Cholesterol biosynthesis supports the growth of hepatocarcinoma lesions depleted of fatty acid synthase in mice and humans

Inhibiting HMGCR represses stemness and metastasis of hepatocellular carcinoma via Hedgehog signaling

Cancer stem cells (CSCs) play a crucial role in tumor initiation, recurrence, metastasis, and drug resistance. However, the current understanding of CSCs in hepatocellular carcinoma (HCC) remains incomplete. Through a comprehensive analysis of the database, it has been observed that 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), a critical enzyme involved in cholesterol synthesis, is up-regulated in HCC tissues and liver CSCs. Moreover, high expression of HMGCR is associated with a poor prognosis in patients with HCC. Functionally, HMGCR promotes the stemness and metastasis of HCC both in vitro and in vivo. By screening various signaling pathway inhibitors, we have determined that HMGCR regulates stemness and metastasis by activating the Hedgehog signaling in HCC. Mechanistically, HMGCR positively correlates with the expression of the Smoothened receptor and facilitates the nuclear translocation of the transcriptional activator GLI family zinc finger 1. Inhibition of the Hedgehog pathway can reverse the stimulatory effects of HMGCR on stemness and metastasis in HCC. Notably, simvastatin, an FDA-approved cholesterol-lowering drug, has been shown to inhibit stemness and metastasis of HCC by targeting HMGCR. Taken together, our findings suggest that HMGCR promotes the regeneration and metastasis of HCC through the activation of Hedgehog signaling, and simvastatin holds the potential for clinical suppression of HCC metastasis.

Valproic acid targets IDH1 mutants through alteration of lipid metabolism

Histone deacetylases (HDACs) have a wide range of targets and can rewire both the chromatin and lipidome of cancer cells. In this study, we show that valproic acid (VPA), a brain penetrant anti-seizure medication and histone deacetylase inhibitor, inhibits the growth of IDH1 mutant tumors in vivo and in vitro, with at least some selectivity over IDH1 wild-type tumors. Surprisingly, genes upregulated by VPA showed no enhanced chromatin accessibility at the promoter, but there was a correlation between VPA-downregulated genes and diminished promoter chromatin accessibility. VPA inhibited the transcription of lipogenic genes and these lipogenic genes showed significant decreases in promoter chromatin accessibility only in the IDH1 MT glioma cell lines tested. VPA inhibited the mTOR pathway and a key lipogenic gene, fatty acid synthase (FASN). Both VPA and a selective FASN inhibitor TVB-2640 rewired the lipidome and promoted apoptosis in an IDH1 MT but not in an IDH1 WT glioma cell line. We further find that HDACs are involved in the regulation of lipogenic genes and HDAC6 is particularly important for the regulation of FASN in IDH1 MT glioma. Finally, we show that FASN knockdown alone and VPA in combination with FASN knockdown significantly improved the survival of mice in an IDH1 MT primary orthotopic xenograft model in vivo. We conclude that targeting fatty acid metabolism through HDAC inhibition and/or FASN inhibition may be a novel therapeutic opportunity in IDH1 mutant gliomas.

The interaction between m6A modification and noncoding RNA in tumor microenvironment on cancer progression

Cancer development is thought to be closely related to aberrant epigenetic regulation, aberrant expression of specific non-coding RNAs (ncRNAs), and tumor microenvironment (TME). The m6A methylation is one of the most abundant RNA modifications found in eukaryotes, and it can determine the fate of RNA at the post-transcriptional level through a variety of mechanisms, which affects important biological processes in the organism. The m6A methylation modification is involved in RNA processing, regulation of RNA nuclear export or localisation, RNA degradation and RNA translation. This process affects the function of mRNAs and ncRNAs, thereby influencing the biological processes of cancer cells. TME accelerates and promotes cancer generation and progression during tumor development. The m6A methylation interacting with ncRNAs is closely linked to TME formation. Mutual regulation and interactions between m6A methylation and ncRNAs in TME create complex networks and mediate the progression of various cancers. In this review, we will focus on the interactions between m6A modifications and ncRNAs in TME, summarising the molecular mechanisms by which m6A interacts with ncRNAs to affect TME and their roles in the development of different cancers. This work will help to deepen our understanding of tumourigenesis and further explore new targets for cancer therapy.

The role of cholesterol-modified prognostic nutritional index in nutritional status assessment and predicting survival after liver resection for hepatocellular carcinoma

Malnutrition, which is often underestimated in patients with hepatocellular carcinoma (HCC), has a proven adverse effect on survival rates. The purpose of this study was to verify the effectiveness of the cholesterol-modified prognostic nutritional index (CPNI) in determining the nutritional status and predicting overall survival (OS) and recurrence-free survival (RFS) in patients with HCC by comparing it with several other nutritional indicators. This retrospective single-center study enrolled 1450 consecutive HCC patients who underwent curative liver resection from January 2015 to November 2019. We evaluated the prognostic significance of several nutritional indicators, including CPNI, the controlling nutritional status (CONUT), the nutritional risk index (NRI), and the prognostic nutritional index (PNI), by applying time-dependent receiver operating characteristic (ROC) curves, Kaplan-Meier survival analysis, and Cox proportional hazards regression analysis. Among several objective nutrition evaluations (including CPNI, CONUT, NRI, and PNI), CPNI demonstrated the greatest prognostic predictive power for predicting OS. Meanwhile, CPNI demonstrated marginally higher accuracy in predicting RFS compared to PNI, and significantly outperformed CONUT and NRI. Univariate and multivariate analyses suggested that CPNI was an independent risk factor for the OS and RFS of patients with HCC undergoing curative liver resection. In most subgroups, malnutrition as identified by CPNI demonstrates strong stratification ability in predicting both OS and RFS. CPNI serves as an accurate and stable instrument for evaluating nutritional status and forecasting survival outcomes in HCC patients following liver resection, which has the potential to markedly influence clinical decision-making processes and the management of patient care.

Crosstalk between Epigenetics and Metabolic Reprogramming in Metabolic Dysfunction-Associated Steatotic Liver Disease-Induced Hepatocellular Carcinoma: A New Sight

Epigenetic and metabolic reprogramming alterations are two important features of tumors, and their reversible, spatial, and temporal regulation is a distinctive hallmark of carcinogenesis. Epigenetics, which focuses on gene regulatory mechanisms beyond the DNA sequence, is a new entry point for tumor therapy. Moreover, metabolic reprogramming drives hepatocellular carcinoma (HCC) initiation and progression, highlighting the significance of metabolism in this disease. Exploring the inter-regulatory relationship between tumor metabolic reprogramming and epigenetic modification has become one of the hot directions in current tumor metabolism research. As viral etiologies have given way to metabolic dysfunction-associated steatotic liver disease (MASLD)-induced HCC, it is urgent that complex molecular pathways linking them and hepatocarcinogenesis be explored. However, how aberrant crosstalk between epigenetic modifications and metabolic reprogramming affects MASLD-induced HCC lacks comprehensive understanding. A better understanding of their linkages is necessary and urgent to improve HCC treatment strategies. For this reason, this review examines the interwoven landscape of molecular carcinogenesis in the context of MASLD-induced HCC, focusing on mechanisms regulating aberrant epigenetic alterations and metabolic reprogramming in the development of MASLD-induced HCC and interactions between them while also updating the current advances in metabolism and epigenetic modification-based therapeutic drugs in HCC.

High-fat diet promotes liver tumorigenesis via palmitoylation and activation of AKT

OBJECTIVE

Whether and how the PI3K-AKT pathway, a central node of metabolic homeostasis, is responsible for high-fat-induced non-alcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC) remain a mystery. Characterisation of AKT regulation in this setting will provide new strategies to combat HCC.

DESIGN

Metabolite library screening disclosed that palmitic acid (PA) could activate AKT. In vivo and in vitro palmitoylation assay were employed to detect AKT palmitoylation. Diverse cell and mouse models, including generation of AKT1C77S and AKT1C224S knock-in cells, Zdhhc17 and Zdhhc24 knockout mice and Akt1C224S knock-in mice were employed. Human liver tissues from patients with NASH and HCC, hydrodynamic transfection mouse model, high-fat/high-cholesterol diet (HFHCD)-induced NASH/HCC mouse model and high-fat and methionine/choline-deficient diet (HFMCD)-induced NASH mouse model were also further explored for our mechanism studies.

RESULTS

By screening a metabolite library, PA has been defined to activate AKT by promoting its palmitoyl modification, an essential step for growth factor-induced AKT activation. Biologically, a high-fat diet could promote AKT kinase activity, thereby promoting NASH and liver cancer. Mechanistically, palmitoyl binding anchors AKT to the cell membrane in a PIP3-independent manner, in part by preventing AKT from assembling into an inactive polymer. The palmitoyltransferases ZDHHC17/24 were characterised to palmitoylate AKT to exert oncogenic effects. Interestingly, the anti-obesity drug orlistat or specific penetrating peptides can effectively attenuate AKT palmitoylation and activation by restricting PA synthesis or repressing AKT modification, respectively, thereby antagonising liver tumorigenesis.

