACs correlates with tumorigenesis. Previous work showed that inhibition of HDACs results in apoptosis and the inhibition of cell proliferation in multiple cells. A significant number of HDAC inhibitors have been developed in the past decade. These inhibitors have strong anticancer effects in vitro and in vivo, inducing growth arrest, differentiation, and programmed cell death, inhibiting cell migration, invasion, and metastasis, and suppressing angiogenesis. In addition, HDAC-mediated deacetylation alters the transcriptional activity of nuclear transcription factors, including p53, E2F, c-Myc, and nuclear factor-κB, as well as the extracellular signal-regulated kinase1/2, phosphatidylinositol 3-kinase, Notch, and Wnt signaling pathways. This review highlights the role of HDACs in cancer pathogenesis and, more importantly, that HDACs are potential novel therapeutic targets.

Combination treatment including targeted therapy for advanced hepatocellular carcinoma

Management of advanced hepatocellular carcinoma (HCC), one of the most lethal cancers worldwide, has presented a therapeutic challenge over past decades. Most patients with advanced HCC and a low possibility of surgical resection have limited treatment options and no alternative but to accept local or palliative treatment. In the new era of cancer therapy, increasing numbers of molecular targeted agents (MTAs) have been applied in the treatment of advanced HCC. However, mono-targeted therapy has shown disappointing outcomes in disease control, primarily because of tumor heterogeneity and complex cell signal transduction. Because incapacitation of a single target is insufficient for cancer suppression, combination treatment for targeted therapy has been proposed and experimentally tested in several clinical trials. In this article, we review research studies aimed to enhance the efficacy of targeted therapy for HCC through combination strategies. Combination treatments involving targeted therapy for advanced HCC are compared and discussed.

Ginsenoside exhibits concentration-dependent dual effects on HepG2 cell proliferation via regulation of c-Myc and HNF-4α

Although ginsenoside can generally promote cell proliferation, it is reported to have anti-proliferative effects in hepatocellular carcinoma (HCC). Whether ginsenoside has concentration-dependent effects on HCC cell proliferation have not been clarified. Transcription factors c-Myc and hepatocyte nuclear factor (HNF)-4α are the most important opposite controllers of HCC cell proliferation. Whether and how ginsenoside regulates c-Myc and HNF-4α as well as their recruitment of the co-activator p300 to exhibit its effects on HCC cell proliferation are pending. In this study, it was found that low concentration ginsenoside promoted HepG2 cell proliferation while high concentration ginsenoside exhibited anti-proliferation effect. For low concentration ginsenoside treatment, c-Myc was up-regulated and the binding of p300 to c-Myc was promoted with obvious co-localization to activate HepG2 cell proliferation. However, for high concentration ginsenoside treatment, besides c-Myc, HNF-4α was also up-regulated might to exhibit an alternative effect. Furthermore, in contrast to the weakened binding and co-localization of c-Myc and p300, the binding of p300 to HNF-4α was enhanced with distinct co-localization to inhibit HepG2 cell proliferation for high concentration ginsenoside treatment. The results manifested that ginsenoside with low and high concentrations may differentially regulate c-Myc and HNF-4α as well as their recruitments of p300, to exhibit concentration-dependent dual effects on HepG2 cell proliferation.

LncSox4 promotes the self-renewal of liver tumour-initiating cells through Stat3-mediated Sox4 expression

Liver cancer has a tendency to develop asymptomatically in patients, so most patients are diagnosed at a later stage. Accumulating evidence implicates that liver tumour-initiating cells (TICs) as being responsible for liver cancer initiation and recurrence. However, the molecular mechanism of liver TIC self-renewal is poorly understood. Here we discover that a long noncoding RNA (lncRNA) termed LncSox4 is highly expressed in hepatocellular carcinoma (HCC) tissues and in liver TICs. We find that LncSox4 is required for liver TIC self-renewal and tumour initiation. LncSox4 interacts with and recruits Stat3 to the Sox4 promoter to initiate the expression of Sox4, which is highly expressed in liver TICs and required for liver TIC self-renewal. The expression level of Sox4 correlates with HCC development, clinical severity and prognosis of patients. Altogether, we find that LncSox4 is highly expressed in liver TICs and is required for their self-renewal.

Liver tumour-initiating cells (TICs) may be responsible for liver cancer initiation and recurrence. In this article, the authors show that a previously unidentified lncRNA, LncSox4, is highly expressed in liver cancer TICs and regulates TIC self-renewal through the Stat3/SOX4 axis.

Toxicogenomics Case Study: Furan

Development of pragmatic methodologies for human health risk assessment is required to address current regulatory challenges. We applied three toxicogenomic approaches—quantitative, predictive, and mechanistic—to a case study in mice exposed for 3 weeks to the hepatocarcinogen furan. We modeled the dose response of a variety of transcriptional endpoints and found that they produced benchmark doses similar to the furan-dependent cancer benchmark doses. Meta-analyses showed strong similarity between furan-dependent gene expression changes and those associated with several hepatic pathologies. Molecular pathways facilitated the development of a molecular mode of action for furan-induced hepatocellular carcinogenicity. Finally, we compared transcriptomic profiles derived from formalin-fixed and paraffin-embedded (FFPE) samples with those from high-quality frozen samples to evaluate whether archival samples are a viable option for toxicogenomic studies. The advantage of using FFPE tissues is that they are very well characterized (phenotypically); the disadvantage is that formalin degrades biomacromolecules, including RNA. We found that FFPE samples can be used for toxicogenomics using a ribo-depletion RNA-seq protocol. Our case study demonstrates the utility of toxicogenomics data to human health risk assessment, the potential of archival FFPE tissue samples, and identifies viable strategies toward the reduction of animal usage in chemical testing.

