Inhibition of ACLY overcomes cancer immunotherapy resistance via polyunsaturated fatty acids peroxidation and cGAS-STING activation

Why and how citrate may sensitize malignant tumors to immunotherapy

Immunotherapy, either alone or in combination with chemotherapy, has demonstrated limited efficacy in a variety of solid cancers. Several factors contribute to explaining primary or secondary resistance. Among them, cancer cells, whose metabolism frequently relies on aerobic glycolysis, promote exhaustion of cytotoxic immune cells by diverting the glucose in the tumor microenvironment (TME) to their own profit, while secreting lactic acid that sustains the oxidative metabolism of immunosuppressive cells. Here, we propose to combine current treatment based on the use of immune checkpoint inhibitors (ICIs) with high doses of sodium citrate (SCT) because citrate inhibits cancer cell metabolism (by targeting both glycolysis and oxidative metabolism) and may active anti-tumor immune response. Indeed, as showed in preclinical studies, SCT reduces cancer cell growth, promoting cell death and chemotherapy effectiveness. Furthermore, since the plasma membrane citrate carrier pmCIC is mainly expressed in cancer cells and low or not expressed in immune and non-transformed cells, we argue that the inhibition of cancer cell metabolism by SCT may increase glucose availability in the TME, thus promoting functionality of anti-tumor immune cells. Concomitantly, the decrease in the amount of lactic acid in the TME may reduce the functionality of immunosuppressive cells. Preclinical studies have shown that SCT can enhance the anti-tumor immune response through an enhancement of T cell infiltration and activation, and a repolarization of macrophages towards a TAM1-like phenotype. Therefore, this simple and cheap strategy may have a major impact to increase the efficacy of current immunotherapies in human solid tumors and we encourage testing it in clinical trials.

The role of cGAS-STING signaling pathway in colorectal cancer immunotherapy: Mechanism and progress

Colorectal cancer (CRC) is a common malignant tumor in the gastrointestinal tract, it is known as the "silent killer", which poses a serious threat to the lives of patients. The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon gene (STING) signaling pathway responds to DNA by sensing, which plays an important role in anti-infection, autoimmune diseases and anti-tumor immunity. Recent studies have found that the activation of cGAS-STING pathway in CRC can induce the expression and secretion of type I interferon (IFN-I) and a variety of inflammatory factors, further activate anti-tumor CD8+ T cells, exert anti-tumor immune response, and inhibit the progression of CRC. Therefore, targeting the cGAS-STING pathway and developing drugs that can regulate the cGAS-STING pathway are of great significance for improving the therapeutic effect and prognosis of CRC patients. In this review, we introduce the cGAS-STING signaling pathway and the regulatory role of this signaling pathway in CRC immune microenvironment. In addition, we discussed the research progress of cGAS-STING pathway in CRC immunotherapy and the clinical research status of STING agonists developed against this pathway, emphasizing the clinical potential of CRC immunotherapy based on the cGAS-STING signaling pathway.

Targeting metabolic pathway enhance CAR-T potency for solid tumor

Chimeric antigen receptor (CAR) T cells have great potential in cancer therapy, particularly in treating hematologic malignancies. However, their efficacy in solid tumors remains limited, with a significant proportion of patients failing to achieve long-term complete remission. One major challenge is the premature exhaustion of CAR-T cells, often due to insufficient metabolic energy. The survival, function and metabolic adaptation of CAR-T cells are key determinants of their therapeutic efficacy. We explore how targeting metabolic pathways in the tumor microenvironment can enhance CAR-T cell therapy by addressing metabolic competition and immunosuppression that impair CAR-T cell function. Tumors undergo metabolically reprogrammed to meet their rapid proliferation, thereby modulating metabolic pathways in immune cells to promote immunosuppression. The distinct metabolic requirements of tumors and T cells create a competitive environment, affecting the efficacy of CAR-T cell therapy. Recent research on glucose, lipid and amino acid metabolism, along with the interactions between tumor and immune cell metabolism, has revealed that targeting these metabolic processes can enhance antitumor immune responses. Combining metabolic interventions with existing antitumor therapies can fulfill the metabolic demands of immune cells, providing new ideas for tumor immunometabolic therapies. This review discusses the latest advances in the immunometabolic mechanisms underlying tumor immunosuppression, their implications for immunotherapy, and summarizes potential metabolic targets to improve the efficacy of CAR-T therapy.

