Dysregulated fatty acid metabolism in hepatocellular carcinoma

Acyl-CoA Synthetase Medium-Chain Family Member 5-Mediated Fatty Acid Metabolism Dysregulation Promotes the Progression of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver cancer, with high incidence and mortality worldwide. Despite diagnostic and therapeutic advancements, HCC remains poorly responsive to treatment, with a poor prognosis. Understanding the molecular mechanisms driving HCC is crucial for developing effective therapies. Emerging evidence indicates that dysregulated fatty acid metabolism contributes to HCC. Acyl-CoA medium-chain synthetase 5 (ACSM5), involved in fatty acid metabolism, is down-regulated in HCC; however, its role is not well understood. In this study, we analyzed ACSM5 expression in HCC patient samples and cell lines. Using newly established ACSM5-overexpressing HCC cell lines, Huh7-ACSM5 and Hepa1-6-ACSM5, we investigated the effects and regulatory mechanisms of ACSM5. Our results showed that ACSM5 was significantly down-regulated in HCC tumor tissues compared with nontumor tissues. ACSM5 expression was regulated by DNA methylation, with a DNMT1 inhibitor effectively increasing ACSM5 expression and reducing promoter region methylation. Overexpression of ACSM5 in Huh7 cells reduced fatty acid accumulation, decreased cell proliferation, migration, and invasion in vitro, and inhibited tumor growth in mouse xenografts. Furthermore, ACSM5 overexpression also decreased STAT3 phosphorylation, subsequently affecting downstream cytokine TGFB and FGF12 mRNA levels. Our findings suggest that ACSM5 down-regulation contributes to HCC progression, providing insights into its oncogenic role and highlighting its potential as a biomarker and therapeutic target for HCC.

TRIM65/NF2/YAP1 Signaling Coordinately Orchestrates Metabolic and Immune Advantages in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer deaths worldwide. Significantly activated uridine nucleotide and fatty acid metabolism in HCC cells promote malignant proliferation and immune evasion. Herein, it is demonstrated that the tripartite motif 65 (TRIM65) E3 ubiquitin-protein ligase, O-GlcNAcylated via O-GlcNAcylation transferase, is highly expressed in HCC and facilitated metabolic remodeling to promote the accumulation of products related to uracil metabolism and palmitic acid, driving the progression of HCC. Mechanistically, it is showed that TRIM65 mediates ubiquitylation at the K44 residue of neurofibromatosis type 2 (NF2), the key protein upstream of classical Hippo signaling. Accelerated NF2 degradation inhibits yes-associated protein 1 phosphorylation, inducing aberrant activation of related metabolic enzyme transcription, and orchestrating metabolic and immune advantages. In conclusion, these results reveal a critical role for the TRIM family molecule TRIM65 in supporting HCC cell survival and highlight the therapeutic potential of targeting its E3 ligase activity to alter the regulation of proteasomal degradation.

Regulation and targeting of SREBP-1 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an increasing burden on global public health and is associated with enhanced lipogenesis, fatty acid uptake, and lipid metabolic reprogramming. De novo lipogenesis is under the control of the transcription factor sterol regulatory element-binding protein 1 (SREBP-1) and essentially contributes to HCC progression. Here, we summarize the current knowledge on the regulation of SREBP-1 isoforms in HCC based on cellular, animal, and clinical data. Specifically, we (i) address the overarching mechanisms for regulating SREBP-1 transcription, proteolytic processing, nuclear stability, and transactivation and (ii) critically discuss their impact on HCC, taking into account (iii) insights from pharmacological approaches. Emphasis is placed on cross-talk with the phosphatidylinositol-3-kinase (PI3K)-protein kinase B (Akt)-mechanistic target of rapamycin (mTOR) axis, AMP-activated protein kinase (AMPK), protein kinase A (PKA), and other kinases that directly phosphorylate SREBP-1; transcription factors, such as liver X receptor (LXR), peroxisome proliferator-activated receptors (PPARs), proliferator-activated receptor γ co-activator 1 (PGC-1), signal transducers and activators of transcription (STATs), and Myc; epigenetic mechanisms; post-translational modifications of SREBP-1; and SREBP-1-regulatory metabolites such as oxysterols and polyunsaturated fatty acids. By carefully scrutinizing the role of SREBP-1 in HCC development, progression, metastasis, and therapy resistance, we shed light on the potential of SREBP-1-targeting strategies in HCC prevention and treatment.

Unique lipid composition maintained by extracellular blockade leads to prooncogenicity

Lipid-mediated inflammation is involved in the development and malignancy of cancer. We previously demonstrated the existence of a novel oncogenic mechanism utilizing membrane lipids of extracellular vesicles in Epstein-Barr virus (EBV)-positive lymphomas and found that the lipid composition of lymphoma cells is skewed toward ω-3 fatty acids, which are anti-inflammatory lipids, suggesting an alteration in systemic lipid composition. The results showed that arachidonic acid (AA), an inflammatory lipid, was significantly reduced in the infected cells but detected at high levels in the sera of EBV-positive patients lead to the finding of the blockade of extracellular AA influx by downregulating FATP2, a long-chain fatty acid transporter that mainly transports AA in EBV-infected lymphoma cells. Low AA levels in tumor cells induced by downregulation of FATP2 expression confer resistance to ferroptosis and support tumor growth. TCGA data analysis and xenograft models have demonstrated that the axis plays a critical role in several types of cancers, especially poor prognostic cancers, such as glioblastoma and melanoma. Overall, our in vitro, in vivo, in silico, and clinical data suggest that several cancers exert oncogenic activity by maintaining their special lipid composition via extracellular blockade.

Metallothionein-3 is a multifunctional driver that modulates the development of sorafenib-resistant phenotype in hepatocellular carcinoma cells

BACKGROUND & AIMS

Metallothionein-3 (hMT3) is a structurally unique member of the metallothioneins family of low-mass cysteine-rich proteins. hMT3 has poorly characterized functions, and its importance for hepatocellular carcinoma (HCC) cells has not yet been elucidated. Therefore, we investigated the molecular mechanisms driven by hMT3 with a special emphasis on susceptibility to sorafenib.

METHODS

Intrinsically sorafenib-resistant (BCLC-3) and sensitive (Huh7) cells with or without up-regulated hMT3 were examined using cDNA microarray and methods aimed at mitochondrial flux, oxidative status, cell death, and cell cycle. In addition, in ovo/ex ovo chick chorioallantoic membrane (CAM) assays were conducted to determine a role of hMT3 in resistance to sorafenib and associated cancer hallmarks, such as angiogenesis and metastastic spread. Molecular aspects of hMT3-mediated induction of sorafenib-resistant phenotype were delineated using mass-spectrometry-based proteomics.

RESULTS

The phenotype of sensitive HCC cells can be remodeled into sorafenib-resistant one via up-regulation of hMT3. hMT3 has a profound effect on mitochondrial respiration, glycolysis, and redox homeostasis. Proteomic analyses revealed a number of hMT3-affected biological pathways, including exocytosis, glycolysis, apoptosis, angiogenesis, and cellular stress, which drive resistance to sorafenib.

CONCLUSIONS

hMT3 acts as a multifunctional driver capable of inducing sorafenib-resistant phenotype of HCC cells. Our data suggest that hMT3 and related pathways could serve as possible druggable targets to improve therapeutic outcomes in patients with sorafenib-resistant HCC.

Advances in Nanodelivery Systems Based on Metabolism Reprogramming Strategies for Enhanced Tumor Therapy

Tumor development and metastasis are closely related to the complexity of the metabolism network. Recently, metabolism reprogramming strategies have attracted much attention in tumor metabolism therapy. Although there is preliminary success of metabolism therapy agents, their therapeutic effects have been restricted by the effective reaching of the tumor sites of drugs. Nanodelivery systems with unique physical properties and elaborate designs can specifically deliver to the tumors. In this review, we first summarize the research progress of nanodelivery systems based on tumor metabolism reprogramming strategies to enhance therapies by depleting glucose, inhibiting glycolysis, depleting lactic acid, inhibiting lipid metabolism, depleting glutamine and glutathione, and disrupting metal metabolisms combined with other therapies, including chemotherapy, radiotherapy, photodynamic therapy, etc. We further discuss in detail the advantages of nanodelivery systems based on tumor metabolism reprogramming strategies for tumor therapy. As well as the opportunities and challenges for integrating nanodelivery systems into tumor metabolism therapy, we analyze the outlook for these emerging areas. This review is expected to improve our understanding of modulating tumor metabolisms for enhanced therapy.

Multiomics identifies metabolic subtypes based on fatty acid degradation allocating personalized treatment in hepatocellular carcinoma

BACKGROUND AND AIMS

Molecular classification is a promising tool for prognosis prediction and optimizing precision therapy for HCC. Here, we aimed to develop a molecular classification of HCC based on the fatty acid degradation (FAD) pathway, fully characterize it, and evaluate its ability in guiding personalized therapy.

