Hepatocellular Carcinomas With Mutational Activation of Beta-Catenin Require Choline and Can Be Detected by Positron Emission Tomography

Phospholipid isotope tracing suggests β-catenin-driven suppression of phosphatidylcholine metabolism in hepatocellular carcinoma

Activating mutations in the CTNNB1 gene encoding β-catenin are among the most frequently observed oncogenic alterations in hepatocellular carcinoma (HCC). Profound alterations in lipid metabolism, including increases in fatty acid oxidation and transformation of the phospholipidome, occur in HCC with CTNNB1 mutations, but it is unclear what mechanisms give rise to these changes. We employed untargeted lipidomics and targeted isotope tracing to measure phospholipid synthesis activity in an inducible human liver cell line expressing mutant β-catenin, as well as in transgenic zebrafish with activated β-catenin-driven HCC. In both models, activated β-catenin expression was associated with large changes in the lipidome including conserved increases in acylcarnitines and ceramides and decreases in triglycerides. Lipid isotope tracing analysis in human cells revealed a reduction in phosphatidylcholine (PC) production rates as assayed by choline incorporation. We developed lipid isotope tracing analysis for zebrafish tumors and observed reductions in phosphatidylcholine synthesis by both the CDP-choline and PEMT pathways. The observed changes in the β-catenin-driven HCC phospholipidome suggest that zebrafish can recapitulate conserved features of HCC lipid metabolism and may serve as a model for identifying future HCC-specific lipid metabolic targets.

Glutamine metabolism, a double agent combating or fuelling hepatocellular carcinoma

The reprogramming of glutamine metabolism is a key event in cancer more generally and in hepatocellular carcinoma (HCC) in particular. Glutamine consumption supplies tumours with ATP and metabolites through anaplerosis of the tricarboxylic acid cycle, while glutamine production can be enhanced by the overexpression of glutamine synthetase. In HCC, increased glutamine production is driven by activating mutations in the CTNNB1 gene encoding β-catenin. Increased glutamine synthesis or utilisation impacts tumour epigenetics, oxidative stress, autophagy, immunity and associated pathways, such as the mTOR (mammalian target of rapamycin) pathway. In this review, we will discuss studies which emphasise the pro-tumoral or tumour-suppressive effect of glutamine overproduction. It is clear that more comprehensive studies are needed as a foundation from which to develop suitable therapies targeting glutamine metabolic pathways, depending on the predicted pro- or anti-tumour role of dysregulated glutamine metabolism in distinct genetic contexts.

Spatial metabolomics and its application in the liver

Hepatocytes work in highly structured, repetitive hepatic lobules. Blood flow across the radial axis of the lobule generates oxygen, nutrient, and hormone gradients, which result in zoned spatial variability and functional diversity. This large heterogeneity suggests that hepatocytes in different lobule zones may have distinct gene expression profiles, metabolic features, regenerative capacity, and susceptibility to damage. Here, we describe the principles of liver zonation, introduce metabolomic approaches to study the spatial heterogeneity of the liver, and highlight the possibility of exploring the spatial metabolic profile, leading to a deeper understanding of the tissue metabolic organization. Spatial metabolomics can also reveal intercellular heterogeneity and its contribution to liver disease. These approaches facilitate the global characterization of liver metabolic function with high spatial resolution along physiological and pathological time scales. This review summarizes the state of the art for spatially resolved metabolomic analysis and the challenges that hinder the achievement of metabolome coverage at the single-cell level. We also discuss several major contributions to the understanding of liver spatial metabolism and conclude with our opinion on the future developments and applications of these exciting new technologies.