CONCLUSIONS

Our findings elucidate a novel fine-tuned regulation of AKT by PA-ZDHHC17/24-mediated palmitoylation, and highlight tumour therapeutic strategies by taking PA-restricted diets, limiting PA synthesis, or directly targeting AKT palmitoylation.

The switch triggering the invasion process: Lipid metabolism in the metastasis of hepatocellular carcinoma

ABSTRACT

In humans, the liver is a central metabolic organ with a complex and unique histological microenvironment. Hepatocellular carcinoma (HCC), which is a highly aggressive disease with a poor prognosis, accounts for most cases of primary liver cancer. As an emerging hallmark of cancers, metabolic reprogramming acts as a runaway mechanism that disrupts homeostasis of the affected organs, including the liver. Specifically, rewiring of the liver metabolic microenvironment, including lipid metabolism, is driven by HCC cells, propelling the phenotypes of HCC cells, including dissemination, invasion, and even metastasis in return. The resulting formation of this vicious loop facilitates various malignant behaviors of HCC further. However, few articles have comprehensively summarized lipid reprogramming in HCC metastasis. Here, we have reviewed the general situation of the liver microenvironment and the physiological lipid metabolism in the liver, and highlighted the effects of different aspects of lipid metabolism on HCC metastasis to explore the underlying mechanisms. In addition, we have recapitulated promising therapeutic strategies targeting lipid metabolism and the effects of lipid metabolic reprogramming on the efficacy of HCC systematical therapy, aiming to offer new perspectives for targeted therapy.

SPARC Stabilizes ApoE to Induce Cholesterol-Dependent Invasion and Sorafenib Resistance in Hepatocellular Carcinoma

Dysregulation of cholesterol homeostasis is implicated in the development and progression of hepatocellular carcinoma (HCC) that is characterized by intrahepatic and early extrahepatic metastases. A better understanding of the underlying mechanisms regulating cholesterol metabolism in HCC could help identify strategies to circumvent the aggressive phenotype. Here, we found that high expression of intracellular SPARC (secreted protein acidic and rich in cysteine) was significantly associated with elevated cholesterol levels and an enhanced invasive phenotype in HCC. SPARC potentiated cholesterol accumulation in HCC cells during tumor progression by stabilizing the ApoE protein. Mechanistically, SPARC competitively bound to ApoE, impairing its interaction with the E3 ligase tripartite motif containing 21 (TRIM21) and preventing its ubiquitylation and subsequent degradation. ApoE accumulation led to cholesterol enrichment in HCC cells, stimulating PI3K-AKT signaling and inducing epithelial-mesenchymal transition (EMT). Importantly, sorafenib-resistant HCC cells were characterized by increased expression of intracellular SPARC, elevated cholesterol levels, and enhanced invasive capacity. Inhibiting SPARC expression or reducing cholesterol levels enhanced the sensitivity of HCC cells to sorafenib treatment. Together, these findings unveil interplay between SPARC and cholesterol homeostasis. Targeting SPARC-triggered cholesterol-dependent oncogenic signaling is a potential therapeutic strategy for advanced HCC.

SIGNIFICANCE

Intracellular SPARC boosts cholesterol availability to fuel invasion and drug resistance in hepatocellular carcinoma, providing a rational approach to improve the treatment of advanced liver cancer.

Role of lipid metabolism in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), an aggressive malignancy with a dismal prognosis, poses a significant public health challenge. Recent research has highlighted the crucial role of lipid metabolism in HCC development, with enhanced lipid synthesis and uptake contributing to the rapid proliferation and tumorigenesis of cancer cells. Lipids, primarily synthesized and utilized in the liver, play a critical role in the pathological progression of various cancers, particularly HCC. Cancer cells undergo metabolic reprogramming, an essential adaptation to the tumor microenvironment (TME), with fatty acid metabolism emerging as a key player in this process. This review delves into intricate interplay between HCC and lipid metabolism, focusing on four key areas: de novo lipogenesis, fatty acid oxidation, dysregulated lipid metabolism of immune cells in the TME, and therapeutic strategies targeting fatty acid metabolism for HCC treatment.

The Role of Metabolic Reprogramming in the Tumor Immune Microenvironment: Mechanisms and Opportunities for Immunotherapy in Hepatocellular Carcinoma

As one of the emerging hallmarks of tumorigenesis and tumor progression, metabolic remodeling is common in the tumor microenvironment. Hepatocellular carcinoma (HCC) is the third leading cause of global tumor-related mortality, causing a series of metabolic alterations in response to nutrient availability and consumption to fulfill the demands of biosynthesis and carcinogenesis. Despite the efficacy of immunotherapy in treating HCC, the response rate remains unsatisfactory. Recently, research has focused on metabolic reprogramming and its effects on the immune state of the tumor microenvironment, and immune response rate. In this review, we delineate the metabolic reprogramming observed in HCC and its influence on the tumor immune microenvironment. We discuss strategies aimed at enhancing response rates and overcoming immune resistance through metabolic interventions, focusing on targeting glucose, lipid, or amino acid metabolism, as well as systemic regulation.

SOAT1 regulates cholesterol metabolism to induce EMT in hepatocellular carcinoma

Cholesterol metabolism reprogramming is one of the significant characteristics of hepatocellular carcinoma (HCC). Cholesterol increases the risk of epithelial-mesenchymal transition (EMT) in cancer. Sterol O-acyltransferases 1 (SOAT1) maintains the cholesterol homeostasis. However, the exact mechanistic contribution of SOAT1 to EMT in HCC remains unclear. Here we demonstrated that SOAT1 positively related to poor prognosis of HCC, EMT markers and promoted cell migration and invasion in vitro, which was mediated by the increased cholesterol in plasmalemma and cholesterol esters accumulation. Furthermore, we reported that SOAT1 disrupted cholesterol metabolism homeostasis to accelerate tumorigenesis and development in HCC xenograft and NAFLD-HCC. Also, we detected that nootkatone, a sesquiterpene ketone, inhibited EMT by targeting SOAT1 in vitro and in vivo. Collectively, our finding indicated that SOAT1 promotes EMT and contributes to hepatocarcinogenesis by increasing cholesterol esterification, which is suppressed efficiently by nootkatone. This study demonstrated that SOAT1 is a potential biomarker and therapeutic target in NAFLD-HCC and SOAT1-targeting inhibitors are expected to be the potential new therapeutic treatment for HCC.

Molecular Genealogy of Metabolic-associated Hepatocellular Carcinoma

This review examines the latest epidemiological and molecular pathogenic findings of metabolic-associated hepatocellular carcinoma (HCC). Its increasing prevalence is a significant concern and reflects the growing burden of obesity and metabolic diseases, including metabolic dysfunction-associated steatotic liver disease, formerly known as nonalcoholic fatty liver disease, and type 2 diabetes. Metabolic-associated HCC has unique molecular abnormality and distinctive gene expression patterns implicating aberrations in bile acid, fatty acid metabolism, oxidative stress, and proinflammatory pathways. Furthermore, a notable frequency of single nucleotide polymorphisms in genes such as patatin-like phospholipase domain-containing 3, transmembrane 6 superfamily member 2, glucokinase regulator, and membrane-bound O-acyltransferase domain-containing 7 has been observed. The tumor immune microenvironment of metabolic-associated HCC is characterized by unique phenotypes of macrophages, neutrophils, and T lymphocytes. Additionally, the pathogenesis of metabolic-associated HCC is influenced by abnormal lipid metabolism, insulin resistance, and dysbiosis. In conclusion, deciphering the intricate interactions among metabolic processes, genetic predispositions, inflammatory responses, immune regulation, and microbial ecology is imperative for the development of novel therapeutic and preventative measures against metabolic-associated HCC.

Improvement of hepatic innate immunity in chemically-injured livers to develop hepatocarcinoma by a serine type-protease inhibitors enriched extract from Chenopodium quinoa

Food ingredients have critical effects on the maturation and development of the immune system, which innate - lymphoid (ILCs) and myeloid - cells play key roles as important regulators of energy storage and hepatic fat accumulation. Therefore, the objective of this study is to define potential links between a dietary immunonutritional induction of the selective functional differentiation of monocytes-derived macrophages, ILCs and lipid homeostasis in hepatocarcinoma (HCC)-developing mice. Hepatic chemically injured (diethylnitrosamine/thiacetamide) Rag2-/- and Rag2-/-Il2-/- mice were administered with serine-type protease inhibitors (SETIs) obtained from Chenopodium quinoa. Early HCC-driven immunometabolic imbalances (infiltrated macrophages, glucose homeostasis, hepatic lipid profile, ILCs expansion, inflammatory conditions, microbiota) in animals put under a high-fat diet for 2 weeks were assessed. It was also approached the potential of SETIs to cause functional adaptations of the bioenergetics of human macrophage-like cells (hMLCs) in vitro conditioning their capacity to accumulate fat. It is showed that Rag2-/-Il2-/- mice, lacking ILCs, are resistant to the SETIs-induced hepatic macrophages (CD68+F4/80+) activation. Feeding SETIs to Rag2-/- mice, carrying ILCs, promoted the expansion towards ILC3s (CD117+Nkp46+CD56+) and reduced that of ILC2s (CD117+KLRG1+) into livers. In vitro studies demonstrate that hMLCs, challenged to SETIs, develop a similar phenotype of that found in mice and bioenergetic adaptations leading to increased lipolysis. It is concluded that SETIs promote liver macrophage activation and ILCs adaptations to ameliorate HCC-driven immunometabolic imbalances.