APPROACH AND RESULTS

We performed RNA sequencing (RNA-seq), PCR-array, lipidomics, metabolomics, and proteomics analysis of 41 patients with HCC, in which 17 patients received anti-programmed cell death-1 (PD-1) therapy. Single-cell RNA sequencing (scRNA-seq) was performed to explore the tumor microenvironment. Nearly, 60 publicly available multiomics data sets were analyzed. The associations between FAD subtypes and response to sorafenib, transarterial chemoembolization (TACE), immune checkpoint inhibitor (ICI) were assessed in patient cohorts, patient-derived xenograft (PDX), and spontaneous mouse model ls. A novel molecular classification named F subtype (F1, F2, and F3) was identified based on the FAD pathway, distinguished by clinical, mutational, epigenetic, metabolic, and immunological characteristics. F1 subtypes exhibited high infiltration with immunosuppressive microenvironment. Subtype-specific therapeutic strategies were identified, in which F1 subtypes with the lowest FAD activities represent responders to compounds YM-155 and Alisertib, sorafenib, anti-PD1, anti-PD-L1, and atezolizumab plus bevacizumab (T + A) treatment, while F3 subtypes with the highest FAD activities are responders to TACE. F2 subtypes, the intermediate status between F1 and F3, are potential responders to T + A combinations. We provide preliminary evidence that the FAD subtypes can be diagnosed based on liquid biopsies.

CONCLUSIONS

We identified 3 FAD subtypes with unique clinical and biological characteristics, which could optimize individual cancer patient therapy and help clinical decision-making.

Targeted Analysis of Glycerophospholipids and Mono-, Di-, or Tri-Acylglycerides in Liver Cancer

The metabolic rearrangements of hepatic metabolism associated with liver cancer are still incompletely understood. There is an ongoing need to identify novel and more efficient diagnostic biomarkers and therapeutic targets based on the metabolic mechanisms of these diseases. In comparison to traditional diagnostic biomarkers, metabolomics is a comprehensive technique for discovering chemical signatures for liver cancer screening, prediction, and earlier diagnosis. Lipids are a large and diverse group of complex biomolecules that are at the heart of liver physiology and play an important role in the development and progression of cancer. In this chapter, we described two detailed protocols for targeted lipids analysis: glycerophospholipids and mono, di, tri-acylglycerides, both by Flow Injection Analysis (FIA) HPLC coupled to a SelexIon/QTRAP 6500+ system. These approaches provide a targeted lipidomic metabolomic signature of dissimilar metabolic disorders affecting liver cancers.

Metabolic transitions regulate global protein fatty acylation

Intermediary metabolites and flux through various pathways have emerged as key determinants of post-translational modifications. Independently, dynamic fluctuations in their concentrations are known to drive cellular energetics in a bi-directional manner. Notably, intracellular fatty acid pools that drastically change during fed and fasted states act as precursors for both ATP production and fatty acylation of proteins. Protein fatty acylation is well regarded for its role in regulating structure and functions of diverse proteins; however, the effect of intracellular concentrations of fatty acids on protein modification is less understood. In this regard, we unequivocally demonstrate that metabolic contexts, viz. fed and fasted states, dictate the extent of global fatty acylation. Moreover, we show that presence or absence of glucose that influences cellular and mitochondrial uptake/utilization of fatty acids and affects palmitoylation and oleoylation, which is consistent with their intracellular abundance in fed and fasted states. Employing complementary approaches including click-chemistry, lipidomics, and imaging, we show the top-down control of cellular metabolic state. Importantly, our results establish the crucial role of mitochondria and retrograde signaling components like SIRT4, AMPK, and mTOR in orchestrating protein fatty acylation at a whole cell level. Specifically, pharmacogenetic perturbations that alter either mitochondrial functions and/or retrograde signaling affect protein fatty acylation. Besides illustrating the cross-talk between carbohydrate and lipid metabolism in mediating bulk post-translational modification, our findings also highlight the involvement of mitochondrial energetics.

The role of tumor-associated macrophages in hepatocellular carcinoma progression: A narrative review

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in the world, with complex etiology and mechanism, and a high mortality rate. Tumor-associated macrophages (TAMs) are an important part of the HCC tumor microenvironment. Studies in recent years have shown that TAMs are involved in multiple stages of HCC and are related to treatment and prognosis in HCC. The specific mechanisms between TAMs and HCC are gradually being revealed. This paper reviews recent advances in the mechanisms associated with TAMs in HCC, concentrating on an overview of effects of TAMs on drug resistance in HCC and the signaling pathways linked with HCC, providing clues for the treatment and prognosis determination of HCC.

Targeting fatty acid uptake and metabolism in cancer cells: A promising strategy for cancer treatment

Despite scientific development, cancer is still a fatal disease. The development of cancer is thought to be significantly influenced by fatty acids. Several mechanisms that control fatty acid absorption and metabolism are reported to be altered in cancer cells to support their survival. Cancer cells can use de novo synthesis or uptake of extracellular fatty acid if one method is restricted. This factor makes it more difficult to target one pathway while failing to treat the disease properly. Side effects may also arise if several inhibitors simultaneously target many targets. If a viable inhibitor could work on several routes, the number of negative effects might be reduced. Comparative investigations against cell viability have found several potent natural and manmade substances. In this review, we discuss the complex roles that fatty acids play in the development of tumors and the progression of cancer, newly discovered and potentially effective natural and synthetic compounds that block the uptake and metabolism of fatty acids, the adverse side effects that can occur when multiple inhibitors are used to treat cancer, and emerging therapeutic approaches.

Chronic Administration of Diethylnitrosamine and 2-Acetylaminofluorene Induces Hepatocellular Carcinoma in Wistar Rats

This study aimed to analyze the biochemical, histological, and gene expression alterations produced in a hepatocarcinogenesis model induced by the chronic administration of diethylnitrosamine (DEN) and 2-acetylaminofluorene (2-AAF) in Wistar rats. Thirteen rats weighing 180 to 200 g were divided into two groups: control and treated. Rats in the treated group were administered an intraperitoneal (i.p.) injection of DEN (50 mg/kg/week) and an intragastric (i.g.) dose of 2-AAF (25 mg/kg/week) for 18 weeks. The treated group had significant increases in their total cholesterol, HDL-C, AST, ALT, ALKP, and GGT levels. Furthermore, a histological analysis showed the loss of normal liver architecture with nuclear pleomorphism in the hepatocytes, atypical mitosis, and fibrous septa that were distributed between the portal triads and collagen fibers through the hepatic sinusoids. The gene expressions of 24 genes related to fibrosis, inflammation, apoptosis, cell growth, angiogenesis, lipid metabolism, and alpha-fetoprotein (AFP) were analyzed; only TGFβ, COL1α1, CYP2E1, CAT, SOD, IL6, TNF-α, and ALB showed significant differences when both groups were compared. Additionally, lung histopathological alterations were found in the treated group, suggesting metastasis. In this model, the chronic administration of DEN+2-AAF induces characteristic alterations of hepatocellular carcinoma in Wistar rats without AFP gene expression changes, highlighting different signatures in hepatocellular carcinoma heterogeneity.

Integrative computational modeling to unravel novel potential biomarkers in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a major health problem around the world. The management of this disease is complicated by the lack of noninvasive diagnostic tools and the few treatment options available. Better clinical outcomes can be achieved if HCC is detected early, but unfortunately, clinical signs appear when the disease is in its late stages. We aim to identify novel genes that can be targeted for the diagnosis and therapy of HCC. We performed a meta-analysis of transcriptomics data to identify differentially expressed genes and applied network analysis to identify hub genes. Fatty acid metabolism, complement and coagulation cascade, chemical carcinogenesis and retinol metabolism were identified as key pathways in HCC. Furthermore, we integrated transcriptomics data into a reference human genome-scale metabolic model to identify key reactions and subsystems relevant in HCC. We conclude that fatty acid activation, purine metabolism, vitamin D, and E metabolism are key processes in the development of HCC and therefore need to be further explored for the development of new therapies. We provide the first evidence that GABRP, HBG1 and DAK (TKFC) genes are important in HCC in humans and warrant further studies.

Lipid metabolism of hepatocellular carcinoma impacts targeted therapy and immunotherapy

Hepatocellular carcinoma (HCC) is a common malignant tumor that affecting many people's lives globally. The common risk factors for HCC include being overweight and obese. The liver is the center of lipid metabolism, synthesizing most cholesterol and fatty acids. Abnormal lipid metabolism is a significant feature of metabolic reprogramming in HCC and affects the prognosis of HCC patients by regulating inflammatory responses and changing the immune microenvironment. Targeted therapy and immunotherapy are being explored as the primary treatment strategies for HCC patients with unresectable tumors. Here, we detail the specific changes of lipid metabolism in HCC and its impact on both these therapies for HCC. HCC treatment strategies aimed at targeting lipid metabolism and how to integrate them with targeted therapy or immunotherapy rationally are also presented.