DLK1/DIO3 locus upregulation by a β-catenin-dependent enhancer drives cell proliferation and liver tumorigenesis

The CTNNB1 gene, encoding β-catenin, is frequently mutated in hepatocellular carcinoma (HCC, ∼30%) and in hepatoblastoma (HB, >80%), in which DLK1/DIO3 locus induction is correlated with CTNNB1 mutations. Here, we aim to decipher how sustained β-catenin activation regulates DLK1/DIO3 locus expression and the role this locus plays in HB and HCC development in mouse models deleted for Apc (ApcΔhep) or Ctnnb1-exon 3 (β-cateninΔExon3) and in human CTNNB1-mutated hepatic cancer cells. We identified an enhancer site bound by TCF-4/β-catenin complexes in an open conformation upon sustained β-catenin activation (DLK1-Wnt responsive element [WRE]) and increasing DLK1/DIO3 locus transcription in β-catenin-mutated human HB and mouse models. DLK1-WRE editing by CRISPR-Cas9 approach impaired DLK1/DIO3 locus expression and slowed tumor growth in subcutaneous CTNNB1-mutated tumor cell grafts, ApcΔhep HB and β-cateninΔExon3 HCC. Tumor growth inhibition resulted either from increased FADD expression and subsequent caspase-3 cleavage in the first case or from decreased expression of cell cycle actors regulated by FoxM1 in the others. Therefore, the DLK1/DIO3 locus is an essential determinant of FoxM1-dependent cell proliferation during β-catenin-driven liver tumorigenesis. Targeting the DLK1-WRE enhancer to silence the DLK1/DIO3 locus might thus represent an interesting therapeutic strategy to restrict tumor growth in primary liver cancers with CTNNB1 mutations.

Chromatin and DNA Dynamics in Mouse Models of Liver Cancers

In recent years, important efforts have been made to understand how the expression of a specific gene repertoire correlates with chromatin accessibility, histone mark deposition, as well as with chromatin looping establishing connectivity with regulatory regions. The emergence of new techniques for genome-wide analyses and their progressive optimization to work on low amounts of material allows the scientific community to obtain an integrated view of transcriptional landscapes in physiology and disease. Here, we describe our own experience aiming at correlating the TCF-4/β-catenin cistrome during liver tumorigenesis with chromatin remodeling, histone mark modifications, and long-distance DNA looping.

Phospholipid isotope tracing reveals β-catenin-driven suppression of phosphatidylcholine metabolism in hepatocellular carcinoma

Background and Aims

Activating mutations in the CTNNB1 gene encoding β-catenin are among the most frequently observed oncogenic alterations in hepatocellular carcinoma (HCC). HCC with CTNNB1 mutations show profound alterations in lipid metabolism including increases in fatty acid oxidation and transformation of the phospholipidome, but it is unclear how these changes arise and whether they contribute to the oncogenic program in HCC.

Methods

We employed untargeted lipidomics and targeted isotope tracing to quantify phospholipid production fluxes in an inducible human liver cell line expressing mutant β-catenin, as well as in transgenic zebrafish with activated β-catenin-driven HCC.

Results

In both models, activated β-catenin expression was associated with large changes in the lipidome including conserved increases in acylcarnitines and ceramides and decreases in triglycerides. Lipid flux analysis in human cells revealed a large reduction in phosphatidylcholine (PC) production rates as assayed by choline tracer incorporation. We developed isotope tracing lipid flux analysis for zebrafish and observed similar reductions in phosphatidylcholine synthesis flux accomplished by sex-specific mechanisms.

Conclusions

The integration of isotope tracing with lipid abundances highlights specific lipid class transformations downstream of β-catenin signaling in HCC and suggests future HCC-specific lipid metabolic targets.

A dual-tracer approach using [11C]CH and [18F]FDG in HCC clinical decision making

BACKGROUND

Early detection of recurrent or progressive HCC remains the strongest prognostic factor for survival. Dual tracer PET/CT imaging with [11C]CH and [18F]FDG can further increase detection rates as both tracers entail different metabolic pathways involved in HCC development. We investigated dual-tracer PET/CT in clinical decision making in patients suspected of recurrent or progressive HCC. All HCC patients who underwent both [11C]CH and [18F]FDG PET/CT in our institute from February 2018 to December 2021 were included. Both tracer PET/CT were within 4 weeks of each other with at least 6-month follow-up. Patients underwent dual tracer PET/CT because of unexplained and suspicious CT/MRI or sudden rise of serum tumour markers. A detected lesion was considered critical when the finding had prognostic consequences leading to treatment changes.