Theoretical framework and emerging challenges of lipid metabolism in cancer

Elevated lipid metabolism is one of hallmarks of malignant tumors. Lipids not only serve as essential structural components of biological membranes but also provide energy and substrates for the proliferation of cancer cells and tumor growth. Cancer cells meet their lipid needs by coordinating the processes of lipid absorption, synthesis, transport, storage, and catabolism. As research in this area continues to deepen, numerous new discoveries have emerged, making it crucial for scientists to stay informed about the developments of cancer lipid metabolism. In this review, we first discuss relevant concepts and theories or assumptions that help us understand the lipid metabolism and -based cancer therapies. We then systematically summarize the latest advancements in lipid metabolism including new mechanisms, novel targets, and up-to-date pre-clinical and clinical investigations of anti-cancer treatment with lipid metabolism targeted drugs. Finally, we emphasize emerging research directions and therapeutic strategies, and discuss future prospective and emerging challenges. This review aims to provide the latest insights and guidance for research in the field of cancer lipid metabolism.

ATP citrate lyase drives vascular remodeling in systemic and pulmonary vascular diseases through metabolic and epigenetic changes

ATP citrate lyase (ACLY), a crucial enzyme in de novo lipid synthesis and histone acetylation, plays a key role in regulating vascular smooth muscle cell (VSMC) proliferation and survival. We found that human coronary and pulmonary artery tissues had up-regulated ACLY expression during vascular remodeling in coronary artery disease and pulmonary arterial hypertension. Pharmacological and genetic inhibition of ACLY in human primary cultured VSMCs isolated from the coronary arteries of patients with coronary artery diseases and from the distal pulmonary arteries of patients with pulmonary arterial hypertension resulted in reduced cellular proliferation and migration and increased susceptibility to apoptosis. These cellular changes were linked to diminished glycolysis, reduced lipid synthesis, impairment in general control nonrepressed protein 5 (GCN5)-dependent histone acetylation and suppression of the transcription factor FOXM1. In vivo studies using a pharmacological inhibitor and VSMC-specific Acly knockout mice showed that ACLY inhibition alleviated vascular remodeling. ACLY inhibition alleviated remodeling in carotid injury and ligation models in rodents and attenuated pulmonary arterial hypertension in Sugen/hypoxia rat and mouse models. Moreover, ACLY inhibition showed improvements in vascular remodeling in human ex vivo models, which included cultured human coronary artery and saphenous vein rings as well as precision-cut lung slices. Our results propose ACLY as a novel therapeutic target for treating complex vascular diseases, offering promising avenues for future clinical intervention.

Immune cells mediate the effects of gut microbiota on neuropathic pain: a Mendelian randomization study

BACKGROUND

The gut microbiota may be involved in neuropathic pain. However, the causal association between gut microbiota and neuropathic pain remains unclear. Whether immune cells and inflammatory factors mediate the pathway from gut microbiota to neuropathic pain has not been elucidated.

METHODS

We obtained the summary data of 412 gut microbiota, 731 immune cells, 91 inflammatory factors, and five types of neuropathic pain (drug-induced neuropathy, postherpetic neuralgia, sciatica, trigeminal neuralgia, and unspecified neuralgia) from large-scale genome-wide association study (GWAS) datasets and the FinnGen database. We used bidirectional Mendelian randomization (MR) analysis to explore the causal association between gut microbiota and neuropathic pain. Additionally, we conducted a mediation analysis to identify whether immune cells and inflammatory factors act as mediators within these causal relationships.

RESULTS

Our study revealed 30 causal relationships between 26 gut bacterial taxa and five types of neuropathic pain, including four associated with drug-induced neuropathy, six with postherpetic neuralgia, five with sciatica, eight with trigeminal neuralgia, and seven with unspecified neuralgia. Moreover, we identified 35 gut bacterial pathway abundances causally involved in neuropathic pain. The reverse MR analysis showed no evidence of reverse causality from gut microbiota to neuropathic pain. Mediation analysis demonstrated that the immune cell phenotype "HLA-DR++ monocyte % leukocyte" mediated the causal relationship between p_Proteobacteria and sciatica with a mediation proportion of 36.15% (P = 0.038), whereas "CD11c on CD62L+ myeloid dendritic cell" mediated the causal pathway from assimilatory sulfate reduction to trigeminal neuralgia with a mediation proportion of 27.90% (P = 0.041).