CSF1R inhibition reprograms tumor-associated macrophages to potentiate anti-PD-1 therapy efficacy against colorectal cancer

PD-1 blockade therapy has made great breakthroughs in treatment of multiple solid tumors. However, patients with microsatellite-stable (MSS) colorectal cancer (CRC) respond poorly to anti-PD-1 immunotherapy. Although CRC patients with microstatellite instability (MSI) or microsatellite instability-high (MSI-H) can benefit from PD-1 blockade therapy, there are still some problems such as tumor recurrence. Tumor-associated macrophages (TAMs), most abundant immune components in tumor microenvironment (TME), largely limit the therapeutic efficacy of anti-PD-1 against CRC. The CSF1/CSF1R pathway plays a key role in regulating macrophage polarization, and blocking CSF1R signaling transduction may be a potential strategy to effectively reprogram macrophages and remodel TME. Here, we found that increasing expression of CSF1R in macrophages predicted poor prognosis in CRC cohort. Furthermore, we discovered a novel potent CSF1R inhibitor, PXB17, which significantly reprogramed M2 macrophages to M1 phenotype. Mechanically, PXB17 significantly blocked activation of PI3K/AKT/mTORC1 signaling, resulting in inhibition of cholesterol biosynthesis. Results from 3D co-culture system suggested that PXB17-repolarized macrophages could induce infiltration of CD8+ T lymphocytes in tumors and improve the immunosuppressive microenvironment. In vivo, PXB17 significantly halted CRC growth, with a stronger effect than PLX3397. In particular, PXB17 potently enhanced therapeutic activity of PD-1 mAb in CT-26 (MSS) model and prevented tumor recurrence in MC-38 (MSI-H) model by promoting formation of long-term memory immunity. Our study opens a new avenue for CSF1R in tumor innate and adaptive anti-tumor immunomodulatory activity and suggests that PXB17 is a promising immunotherapy molecule for enhancing the efficacy of PD-1 mAb or reducing tumor recurrence of CRC.

Comprehensive prognostic and immune analysis of sterol O-acyltransferase 1 in patients with hepatocellular carcinoma

BACKGROUND

Sterol O-acyltransferase 1 (SOAT1) is an important target in the diagnosis and treatment of liver cancer. However, the prognostic value of SOAT1 in patients with hepatocellular carcinoma (HCC) is still not clear.

AIM

To investigate the correlation of SOAT1 expression with HCC, using RNA-seq and gene expression data of The Cancer Genome Atlas (TCGA)-liver hepatocellular carcinoma (LIHC) and pan-cancer.

METHODS

The correlation between SOAT1 expression and HCC was analyzed. Cox hazard regression models were conducted to investigate the prognostic value of SOAT1 in HCC. Overall survival and disease-specific survival were explored based on TCGA-LIHC data. Biological processes and functional pathways mediated by SOAT1 were characterized by gene ontology (GO) analysis and the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of differentially expressed genes. In addition, the protein-protein interaction network and co-expression analyses of SOAT1 in HCC were performed to better understand the regulatory mechanisms of SOAT1 in this malignancy.

RESULTS

SOAT1 and SOAT2 were highly expressed in unpaired samples, while only SOAT1 was highly expressed in paired samples. The area under the receiver operating characteristic curve of SOAT1 expression in tumor samples from LIHC patients compared with para-carcinoma tissues was 0.748, while the area under the curve of SOAT1 expression in tumor samples from LIHC patients compared with GTEx was 0.676. Patients with higher SOAT1 expression had lower survival rates. Results from GO/KEGG and gene set enrichment analyses suggested that the PI3K/AKT signaling pathway, the IL-18 signaling pathway, the calcium signaling pathway, secreted factors, the Wnt signaling pathway, the Jak/STAT signaling pathway, the MAPK family signaling pathway, and cell-cell communication were involved in such association. SOAT1 expression was positively associated with the abundance of macrophages, Th2 cells, T helper cells, CD56bright natural killer cells, and Th1 cells, and negatively linked to the abundance of Th17 cells, dendritic cells, and cytotoxic cells.

CONCLUSION

Our findings demonstrate that SOAT1 may serve as a novel target for HCC treatment, which is helpful for the development of new strategies for immunotherapy and metabolic therapy.

Targeting YAP1 to improve the efficacy of immune checkpoint inhibitors in liver cancer: mechanism and strategy

Liver cancer is the third leading of tumor death, including hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC). Immune checkpoint inhibitors (ICIs) are yielding much for sufferers to hope for patients, but only some patients with advanced liver tumor respond. Recent research showed that tumor microenvironment (TME) is critical for the effectiveness of ICIs in advanced liver tumor. Meanwhile, metabolic reprogramming of liver tumor leads to immunosuppression in TME. These suggest that regulating the abnormal metabolism of liver tumor cells and firing up TME to turn "cold tumor" into "hot tumor" are potential strategies to improve the therapeutic effect of ICIs in liver tumor. Previous studies have found that YAP1 is a potential target to improve the efficacy of anti-PD-1 in HCC. Here, we review that YAP1 promotes immunosuppression of TME, mainly due to the overstimulation of cytokines in TME by YAP1. Subsequently, we studied the effects of YAP1 on metabolic reprogramming in liver tumor cells, including glycolysis, gluconeogenesis, lipid metabolism, arachidonic acid metabolism, and amino acid metabolism. Lastly, we summarized the existing drugs targeting YAP1 in the treatment of liver tumor, including some medicines from natural sources, which have the potential to improve the efficacy of ICIs in the treatment of liver tumor. This review contributed to the application of targeted YAP1 for combined therapy with ICIs in liver tumor patients.

Targeting RORγ inhibits the growth and metastasis of hepatocellular carcinoma

Approximately 80%-90% of hepatocellular carcinomas (HCC) occur in a premalignant environment of fibrosis and abnormal extracellular matrix (ECM), highlighting an essential role of ECM in the tumorigenesis and progress of HCC. However, the determinants of ECM in HCC are poorly defined. Here, we show that nuclear receptor RORγ is highly expressed and amplified in HCC tumors. RORγ functions as an essential activator of the matrisome program via directly driving the expression of major ECM genes in HCC cells. Elevated RORγ increases fibronectin-1 deposition, cell-matrix adhesion, and collagen production, creating a favorable microenvironment to boost liver cancer metastasis. Moreover, RORγ antagonists effectively inhibit tumor growth and metastasis in multiple HCC xenografts and immune-intact models, and they effectively sensitize HCC tumors to sorafenib therapy in mice. Notably, elevated RORγ expression is associated with ECM remodeling and metastasis in patients with HCC. Taken together, we identify RORγ as a key player of ECM remodeling in HCC and as an attractive therapeutic target for advanced HCC.

CircHIPK3 regulates fatty acid metabolism through miR-637/FASN axis to promote esophageal squamous cell carcinoma

The oncogenic role of circRNA in cancers including esophageal cancer (EC) has been well studied. However, whether and how circRNAs are involved in cancer cell metabolic processes remains largely unknown. Here, we reported that circRNA, circHIPK3, is highly expressed in ESCC cell lines and tissues. Knockdown of circHIPK3 significantly restrained cell proliferation, colony formation, migration, and invasion in vitro and inhibited tumor growth in vivo. Mechanistically, circHIPK3 was found to act as a ceRNA by sponging miR-637 to regulate FASN expression and fatty acid metabolism in ESCC cells. Anti-sense oligonucleotide (ASO) targeting circHIPK3 substantially inhibited ESCC both in vitro and in vivo. Therefore, these results uncover a modulatory axis constituting of circHIPK3/miR-637/FASN may be a potential biomarker and therapeutic target for ESCC in the clinic.

Cinobufacini injection delays hepatocellular carcinoma progression by regulating lipid metabolism via SREBP1 signaling pathway and affecting macrophage polarization

ETHNOPHARMACOLOGICAL RELEVANCE

Cinobufacini injection, an aqueous extract of the toad, is a commonly used anti-tumor animal herbal medicine in clinical practice. It has the effects of detoxifying, reducing swelling, and relieving pain.

AIMS OF THE STUDY

To investigate the effects of Cinobufacini injection on hepatocellular carcinoma progression by regulating lipid metabolism and macrophage polarization in the tumor microenvironment and to identify the potential molecular mechanisms.