RESULTS

Nineteen patients who underwent [11C]CH and [18F]FDG PET/CT were included of which all but six patients were previously treated for HCC. Dual-tracer critical finding detection rate was 95%, with [18F]FDG 68%, and [11C]CH 84%. Intrahepatic HCC recurrence finding rate was 65% for both tracers. [18F]FDG found more ablation site recurrences (4/5) compared to [11C]CH (2/5). Only [11C]CH found two needle tract metastases. Both tracers found 75% of the positive lymph nodes. Two new primary tumours were found, one by [18F]FDG and both by [11C]CH.

CONCLUSIONS

Our study favours a dual-tracer approach in HCC staging in high-risk patients or when conventional imaging is non-conclusive.

Antagonism between wild-type and mutant β-catenin controls hepatoblastoma differentiation via fascin-1

Background & Aims

β-catenin is a well-known effector of the Wnt pathway, and a key player in cadherin-mediated cell adhesion. Oncogenic mutations of β-catenin are very frequent in paediatric liver primary tumours. Those mutations are mostly heterozygous, which allows the co-expression of wild-type (WT) and mutated β-catenins in tumour cells. We investigated the interplay between WT and mutated β-catenins in liver tumour cells, and searched for new actors of the β-catenin pathway.

Methods

Using an RNAi strategy in β-catenin-mutated hepatoblastoma (HB) cells, we dissociated the structural and transcriptional activities of β-catenin, which are carried mainly by WT and mutated proteins, respectively. Their impact was characterised using transcriptomic and functional analyses. We studied mice that develop liver tumours upon activation of β-catenin in hepatocytes (APC^KO and β-catenin^Δexon3 mice). We used transcriptomic data from mouse and human HB specimens, and used immunohistochemistry to analyse samples.

Results

We highlighted an antagonistic role of WT and mutated β-catenins with regard to hepatocyte differentiation, as attested by alterations in the expression of hepatocyte markers and the formation of bile canaliculi. We characterised fascin-1 as a transcriptional target of mutated β-catenin involved in tumour cell differentiation. Using mouse models, we found that fascin-1 is highly expressed in undifferentiated tumours. Finally, we found that fascin-1 is a specific marker of primitive cells including embryonal and blastemal cells in human HBs.

Conclusions

Fascin-1 expression is linked to a loss of differentiation and polarity of hepatocytes. We present fascin-1 as a previously unrecognised factor in the modulation of hepatocyte differentiation associated with β-catenin pathway alteration in the liver, and as a new potential target in HB.

Impact and implications

The FSCN1 gene, encoding fascin-1, was reported to be a metastasis-related gene in various cancers. Herein, we uncover its expression in poor-prognosis hepatoblastomas, a paediatric liver cancer. We show that fascin-1 expression is driven by the mutated beta-catenin in liver tumour cells. We provide new insights on the impact of fascin-1 expression on tumour cell differentiation. We highlight fascin-1 as a marker of immature cells in mouse and human hepatoblastomas.

Mechanism of Cytotoxic Action of Gold Nanorods Photothermal Therapy for A549 Cell

Photothermal therapy has developed into an important field of tumor treatment research, and numerous studies have focused on the preparation of photothermal therapeutic agents, tumor targeting, diagnosis, and treatment integration. However, there are few studies on the mechanism of photothermal therapy acting on cancer cells. Here we investigated the metabolomics of lung cancer cell A549 during gold nanorod (GNR) photothermal treatment by high-resolution LC/MS, and several differential metabolites and corresponding metabolic pathways during photothermal therapy were found. The main differential metabolites contained 18-hydroxyoleate, beta-alanopine and cis-9,10-epoxystearic acid, and phosphorylcholine. Pathway analysis also showed metabolic changes involving cutin, suberine, and wax biosynthesis, pyruvate and glutamic acid synthesis, and choline metabolism. Analysis also showed that the photothermal process of GNRs may induce cytotoxicity by affecting pyruvate and glutamate synthesis, normal choline metabolism, and ultimately apoptosis.