Comprehensive analysis reveals TSEN54 as a robust prognosis biomarker and promising immune-related therapeutic target for hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma represents the most common primary malignancy of all liver cancer types and its prognosis is usually unsatisfactory. TSEN54 encodes a protein constituting a subunit of the tRNA splicing endonuclease heterotetramer. Previous researches concentrated on the contribution of TSEN54 in pontocerebellar hypoplasia, but no studies have yet reported its role in HCC.

METHODS

TIMER, HCCDB, GEPIA, HPA, UALCAN, MEXPRESS, SMART, TargetScan, RNAinter, miRNet, starBase, Kaplan-Meier Plotter, cBioPortal, LinkedOmics, GSEA, TISCH, TISIDB, GeneMANIA, PDB, GSCALite were applied in this research.

RESULTS

We identified the upregulation of TSEN54 expression in HCC and related it to multiple clinicopathological features. Hypomethylation of TSEN54 was closely associated with its high expression. HCC sufferers who held high TSEN54 expression typically had shorter survival expectations. Enrichment analysis showed the involvement of TSEN54 in the cell cycle and metabolic processes. Afterward, we observed that TSEN54 expression level had a positive relationship to the infiltration level of multiple immune cells and the expression of several chemokines. We additionally identified that TSEN54 was related to the expression level of several immune checkpoints and TSEN54 was linked to several m6A-related regulators.

CONCLUSIONS

TSEN54 is a prognostic marker of HCC. TSEN54 could become a prospective candidate for HCC diagnosis and therapy.

Location matters: cellular heterogeneity in the hepatic lobule and hepatocellular carcinoma

Tumor heterogeneity is a hallmark of cancer but a challenging problem to dissect mechanistically. Less recognized is that cells within normal tissues are also remarkably diverse. Hepatocytes are a great example because their spatial positioning and the local microenvironment govern their genetic heterogeneity. Recent studies show that primary liver tumors display heterogeneity similar to that observed in the normal tissue providing clues to the cellular precursor of the tumor and how variations in the lobule microenvironment support tumor formation and aggressiveness. Identifying the principles that control cellular diversity in a healthy liver may highlight potential mechanisms driving hepatic tumor heterogeneity.

A novel fatty acid metabolism-related gene prognostic signature and candidate drugs for patients with hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the deadliest cancers. Fatty acid metabolism (FAM) is associated with the development and treatment of HCC. This study aimed to build a FAM-related gene model to assess the prognosis of HCC and provide guidance for individual treatment. RNA-sequencing data of patients with HCC from The Cancer Genome Atlas and Gene Expression Omnibus database (GSE14520) were extracted as the training and validation sets, respectively. A FAM-related gene predictive signature was built, and the performance of prognostic model was assessed. The immune infiltration and drug sensitivity were also evaluated. Quantitative real-time polymerase chain reaction and western blot were performed to evaluate the levels of the model genes. A 12-gene FAM-related risk signature was constructed; patients with a higher risk score had poorer prognosis than those with a lower risk score. Risk score was shown as an independent risk factor for overall survival of HCC, and the signature was further confirmed as an effective and accurate model. A nomogram was constructed, and it exhibited the good performance in the prognostic prediction. In addition, the immune cell infiltration and sensitivity to chemotherapy drugs were correlated with different risk levels. Finally, quantitative real-time polymerase chain reaction and western blot proved the changes of above genes. Differential expression of FAM-related genes can be used to predict response to immunotherapy and chemotherapy, and improve the clinical prognosis evaluation of patients with HCC, which provides new clues for further experimental exploration and verification on FAM-related genes in HCC.

Targeting SLP2-mediated lipid metabolism reprograming restricts proliferation and metastasis of hepatocellular carcinoma and promotes sensitivity to Lenvatinib

SLP2, a protein located on mitochondrial, has been shown to be associated with mitochondrial biosynthesis. Here we explored the potential mechanisms by which SLP2 regulates the development of hepatocellular carcinoma. SLP2 could bind to the c-terminal of JNK2 to affect the ubiquitinated proteasomal degradation pathway of JNK2 and maintain the protein stability of JNK2. The increase of JNK2 markedly increases SREBP1 activity, promoting SREBP1 translocation into the nucleus to promote de novo lipogenesis. Alteration of the JNK2 C-terminal disables SLP2 from mediating SLP2-enhanced de novo lipogenesis. YTHDF1 interacts with SLP2 mRNA in a METTL3/m⁶A-dependent manner. In a spontaneous HCC animal model, SLP2/c-Myc/sgP53 increases the incidence rate of spontaneous HCC, tumor volume, and tumor number. Importantly, statistical analyses show that levels of SLP2 correlate with tumor sizes, tumor metastasis, overall survival, and disease-free survival of the patients. Targeting the SLP2/SREBP1 pathway effectively inhibits proliferation and metastasis of HCC tumors with high SLP2 expression in vivo combined with lenvatinib. These results illustrate a direct lipogenesis-promoting role of the pro-oncogenic SLP2, providing a mechanistic link between de novo lipogenesis and HCC.

Metabolomics and Lipidomics Screening Reveal Reprogrammed Signaling Pathways toward Cancer Development in Non-Alcoholic Steatohepatitis

With the rising incidence of hepatocellular carcinoma (HCC) from non-alcoholic steatohepatitis (NASH), identifying new metabolic readouts that function in metabolic pathway perpetuation is still a demand. The study aimed to compare the metabolic signature between NASH and NASH-HCC patients to explore novel reprogrammed metabolic pathways that might modulate cancer progression in NASH patients. NASH and NASH-HCC patients were recruited and screened for metabolomics, and isotope-labeled lipidomics were targeted and profiled using the EXION-LCTM system equipped with a Triple-TOFTM 5600+ system. Results demonstrated significantly (p ≤ 0.05) higher levels of triacylglycerol, AFP, AST, and cancer antigen 19-9 in NASH-HCC than in NASH patients, while prothrombin time, platelet count, and total leukocyte count were decreased significantly (p ≤ 0.05). Serum metabolic profiling showed a panel of twenty metabolites with 10% FDR and p ≤ 0.05 in both targeted and non-targeted analysis that could segregate NASH-HCC from NASH patients. Pathway analysis revealed that the metabolites are implicated in the down-regulation of necroptosis, amino acid metabolism, and regulation of lipid metabolism by PPAR-α, biogenic amine synthesis, fatty acid metabolism, and the mTOR signaling pathway. Cholesterol metabolism, DNA repair, methylation pathway, bile acid, and salts metabolism were significantly upregulated in NASH-HCC compared to the NASH group. Metabolite-protein interactions network analysis clarified a set of well-known protein encoding genes that play crucial roles in cancer, including PEMT, IL4I1, BAAT, TAT, CDKAL1, NNMT, PNP, NOS1, and AHCYL. Taken together, reliable metabolite fingerprints are presented and illustrated in a detailed map for the most predominant reprogrammed metabolic pathways that target HCC development from NASH.

The Tumor Microenvironment of Hepatocellular Carcinoma: Untying an Intricate Immunological Network

HCC, the most prevalent form of primary liver cancer, is prototypically an inflammation-driven cancer developing after years of inflammatory insults. Consequently, the hepatic microenvironment is a site of complex immunological activities. Moreover, the tolerogenic nature of the liver can act as a barrier to anti-tumor immunity, fostering cancer progression and resistance to immunotherapies based on immune checkpoint inhibitors (ICB). In addition to being a site of primary carcinogenesis, many cancer types have high tropism for the liver, and patients diagnosed with liver metastasis have a dismal prognosis. Therefore, understanding the immunological networks characterizing the tumor microenvironment (TME) of HCC will deepen our understanding of liver immunity, and it will underpin the dominant mechanisms controlling both spontaneous and therapy-induced anti-tumor immune responses. Herein, we discuss the contributions of the cellular and molecular components of the liver immune contexture during HCC onset and progression by underscoring how the balance between antagonistic immune responses can recast the properties of the TME and the response to ICB.

Abnormal expression of HADH, an enzyme of fatty acid oxidation, affects tumor development and prognosis (Review)

Tumor occurrence and progression are closely associated with abnormal energy metabolism and energy metabolism associated with glucose, proteins and lipids. The reprogramming of energy metabolism is one of the hallmarks of cancer. As a form of energy metabolism, fatty acid metabolism includes fatty acid uptake, de novo synthesis and β‑oxidation. In recent years, the role of abnormal fatty acid β‑oxidation in tumors has gradually been recognized. Mitochondrial trifunctional protein (MTP) serves an important role in fatty acid β‑oxidation and HADH (two subtypes: α subunit, HADHA and β subunit, HADHB) are important subunits of MTP. HADH participates in the steps of 2, 3 and 4 fatty acid β‑oxidation. However, there is no review summarizing the specific role of HADH in tumors. Therefore, the present study focused on HADH as the main indicator to explore the changes in fatty acid β‑oxidation in several types of tumors. The present review summarized the changes in HADH in 11 organs (cerebrum, oral cavity, esophagus, liver, pancreas, stomach, colorectum, lymph, lung, breast, kidney), the effect of up‑ and downregulation and the relationship of HADH with prognosis. In summary, HADH can be either a suppressor or a promoter depending on where the tumor is located, which is closely associated with prognostic assessment. HADHA and HADHB have similar prognostic roles in known and comparable tumors.