MATERIALS AND METHODS

To establish the axillary transplantation tumor model of hepatocellular carcinoma Hepa1-6 in C57BL/6 mice, and to evaluate the inhibitory effect of Cinobufacini injection on hepatocellular carcinoma in vivo as well as drug delivery security. Combined metabolomics and transcriptomics analysis of the effect of Cinobufagin Injection on tumor microenvironment. An in vitro mouse co-culture model of peritoneal macrophages and Hepa1-6 cells was established to research the effects of Cinobufacini injection on macrophage polarization, hepatocellular carcinoma cell growth, migration, and changes in lipid metabolism. Cinobufacini injection inhibition of the AMPK/SREBP1/FASN signaling pathway regulating cholesterol metabolism and affecting macrophage polarization was examined using qRT-PCR, lentiviral transfection, immunofluorescence, and Western blot.

RESULT

In vivo experiments demonstrated that Cinobufacini injection treatment significantly inhibited the growth of Hepa1-6 hepatomas, along with a reduction in cholesterol content and a decrease in the percentage of M2 macrophages in tumor tissue. In vitro, we found that Cinobufacini injection inhibits IL-4-induced M2 macrophage polarization, reduces the cholesterol content of Hepa1-6 cells in a co-culture system, and inhibits the promotion of hepatocellular carcinoma cells by M2 macrophages. In addition, successful overexpression of SREBP1 in Hepa1-6 cells showed more pronounced cellular activity whereas Cinobufacini injection inhibited this change and reduced intracellular lipid levels.

CONCLUSION

Cinobufacini injection inhibits cholesterol synthesis within the tumor microenvironment via the AMPK/SERBP1/FASN signaling pathway, which in turn blocks the M2 polarization of macrophages, leading to the weakening of hepatocellular carcinoma growth and migration, and the promotion of its apoptosis. Our findings provide an important Introduction to understanding the molecular mechanism of Cinobufacini injection's anticancer activity and provide reliable theoretical and experimental support for its clinical application.

Influence of dietary sodium taurocholate on the growth performance and liver health of Nile tilapia (Oreochromis niloticus)

Bile acids (BAs) are a class of cholesterol-derived amphipathic molecules approved as new animal feed additives. However, the functional researches mainly focused on BAs mixture, and the influence of the individual BA on fishes was still limited. In the present study, Nile tilapia were fed basal diet with three levels of sodium taurocholate at 0 mg/kg (CON), 300 mg/kg (TCAL), and 600 mg/kg (TCAH) for 8 weeks. The results indicated that addition of sodium taurocholate did not significantly influence the growth performance. Instead, TCAH group had higher cholesterol accumulation with liver fibrosis. In TCAH group, the level of nuclear factor E2-related factor 2 (nrf2) signaling-associated oxidative stress factors significantly increased in the liver. Additionally, fish in TCAH group had the highest expression level of genes encoding endoplasmic reticulum (ER) stress and inflammatory cytokines in the liver. In conclusion, 300 mg/kg of sodium taurocholate did not significantly influence the growth performance of fish, while 600 mg/kg of sodium taurocholate markedly induced cholesterol accumulation and liver injury, suggesting that the application of taurocholic acid in aquafeed should be re-evaluated.

Advances in Targeted Drug Resistance Associated with Dysregulation of Lipid Metabolism in Hepatocellular Carcinoma

Hepatocellular carcinoma is the prevailing malignant neoplasm affecting the liver, often diagnosed at an advanced stage and associated with an unfavorable overall prognosis. Sorafenib and Lenvatinib have emerged as first-line therapeutic drugs for advanced hepatocellular carcinoma, improving the prognosis for these patients. Nevertheless, the issue of tyrosine kinase inhibitor (TKI) resistance poses a substantial obstacle in the management of advanced hepatocellular carcinoma. The pathogenesis and advancement of hepatocellular carcinoma exhibit a close association with metabolic reprogramming, yet the attention given to lipid metabolism dysregulation in hepatocellular carcinoma development remains relatively restricted. This review summarizes the potential significance and research progress of lipid metabolism dysfunction in Sorafenib and Lenvatinib resistance in hepatocellular carcinoma. Targeting hepatocellular carcinoma lipid metabolism holds promising potential as an effective strategy to overcome hepatocellular carcinoma drug resistance in the future.

The inhibition of YTHDF3/m6A/LRP6 reprograms fatty acid metabolism and suppresses lymph node metastasis in cervical cancer

The lipid synthesis of fatty acid (FA) represents a significant hallmark in the occurrence and progression of malignant tumor, which are associated with lymph node (LN) metastasis. Elucidation of the molecular mechanisms underlying LN metastasis could provide therapeutic strategies for cervical cancer (CCa). N6-Methyladenosine (m6A), the most prevalent and abundant RNA modification, exerts specific regulatory control over a series of oncogene expressions. This study demonstrated a clinical correlation between the upregulation of the m6A reader YTHDF3 and LN metastasis, thereby contributing to poor overall survival probability (OS) among CCa patients. The mechanistic investigation revealed that SREBF1 transcriptionally activated YTHDF3 expression by binding to its promoter. Functional experiments demonstrated that the upregulation of YTHDF3 significantly enhanced the in vitro proliferative, migratory, and invasive capacities of CCa cells, while also promoting lymphangiogenesis and facilitating LN metastasis in vivo. Mechanistically, the upregulation of LRP6 through YTHDF3-mediated m6A modification resulted in increased expression of FASN and ACC1, leading to both lipolysis of lipid droplets and synthesis of free fatty acid. Ultimately, this promoted fatty acid metabolism and enhanced LN metastasis by activating the LRP6-YAP-VEGF-C axis, which could induce lymphangiogenesis in CCa. Our study highlighted that YTHDF3 can serve as a promising therapeutic target and predictive biomarker for CCa patients with LN metastasis.

The roles of nuclear receptors in cholesterol metabolism and reverse cholesterol transport in nonalcoholic fatty liver disease

As the most prevalent chronic liver disease globally, NAFLD encompasses a pathological process that ranges from simple steatosis to NASH, fibrosis, cirrhosis, and HCC, closely associated with numerous extrahepatic diseases. While the initial etiology was believed to be hepatocyte injury caused by lipid toxicity from accumulated triglycerides, recent studies suggest that an imbalance of cholesterol homeostasis is of greater significance. The role of nuclear receptors in regulating liver cholesterol homeostasis has been demonstrated to be crucial. This review summarizes the roles and regulatory mechanisms of nuclear receptors in the 3 main aspects of cholesterol production, excretion, and storage in the liver, as well as their cross talk in reverse cholesterol transport. It is hoped that this review will offer new insights and theoretical foundations for the study of the pathogenesis and progression of NAFLD and provide new research directions for extrahepatic diseases associated with NAFLD.

SREBP Regulation of Lipid Metabolism in Liver Disease, and Therapeutic Strategies

Sterol regulatory element-binding proteins (SREBPs) are master transcription factors that play a crucial role in regulating genes involved in the biogenesis of cholesterol, fatty acids, and triglycerides. As such, they are implicated in several serious liver diseases, including non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), fibrosis, and hepatocellular carcinoma (HCC). SREBPs are subject to regulation by multiple cofactors and critical signaling pathways, making them an important target for therapeutic interventions. In this review, we first introduce the structure and activation of SREBPs, before focusing on their function in liver disease. We examine the mechanisms by which SREBPs regulate lipogenesis, explore how alterations in these processes are associated with liver disease, and evaluate potential therapeutic strategies using small molecules, natural products, or herb extracts that target these pathways. Through this analysis, we provide new insights into the versatility and multitargets of SREBPs as factors in the modulation of different physiological stages of liver disease, highlighting their potential targets for therapeutic treatment.

Dysregulated cholesterol regulatory genes in hepatocellular carcinoma

Cholesterol is an indispensable component in mammalian cells, and cholesterol metabolism performs important roles in various biological activities. In addition to the Warburg effect, dysregulated cholesterol metabolism is one of the metabolic hallmarks of several cancers. It has reported that reprogrammed cholesterol metabolism facilitates carcinogenesis, metastasis, and drug-resistant in various tumors, including hepatocellular carcinoma (HCC). Some literatures have reported that increased cholesterol level leads to lipotoxicity, inflammation, and fibrosis, ultimately promoting the development and progression of HCC. Contrarily, other clinical investigations have demonstrated a link between higher cholesterol level and lower risk of HCC. These incongruent findings suggest that the connection between cholesterol and HCC is much complicated. In this report, we summarize the roles of key cholesterol regulatory genes including cholesterol biosynthesis, uptake, efflux, trafficking and esterification in HCC. In addition, we discuss promising related therapeutic targets for HCC.

Hepatic mitochondrial NAD + transporter SLC25A47 activates AMPKα mediating lipid metabolism and tumorigenesis

BACKGROUND AIMS

SLC25A47 was initially identified as a mitochondrial HCC-downregulated carrier protein, but its physiological functions and transport substrates are unknown. We aimed to investigate the physiological role of SLC25A47 in hepatic metabolism.