Current Imaging Diagnosis of Hepatocellular Carcinoma

Simple Summary

The role of imaging in the management of hepatocellular carcinoma (HCC) has significantly evolved and expanded beyond the plain radiological confirmation of the tumor based on the typical appearance in a multiphase contrast-enhanced CT or MRI examination. The introduction of hepatobiliary contrast agents has enabled the diagnosis of hepatocarcinogenesis at earlier stages, while the application of ultrasound contrast agents has drastically upgraded the role of ultrasound in the diagnostic algorithms. Newer quantitative techniques assessing blood perfusion on CT and MRI not only allow earlier diagnosis and confident differentiation from other lesions, but they also provide biomarkers for the evaluation of treatment response. As distinct HCC subtypes are identified, their correlation with specific imaging features holds great promise for estimating tumor aggressiveness and prognosis. This review presents the current role of imaging and underlines its critical role in the successful management of patients with HCC.

Abstract

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer related death worldwide. Radiology has traditionally played a central role in HCC management, ranging from screening of high-risk patients to non-invasive diagnosis, as well as the evaluation of treatment response and post-treatment follow-up. From liver ultrasonography with or without contrast to dynamic multiple phased CT and dynamic MRI with diffusion protocols, great progress has been achieved in the last decade. Throughout the last few years, pathological, biological, genetic, and immune-chemical analyses have revealed several tumoral subtypes with diverse biological behavior, highlighting the need for the re-evaluation of established radiological methods. Considering these changes, novel methods that provide functional and quantitative parameters in addition to morphological information are increasingly incorporated into modern diagnostic protocols for HCC. In this way, differential diagnosis became even more challenging throughout the last few years. Use of liver specific contrast agents, as well as CT/MRI perfusion techniques, seem to not only allow earlier detection and more accurate characterization of HCC lesions, but also make it possible to predict response to treatment and survival. Nevertheless, several limitations and technical considerations still exist. This review will describe and discuss all these imaging modalities and their advances in the imaging of HCC lesions in cirrhotic and non-cirrhotic livers. Sensitivity and specificity rates, method limitations, and technical considerations will be discussed.

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.

Utility of Early Posttreatment PET/CT Evaluation Using FDG or 18F-FCH to Predict Response to 90Y Radioembolization in Patients With Hepatocellular Carcinoma

Background: Assessment of hepatocellular carcinoma (HCC) treatment response after transarterial radioembolization (TARE) is challenging, as response by conventional imaging criteria may not become apparent until 6 months after treatment. Though HCC exhibits variability avidity for FDG, some cases of HCC without avidity for FDG show avidity for 18F-FCH. Objectives: To evaluate the utility of early posttreatment evaluation by PET/CT using FDG or 18F-FCH to predict 6-month treatment response and survival after TARE in patients with HCC. Methods: This retrospective study included 37 patients (mean age 67 years; 34 men, 3 women) with documented HCC treated by TARE who underwent both pretreatment FDG PET/CT and 18F-FCH PET/CT, as well as early FDG PET/CT and/or 18F-FCH PET/CT 4-8 weeks after treatment; FDG PET/CT and 18F-FCH PET/CT examinations were performed on separate dates. Only one of 73 initially identified potentially eligible patients was excluded due to lack of HCC avidity for both FDG and 18F-FCH. Response assessment by mRECIST on multiphase CT or MRI was performed at one-month and six-months in 23 patients. Early PET/CT response and one-month mRECIST response were assessed as predictors of six-month mRECIST response. Univariable and multivariable predictors of overall survival (OS) were identified. Results: On pretreatment PET/CT, 28 (76%) patients were FDG-positive, 15 (41%) FCH-positive 6 (16%) both FDG-positive and FCH-positive. Twelve of 28 FDG-positive HCCs exhibited early response by FDG PET/CT; 7 of 15 FCH-positive HCCs exhibited early response by 18F-FCH PET/CT. Twelve (52%) patients exhibited six-month mRECIST response. Early posttreatment PET/CT response exhibited 100% (12/12) sensitivity and 100% (11/11) specificity for six-month mRECIST response, whereas one-month mRECIST response exhibited 67% (8/12) sensitivity and 100% (11/11) specificity for six-month mRECIST response. Early postteatment PET/CT response was a significant independent predictor of OS on univariable (hazard ratio: 0.37, 95% CI: 0.15-0.93, p=.03) and multivariable analyses (hazard ratio: 0.24, 95% CI: 0.08-0.76, p=.01). Conclusion: Early post-TARE evaluation by PET/CT using FDG or 18F-FCH may predict six-month response and OS in patients with HCC. Clinical Impact: Early posttreatment evaluation with PET/CT could help more reliably identify true nonresponders after TARE, which in turn could prompt early adapted therapeutic management.