CONCLUSION

This study identified the causal relationships between several specific gut microbiota and various neuropathic pain subtypes. Additionally, two immune cells may act as potential mediators in the pathways from gut microbiota to neuropathic pain.

Synergistic antimicrobial activity of alpha-linolenic acid in combination with tetracycline or florfenicol against multidrug-resistant Salmonella typhimurium

Salmonella is a major foodborne pathogen that can be transmitted from livestock and poultry to humans through the food chain. Due to the widespread use of antibiotics, antibiotic resistance Salmonella has become an important factor threatening food safety. Combining antibiotic and non-antibiotic agents is a promising approach to address the widespread emergence of antibiotic-resistant pathogens. In this study, we investigated the antibiotic resistance profile and molecular characterization of different serotypes of Salmonella isolated from large-scale egg farms using drug susceptibility testing and whole genome sequencing. The synergistic effect of alpha-linolenic acid (ALA) with antibiotics was evaluated using the checkerboard test and time-kill curve. The molecular mechanism of α-linolenic acid synergism was explored using biochemical assays, pull-down assays, and molecular docking. In vivo efficacy of ALA in combination with florfenicol (FFC) or tetracycline (TET) against multidrug-resistant (MDR) Salmonella enterica subsp. enterica serovar typhimurium was also investigated using a mouse model. We found that ALA reduced the minimum inhibitory concentration (MIC) of tetracycline and florfenicol in all strains tested. When ALA (512 mg/L) was combined with florfenicol (32 mg/L) or tetracycline (16 mg/L), we observed disruption of cell membrane integrity, increased outer membrane permeability, lowered cell membrane potential, and inhibition of proton-drive-dependent efflux pumps. The synergistic treatment also inhibited biofilm production and promoted oxidative damage. These changes together led to an increase in bacterial antibiotic susceptibility. The improved efficacy of ALA combination treatment with antibiotics was validated in the mouse model. Molecular docking results indicate that ALA can bind to membrane proteins via hydrogen bonding. Our findings demonstrated that combined treatment using ALA and antibiotics is effective in preventing infections involving MDR bacteria. Our results are of great significance for the scientific and effective prevention and control of antibiotic resistance Salmonella, as well as ensuring food safety.

Metabolism and epigenetics: drivers of tumor cell plasticity and treatment outcomes

Emerging evidence indicates that metabolism not only is a source of energy and biomaterials for cell division but also acts as a driver of cancer cell plasticity and treatment resistance. This is because metabolic changes lead to remodeling of chromatin and reprogramming of gene expression patterns, furthering tumor cell phenotypic transitions. Therefore, the crosstalk between metabolism and epigenetics seems to hold immense potential for the discovery of novel therapeutic targets for various aggressive tumors. Here, we highlight recent discoveries supporting the concept that the cooperation between metabolism and epigenetics enables cancer to overcome mounting treatment-induced pressures. We discuss how specific metabolites contribute to cancer cell resilience and provide perspective on how simultaneously targeting these key forces could produce synergistic therapeutic effects to improve treatment outcomes.

Precise targeting of lipid metabolism in the era of immuno-oncology and the latest advances in nano-based drug delivery systems for cancer therapy

Over the past decade, research has increasingly identified unique dysregulations in lipid metabolism within the tumor microenvironment (TME). Lipids, diverse biomolecules, not only constitute biological membranes but also function as signaling molecules and energy sources. Enhanced synthesis or uptake of lipids in the TME significantly promotes tumorigenesis and proliferation. Moreover, lipids secreted into the TME influence tumor-resident immune cells (TRICs), thereby aiding tumor survival against chemotherapy and immunotherapy. This review aims to highlight recent advancements in understanding lipid metabolism in both tumor cells and TRICs, with a particular emphasis on exogenous lipid uptake and endogenous lipid de novo synthesis. Targeting lipid metabolism for intervention in anticancer therapies offers a promising therapeutic avenue for cancer treatment. Nano-drug delivery systems (NDDSs) have emerged as a means to maximize anti-tumor effects by rewiring tumor metabolism. This review provides a comprehensive overview of recent literature on the development of NDDSs targeting tumor lipid metabolism, particularly in the context of tumor immunotherapy. It covers four key aspects: reprogramming lipid uptake, reprogramming lipolysis, reshaping fatty acid oxidation (FAO), and reshuffling lipid composition on the cell membrane. The review concludes with a discussion of future prospects and challenges in this burgeoning field of research.