APPROACH RESULTS

In the treatment of hepatocytes with metformin, we found that metformin can transcriptionally activate the expression of Slc25a47 , which is required for AMP-activated protein kinase α (AMPKα) phosphorylation. Slc25a47 -deficient mice had increased hepatic lipid content, triglycerides, and cholesterol levels, and we found that Slc25a47 deficiency suppressed AMPKα phosphorylation and led to an increased accumulation of nuclear SREBPs, with elevated fatty acid and cholesterol biosynthetic activities. Conversely, when Slc25a47 was overexpressed in mouse liver, AMPKα was activated and resulted in the inhibition of lipogenesis. Moreover, using a diethylnitrosamine-induced mouse HCC model, we found that the deletion of Slc25a47 promoted HCC tumorigenesis and development through the activated mammalian target of rapamycin cascade. Employing homology modeling of SLC25A47 and virtual screening of the human metabolome database, we demonstrated that NAD + was an endogenous substrate for SLC25A47, and the activity of NAD + -dependent sirtuin 3 declined in Slc25a47 -deficient mice, followed by inactivation of AMPKα.

CONCLUSIONS

Our findings reveal that SLC25A47, a hepatocyte-specific mitochondrial NAD + transporter, is one of the pharmacological targets of metformin and regulates lipid homeostasis through AMPKα, and may serve as a potential drug target for treating NAFLD and HCC.

Targeting dysregulated lipid metabolism in the tumor microenvironment

The reprogramming of lipid metabolism and its association with oncogenic signaling pathways within the tumor microenvironment (TME) have emerged as significant hallmarks of cancer. Lipid metabolism is defined as a complex set of molecular processes including lipid uptake, synthesis, transport, and degradation. The dysregulation of lipid metabolism is affected by enzymes and signaling molecules directly or indirectly involved in the lipid metabolic process. Regulation of lipid metabolizing enzymes has been shown to modulate cancer development and to avoid resistance to anticancer drugs in tumors and the TME. Because of this, understanding the metabolic reprogramming associated with oncogenic progression is important to develop strategies for cancer treatment. Recent advances provide insight into fundamental mechanisms and the connections between altered lipid metabolism and tumorigenesis. In this review, we explore alterations to lipid metabolism and the pivotal factors driving lipid metabolic reprogramming, which exacerbate cancer progression. We also shed light on the latest insights and current therapeutic approaches based on small molecular inhibitors and phytochemicals targeting lipid metabolism for cancer treatment. Further investigations are worthwhile to fully understand the underlying mechanisms and the correlation between altered lipid metabolism and carcinogenesis.

Cholesterol esterification and p53-mediated tumor suppression

Many human cancers carry missense mutations in or deletions of the tumor protein 53 (TP53) tumor suppressor gene. TP53's product, p53 regulates many biological processes, including cell metabolism. Cholesterol is a key lipid needed for the maintenance of membrane function and tissue homeostasis while also serving as a precursor for steroid hormone and bile acid synthesis. An over-abundance of cholesterol can lead to its esterification and storage as cholesterol esters. The recent study has shown that the loss of p53 leads to excessive cholesterol ester biosynthesis, which promotes hepatocellular carcinoma in mice. Blocking cholesterol esterification improves treatment outcomes, particularly for liver cancers with p53 deletions/mutations that originate in a background of non-alcoholic fatty liver disease.

Combined Inhibition of UBE2C and PLK1 Reduce Cell Proliferation and Arrest Cell Cycle by Affecting ACLY in Pan-Cancer

Various studies have shown that the cell-cycle-related regulatory proteins UBE2C, PLK1, and BIRC5 promote cell proliferation and migration in different types of cancer. However, there is a lack of in-depth and systematic research on the mechanism of these three as therapeutic targets. In this study, we found a positive correlation between the expression of UBE2C and PLK1/BIRC5 in the Cancer Genome Atlas (TCGA) database, revealing a potential combination therapy candidate for pan-cancer. Quantitative real-time PCR (qRT-PCR), Western blotting (WB), cell phenotype detection, and RNA-seq techniques were used to evidence the effectiveness of the combination candidate. We found that combined interference of UBE2C with PLK1 and UBE2C with BIRC5 affected metabolic pathways by significantly downregulating the mRNA expression of IDH1 and ACLY, which was related to the synthesis of acetyl-CoA. By combining the PLK1 inhibitor volasertib and the ACLY inhibitor bempedoic acid, it showed a higher synergistic inhibition of cell viability and higher synergy scores in seven cell lines, compared with those of other combination treatments. Our study reveals the potential mechanisms through which cell-cycle-related genes regulate metabolism and proposes a potential combined targeted therapy for patients with higher PLK1 and ACLY expression in pan-cancer.

Don't Judge a Book by Its Cover: The Role of Statins in Liver Cancer

Statins, which are inhibitors of 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase, are an effective pharmacological tool for lowering blood cholesterol levels. This property makes statins one of the most popular drugs used primarily to prevent cardiovascular diseases, where hyperlipidemia is a significant risk factor that increases mortality. Nevertheless, studies conducted mainly in the last decade have shown that statins might prevent and treat liver cancer, one of the leading causes of cancer-related mortality worldwide. This narrative review summarizes the scientific achievements to date regarding the role of statins in liver tumors. Molecular biology tools have revealed that cell growth and proliferation can be inhibited by statins, which further inhibit angiogenesis. Clinical studies, supported by meta-analysis, confirm that statins are highly effective in preventing and treating hepatocellular carcinoma and cholangiocarcinoma. However, this effect may depend on the statin's type and dose, and more clinical trials are required to evaluate clinical effects. Moreover, their potential hepatotoxicity is a significant caveat for using statins in clinical practice. Nevertheless, this group of drugs, initially developed to prevent cardiovascular diseases, is now a key candidate in hepato-oncology patient management. The description of new drug-statin-like structures, e.g., with low toxicity to liver cells, may bring another clinically significant improvement to current cancer therapies.

Loss of hepatic FTCD promotes lipid accumulation and hepatocarcinogenesis by upregulating PPARγ and SREBP2

Background & Aims

Exploiting key regulators responsible for hepatocarcinogenesis is of great importance for the prevention and treatment of hepatocellular carcinoma (HCC). However, the key players contributing to hepatocarcinogenesis remain poorly understood. We explored the molecular mechanisms underlying the carcinogenesis and progression of HCC for the development of potential new therapeutic targets.

Methods

The Cancer Genome Atlas-Liver Hepatocellular Carcinoma (TCGA-LIHC) and Genotype-Tissue Expression (GTEx) databases were used to identify genes with enhanced expression in the liver associated with HCC progression. A murine liver-specific Ftcd knockout (Ftcd-LKO) model was generated to investigate the role of formimidoyltransferase cyclodeaminase (FTCD) in HCC. Multi-omics analysis of transcriptomics, metabolomics, and proteomics data were applied to further analyse the molecular effects of FTCD expression on hepatocarcinogenesis. Functional and biochemical studies were performed to determine the significance of loss of FTCD expression and the therapeutic potential of Akt inhibitors in FTCD-deficient cancer cells.

Results

FTCD is highly expressed in the liver but significantly downregulated in HCC. Patients with HCC and low levels of FTCD exhibited worse prognosis, and patients with liver cirrhosis and low FTCD levels exhibited a notable higher probability of developing HCC. Hepatocyte-specific knockout of FTCD promoted both chronic diethylnitrosamine-induced and spontaneous hepatocarcinogenesis in mice. Multi-omics analysis showed that loss of FTCD affected fatty acid and cholesterol metabolism in hepatocarcinogenesis. Mechanistically, loss of FTCD upregulated peroxisome proliferator-activated receptor (PPAR)γ and sterol regulatory element-binding protein 2 (SREBP2) by regulating the PTEN/Akt/mTOR signalling axis, leading to lipid accumulation and hepatocarcinogenesis.

Conclusions

Taken together, we identified a FTCD-regulated lipid metabolic mechanism involving PPARγ and SREBP2 signaling in hepatocarcinogenesis and provide a rationale for therapeutically targeting of HCC driven by downregulation of FTCD.

Impact and implications

Exploiting key molecules responsible for hepatocarcinogenesis is significant for the prevention and treatment of HCC. Herein, we identified formimidoyltransferase cyclodeaminase (FTCD) as the top enhanced gene, which could serve as a predictive and prognostic marker for patients with HCC. We generated and characterised the first Ftcd liver-specific knockout murine model. We found loss of FTCD expression upregulated peroxisome proliferator-activated receptor (PPAR)γ and sterol regulatory element-binding protein 2 (SREBP2) by regulating the PTEN/Akt/mTOR signalling axis, leading to lipid accumulation and hepatocarcinogenesis, and provided a rationale for therapeutic targeting of HCC driven by downregulation of FTCD.