β-Catenin Activation in Hepatocellular Cancer: Implications in Biology and Therapy

Simple Summary

Liver cancer is a dreadful tumor which has gradually increased in incidence all around the world. One major driver of liver cancer is the Wnt–β-catenin pathway which is active in a subset of these tumors. While this pathway is normally important in liver development, regeneration and homeostasis, it’s excessive activation due to mutations, is detrimental and leads to tumor cell growth, making it an important therapeutic target. There are also some unique characteristics of this pathway activation in liver cancer. It makes the tumor addicted to specific amino acids and in turn to mTOR signaling, which can be treated by certain existing therapies. In addition, activation of the Wnt–β-catenin in liver cancer appears to alter the immune cell landscape making it less likely to respond to the new immuno-oncology treatments. Thus, Wnt–β-catenin active tumors may need to be treated differently than non-Wnt–β-catenin active tumors.

Abstract

Hepatocellular cancer (HCC), the most common primary liver tumor, has been gradually growing in incidence globally. The whole-genome and whole-exome sequencing of HCC has led to an improved understanding of the molecular drivers of this tumor type. Activation of the Wnt signaling pathway, mostly due to stabilizing missense mutations in its downstream effector β-catenin (encoded by CTNNB1) or loss-of-function mutations in AXIN1 (the gene which encodes for Axin-1, an essential protein for β-catenin degradation), are seen in a major subset of HCC. Because of the important role of β-catenin in liver pathobiology, its role in HCC has been extensively investigated. In fact, CTNNB1 mutations have been shown to have a trunk role. β-Catenin has been shown to play an important role in regulating tumor cell proliferation and survival and in tumor angiogenesis, due to a host of target genes regulated by the β-catenin transactivation of its transcriptional factor TCF. Proof-of-concept preclinical studies have shown β-catenin to be a highly relevant therapeutic target in CTNNB1-mutated HCCs. More recently, studies have revealed a unique role of β-catenin activation in regulating both tumor metabolism as well as the tumor immune microenvironment. Both these roles have notable implications for the development of novel therapies for HCC. Thus, β-catenin has a pertinent role in driving HCC development and maintenance of this tumor-type, and could be a highly relevant therapeutic target in a subset of HCC cases.

Prognostic Value of Metabolic Imaging Data of 11C-choline PET/CT in Patients Undergoing Hepatectomy for Hepatocellular Carcinoma

Simple Summary

Few data are available for the use of ¹¹C-choline positron emission tomography/computed tomography (PET/CT) in patients with hepatocellular carcinoma (HCC). The aim of the study was to analyze the clinical impact of this metabolic imaging in patients with HCC candidates for hepatectomy. Seven parameters were recorded for PET/CT in 60 patients. The Cox regression for overall survival (OS) showed that Barcelona stages (p = 0.003) and metabolic tumor volume (MTV) (p = 0.026) were the only factors independently associated with OS and furthermore, curve analysis revealed MTV ability in predicting OS. Patients with MTV ≥ 380 had worse OS (p = 0.015). The use of ¹¹C-choline PET/CT allows for better prognostic refinement in patients undergoing hepatectomy for HCC: integration of such metabolic modality into HCC staging system should be considered.