CADM1 regulates the G1/S transition and represses tumorigenicity through the Rb-E2F pathway in hepatocellular carcinoma

BACKGROUND

Increasing evidence indicates that downregulation of cell adhesion molecule 1 (CADM1) contributes to tumorigenesis in various cancers. The present study was undertaken to investigate the CADM1 expression pattern in human hepatocellular carcinoma (HCC), and to elucidate the mechanism underlying CADM1-mediated tumor suppression.

METHODS

CADM1 expression in HCC cell lines was measured by quantitative real-time PCR. The function of CADM1 in the context of tumor suppression in HCC cells was determined using proliferation assays, cell cycle analysis, EdU incorporation assays, in vitro colony formation analysis, and in vivo tumorigenicity assays. The mechanism by which CADM1 acts as a tumor suppressor gene in HCC was investigated using Western blotting analysis.

RESULTS

Downregulation of CADM1 expression is frequently detected in both HCC cells and clinical samples. Restoration of CADM1 expression in HCC cell lines significantly inhibits cell growth and negatively regulates the G1/S transition. CADM1 overexpression can inhibit the tumorigenicity of HCC cells both in vitro and in vivo. Western blotting analysis revealed that ectopic expression of CADM1 in HCC cells is associated with increased expression of Retinoblastoma (Rb) protein.

CONCLUSIONS

Our results showed that suppression of tumorigenesis by CADM1 may be mediated by the Rb-E2F pathway, involving upregulation of Rb protein levels. This pathway could therefore represent an attractive target for HCC therapy.

Systemic genome screening identifies the outcome associated focal loss of long noncoding RNA PRAL in hepatocellular carcinoma

Systemic analyses using large-scale genomic profiles have successfully identified cancer-driving somatic copy number variations (SCNVs) loci. However, functions of vast focal SCNVs in "protein-coding gene desert" regions are largely unknown. The integrative analysis of long noncoding RNA (lncRNA) expression profiles with SCNVs in hepatocellular carcinoma (HCC) led us to identify the recurrent deletion of lncRNA-PRAL (p53 regulation-associated lncRNA) on chromosome 17p13.1, whose genomic alterations were significantly associated with reduced survival of HCC patients. We found that lncRNA-PRAL could inhibit HCC growth and induce apoptosis in vivo and in vitro through p53. Subsequent investigations indicated that the three stem-loop motifs at the 5' end of lncRNA-PRAL facilitated the combination of HSP90 and p53 and thus competitively inhibited MDM2-dependent p53 ubiquitination, resulting in enhanced p53 stability. Additionally, in vivo lncRNA-PRAL delivery efficiently reduced intrinsic tumors, indicating its potential therapeutic application.

CONCLUSIONS

lncRNA-PRAL, one of the key cancer-driving SCNVs, is a crucial stimulus for HCC growth and may serve as a potential target for antitumor therapy.

PDZRN4 acts as a suppressor of cell proliferation in human liver cancer cell lines

Recently, some reports show that Ligand of Numb Protein-X 1 (LNX1) could be a suppressor gene in gliomas, while our current research has firstly shown that PDZ domain containing ring finger 4 (PDZRN4), another member of LNX family, could also be a potential suppressor in hepatocellular carcinoma (HCC). PDZRN4, also named LNX4 (Ligand of Numb Protein-X 4), is a member of the LNX family. We recently found that PDZRN4, but not LNX1, was down-regulated in HCC samples, and the role of PDZRN4 in the progression of HCC had not been studied before. To address this question, firstly, we evaluated the expression of PDZRN4 in HCC samples and adjacent non-cancerous tissues. Semi-quantitative polymerase chain reaction showed that PDZRN4 was down-regulated in 24/36 (66.7%) HCC samples separately. In addition, our research shows that PDZRN4 is silenced in all of the 12 HCC cell lines tested. Subsequently, cell-based functional assay exhibited that ectopic expression of PDZRN4 inhibits the proliferation, plate colony formation and anchorage-independent colony formation of HCC cells. Collectively, our results showed that PDZRN4 might be a potential tumour suppressor gene and had anti-proliferative effect on HCC cell proliferation, which would be of great significance to the researches on HCC.

Chronic alcohol drinking: Liver and pancreatic cancer?

Cancer is a multifactorial disease that results from complex interactions of numerous risk factors - genetic and environmental - over time, eventually leading to the diseased phenotypes. Thus, while epidemiological studies can point to risk factors, they cannot determine cause and effect relationships, and are unable to give biological and clinical insights into carcinogenesis. The link between any risk factor and carcinogenesis needs to be validated in experimental models. This is particularly true in epidemiological studies on alcohol consumption and its consequences. While there is no doubt that heavy alcohol consumption has devastating health effects, the inconsistencies in alcohol-related epidemiological studies and cancer suffer from possible sources of the variability in outcomes, ranging from inaccuracy of self-report of consumption to the problem of correlating cancer that started decades earlier to current or recent alcohol consumption. To further study the interactions between alcohol and cancer, the use of "Molecular Pathological Epidemiology" (MPE) advocated by Ogino et al. for dissecting the interplay between etiological factors, cellular and molecular characteristics, and disease progression in cancer is appropriate. MPE does not consider cancer as a single entity, rather it integrates analyses of epidemiological studies with the macroenvironment and molecular and microenvironment. This approach allows investigating the relationships between potential etiological agents and cancer based on molecular signatures. More research is needed to fully elucidate the link between heavy alcohol consumption and pancreatic cancer, and to further investigate the roles of acetaldehyde and FAEEs in pancreatic carcinogenesis.