Exploring a four-gene risk model based on doxorubicin resistance-associated lncRNAs in hepatocellular carcinoma

Background: Liver cancer is a lethal cancer type among which hepatocellular carcinoma (HCC) is the most common manifestation globally. Drug resistance is a central problem impeding the efficiency of HCC treatment. Long non-coding RNAs reportedly result in drug resistance. This study aimed to identify key lncRNAs associated with doxorubicin resistance and HCC prognosis.

Materials and Methods: HCC samples with gene expression profiles and clinical data were accessed from public databases. We applied differential analysis to identify key lncRNAs that differed between HCC and normal samples and between drug-fast and control samples. We also used univariate Cox regression analysis to screen lncRNAs or genes associated with HCC prognosis. The least absolute shrinkage and selection operator (LASSO) was used to identify the key prognostic genes. Finally, we used receiver operating characteristic analysis to validate the effectiveness of the risk model.

Results: The results of this study revealed RNF157-AS1 as a key lncRNA associated with both doxorubicin resistance and HCC prognosis. Metabolic pathways such as fatty acid metabolism and oxidative phosphorylation were enriched in RNF157-AS1-related genes. LASSO identified four protein-coding genes—CENPP, TSGA10, MRPL53, and BFSP1—to construct a risk model. The four-gene risk model effectively classified HCC samples into two risk groups with different overall survival. Finally, we established a nomogram, which showed superior performance in predicting the long-term prognosis of HCC.

Conclusion: RNF157-AS1 may be involved in doxorubicin resistance and may serve as a potential therapeutic target. The four-gene risk model showed potential for the prediction of HCC prognosis.

Identification and validation of a fatty acid metabolism-related lncRNA signature as a predictor for prognosis and immunotherapy in patients with liver cancer

Background

Fatty acid (FA) metabolism is considered the emerging cause of tumor development and metastasis, driving poor prognosis. Long non-coding RNAs (lncRNAs) are closely related to cancer progression and play important roles in FA metabolism. Thus, the discovery of FA metabolism-related lncRNA signatures to predict outcome and immunotherapy response is critical in improving the survival of patients with hepatocellular carcinoma (HCC).

Methods

FA metabolism scores and a FA metabolism-related lncRNA signature were constructed using a single-sample gene set enrichment analysis based on The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. “ConsensusClusterPlus” was used to screen molecular subtypes. Chi-squared test and Fisher’s exact test were applied to explore the relationship between clinical, genomic mutation characteristics and subtypes. Transcription factor (TF) activity scores, cellular distributions, immune cell infiltration, and immunotherapy response were employed to investigate the functions of FA metabolism-related lncRNA signatures. FA metabolism microarray and western blot were performed to detect the biological function of candidate lncRNAs.

Results

A total of 70 lncRNAs that highly correlated with FA metabolism scores in two cohorts were used to construct two distinct clusters. Patients in cluster 2 had lower FA metabolism scores and worse survival than those in cluster 1. Patients in cluster 2 exhibited a high frequency of DNA damage, gene mutations, oncogenic signaling such as epithelial-to-mesenchymal transition, and a high degree of immune cell infiltration. Moreover, the lncRNA signature could predict the effects of immunotherapy in patients with HCC. Furthermore, three lncRNAs (SNHG1, LINC00261, and SNHG7) were identified that were highly correlated with FA metabolism. Additionally, SNHG1 and SNHG7 were found to regulate various FA metabolism-related genes and ferroptosis-related genes in vitro experiments. GSEA analysis revealed that SNHG1 and SNHG7 promote fatty acid beta-oxidation. SNHG1 and SNHG7 silencing dramatically reduced lipid droplets in HCC cells. Many immune-infiltration genes and TFs were overexpressed in HCC tissues with SNHG1 and SNHG7 high expression.

Conclusions

A novel molecular model of FA metabolism-related lncRNAs was developed, which has significantly prognostic potential in HCC diagnosis and aids in clinical decision making.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-10122-4.

Bioinformatics analysis and experimental verification of the prognostic and biological significance mediated by fatty acid metabolism related genes for hepatocellular carcinoma

Background

Liver cancer is among the leading causes of death related to cancer around the world. The most frequent type of human liver cancer is hepatocellular carcinoma (HCC). Fatty acid (FA) metabolism is an emerging hallmark that plays a promoting role in numerous malignancies. This study aimed to discover a FA metabolism-related risk signature and formulate a better model for HCC patients’ prognosis prediction.

Methods

We collected mRNA expression data and clinical parameters of patients with HCC using the TCGA databases, and the differential FA metabolism-related genes were explored. To create a risk prognostic model, we carried out the consensus clustering as well as univariate and multivariate Cox regression analyses. 16 genes were used to establish a prognostic model, which was then validated in the ICGC dataset. The accuracy of the model was performed using receiver operating characteristic (ROC) analyses, decision curve analysis (DCA) and nomogram. The immune cell infiltration level of risk genes was evaluated with single-sample GSEA (ssGSEA) algorithm. To reflect the response to immunotherapy, immunophenoscore (IPS) was obtained from TCGA-LIHC. Then, the expression of the candidate risk genes (p < 0.05) was validated by qRT-PCR, Western blotting and single-cell transcriptomics. Cellular function assays were performed to revealed the biological function of HAVCR1.

Results

According to the TCGA-LIHC cohort analysis, the majority of the FA metabolism-related genes were expressed differentially in the HCC and normal tissues. The prognosis of patients with high-risk scores was observed to be worse. Multivariate COX regression analysis confirmed that the model can be employed as an independent prognosis factor for HCC patients. Furthermore, ssGSEA analysis revealed a link between the model and the levels of immune cell infiltration. Our model scoring mechanism also provides a high predictive value in HCC patients receiving anti-PDL1 immunotherapy. One of the FA metabolism-related genes, HAVCR1, displays a significant differential expression between normal and HCC cell lines. Hepatocellular carcinoma cells (Huh7, and HepG2) proliferation, motility, and invasion were all remarkably inhibited by HAVCR1 siRNA.

Conclusion

Our study identified a novel FA metabolism-related prognostic model, revealing a better potential treatment and prevention strategy for HCC.

Tuftelin 1 Facilitates Hepatocellular Carcinoma Progression through Regulation of Lipogenesis and Focal Adhesion Maturation

Hepatocellular carcinoma (HCC) is the most common type of primary liver malignancy with poor prognosis worldwide. Emerging evidences demonstrated critical roles of lipid de novo synthesis in HCC progression, yet its regulatory mechanisms are not fully understood. Herein, we found that tuftelin 1 (TUFT1), an acidic phosphorylated glycoprotein with secretory capacity, was significantly upregulated in HCC and had an excellent correlation with patient survival and malignancy features. Through database mining and experimental validation, we found that TUFT1 was associated with fatty acid metabolism and promoted lipid accumulation in HCC cells. Further, we found that TUFT1 can interact with CREB1, a transcription factor for hepatic lipid metabolism, and regulate its activity and the transcriptions of key enzymes for lipogenesis. TUFT1 promoted HCC cell proliferation significantly, which was partially reversed by treatment of an inhibitor of CREB1, KG-501. Moreover, TUFT1 promoted the capacity of HCC cell invasion in vitro, which was likely mediated by its association with zyxin, a zinc-binding phosphoprotein responsible for the formation of fully mature focal adhesions on extracellular matrix. We found that TUFT1 can interact with ZYX and inhibit its expression and recruitments to focal complexes in HCC cells. Collectively, our study uncovered new regulatory mechanisms of TUFT1-mediated lipogenesis, cell proliferation, and invasion.