Abstract

¹¹C-choline positron emission tomography/computed tomography (PET/CT) has been used for patients with some types of tumors, but few data are available for hepatocellular carcinoma (HCC). We queried our prospective database for patients with HCC staged with ¹¹C-choline PET/CT to assess the clinical impact of this imaging modality. Seven parameters were recorded: maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), liver standardized uptake value (SUVliver), metabolic tumor volume (MTV), photopenic area, metabolic tumor burden (MTB = MTVxSUVmean), and SUVratio (SUVmax/SUVliver). Analysis was performed to identify parameters that could be predictors of overall survival (OS). Sixty patients were analyzed: fourteen (23%) were in stage 0-A, 37 (62%) in stage B, and 9 (15%) in stage C of the Barcelona classification. The Cox regression for OS showed that Barcelona stages (HR = 2.94; 95%CI = 1.41–4.51; p = 0.003) and MTV (HR = 2.11; 95%CI = 1.51–3.45; p = 0.026) were the only factors independently associated with OS. Receiver operating characteristics curve analysis revealed MTV ability in discriminating survival (area under the curve (AUC) = 0.77; 95%CI = 0.57–097; p < 0.001: patients with MTV ≥ 380 had worse OS (p = 0.015)). The use of ¹¹C-choline PET/CT allows for better prognostic refinement in patients undergoing hepatectomy for HCC. Incorporation of such modality into HCC staging system should be considered.

Beta-catenin activation and immunotherapy resistance in hepatocellular carcinoma: mechanisms and biomarkers

Mutations involving CTNNB1, the gene encoding beta-catenin, and other molecular alterations that affect the Wnt/beta-catenin signaling pathway are exceptionally common in hepatocellular carcinoma. Several of these alterations have also been associated with scarcity of immune cells in the tumor microenvironment and poor clinical response to immune checkpoint inhibitor therapy. In light of these associations, tumor biomarkers of beta-catenin status could have the potential to serve as clinical predictors of immunotherapy outcome. This editorial review article summarizes recent pre-clinical and clinical research pertaining to associations between beta-catenin activation and diminished anti-tumor immunity. Potential non-invasive biomarkers that may provide a window into this oncogenic mechanism of immune evasion are also presented and discussed.

Methionine metabolism in chronic liver diseases: an update on molecular mechanism and therapeutic implication

As one of the bicyclic metabolic pathways of one-carbon metabolism, methionine metabolism is the pivot linking the folate cycle to the transsulfuration pathway. In addition to being a precursor for glutathione synthesis, and the principal methyl donor for nucleic acid, phospholipid, histone, biogenic amine, and protein methylation, methionine metabolites can participate in polyamine synthesis. Methionine metabolism disorder can aggravate the damage in the pathological state of a disease. In the occurrence and development of chronic liver diseases (CLDs), changes in various components involved in methionine metabolism can affect the pathological state through various mechanisms. A methionine-deficient diet is commonly used for building CLD models. The conversion of key enzymes of methionine metabolism methionine adenosyltransferase (MAT) 1 A and MAT2A/MAT2B is closely related to fibrosis and hepatocellular carcinoma. In vivo and in vitro experiments have shown that by intervening related enzymes or downstream metabolites to interfere with methionine metabolism, the liver injuries could be reduced. Recently, methionine supplementation has gradually attracted the attention of many clinical researchers. Most researchers agree that adequate methionine supplementation can help reduce liver damage. Retrospective analysis of recently conducted relevant studies is of profound significance. This paper reviews the latest achievements related to methionine metabolism and CLD, from molecular mechanisms to clinical research, and provides some insights into the future direction of basic and clinical research.

ARID1A loss in adult hepatocytes activates β-catenin-mediated erythropoietin transcription

Erythropoietin (EPO) is a key regulator of erythropoiesis. The embryonic liver is the main site of erythropoietin synthesis, after which the kidney takes over. The adult liver retains the ability to express EPO, and we discovered here new players of this transcription, distinct from the classical hypoxia-inducible factor pathway. In mice, genetically invalidated in hepatocytes for the chromatin remodeler Arid1a, and for Apc, the major silencer of Wnt pathway, chromatin was more accessible and histone marks turned into active ones at the Epo downstream enhancer. Activating β-catenin signaling increased binding of Tcf4/β-catenin complex and upregulated its enhancer function. The loss of Arid1a together with β-catenin signaling, resulted in cell-autonomous EPO transcription in mouse and human hepatocytes. In mice with Apc-Arid1a gene invalidations in single hepatocytes, Epo de novo synthesis led to its secretion, to splenic erythropoiesis and to dramatic erythrocytosis. Thus, we identified new hepatic EPO regulation mechanism stimulating erythropoiesis.