Gypenosides suppress hepatocellular carcinoma cells by blocking cholesterol biosynthesis through inhibition of MVA pathway enzyme HMGCS1

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors with high morbidity and mortality. Targeting abnormal cholesterol metabolism is a potential therapeutic direction. Therefore, more natural drugs targeting cholesterol in HCC need to be developed. Gypenosides (Gyp), the major constituent of Gynostemma pentaphyllum, has been demonstrated to have pharmacological properties on anti-cancer, anti-obesity, and hepatoprotective. We investigated whether Gyp, isolated and purified by our lab, could inhibit HCC progression by inhibiting cholesterol synthesis. The present research showed that Gyp inhibited proliferation and migration, and induced apoptosis in Huh-7 and Hep3B cells. Metabolomics, transcriptomics, and target prediction all suggested that lipid metabolism and cholesterol biosynthesis were the mechanisms of Gyp. Gyp could limit the production of cholesterol and target HMGCS1, the cholesterol synthesis-related protein. Downregulation of HMGCS1 could suppress the progression and abnormal cholesterol metabolism of HCC. In terms of mechanism, Gyp suppressed mevalonate (MVA) pathway mediated cholesterol synthesis by inhibiting HMGCS1 transcription factor SREBP2. And the high expression of HMGCS1 in HCC human specimens was correlated with poor clinical prognosis. The data suggested that Gyp could be a promising cholesterol-lowering drug for the prevention and treatment of HCC. And targeting SREBP2-HMGCS1 axis in MVA pathway might be an effective HCC therapeutic strategy.

Hepatic FASN deficiency differentially affects nonalcoholic fatty liver disease and diabetes in mouse obesity models

Nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes are interacting comorbidities of obesity, and increased hepatic de novo lipogenesis (DNL), driven by hyperinsulinemia and carbohydrate overload, contributes to their pathogenesis. Fatty acid synthase (FASN), a key enzyme of hepatic DNL, is upregulated in association with insulin resistance. However, the therapeutic potential of targeting FASN in hepatocytes for obesity-associated metabolic diseases is unknown. Here, we show that hepatic FASN deficiency differentially affects NAFLD and diabetes depending on the etiology of obesity. Hepatocyte-specific ablation of FASN ameliorated NAFLD and diabetes in melanocortin 4 receptor-deficient mice but not in mice with diet-induced obesity. In leptin-deficient mice, FASN ablation alleviated hepatic steatosis and improved glucose tolerance but exacerbated fed hyperglycemia and liver dysfunction. The beneficial effects of hepatic FASN deficiency on NAFLD and glucose metabolism were associated with suppression of DNL and attenuation of gluconeogenesis and fatty acid oxidation, respectively. The exacerbation of fed hyperglycemia by FASN ablation in leptin-deficient mice appeared attributable to impairment of hepatic glucose uptake triggered by glycogen accumulation and citrate-mediated inhibition of glycolysis. Further investigation of the therapeutic potential of hepatic FASN inhibition for NAFLD and diabetes in humans should thus consider the etiology of obesity.

CircRREB1 mediates lipid metabolism related senescent phenotypes in chondrocytes through FASN post-translational modifications

Osteoarthritis is a prevalent age-related disease characterized by dysregulation of extracellular matrix metabolism, lipid metabolism, and upregulation of senescence-associated secretory phenotypes. Herein, we clarify that CircRREB1 is highly expressed in secondary generation chondrocytes and its deficiency can alleviate FASN related senescent phenotypes and osteoarthritis progression. CircRREB1 impedes proteasome-mediated degradation of FASN by inhibiting acetylation-mediated ubiquitination. Meanwhile, CircRREB1 induces RanBP2-mediated SUMOylation of FASN and enhances its protein stability. CircRREB1-FASN axis inhibits FGF18 and FGFR3 mediated PI3K-AKT signal transduction, then increased p21 expression. Intra-articular injection of adenovirus-CircRreb1 reverses the protective effects in CircRreb1 deficiency mice. Further therapeutic interventions could have beneficial effects in identifying CircRREB1 as a potential prognostic and therapeutic target for age-related OA.

Puerarin Prevents Bisphenol S Induced Lipid Accumulation by Reducing Liver Lipid Synthesis and Promoting Lipid Metabolism in C57BL/6J Mice

Bisphenol S (BPS) is an environmental pollutant that can accumulate in the human body and cause harm. Puerarin (PUE) is a flavonoid with anti-inflammatory and antioxidant effects. In this study, we used 50 mg/kg/d BPS as a poison and PUE as an intervention for model mice for 42 d. BPS exposure significantly increased the levels of the impairment of the mice's liver function, T-CHO, TG, LDL-C, ALT, and AST in the BPS group were significantly increased (p < 0.05). Additionally, BPS exposure caused inflammatory cell infiltration in the mice liver tissue and enhanced oxidative stress response, the level of MDA was significantly increased (p < 0.05). The expression of CD36 and pparγ was stimulated after BPS exposure. Moreover, the expression of cpt1a and cpt1b, which promote fatty acid oxidation, was downregulated. After PUE intervention, the levels of genes and proteins involved in lipid synthesis (PPARγ, SREBP1C, and FASN) and metabolism (Cpt1a, Cpt1b, and PPARα) in mice returned to those of the control group, or much higher than those in the BPS group. Therefore, we hypothesized that BPS causes lipid accumulation in the liver by promoting lipid synthesis and reducing lipid metabolism, whereas PUE reduces lipid synthesis and promotes lipid metabolism. Conclusively, our results imply that long-term exposure to BPS in mice affects liver lipid metabolism and that PUE intervention could maintain the liver function of mice at normal metabolic levels.

SREBP2 inhibitor betulin sensitizes hepatocellular carcinoma to lenvatinib by inhibiting the mTOR/IL-1β pathway

Lenvatinib has become the first-line therapy in advanced hepatocellular carcinoma (HCC), but its efficacy is still limited because of the inevitable development of resistance. It has been reported that cellular cholesterol levels are associated with tyrosine kinase inhibitor (TKI) efficacy. Here, we show that betulin, a sterol regulatory element-binding protein 2 (SREBP2) inhibitor, markedly enhances the anti-tumor effect of lenvatinib in HCC both in vitro and in vivo. Our results also show that the combination treatment of lenvatinib and betulin synergistically inhibits the proliferation and clonogenicity of HCC cells. The mRNA and protein expressions of IL-1β are markedly decreased in HCC cells treated with betulin, while the sensitivity of HCC cells to lenvatinib is enhanced. Moreover, we find that the knockdown of IL-1β also enhances the efficacy of lenvatinib, and recombinant IL-1β protein rescues cell viability, which is reduced by lenvatinib in HCC cells. Further mechanistic studies indicate that betulin decreases the level of IL-1β in HCC cells by inhibiting the mTOR signaling pathway. Finally, the growth of the tumors in xenograft mouse models subjected to combination treatment is significantly suppressed. In summary, our study reveals that the SREBP2 inhibitor betulin sensitizes hepatocellular carcinoma to lenvatinib by inhibiting the mTOR/IL-1β pathway, which may be a promising therapeutic strategy for patients with HCC.

Acyl-CoA thioesterase 12 suppresses YAP-mediated hepatocarcinogenesis by limiting glycerolipid biosynthesis

Cancer cells use acetate to support the higher demand for energy and lipid biosynthesis during uncontrolled cell proliferation, as well as for acetylation of regulatory proteins. Acyl-CoA thioesterase 12 (Acot12) is the enzyme that hydrolyzes acetyl-CoA to acetate in liver cytosol and is downregulated in hepatocellular carcinoma (HCC). A mechanistic role for Acot12 in hepatocarcinogenesis was assessed in mice in response to treatment with diethylnitrosamine(DEN)/carbon tetrachloride (CCl4) administration or prolonged feeding of a diet that promotes non-alcoholic steatohepatitis (NASH). Relative to controls, Acot12-/- mice exhibited accelerated liver tumor formation that was characterized by the hepatic accumulation of glycerolipids, including lysophosphatidic acid (LPA), and that was associated with reduced Hippo signaling and increased yes-associated protein (YAP)-mediated transcriptional activity. In Acot12-/- mice, restoration of hepatic Acot12 expression inhibited hepatocarcinogenesis and YAP activation, as did knockdown of hepatic YAP expression. Excess LPA produced due to deletion of Acot12 signaled through LPA receptors (LPARs) coupled to Gα12/13 subunits to suppress YAP phosphorylation, thereby promoting its nuclear localization and transcriptional activity. These findings identify a protective role for Acot12 in suppressing hepatocarcinogenesis by limiting biosynthesis of glycerolipids including LPA, which preserves Hippo signaling.

Cholesterol metabolism in cancer and cell death

SIGNIFICANCE

Cholesterol is a type of lipid that plays a crucial role in building and maintaining cell membranes, producing certain hormones, and aiding in digestion. The two main types of cholesterol are low-density lipoprotein and high-density lipoprotein, and maintaining a healthy balance between them is essential for cellular function and organism health.

RECENT ADVANCES

Cholesterol metabolism is a complex and dynamic process that involves biosynthesis, uptake, efflux, transport, and esterification. Disruptions in cholesterol metabolism are implicated in all stages of cancer, contributing to drug resistance, immune evasion, and autophagy dysfunction. These disruptions have also been linked to various types of regulated cell death, such as apoptosis, anoikis, lysosome-dependent cell death, pyroptosis, NETosis, necroptosis, entosis, ferroptosis, alkaliptosis, immunogenic cell death, and paraptosis.