Machine Learning-Assisted FTIR Analysis of Circulating Extracellular Vesicles for Cancer Liquid Biopsy

Extracellular vesicles (EVs) are abundantly released into the systemic circulation, where they show remarkable stability and harbor molecular constituents that provide biochemical information about their cells of origin. Due to this characteristic, EVs are attracting increasing attention as a source of circulating biomarkers for cancer liquid biopsy and personalized medicine. Despite this potential, none of the discovered biomarkers has entered the clinical practice so far, and novel approaches for the label-free characterization of EVs are highly demanded. In this regard, Fourier Transform Infrared Spectroscopy (FTIR) has great potential as it provides a quick, reproducible, and informative biomolecular fingerprint of EVs. In this pilot study, we investigated, for the first time in the literature, the capability of FTIR spectroscopy to distinguish between EVs extracted from sera of cancer patients and controls based on their mid-IR spectral response. For this purpose, EV-enriched suspensions were obtained from the serum of patients diagnosed with Hepatocellular Carcinoma (HCC) of nonviral origin and noncancer subjects. Our data point out the presence of statistically significant differences in the integrated intensities of major mid-IR absorption bands, including the carbohydrate and nucleic acids band, the protein amide I and II bands, and the lipid CH stretching band. Additionally, we used Principal Component Analysis combined with Linear Discriminant Analysis (PCA-LDA) for the automated classification of spectral data according to the shape of specific mid-IR spectral signatures. The diagnostic performances of the proposed spectral biomarkers, alone and combined, were evaluated using multivariate logistic regression followed by a Receiving Operator Curve analysis, obtaining large Areas Under the Curve (AUC = 0.91, 95% CI 0.81–1.0). Very interestingly, our analyses suggest that the discussed spectral biomarkers can outperform the classification ability of two widely used circulating HCC markers measured on the same groups of subjects, namely alpha-fetoprotein (AFP), and protein induced by the absence of vitamin K or antagonist-II (PIVKA-II).

High childhood serum triglyceride concentrations associate with hepatocellular adenoma development in patients with glycogen storage disease type Ia

Background & Aims

Glycogen storage disease type Ia (GSDIa) is an inborn error of carbohydrate metabolism caused by pathogenic variants in the glucose-6-phosphatase catalytic subunit 1 (G6PC1) gene and is associated with hepatocellular adenoma (HCA) formation. Data on risk factors for HCA occurrence in GSDIa are scarce. We investigated HCA development in relation to sex, G6PC1 genotype, and serum triglyceride concentration (TG).

Methods

An observational study of patients with genetically confirmed GSDIa ≥12 years was performed. Patients were categorised for sex; presence of 2, 1, or 0 predicted severe G6PC1 variant (PSV); and median TG during childhood (<12 years; stratified for above/below 5.65 mmol/L, i.e. 500 mg/dl).

Results

Fifty-three patients (23 females) were included, of which 26 patients developed HCA at a median (IQR) age of 21 (17–25) years. At the age of 25 years, 48% of females and 30% of males had developed HCA (log-rank p = 0.045). Two-thirds of patients with GSDIa carried 2 PSVs, 20% carried 1, and 13% carried none. Neither the number of PSVs nor any specific G6PC1 variants were associated with HCA occurrence. Childhood TG was 3.4 (3.0–4.2) mmol/L in males vs. 5.6 (4.0–7.9) mmol/L in females (p = 0.026). Childhood TG >5.65 mmol/L was associated with HCA development at younger age, compared with patients with childhood TG <5.65 mmol/L (18 vs. 33 years; log-rank p = 0.001). Cox regression analysis including TG, sex, and TG–sex interaction correction revealed childhood TG >5.65 mmol/L as an independent risk factor for HCA development (hazard ratio [HR] 6.0; 95% CI 1.2–29.8; p = 0.028).

Conclusions

In patients with GSDIa, high childhood TG was associated with an increased risk of HCA, and earlier onset of HCA development, independent of sex-associated hypertriglyceridaemia, and G6PC1 genotype.

Lay summary

Glycogen storage disease type Ia (GSDIa) is a rare, inherited metabolic disease that can be complicated by liver tumours (hepatocellular adenomas), which in turn may cause bleeding or progress to liver cancer. Risk factors associated with hepatocellular adenoma formation in patients with GSDIa are largely unknown. In our study, we found that high serum triglyceride concentrations during childhood, but not specific genetic variants, were associated with increased risk of hepatocellular adenoma diagnosis later in life.

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Glycogen storage disease Ia (GSDIa) is a metabolic disease caused by mutations in glucose-6-phosphatase catalytic subunit 1 (G6PC1).

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Patients with GSDIa often develop hepatocellular adenoma (HCA), with unclear risk factors.

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Metabolic control in GSDIa is commonly evaluated through serum triglyceride concentration (TG).

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Patients with GSDIa with high childhood TG had increased risk and earlier onset of HCA.

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Sex-associated hypertriglyceridaemia and G6PC1 genotype were not associated with HCA.

Navigating through the Lipid Metabolism Maze: Diagnosis and Prognosis Metabolites of Hepatocellular Carcinoma versus Compensated Cirrhosis

(1) Background: The pursuit of finding biomarkers for the diagnosis and prognosis of hepatocellular carcinoma (HCC) has never been so paramount in the days of personalized medicine. The main objective of our study is to identify new biomarkers for diagnosing HCC, and to identify which patients are at risk of developing tumor recurrence, decompensation, or even possesses the risk of cancer-related death. (2) Methods: We have conducted an untargeted metabolomics study from the serum of 69 European patients—32 compensated cirrhotic patients without HCC (controls), and 37 cirrhotic patients with HCC with compensated underlying liver disease (cases), that underwent curative treatment (surgery or ablation), performing ultra-high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (UHPLC-QTOF- (ESI+)-MS) with an emphasis on lipid metabolites. (3) Results: 1,25-dihydroxy cholesterol (m/z = 419.281), myristyl palmitate (m/z = 453.165), 25-hydroxy vitamin D2 (m/z = 413.265), 12-ketodeoxycholic acid (m/z = 391.283), lysoPC (21:4) (m/z = 558.291), and lysoPE (22:2) (m/z = 534.286) represent notable biomarkers that differentiate compensated cirrhosis from early HCC, and ceramide species are depleted in the serum of HCC patients. Regarding prognosis, no metabolite identified in our study could determine tumor relapse. To distinguish between the HCC patients that survived curative treatment and those at risk that developed tumor burden, we have identified two notable phosphocholines (PC (30:2); PC (30:1)) with AUROCs of 0.820 and 0.807, respectively, that seem to increase when patients are at risk. In a univariate analysis, arachidonic acid was the only metabolite to predict decompensation (OR = 0.1, 95% CI: 0−0.16, p < 0.005), while in the multivariate analysis, dismally, no variable was associated with decompensation. Furthermore, in the multivariate analysis, we have found out for the first time that the increased expression of 1,25-dihydroxy cholesterol, myristyl palmitate, 12-keto deoxycholic acid, lysoPC (21:4), and lysoPE (22:2) are independent markers of survival. (4) Conclusions: Our study reveals that lipids play a crucial role in discriminating compensated cirrhosis and early hepatocellular carcinoma, and might represent markers of survival and prognosis in personalized and minimally invasive medicine.

Metabolic dysregulation and emerging therapeutical targets for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an aggressive human cancer with increasing incidence worldwide. Multiple efforts have been made to explore pharmaceutical therapies to treat HCC, such as targeted tyrosine kinase inhibitors, immune based therapies and combination of chemotherapy. However, limitations exist in current strategies including chemoresistance for instance. Tumor initiation and progression is driven by reprogramming of metabolism, in particular during HCC development. Recently, metabolic associated fatty liver disease (MAFLD), a reappraisal of new nomenclature for non-alcoholic fatty liver disease (NAFLD), indicates growing appreciation of metabolism in the pathogenesis of liver disease, including HCC, thereby suggesting new strategies by targeting abnormal metabolism for HCC treatment. In this review, we introduce directions by highlighting the metabolic targets in glucose, fatty acid, amino acid and glutamine metabolism, which are suitable for HCC pharmaceutical intervention. We also summarize and discuss current pharmaceutical agents and studies targeting deregulated metabolism during HCC treatment. Furthermore, opportunities and challenges in the discovery and development of HCC therapy targeting metabolism are discussed.

Citrate enrichment in a Western diet reduces weight gain via browning of adipose tissues without resolving diet-induced insulin resistance in mice

Citrate, a major component of processed foods, reduces weight gain without resolving insulin resistance.

Fatty acid transport protein-5 (FATP5) deficiency enhances hepatocellular carcinoma progression and metastasis by reprogramming cellular energy metabolism and regulating the AMPK-mTOR signaling pathway

Aberrant lipid metabolism is an essential feature of hepatocellular carcinoma (HCC). Fatty acid transport protein-5 (FATP5) is highly expressed in the liver and is involved in the fatty acid transport pathway. However, the potential role of FATP5 in the pathogenesis of HCC remains largely unknown. Herein, we showed that FATP5 was downregulated in HCC tissues and even much lower in vascular tumor thrombi. Low expression of FATP5 was correlated with multiple aggressive and invasive clinicopathological characteristics and contributed to tumor metastasis and a poor prognosis in HCC patients. FATP5 inhibited the epithelial–mesenchymal transition (EMT) process and suppressed HCC cell migration and invasion, while silencing FATP5 had the opposite effects. Mechanistically, knockdown of FATP5 promoted cellular glycolytic flux and ATP production, thus suppressing AMP-activated protein kinase (AMPK) and activating its downstream signaling mammalian target of rapamycin (mTOR) to support HCC progression and metastasis. Activation of AMPK using metformin reversed the EMT program and impaired the metastatic capacity of FATP5-depleted HCC cells. Collectively, FATP5 served as a novel suppressor of HCC progression and metastasis partly by regulating the AMPK/mTOR pathway in HCC, and targeting the FATP5-AMPK axis may be a promising therapeutic strategy for personalized HCC treatment.