Targeting ACSLs to modulate ferroptosis and cancer immunity

Five acyl-CoA synthetase long-chain family members (ACSLs) are responsible for catalyzing diverse long-chain fatty acids (LCFAs) into LCFA-acyl-coenzyme A (CoA) for their subsequent metabolism, including fatty acid oxidation (FAO), lipid synthesis, and protein acylation. In this review, we focus on ACSLs and their LCFA substrates and introduce their involvement in regulation of cancer proliferation, metastasis, and therapeutic resistance. Along with the recognition of the decisive role of ACSL4 in ferroptosis - an immunogenic cell death (ICD) initiated by lipid peroxidation - we review the functions of ACSLs on regulating ferroptosis sensitivity. Last, we discuss the current understanding of ACSL on the antitumor immune response. We emphasize the necessity to explore the functions of immune cells expressing ACSLs for developing novel strategies to augment immunotherapy by targeting ACSL.

A prognostic model for hepatocellular carcinoma patients based on polyunsaturated fatty acid-related genes

OBJECTIVE

Polyunsaturated fatty acids (PUFAs) have attracted increasing attention for their role in liver cancer development. The objective of this study is to develop a prognosis prediction model for patients with liver cancer based on PUFA-related metabolic gene characteristics.

METHOD

Transcriptome data and clinical data were obtained from public databases, while gene sets related to PUFAs were acquired from the gene set enrichment analysis (GSEA) database. Univariate Cox analysis was conducted on the training set, followed by LASSO logistic regression and multivariate Cox analysis on genes with p < .05. Subsequently, the stepwise Akaike information criterion method was employed to construct the model. The high- and low-risk groups were divided based on the median score, and the model's survival prediction ability, diagnostic efficiency, and risk score distribution of clinical features were validated. The above procedures were also validated in the validation set. Immune infiltration levels were evaluated using four algorithms, and the immunotherapeutic potential of different groups was explored. Significant enrichment pathways among different groups were selected based on the GSEA algorithm, and mutation analyses were conducted. Nomogram prognostic models were constructed by incorporating clinical factors and risk scores using univariate and multivariate Cox regression analysis, validated through calibration curves and clinical decision curves. Additionally, sensitivity analysis of drugs was performed to screen potential targeted drugs.

RESULTS

We constructed a prognostic model comprising eight genes (PLA2G12A, CYP2C8, ABCCI, CD74, CCR7, P2RY4, P2RY6, and YY1). Validation across multiple datasets indicated the model's favorable prognostic prediction ability and diagnostic efficiency, with poorer grading and staging observed in the high-risk group. Variations in mutation status and pathway enrichment were noted among different groups. Incorporating Stage, Grade, T.Stage, and RiskScore into the nomogram prognostic model demonstrated good accuracy and clinical decision benefits. Multiple immune analyses suggested greater benefits from immunotherapy in the low-risk group. We predicted multiple targeted drugs, providing a basis for drug development.

CONCLUSION

Our study's multifactorial prognostic model across multiple datasets demonstrates good applicability, offering a reliable tool for personalized therapy. Immunological and mutation-related analyses provide theoretical foundations for further research. Drug predictions offer important insights for future drug development and treatment strategies. Overall, this study provides comprehensive insights into tumor prognosis assessment and personalized treatment planning.

The Mutual Regulatory Role of Ferroptosis and Immunotherapy in Anti-tumor Therapy

Ferroptosis is a form of cell death that is triggered by the presence of ferrous ions and is characterized by lipid peroxidation induced by these ions. The mechanism exhibits distinct morphological characteristics compared to apoptosis, autophagy, and necrosis. A notable aspect of ferroptosis is its ability to inhibit uncontrolled tumor replication and immortalization, especially in malignant, drug-resistant, and metastatic tumors. Additionally, immunotherapy, a novel therapeutic approach for tumors, has been found to have a reciprocal regulatory relationship with ferroptosis in the context of anti-tumor therapy. A comprehensive analysis of ferroptosis and immunotherapy in tumor therapy is presented in this paper, highlighting the potential for mutual adjuvant effects. Specifically, we discuss the mechanisms underlying ferroptosis and immunotherapy, emphasizing their ability to improve the tumor immune microenvironment and enhance immunotherapeutic effects. Furthermore, we investigate how immunotherapeutic factors may increase the sensitivity of tumor cells to ferroptosis. We aim to provide a prospective view of the promising value of combined ferroptosis and immunotherapy in anticancer therapy by elucidating the mutual regulatory network between each.