CRITICAL ISSUES

Understanding the complex interplay between cholesterol metabolism and cell death and their impact on cancer development and progression is still a significant challenge. Additionally, there is currently a lack of reliable biomarkers that can accurately reflect cholesterol metabolism dysregulation in cancer.

FUTURE DIRECTIONS

To develop more specific and effective cholesterol metabolism-targeted therapies, a better understanding of the mechanisms by which cholesterol metabolism dysregulation contributes to cell death and cancer progression is needed. Additionally, improving the accuracy and reliability of biomarkers will be crucial for monitoring and diagnosing cholesterol-related cancer subtypes and evaluating the effectiveness of cholesterol metabolism-targeted therapies. These efforts will require ongoing research and collaboration among multidisciplinary teams of scientists and clinicians.

Sparse Independence Component Analysis for Competitive Endogenous RNA Co-Module Identification in Liver Hepatocellular Carcinoma

OBJECTIVE

Long non-coding RNAs (lncRNAs) have been shown to be associated with the pathogenesis of different kinds of diseases and play important roles in various biological processes. Although numerous lncRNAs have been found, the functions of most lncRNAs and physiological/pathological significance are still in its infancy. Meanwhile, their expression patterns and regulation mechanisms are also far from being fully understood.

METHODS

In order to reveal functional lncRNAs and identify the key lncRNAs, we develop a new sparse independence component analysis (ICA) method to identify lncRNA-mRNA-miRNA expression co-modules based on the competitive endogenous RNA (ceRNA) theory using the sample-matched lncRNA, mRNA and miRNA expression profiles. The expression data of the three RNA combined together is approximated sparsely to obtain the corresponding sparsity coefficient, and then it is decomposed by using ICA constraint optimization to obtain the common basis and modules. Subsequently, affine propagation clustering is used to perform cluster analysis on the common basis under multiple running conditions to obtain the co-modules for the selection of different RNA elements.

RESULTS

We applied sparse ICA to Liver Hepatocellular Carcinoma (LIHC) dataset and the experiment results demonstrate that the proposed sparse ICA method can effectively discover biologically functional expression common modules.

CONCLUSION

It may provide insights into the function of lncRNAs and molecular mechanism of LIHC. Clinical and Translational Impact Statement-The results on LIHC dataset demonstrate that the proposed sparse ICA method can effectively discover biologically functional expression common modules, which may provide insights into the function of IncRNAs and molecular mechanism of LIHC.

Nobiletin inhibits de novo FA synthesis to alleviate gastric cancer progression by regulating endoplasmic reticulum stress

BACKGROUND

Gastric cancer (GC) is a common malignant tumor with limited treatment options. The natural flavonoid nobiletin (NOB) is a beneficial antioxidant that possesses anticancer activity. However, the mechanisms by which NOB inhibits GC progression remain unclear.

METHODS

A CCK-8 assay was performed to determine cytotoxicity. Cell cycle and apoptosis analyses were performed by flow cytometry. RNA-seq was performed to detect differential gene expression after NOB treatment. RT‒qPCR, Western blot and immunofluorescence staining were used to examine the underlying mechanisms of NOB in GC. Xenograft tumor models were constructed to verify the effect of NOB and its specific biological mechanism in GC.

RESULTS

NOB inhibited cell proliferation, caused cell cycle arrest and induced apoptosis in GC cells. KEGG classification identified that the inhibitory effect of NOB on GC cells mainly involved the lipid metabolism pathway. We further showed that NOB reduced de novo fatty acid (FA) synthesis, as evidenced by the decreased levels of neutral lipids and the expression levels of ACLY, ACACA and FASN, and ACLY abrogated the effect of NOB on lipid deposits in GC cells. In addition, we also found that NOB triggered endoplasmic reticulum (ER) stress by activating the IRE-1α/GRP78/CHOP axis, but overexpression of ACLY reversed ER stress. Mechanistically, inhibiting ACLY expression with NOB significantly reduced neutral lipid accumulation, thereby inducing apoptosis by activating IRE-1α-mediated ER stress and inhibiting GC cell progression. Finally, in vivo results also demonstrated that NOB inhibited tumor growth by decreasing de novo FA synthesis.

CONCLUSION

NOB could inhibit the expression of ACLY to activate IRE-1α-induced ER stress, which ultimately led to GC cell apoptosis. Our results provide novel insight into the use of de novo FA synthesis for GC treatment and are the first to reveal that NOB inhibits GC progression by ACLY-dependent ER stress.

FBXW7β loss-of-function enhances FASN-mediated lipogenesis and promotes colorectal cancer growth

Continuous de novo fatty acid synthesis is required for the biosynthetic demands of tumor. FBXW7 is a highly mutated gene in CRC, but its biological functions in cancer are not fully characterized. Here, we report that FBXW7β, a FBXW7 isoform located in the cytoplasm and frequently mutated in CRC, is an E3 ligase of fatty acid synthase (FASN). Cancer-specific FBXW7β mutations that could not degrade FASN can lead to sustained lipogenesis in CRC. COP9 signalosome subunit 6 (CSN6), an oncogenic marker of CRC, increases lipogenesis via interacting with and stabilizing FASN. Mechanistic studies show that CSN6 associates with both FBXW7β and FASN, and antagonizes FBXW7β's activity by enhancing FBXW7β autoubiquitination and degradation, which in turn prevents FBXW7β-mediated FASN ubiquitination and degradation, thereby regulating lipogenesis positively. Both CSN6 and FASN are positively correlated in CRC, and CSN6-FASN axis, regulated by EGF, is responsible for poor prognosis of CRC. The EGF-CSN6-FASN axis promotes tumor growth and implies a treatment strategy of combination of orlistat and cetuximab. Patient-derived xenograft experiments prove the effectiveness of employing orlistat and cetuximab combination in suppressing tumor growth for CSN6/FASN-high CRC. Thus, CSN6-FASN axis reprograms lipogenesis to promote tumor growth and is a target for cancer intervening strategy in CRC.

Lipophagy-mediated cholesterol synthesis inhibition is required for the survival of hepatocellular carcinoma under glutamine deprivation

Glutamine is critical for tumor progression, and restriction of its availability is emerging as a potential therapeutic strategy. The metabolic plasticity of tumor cells helps them adapting to glutamine restriction. However, the role of cholesterol metabolism in this process is relatively unexplored. Here, we reported that glutamine deprivation inhibited cholesterol synthesis in hepatocellular carcinoma (HCC). Reactivation of cholesterol synthesis enhanced glutamine-deprivation-induced cell death of HCC cells, which is partially duo to augmented NADPH depletion and lipid peroxidation. Mechanistically, glutamine deprivation induced lipophagy to transport cholesterol from lipid droplets (LDs) to endoplasmic reticulum (ER), leading to inhibit SREBF2 maturation and cholesterol synthesis, and maintain redox balance for survival. Glutamine deprivation decreased mTORC1 activity to induce lipophagy. Importantly, administration of U18666A, CQ, or shTSC2 viruses further augmented GPNA-induced inhibition of xenograft tumor growth. Clinical data supported that glutamine utilization positively correlated with cholesterol synthesis, which is associated with poor prognosis of HCC patients. Collectively, our study revealed that cholesterol synthesis inhibition is required for the survival of HCC under glutamine-restricted tumor microenvironment.

P53 deficiency affects cholesterol esterification to exacerbate hepatocarcinogenesis

BACKGROUND AND AIMS

Cholesterol ester (CE) biosynthesis and homeostasis play critical roles in many cancers, including HCC, but their exact mechanistic contributions to HCC disease development require further study.

APPROACH AND RESULTS

Here, we report on a proposed role of tumor suppressor P53 in its repressing ubiquitin-specific peptidase 19 (USP19) and sterol O-acyltransferase (SOAT) 1, which maintains CE homeostasis. USP19 enhances cholesterol esterification and contributes to hepatocarcinogenesis (HCG) by deubiquitinating and stabilizing SOAT1. Loss of either SOAT1 or USP19 dramatically attenuates cholesterol esterification and HCG in P53-deficient mice fed with either a normal chow diet or a high-cholesterol, high-fat diet (HCHFD). SOAT1 inhibitor avasimibe has more inhibitory effect on HCC progression in HCHFD-maintained P53-deficient mice when compared to the inhibitors of de novo cholesterol synthesis. Consistent with our findings in the mouse model, the P53-USP19-SOAT1 signaling axis is also dysregulated in human HCCs.

CONCLUSIONS

Collectively, our findings demonstrate that SOAT1 participates in HCG by increasing cholesterol esterification, thus indicating that SOAT1 is a potential biomarker and therapeutic target in P53-deficient HCC.