The immunological and metabolic landscape in primary and metastatic liver cancer

The liver is the sixth most common site of primary cancer in humans, and generally arises in a background of cirrhosis and inflammation. Moreover, the liver is frequently colonized by metastases from cancers of other organs (particularly the colon) because of its anatomical location and organization, as well as its unique metabolic and immunosuppressive environment. In this Review, we discuss how the hepatic microenvironment adapts to pathologies characterized by chronic inflammation and metabolic alterations. We illustrate how these immunological or metabolic changes alter immunosurveillance and thus hinder or promote the development of primary liver cancer. In addition, we describe how inflammatory and metabolic niches affect the spreading of cancer metastases into or within the liver. Finally, we review the current therapeutic options in this context and the resulting challenges that must be surmounted.

An Integrated Transcriptomics and Proteomics Analysis Implicates lncRNA MALAT1 in the Regulation of Lipid Metabolism

Long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is upregulated in various cancers, and its overexpression is associated with tumor growth and metastasis. MALAT1 has been recognized as a key player in the regulation of RNA splicing and transcription; however, the landscape of gene expression regulated by MALAT1 remains unclear. In this study, we employed an integrated transcriptomics and proteomics strategy to characterize the alterations in gene expression induced by MALAT1 knockdown in hepatocellular carcinoma (HCC) cells and identified 2662 differentially expressed transcripts and 1149 differentially expressed proteins. Interestingly, downregulation of MALAT1 reduced the abundances of multiple genes in the AMP-activated protein kinase (AMPK) signaling and biosynthesis of unsaturated fatty acids pathways. Further investigation showed that MALAT1 knockdown inhibited glucose uptake and lipogenesis by reducing the expression levels of these lipid metabolism related genes, which contributes to the oncogenic role of MALAT1 in tumor cell proliferation and invasion. This study uncovers the function of MALAT1 in the modulation of cancer lipid metabolism, reveals the underlying molecular mechanism, and further supports the potential therapeutic opportunities for targeting MALAT1 in HCC treatment.

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Multiomic analysis characterizes MALAT1-regulated gene expression in HCC cells.

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MALAT1 knockdown reduces the expression of genes involving in lipid metabolism.

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MALAT1 knockdown inhibits glucose uptake and lipogenesis.

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MALAT1 promotes HCC cell proliferation and migration through regulating lipid metabolism.

Facile Synthesis of Antibody-Coupled Polydopamine-Coated Magnetic Graphene Oxide Composites for Efficient Immunopurification and Metabolomics Analysis of Mitochondria

As a vital hub, a mitochondrion houses metabolic pathways that play important roles in cellular physiology. Aberrant metabolites occurring in mitochondria are closely associated with the emergence and progression of various mitochondria-related diseases. Therefore, a simple and versatile approach to efficiently purify intact mitochondria is urgently needed to precisely and comprehensively characterize the composition and abundance of the mitochondrial metabolome in different physiological and pathological states. In this work, novel immunoaffinitive magnetic composites MagG@PD@Avidin@TOM20 were prepared to achieve highly selective isolation of intact mitochondria from three different hepatocytes (LO2, HepG2, and Huh7). The prepared composites inherit combined merits, including strong magnetic responsiveness, excellent stability, and specific and high affinity between antibody TOM20 and mitochondrial outer membrane protein. These mitochondria attached on MagG@PD@Avidin@TOM20 were characterized by the western blot and fluorescence microscopy to confirm their purity and integrity, which are vital for reliable mitochondrial metabolic analysis. Subsequently, ultrahigh-performance liquid chromatography-high-resolution mass spectrometry-based untargeted metabolomics analysis was conducted to characterize the metabolomes in the immunopurified mitochondria and whole cells. Notably, the metabolite profiles of whole cells and mitochondria including itaconic acid, acetylcarnitine, malic acid, etc., were significantly different. These data underscore the importance of determining metabolites at the mitochondrial level, which would supplement us new knowledge at the subcellular level.

Current Trends in Non-Invasive Imaging of Interactions in the Liver Tumor Microenvironment Mediated by Tumor Metabolism

Simple Summary

Deregulated tumor metabolism is known to shape the tumor microenvironment and directly affect the local immune response, promoting tumor growth, metastasis, and resistance to treatment. However, the metabolic profile or tumor cells, and therefore, the composition of their microenvironment, are highly variable among patients and even within the same tumor, resulting in heterogeneous response rates to oncologic therapies, making patient selection a key issue. This review article focuses on non-invasive imaging techniques that aim to visualize the crosstalk between tumor cells and their microenvironment in liver cancer mediated by tumor metabolism. In addition to improved tumor detection, such imaging tools may be able to provide a more accurate characterization of the individual tumor and ultimately improve understanding, as well as guide personalized treatment regimens for patients with liver cancer.

Abstract

With the increasing understanding of resistance mechanisms mediated by the metabolic reprogramming in cancer cells, there is a growing clinical interest in imaging technologies that allow for the non-invasive characterization of tumor metabolism and the interactions of cancer cells with the tumor microenvironment (TME) mediated through tumor metabolism. Specifically, tumor glycolysis and subsequent tissue acidosis in the realms of the Warburg effect may promote an immunosuppressive TME, causing a substantial barrier to the clinical efficacy of numerous immuno-oncologic treatments. Thus, imaging the varying individual compositions of the TME may provide a more accurate characterization of the individual tumor. This approach can help to identify the most suitable therapy for each individual patient and design new targeted treatment strategies that disable resistance mechanisms in liver cancer. This review article focuses on non-invasive positron-emission tomography (PET)- and MR-based imaging techniques that aim to visualize the crosstalk between tumor cells and their microenvironment in liver cancer mediated by tumor metabolism.

Identification of Multiple Hub Genes and Pathways in Hepatocellular Carcinoma: A Bioinformatics Analysis

Hepatocellular carcinoma (HCC) is a common malignant tumor of the digestive system, and its early asymptomatic characteristic increases the difficulty of diagnosis and treatment. This study is aimed at obtaining some novel biomarkers with diagnostic and prognostic meaning and may find out potential therapeutic targets for HCC. We screen differentially expressed genes (DEGs) from the HCC gene expression profile GSE14520 using GEO2R. Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were conducted by using the clusterProfiler software while a protein-protein interaction (PPI) network was performed based on the STRING database. Then, prognosis analysis of hub genes was conducted using The Cancer Genome Atlas (TCGA) database. Quantitative real-time polymerase chain reaction (qRT-PCR) was utilized to further verify the expression of hub genes and explore the correlation between gene expression and clinicopathological parameters. A total of 1053 DEGs were captured, containing 497 upregulated genes and 556 downregulated genes. GO and KEGG analysis indicated that the downregulated DEGs were mainly enriched in the fatty acid catabolic process while upregulated DEGs were primarily enriched in the cell cycle. Simultaneously, ten hub genes (CYP3A4, UGT1A6, AOX1, UGT1A4, UGT2B15, CDK1, CCNB1, MAD2L1, CCNB2, and CDC20) were identified by the PPI network. Five prognosis-related hub genes (CYP3A4, CDK1, CCNB1, MAD2L1, and CDC20) were uncovered by the survival analysis based on TCGA database. The ten hub genes were further validated by qRT-PCR using samples obtained from our hospital. The prognosis-related hub genes such as CYP3A4, CDK1, CCNB1, MAD2L1, and CDC20 could be considered potential diagnosis biomarkers and prognosis targets for HCC. We also use Oncomine for further verification, and we found CCNB1, CCNB2, CDK1, and CYP3A4 which were highly expressed in HCC. Meanwhile, CCNB1, CCNB2, and CDK1 are highly expressed in almost all cancer types, which may play an important role in cancer. Still, further functional study should be conducted to explore the underlying mechanism and biological effect in the near future.

The Role of Fatty Acids in Non-Alcoholic Fatty Liver Disease Progression: An Update

Non-alcoholic fatty liver disease (NAFLD) is a major public health problem worldwide. NAFLD (both simple steatosis and steatohepatitis) is characterized by alterations in hepatic lipid metabolism, which may lead to the development of severe liver complications including cirrhosis and hepatocellular carcinoma. Thus, an exhaustive examination of lipid disorders in the liver of NAFLD patients is much needed. Mass spectrometry-based lipidomics platforms allow for in-depth analysis of lipid alterations in a number of human diseases, including NAFLD. This review summarizes the current research on lipid alterations associated with NAFLD and related complications, with special emphasis on the changes in long-chain and short-chain fatty acids levels in both serum and liver tissue, as well as in the hepatic expression of genes encoding the enzymes catalyzing lipid interconversions.