The pathological significance and potential mechanism of ACLY in cholangiocarcinoma

Background and aim

Cholangiocarcinoma (CCA) is a rare cancer, yet its incidence and mortality rates have been steadily increasing globally over the past few decades. Currently, there are no effective targeted treatment strategies available for patients. ACLY (ATP Citrate Lyase), a key enzyme in de novo lipogenesis, is aberrantly expressed in several tumors and is associated with malignant progression. However, its role and mechanisms in CCA have not yet been elucidated.

Methods

The expression of ACLY in CCA was assessed using transcriptomic profiles and tissue microarrays. Kaplan-Meier curves were employed to evaluate the prognostic significance of ACLY in CCA. Functional enrichment analysis was used to explore the potential mechanisms of ACLY in CCA. A series of assays were conducted to examine the effects of ACLY on the proliferation and migration of CCA cells. Ferroptosis inducers and inhibitors, along with lipid peroxide probes and MDA assay kits, were utilized to explore the role of ACLY in ferroptosis within CCA. Additionally, lipid-depleted fetal bovine serum and several fatty acids were used to evaluate the impact of fatty acids on ferroptosis induced by ACLY inhibition. Correlation analyses were performed to elucidate the relationship between ACLY and tumor stemness as well as tumor microenvironment.

Results

The expression of ACLY was found to be higher in CCA tissues compared to adjacent normal tissues. Patients with elevated ACLY expression demonstrated poorer overall survival outcomes. ACLY were closed associated with fatty acid metabolism and tumor-initiating cells. Knockdown of ACLY did not significantly impact the proliferation and migration of CCA cells. However, ACLY inhibition led to increased accumulation of lipid peroxides and enhanced sensitivity of CCA cells to ferroptosis inducers. Polyunsaturated fatty acids were observed to inhibit the proliferation of ACLY-knockdown cells; nonetheless, this inhibitory effect was diminished when the cells were cultured in medium supplemented with lipid-depleted fetal bovine serum. Additionally, ACLY expression was negatively correlated with immune cell infiltration and immune scores in CCA.

Conclusion

ACLY promotes ferroptosis by disrupting the balance of saturated and unsaturated fatty acids. ACLY may therefore serve as a potential diagnostic and therapeutic target for CCA.

Cancer knocks you out by fasting: Cachexia as a consequence of metabolic alterations in cancer

Neoplastic transformation reprograms tumor and surrounding host cell metabolism, increasing nutrient consumption and depletion in the tumor microenvironment. Tumors uptake nutrients from neighboring normal tissues or the bloodstream to meet energy and anabolic demands. Tumor-induced chronic inflammation, a high-energy process, also consumes nutrients to sustain its dysfunctional activities. These tumor-related metabolic and physiological changes, including chronic inflammation, negatively impact systemic metabolism and physiology. Furthermore, the adverse effects of antitumor therapy and tumor obstruction impair the endocrine, neural, and gastrointestinal systems, thereby confounding the systemic status of patients. These alterations result in decreased appetite, impaired nutrient absorption, inflammation, and shift from anabolic to catabolic metabolism. Consequently, cancer patients often suffer from malnutrition, which worsens prognosis and increases susceptibility to secondary adverse events. This review explores how neoplastic transformation affects tumor and microenvironment metabolism and inflammation, leading to poor prognosis, and discusses potential strategies and clinical interventions to improve patient outcomes.

Comprehensive molecular classification predicted microenvironment profiles and therapy response for HCC

BACKGROUND AND AIMS

Tumor microenvironment (TME) heterogeneity leads to a discrepancy in survival prognosis and clinical treatment response for patients with HCC. The clinical applications of documented molecular subtypes are constrained by several issues.