Phosphomevalonate Kinase Controls β-Catenin Signaling via the Metabolite 5-Diphosphomevalonate

β-catenin signaling is abnormally activated in cancer. Here, this work screens the mevalonate metabolic pathway enzyme PMVK to stabilize β-catenin signaling using a human genome-wide library. On the one hand, PMVK-produced MVA-5PP competitively binds to CKIα to prevent β-catenin Ser45 phosphorylation and degradation. On the other hand, PMVK functions as a protein kinase to directly phosphorylate β-catenin Ser184 to increase its protein nuclear localization. This synergistic effect of PMVK and MVA-5PP together promotes β-catenin signaling. In addition, PMVK deletion impairs mouse embryonic development and causes embryonic lethal. PMVK deficiency in liver tissue alleviates DEN/CCl₄ -induced hepatocarcinogenesis. Finally, the small molecule inhibitor of PMVK, PMVKi5, is developed and PMVKi5 inhibits carcinogenesis of liver and colorectal tissues. These findings reveal a non-canonical function of a key metabolic enzyme PMVK and a novel link between the mevalonate pathway and β-catenin signaling in carcinogenesis providing a new target for clinical cancer therapy.

Fatty acid metabolism: A new therapeutic target for cervical cancer

Cervical cancer (CC) is one of the most common malignancies in women. Cancer cells can use metabolic reprogramming to produce macromolecules and ATP needed to sustain cell growth, division and survival. Recent evidence suggests that fatty acid metabolism and its related lipid metabolic pathways are closely related to the malignant progression of CC. In particular, it involves the synthesis, uptake, activation, oxidation, and transport of fatty acids. Similarly, more and more attention has been paid to the effects of intracellular lipolysis, transcriptional regulatory factors, other lipid metabolic pathways and diet on CC. This study reviews the latest evidence of the link between fatty acid metabolism and CC; it not only reveals its core mechanism but also discusses promising targeted drugs for fatty acid metabolism. This study on the complex relationship between carcinogenic signals and fatty acid metabolism suggests that fatty acid metabolism will become a new therapeutic target in CC.

A Novel Phenazine Analog, CPUL1, Suppresses Autophagic Flux and Proliferation in Hepatocellular Carcinoma: Insight from Integrated Transcriptomic and Metabolomic Analysis

BACKGROUND

CPUL1, a phenazine analog, has demonstrated potent antitumor properties against hepatocellular carcinoma (HCC) and indicates a promising prospect in pharmaceutical development. However, the underlying mechanisms remain largely obscure.

METHODS

Multiple HCC cell lines were used to investigate the in vitro effects of CPUL1. The antineoplastic properties of CPUL1 were assessed in vivo by establishing a xenograft nude mice model. After that, metabolomics, transcriptomics, and bioinformatics were integrated to elucidate the mechanisms underlying the therapeutic efficacy of CPUL1, highlighting an unanticipated involvement of autophagy dysregulation.

RESULTS

CPUL1 suppressed HCC cell proliferation in vitro and in vivo, thereby endorsing the potential as a leading agent for HCC therapy. Integrative omics characterized a deteriorating scenario of metabolic debilitation with CPUL1, presenting an issue in the autophagy contribution of autophagy. Subsequent observations indicated that CPUL1 treatment could impede autophagic flow by suppressing autophagosome degradation rather than its formation, which supposedly exacerbated cellular damage triggered by metabolic impairment. Moreover, the observed late autophagosome degradation may be attributed to lysosome dysfunction, which is essential for the final stage of autophagy and cargo disposal.

CONCLUSIONS

Our study comprehensively profiled the anti-hepatoma characteristics and molecular mechanisms of CPUL1, highlighting the implications of progressive metabolic failure. This could partially be ascribed to autophagy blockage, which supposedly conveyed nutritional deprivation and intensified cellular vulnerability to stress.

The IDI1/SREBP2 axis drives intrahepatic cholestasis and is a treatment target of San-Huang-Cai-Zhu formula identified by sequencing and experiments

San-Huang-Chai-Zhu formula (SHCZF), originates from Da-Huang-Xiao-Shi decoction (DHXSD) for the treatment of jaundice as recorded in the Chinese traditional Chinese medicine book Jin Gui Yao Lue. In the clinic, SHCZF has been used to treat cholestasis-related liver disease by improving intrahepatic cholestasis, but the treatment mechanism has not been elucidated. In this study, 24 Sprague-Dawley (SD) rats were randomly assigned to the normal, acute intrahepatic cholestasis (AIC), SHCZF, and ursodeoxycholic acid (UDCA) groups. In addition, 36 SD rats were divided into dynamic groups, namely, normal 24 h, AIC 24 h, normal 48 h, AIC 48 h, normal 72 h, and AIC 72 h groups. Alpha-naphthylisothiocyanate (ANIT) was used to induce an AIC rat model. Serum biochemical indices and hepatic pathology were detected. Part of the hepatic tissues was used for sequencing, and others were used for subsequent experiments. Sequencing data combined with bioinformatics analysis were used to screen target genes and identify the mechanisms of SHCZF in treating AIC rats. Quantitative real-time PCR (qRT-PCR) and Western blotting (WB) were used to detect the RNA/Protein expression levels of screened genes. Rats in the dynamic group were used to determine the sequence of cholestasis and liver injury. High-performance liquid chromatography (HPLC) was used to determine the representative bioingredients of SHCZF. Sequencing and bioinformatics analysis suggested that IDI1 and SREBP2 are hub target genes of SHCZF to ameliorate ANTI-induced intrahepatic cholestasis in rats. The treatment mechanism is associated with the regulation of lipoprotein receptor (LDLr) to reduce cholesterol intake and 3-Hydroxy-3-Methylglutaryl-CoA reductase (HMGCR), and 3-Hydroxy-3-Methylglutaryl-CoA synthase 1 (HMGCS1) to decrease cholesterol synthesis. Animal experiments showed that SHCZF significantly reduced the expression levels of the above genes and proinflammatory cytokine lipocalin 2 (LCN2), inflammatory cytokines interleukin 1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α), thereby improving intrahepatic cholestasis and inflammation and liver injury.

Fatty acid synthase (FASN) inhibits the cervical squamous cell carcinoma (CESC) progression through the Akt/mTOR signaling pathway

BACKGROUND

Cervical cancer is a malignant tumor that affects females and remains the cause of the highest morbidity and mortality among women worldwide. Currently, gene-targeted therapy is a novel treatment option for clinicians. Furthermore, fatty acid synthase (FASN) plays a therapeutic role in various cancers. Nonetheless, the mechanism of action of this enzyme in cervical squamous cell carcinoma and cervical duct adenocarcinoma (CESC) has not yet been reported.

METHODS

RNA (ribonucleic acid) sequencing data and clinical information were obtained from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx). The expression levels of FASN were obtained from Gene Expression Profiling Interactive Analysis 2 (GEPIA2) and Human Protein Atlas (HPA). Univariate and multivariate Cox regression analyses were utilized to assess independent prognostic factors associated with survival. A nomogram and receiver operating characteristic curve (ROC) were employed to evaluate survival and predictive power. In vitro experiments and real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) were conducted to identify cell interference efficiency. MTS, monoclonal formation, and EDU assays were used to determine cell viability. Wound healing and invasion assays (transwell assay) were used to evaluate cell migration and invasion. Finally, Hoechst 33342, propidium iodide (PI) staining and Annexin V-FITC staining were used to assess apoptosis and the cell cycle, while western blotting was utilized to determine the protein expression levels.

RESULTS

FASN was aberrantly expressed in various cancers, including CESC, where it was highly expressed. Kaplan-Meier, univariate, multivariate Cox regression analyses and ROC curve indicated that FASN is a potential key indicator of survival prognosis among CESC patients and demonstrated good predictive ability and efficacy. Complementary in vitro experiments confirmed that FASN is an important target for CESC therapy.

CONCLUSION

The current study validated the biological and clinical significance of FASN in CESC prognosis, suggesting that FASN knockdown may exert antitumor activity against cervical cancer through the Akt/mTOR signaling pathway.

Rapid discovery and classification of inhibitors of coronavirus infection by pseudovirus screen and amplified luminescence proximity homogeneous assay

To identify potent antiviral compounds, we introduced a high-throughput screen platform that can rapidly classify hit compounds according to their target. In our platform, we performed a compound screen using a lentivirus-based pseudovirus presenting a spike protein of coronavirus, and we evaluated the hit compounds using an amplified luminescence proximity homogeneous assay (alpha) test with purified host receptor protein and the receptor binding domain of the viral spike. With our screen platform, we were able to identify both spike-specific compounds (class I) and broad-spectrum antiviral compounds (class II). Among the hit compounds, thiosemicarbazide was identified to be selective to the interaction between the viral spike and its host cell receptor, and we further optimized the binding potency of thiosemicarbazide through modification of the pyridine group. Among the class II compounds, we found raloxifene and amiodarone to be highly potent against human coronaviruses including Middle East respiratory syndrome coronavirus (MERS-CoV), severe acute respiratory syndrome coronavirus (SARS-CoV), and SARS-CoV-2. In particular, using analogs of the benzothiophene moiety, which is also present in raloxifene, we have identified benzothiophene as a novel structural scaffold for broad-spectrum antivirals. This work highlights the strong utility of our screen platform using a pseudovirus assay and an alpha test for rapid identification of potential antiviral compounds and their mechanism of action, which can lead to the accelerated development of therapeutics against newly emerging viral infections.