Cancer-associated cells release citrate to support tumour metastatic progression

Citrate is important for lipid synthesis and epigenetic regulation in addition to ATP production. We have previously reported that cancer cells import extracellular citrate via the pmCiC transporter to support their metabolism. Here, we show for the first time that citrate is supplied to cancer by cancer-associated stroma (CAS) and also that citrate synthesis and release is one of the latter's major metabolic tasks. Citrate release from CAS is controlled by cancer cells through cross-cellular communication. The availability of citrate from CAS regulated the cytokine profile, metabolism and features of cellular invasion. Moreover, citrate released by CAS is involved in inducing cancer progression especially enhancing invasiveness and organ colonisation. In line with the in vitro observations, we show that depriving cancer cells of citrate using gluconate, a specific inhibitor of pmCiC, significantly reduced the growth and metastatic spread of human pancreatic cancer cells in vivo and muted stromal activation and angiogenesis. We conclude that citrate is supplied to tumour cells by CAS and citrate uptake plays a significant role in cancer metastatic progression.

GDF11 rapidly increases lipid accumulation in liver cancer cells through ALK5-dependent signaling

Hepatocellular carcinoma (HCC) is one of the fastest-growing causes of cancer-related mortalities worldwide and this trend is mimicked by the surge of non-alcoholic fatty liver disease (NAFLD). Altered hepatic lipid metabolism promotes HCC development through inflammation and activation of oncogenes. GDF11 is a member of the TGF-β superfamily and recent data have implicated GDF11 as an anti-aging factor that can alleviate high-fat diet induced obesity, hyperglycemia, insulin resistance and NAFLD. However, its role in hepatic lipid metabolism is still not fully delineated. The aim of the present study was to characterize the role of GDF11 in hepatic and HCC cells lipid accumulation. To achieve this, we performed imaging, biochemical, lipidomic, and transcriptomic analyses in primary hepatocytes and in HCC cells treated with GDF11 to study the GDF11-activated signaling pathways. GDF11 treatment rapidly triggered ALK5-dependent SMAD2/3 nuclear translocation and elevated lipid droplets in HCC cells, but not in primary hepatocytes. In HCC cells, ALK5 inhibition hampered GDF11-mediated SMAD2/3 signaling and attenuated lipid accumulation. Using ultra-high-performance liquid chromatography/mass spectrometry, we detected increased accumulation of longer acyl-chain di/tri-acylglycerols and glycerophospholipids. Unbiased transcriptomic analysis identified TGF-β and PI3K-AKT signaling among the top pathways/cellular processes activated in GDF11 treated HCC cells. In summary, GDF11 supplementation promotes pro-lipogenic gene expression and lipid accumulation in HCC cells. Integration of our "omics" data pointed to a GDF11-induced upregulation of de novo lipogenesis through activation of ALK5/SMAD2/3/PI3K-AKT pathways. Thus, GDF11 could contribute to metabolic reprogramming and dysregulation of lipid metabolism in HCC cells, without effects on healthy hepatocytes.

Remodeling Lipids in the Transition from Chronic Liver Disease to Hepatocellular Carcinoma

Simple Summary

Hepatocellular carcinoma (HCC) has poor prognosis. We studied blood lipids by comparing healthy volunteers to patients with chronic liver disease (CLD), and to patients with HCC caused by viral infections. We contrasted our findings in blood to lipid alterations in liver tumor and nontumor tissue samples from HCC patients. In blood, most lipid species were found at increased levels in CLD patients compared to healthy volunteers. This trend was mostly reversed in HCC versus CLD patients. In liver tumor tissues, levels of many lipids were decreased compared to paired nontumor liver tissues. Differences in lipid levels were further defined by alterations in the degree of saturation in the fatty acyl chains. Some lipids, including free fatty acids, saturated lysophosphatidylcholines and saturated triacylglycerides, showed a continuous trend in the transition from the blood of healthy controls to CLD and HCC patients. For HCC patients, phosphatidylglycerides showed similar alterations in both blood and tissues.

Abstract

Hepatocellular carcinoma (HCC) is a worldwide health problem. HCC patients show a 50% mortality within two years of diagnosis. To better understand the molecular pathogenesis at the level of lipid metabolism, untargeted UPLC MS—QTOF lipidomics data were acquired from resected human HCC tissues and their paired nontumor hepatic tissues (n = 46). Blood samples of the same HCC subjects (n = 23) were compared to chronic liver disease (CLD) (n = 15) and healthy control (n = 15) blood samples. The participants were recruited from the National Liver Institute in Egypt. The lipidomics data yielded 604 identified lipids that were divided into six super classes. Five-hundred and twenty-four blood lipids were found as significantly differentiated (p < 0.05 and qFDR p < 0.1) between the three study groups. In the blood of CLD patients compared to healthy control subjects, almost all lipid classes were significantly upregulated. In CLD patients, triacylglycerides were found as the most significantly upregulated lipid class at qFDR p = 1.3 × 10⁻⁵⁶, followed by phosphatidylcholines at qFDR p = 3.3 × 10⁻⁵¹ and plasmalogens at qFDR p = 1.8 × 10^-46. In contrast, almost all blood lipids were significantly downregulated in HCC patients compared to CLD patients, and in HCC tissues compared to nontumor hepatic tissues. Ceramides were found as the most significant lipid class (qFDR p = 1 × 10⁻¹⁴) followed by phosphatidylglycerols (qFDR p = 3 × 10⁻⁹), phosphatidylcholines and plasmalogens. Despite these major differences, there were also common trends in the transitions between healthy controls, CLD and HCC patients. In blood, several mostly saturated triacylglycerides showed a continued increase in the trajectory towards HCC, accompanied by reduced levels of saturated free fatty acids and saturated lysophospatidylcholines. In contrast, the largest overlaps of lipid alterations that were found in both HCC tissue and blood comparisons were decreased levels of phosphatidylglycerols and sphingolipids. This study highlights the specific impact of HCC tumors on the circulating lipids. Such data may be used to target lipid metabolism for prevention, early detection and treatment of HCC in the background of viral-related CLD etiology.

Construction of a lipid metabolism-related and immune-associated prognostic signature for hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most lethal malignancies. We aimed to identify a robust lipid metabolism-related signature associated with the HCC microenvironment to improve the prognostic prediction of HCC patients.

METHODS

We analyzed the gene expression profiles of lipid metabolism from Molecular Signatures Database and information of patients from The Cancer Genome Atlas. Gene set variation analysis (GSVA), gene set enrichment analysis (GSEA), and principal component analysis (PCA) were employed for functional annotation. Quantitative real-time polymerase chain reaction (qRT-PCR) was employed to verify the expression of model genes in HCC and adjacent tissues.

RESULTS

As a result, a lipid metabolism-related signature consisting of acyl-CoA synthetase long-chain family member 6 (ACSL6), lysophosphatidylcholine acyltransferase 1, phospholipase A2 group 1B, lecithin-cholesterol acyltransferase (LCAT), and sphingomyelin phosphodiesterase 4 (SMPD4) was identified among HCC patients. Lysophosphatidylcholine acyltransferase 1, PLA2G1B, and SMPD4 were proved significantly high expression while ACSL6 and LCAT were remarkably low expression in our 15 pairs of matched HCC and normal tissues by qRT-PCR. Under different conditions, the overall survival (OS) of patients in low-risk group was prolonged than that in high-risk group. Moreover, the as-constructed signature was an independent factor, which was remarkably associated with gender, histologic grade, and platelet level of HCC patients. In addition, the receiver operating characteristic (ROC) curve analysis confirmed the good potency of the model. Functional enrichment analysis further revealed that lower fatty acid (FA) oxidation and higher infiltration of immunocytes were detected in patients from the high-risk group compared with those in the low-risk group.

CONCLUSIONS

Our findings indicate that the lipid metabolism-related signature shows prognostic significance for HCC.

Lipids and cancer: Emerging roles in pathogenesis, diagnosis and therapeutic intervention

With the advent of effective tools to study lipids, including mass spectrometry-based lipidomics, lipids are emerging as central players in cancer biology. Lipids function as essential building blocks for membranes, serve as fuel to drive energy-demanding processes and play a key role as signaling molecules and as regulators of numerous cellular functions. Not unexpectedly, cancer cells, as well as other cell types in the tumor microenvironment, exploit various ways to acquire lipids and extensively rewire their metabolism as part of a plastic and context-dependent metabolic reprogramming that is driven by both oncogenic and environmental cues. The resulting changes in the fate and composition of lipids help cancer cells to thrive in a changing microenvironment by supporting key oncogenic functions and cancer hallmarks, including cellular energetics, promoting feedforward oncogenic signaling, resisting oxidative and other stresses, regulating intercellular communication and immune responses. Supported by the close connection between altered lipid metabolism and the pathogenic process, specific lipid profiles are emerging as unique disease biomarkers, with diagnostic, prognostic and predictive potential. Multiple preclinical studies illustrate the translational promise of exploiting lipid metabolism in cancer, and critically, have shown context dependent actionable vulnerabilities that can be rationally targeted, particularly in combinatorial approaches. Moreover, lipids themselves can be used as membrane disrupting agents or as key components of nanocarriers of various therapeutics. With a number of preclinical compounds and strategies that are approaching clinical trials, we are at the doorstep of exploiting a hitherto underappreciated hallmark of cancer and promising target in the oncologist's strategy to combat cancer.