APPROACH AND RESULTS

We integrated 3 single-cell data sets to describe the TME landscape and identified 6 prognosis-related cell subclusters. Unsupervised clustering of subcluster-specific markers was performed to generate transcriptomic subtypes. The predictive value of these molecular subtypes for prognosis and treatment response was explored in multiple external HCC cohorts and the Xiangya HCC cohort. TME features were estimated using single-cell immune repertoire sequencing, mass cytometry, and multiplex immunofluorescence. The prognosis-related score was constructed based on a machine-learning algorithm. Comprehensive single-cell analysis described TME heterogeneity in HCC. The 5 transcriptomic subtypes possessed different clinical prognoses, stemness characteristics, immune landscapes, and therapeutic responses. Class 1 exhibited an inflamed phenotype with better clinical outcomes, while classes 2 and 4 were characterized by a lack of T-cell infiltration. Classes 5 and 3 indicated an inhibitory tumor immune microenvironment. Analysis of multiple therapeutic cohorts suggested that classes 5 and 3 were sensitive to immune checkpoint blockade and targeted therapy, whereas classes 1 and 2 were more responsive to transcatheter arterial chemoembolization treatment. Class 4 displayed resistance to all conventional HCC therapies. Four potential therapeutic agents and 4 targets were further identified for high prognosis-related score patients with HCC.

CONCLUSIONS

Our study generated a clinically valid molecular classification to guide precision medicine in patients with HCC.

Construction of a prognostic model via WGCNA combined with the LASSO algorithm for stomach adenocarcinoma patients

Objective

This study aimed to identify prognostic signatures to predict the prognosis of patients with stomach adenocarcinoma (STAD), which is necessary to improve poor prognosis and offer possible treatment strategies for STAD patients.

Methods

The overlapping genes between the key model genes that were screened by the weighted gene co-expression network analysis (WGCNA) and differentially expressed genes (DEGs) whose expression was different with significance between normal and tumor tissues were extracted to serve as co-expression genes. Then, enrichment analysis was performed on these genes. Furthermore, the least absolute shrinkage and selection operator (LASSO) regression was performed to screen the hub genes among overlapping genes. Finally, we constructed a model to explore the influence of polygenic risk scores on the survival probability of patients with STAD, and interaction effect and mediating analyses were also performed.

Results

DEGs included 2,899 upregulated genes and 2,896 downregulated genes. After crossing the DEGs and light-yellow module genes that were obtained by WGCNA, a total of 39 overlapping genes were extracted. The gene enrichment analysis revealed that these genes were enriched in the prion diseases, biosynthesis of unsaturated fatty acids, RNA metabolic process, hydrolase activity, etc. PIP5K1P1, PTTG3P, and SNORD15B were determined by LASSO-Cox. The prognostic prediction of the three-gene model was established. The Cox regression analysis showed that the comprehensive risk score for three genes was an independent prognosis factor.

Conclusion

PIP5K1P1, PTTG3P, and SNORD15B are related to the prognosis and overall survival of patients. The three-gene risk model constructed has independent prognosis predictive ability for STAD.

Dietary α-linolenic acid supplementation enhances resistance to Salmonella Typhimurium challenge in chickens by altering the intestinal mucosal barrier integrity and cecal microbes

Salmonella is an important foodborne pathogen. Given the ban on the use of antibiotics during the egg-laying period in China, finding safe and effective alternatives to antibiotics to reduce Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) infections in chickens is essential for the prevention and control of this pathogen and the protection of human health. Numerous studies have shown that unsaturated fatty acids have a positive effect on intestinal inflammation and resistance to infection by intestinal pathogens. Here we investigated the protective effect of α-linolenic acid (ALA) against S. Typhimurium infection in chickens and further explored its mechanism of action. We added different proportions of ALA to the feed and observed the effect of ALA on S. Typhimurium colonization using metagenomic sequencing technology and physiological index measurements. The role of gut flora on S. Typhimurium colonization was subsequently verified by fecal microbiota transplantation (FMT). We found that ALA protects chickens from S. Typhimurium infection by reducing intestinal inflammation through remodeling the gut microbiota, up-regulating the expression of ileocecal barrier-related genes, and maintaining the integrity of the intestinal epithelium. Our data suggest that supplementation of feed with ALA may be an effective strategy to alleviate S. Typhimurium infection in chickens.

Targeting metabolic pathways to counter cancer immunotherapy resistance

Immunotherapies have revolutionized the treatment of certain cancers, but challenges remain in overcoming immunotherapy resistance. Research shows that metabolic modulation of the tumor microenvironment can enhance antitumor immunity. Here, we discuss recent preclinical and clinical evidence for the efficacy of combining metabolic modifiers with immunotherapies. While this combination holds great promise, a few key areas must be addressed, which include identifying the effects of metabolic modifiers on immune cell metabolism, the putative biomarkers of therapeutic efficacy, the efficacy of modifiers on tumors harboring metabolic heterogeneity, and the potential development of resistance due to tumor reliance on alternative metabolic pathways. We propose solutions to these problems and posit that assessing these parameters is crucial for considering the potential of metabolic modifiers in sensitizing tumors to immunotherapies.