NCSTN promotes hepatocellular carcinoma cell growth and metastasis via β-catenin activation in a Notch1/AKT dependent manner

BACKGROUND

Hepatocellular carcinoma is the third top cause of cancer-related mortalities worldwide. The prognosis of HCC patients remains poor due to rapid progression and high incidence of tumor recurrence. Nicastrin (NCSTN), a core subunit of γ-Secretase, has been reported to play a vital role in tumor progression. However, no study till now has revealed its role in HCC.

METHODS

The expression of NCSTN was evaluated by immunohistochemical staining, Western blot, and quantitative real-time PCR. Cell counting kit-8, colony formation and cell cycle assays were used for evaluating cell growth in vitro. Transwell and wound-healing assays were used for evaluating cell migration and invasion capacity. Immunofluorescence, subcellular protein fractionation and co-immunoprecipitation were used for location analysis of β-catenin. The in vivo functions of NCSTN were illustrated by xenograft tumor models.

RESULTS

NCSTN was dramatically overexpressed in HCC compared to normal liver tissues. Elevated NCSTN expression level was significantly correlated to worse overall and recurrence-free survival of HCC patients. Enhanced NCSTN expression promoted HCC cell growth, migration and invasion in vitro and in vivo. Mechanistic investigations showed that NCSTN induced epithelial-mesenchymal transition (EMT) process via upregulation of Zeb1. Subsequently, we revealed that NCSTN facilitated nuclear translocation of β-catenin, a positive transcriptional regulator of Zeb1. Using Notch and AKT inhibitors, we revealed that NCSTN promoted β-catenin activation through Notch1 and AKT signaling pathway. NCSTN increased AKT and GSK-3β phosphorylation by cleavage of Notch1, which decreased GSK-3β/β-catenin complex. The inactivation of GSK-3β inhibited the β-catenin degradation and promoted nuclear translocation of β-catenin to initiate transcription of Zeb1, resulting in malignant phenotype.

CONCLUSIONS

Our results demonstrated that NCSTN promoted HCC cell growth and metastasis via β-catenin-mediated upregulation of Zeb1 in a Notch1/AKT dependent manner, suggesting that NCSTN might serve as a potential prognostic marker and therapeutic target for HCC.

Phospholipids are A Potentially Important Source of Tissue Biomarkers for Hepatocellular Carcinoma: Results of a Pilot Study Involving Targeted Metabolomics

Background: Hepatocellular carcinoma (HCC) pathogenesis involves the alteration of multiple liver-specific metabolic pathways. We systematically profiled cancer- and liver-related classes of metabolites in HCC and adjacent liver tissues and applied supervised machine learning to compare their potential yield for HCC biomarkers. Methods: Tumor and corresponding liver tissue samples were profiled as follows: Bile acids by ultra-performance liquid chromatography (LC) coupled to tandem mass spectrometry (MS), phospholipids by LC-MS/MS, and other small molecules including free fatty acids by gas chromatography—time of flight MS. The overall classification performance of metabolomic signatures derived by support vector machine (SVM) and random forests machine learning algorithms was then compared across classes of metabolite. Results: For each metabolite class, there was a plateau in classification performance with signatures of 10 metabolites. Phospholipid signatures consistently showed the highest discrimination for HCC followed by signatures derived from small molecules, free fatty acids, and bile acids with area under the receiver operating characteristic curve (AUC) values of 0.963, 0.934, 0.895, 0.695, respectively, for SVM-generated signatures comprised of 10 metabolites. Similar classification performance patterns were observed with signatures derived by random forests. Conclusion: Membrane phospholipids are a promising source of tissue biomarkers for discriminating between HCC tumor and liver tissue.