Computational Analysis of Transcriptomic and Proteomic Data for Deciphering Molecular Heterogeneity and Drug Responsiveness in Model Human Hepatocellular Carcinoma Cell Lines

Hepatocellular carcinoma (HCC) is associated with high mortality due to its inherent heterogeneity, aggressiveness, and limited therapeutic regimes. Herein, we analyzed 21 human HCC cell lines (HCC lines) to explore intertumor molecular diversity and pertinent drug sensitivity. We used an integrative computational approach based on exploratory and single-sample gene-set enrichment analysis of transcriptome and proteome data from the Cancer Cell Line Encyclopedia, followed by correlation analysis of drug-screening data from the Cancer Therapeutics Response Portal with curated gene-set enrichment scores. Acquired results classified HCC lines into two groups, a poorly and a well-differentiated group, displaying lower/higher enrichment scores in a "Specifically Upregulated in Liver" gene-set, respectively. Hierarchical clustering based on a published epithelial-mesenchymal transition gene expression signature further supported this stratification. Between-group comparisons of gene and protein expression unveiled distinctive patterns, whereas downstream functional analysis significantly associated differentially expressed genes with crucial cancer-related biological processes/pathways and revealed concrete driver-gene signatures. Finally, correlation analysis highlighted a diverse effectiveness of specific drugs against poorly compared to well-differentiated HCC lines, possibly applicable in clinical research with patients with analogous characteristics. Overall, this study expanded the knowledge on the molecular profiles, differentiation status, and drug responsiveness of HCC lines, and proposes a cost-effective computational approach to precision anti-HCC therapies.

Beyond the Warburg Effect: N-Myc Contributes to Metabolic Reprogramming in Cancer Cells

Cancer cells generate large amounts of lactate derived from glucose regardless of the available oxygen level. Cancer cells finely control ATP synthesis by modulating the uptake of substrates and the activity of enzymes involved in aerobic glycolysis (Warburg effect), which enables them to adapt to the tumor microenvironment. However, increasing evidence suggests that mitochondrial metabolism, including the tricarboxylic acid (TCA) cycle, oxidative phosphorylation (OXPHOS), and glutaminolysis, is paradoxically activated in MYCN-amplified malignancies. Unlike non-amplified cells, MYCN-amplified cancer cells significantly promote OXPHOS-dependent ATP synthesis. Furthermore, tumor cells are differentially dependent on fatty acid β-oxidation (FAO) according to N-Myc status. Therefore, upregulation of FAO-associated enzymes is positively correlated with both N-Myc expression level and poor clinical outcome. This review explores therapeutic strategies targeting cancer stem-like cells for the treatment of tumors associated with MYCN amplification.

Development and validation of a 14-gene signature for prognosis prediction in hepatocellular carcinoma

Worldwide, hepatocellular carcinoma (HCC) remains a crucial medical problem. Precise and concise prognostic models are urgently needed because of the intricate gene variations among liver cancer cells. We conducted this study to identify a prognostic gene signature with biological significance. We applied two algorithms to generate differentially expressed genes (DEGs) between HCC and normal specimens in The Cancer Genome Atlas cohort (training set included) and performed enrichment analyses to expound on their biological significance. A protein-protein interactions network was established based on the STRING online tool. We then used Cytoscape to screen hub genes in crucial modules. A multigene signature was constructed by Cox regression analysis of hub genes to stratify the prognoses of HCC patients in the training set. The prognostic value of the multigene signature was externally validated in two other sets from Gene Expression Omnibus (GSE14520 and GSE76427), and its role in recurrence prediction was also investigated. A total of 2000 DEGs were obtained, including 1542 upregulated genes and 458 downregulated genes. Subsequently, we constructed a 14-gene signature on the basis of 56 hub genes, which was a good predictor of overall survival. The prognostic signature could be replicated in GSE14520 and GSE76427. Moreover, the 14-gene signature could be applied for recurrence prediction in the training set and GSE14520. In summary, the 14-gene signature extracted from hub genes was involved in some of the HCC-related signalling pathways; it not only served as a predictive signature for HCC outcome but could also be used to predict HCC recurrence.

Defects in long-chain 3-hydroxy acyl-CoA dehydrogenase lead to hepatocellular carcinoma: A novel etiology of hepatocellular carcinoma

The incidence of both nonalcoholic fatty liver disease (NAFLD) and hepatocellular carcinoma (HCC) have been increasing at an alarming rate. Little is known about NAFLD without cirrhosis as a risk for HCC. Here we report, for the first time, generation of a mouse model with a defect in long-chain 3-hydoxy acyl-CoA dehydrogenase (LCHAD). The LCHAD exon 15 deletion was embryonic lethal to the homozygous mice whereas heterozygous mice (HT) develop significant hepatic steatosis starting at young age (3 months old) and HCC at older age (>13 months old) without any evidence of fibrosis or cirrhosis. None of the wild-type (WT) mice developed steatosis and HCC (n = 39), whereas HT-LCHAD mice (n = 41) showed steatosis and ~20% (8/41) developed liver masses with histological features of HCC. Proteomic analysis of liver tissues from WT-mice and HT-mice with no signs of HCC was conducted. Proteins with significant changes in abundance were identified by mass spectrometry. Abundance of 24 proteins was significantly different (p < 0.01) between WT and HT-LCHAD mice. The proteins found to vary in abundance are associated with different cellular response processes ranging from intermediary metabolism of carbohydrate, protein and lipid to oxidative stress, signal transduction and the process of tumorigenesis. Protein expression pattern of the HT-LCHAD mouse liver indicates predisposition to HCC and suggests that impaired hepatic mitochondrial fatty acid oxidation plays an important role in the development and progression of HCC. To assess the implication of these studies in human disease, we demonstrated significant downregulation of HADHA transcripts in HCC patients.

SLC27A5 deficiency activates NRF2/TXNRD1 pathway by increased lipid peroxidation in HCC

Solute carrier family 27 member 5 (SLC27A5/FATP5) is involved in fatty acid transport and bile acid metabolism; however, little is known about its role in human diseases. Here, we first show that SLC27A5 expression is downregulated in hepatocellular carcinoma (HCC) by DNA hypermethylation, and reduced SCL27A5 expression contributes to tumor progression and poor prognosis. Both gain- and loss-of-function studies demonstrated that SLC27A5 has an antiproliferative effect on HCC cells in vitro and in vivo. Knockout of SLC27A5 increases polyunsaturated lipids, leading to increased NADP+/NADPH ratio, ROS production as well as lipid peroxidation and the subsequent accumulation of 4-hydroxy-2-nonenal (4-HNE) in hepatoma cells. Mass spectrometry analysis found that 4-HNE directly modifies cysteine residues (Cys513, 518) on KEAP1, thus leading KEAP1/NRF2 pathway activation and increases the expression levels of NRF2 target genes, such as TXNRD1. Further, SLC27A5 expression negatively correlates with TXNRD1 expression in hepatoma cells and clinical HCC samples, and blockade of NRF2/TXNRD1 using genetic approaches or inhibitors sensitizes SLC27A5-deficient hepatoma cells to sorafenib treatment. Collectively, we demonstrated that SLC27A5 acts as a novel tumor suppressor by suppressing TXNRD1 expression via the KEAP1/NRF2 pathway in HCC. Combination therapy of sorafenib and NRF2/TXNRD1 inhibitors may be a promising strategy in personalized HCC treatment.

Role of lipids in pathophysiology, diagnosis and therapy of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an aggressive and widespread cancer. Patients with liver cirrhosis of different aetiologies are at a risk to develop HCC. It is important to know that in approximately 20% of cases primary liver tumors arise in a non-cirrhotic liver. Lipid metabolism is variable in patients with chronic liver diseases, and lipid metabolites involved therein do play a role in the development of HCC. Of note, lipid composition of carcinogenic tissues differs from non-affected liver tissues. High cholesterol and low ceramide levels in the tumors protect the cells from oxidative stress and apoptosis, and do also promote cell proliferation. So far, detailed characterization of the mechanisms by which lipids enable the development of HCC has received little attention. Evaluation of the complex roles of lipids in HCC is needed to better understand the pathophysiology of HCC, the later being of paramount importance for the development of urgently needed therapeutic interventions. Disturbed hepatic lipid homeostasis has systemic consequences and lipid species may emerge as promising biomarkers for early diagnosis of HCC. The challenge is to distinguish lipids specifically related to HCC from changes simply related to the underlying liver disease. This review article discusses aberrant lipid metabolism in patients with HCC.