Emerging targets in lipid metabolism for cancer therapy

Cancer cells perturb lipid metabolic pathways for a variety of pro-tumorigenic functions, and deregulated cellular metabolism is a hallmark of cancer cells. Although alterations in lipid metabolism in cancer cells have been appreciated for over 20 years, there are no FDA-approved cancer treatments that target lipid-related pathways. Recent advances pertaining to cancer cell fatty acid synthesis (FAS), desaturation, and uptake, microenvironmental and dietary lipids, and lipid metabolism of tumor-infiltrating immune cells have illuminated promising clinical applications for targeting lipid metabolism. This review highlights emerging pathways and targets for tumor lipid metabolism that may soon impact clinical treatment.

The roles of cancer stem cell-derived secretory factors in shaping the immunosuppressive tumor microenvironment in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most prevalent malignancies worldwide and has a poor prognosis. Although immune checkpoint inhibitors have entered a new era of HCC treatment, their response rates are modest, which can be attributed to the immunosuppressive tumor microenvironment within HCC tumors. Accumulating evidence has shown that tumor growth is fueled by cancer stem cells (CSCs), which contribute to therapeutic resistance to the above treatments. Given that CSCs can regulate cellular and physical factors within the tumor niche by secreting various soluble factors in a paracrine manner, there have been increasing efforts toward understanding the roles of CSC-derived secretory factors in creating an immunosuppressive tumor microenvironment. In this review, we provide an update on how these secretory factors, including growth factors, cytokines, chemokines, and exosomes, contribute to the immunosuppressive TME, which leads to immune resistance. In addition, we present current therapeutic strategies targeting CSC-derived secretory factors and describe future perspectives. In summary, a better understanding of CSC biology in the TME provides a rational therapeutic basis for combination therapy with ICIs for effective HCC treatment.

The SP1/SIRT1/ACLY signaling axis mediates fatty acid oxidation in renal ischemia-reperfusion-induced renal fibrosis

BACKGROUND

Renal ischemia-reperfusion is the primary cause of acute kidney injury (AKI). Clinically, most patients who experience ischemia-reperfusion injury eventually progress gradually to renal fibrosis and chronic kidney disease (CKD). However, the underlying mechanism for AKI to CKD transition remain absent. Our study demonstrated that the downregulation of sirtuin 1 (Sirt1)-mediated fatty acid oxidation (FAO) facilitates IRI-induced renal fibrosis.

METHODS

The IRI animal model was established, and ribonucleic acid (RNA) sequencing was used to explore potential differentially expressed genes (DEGs) and pathways. The SIRT1 knockout mice were generated, and a recombinant adeno-associated virus that overexpresses SIRT1 was injected into mice to explore the function of SIRT1 in renal fibrosis induced by renal IRI. In vitro, hypoxia/reoxygenation (H/R) was used to establish the classical model of renal IRI and overexpression or knockdown of SIRT1 to investigate the SIRT1 function through lentiviral plasmids. The underlying molecular mechanism was explored through RNA sequencing, bioinformatics analysis, and chromatin immunoprecipitation assay.

RESULTS

RNA sequencing analysis and western blot demonstrated that the expression of SIRT1 was significantly decreased in IRI mice. Overexpression of SIRT1 improved renal function and reduced lipid deposition and renal fibrosis. On the contrary, knockout of SIRT1 aggravated kidney injury and renal fibrosis. RNA sequencing, bioinformatics analysis, and chromatin immunoprecipitation assay mechanistically revealed that SIRT1 impairs the acetylation of histone H3K27 on the promoter region of ACLY, thereby impeding FAO activity and promoting renal fibrosis. Additionally, SP1 regulated FAO by directly modulating SIRT1 expression.

CONCLUSION

Our findings highlight that downregulation of SIRT1-modulated FAO facilitated by the SP1/SIRT1/ACLY axis in the kidney increases IRI, suggesting SIRT1 to be a potential therapeutic target for renal fibrosis induced by renal IRI.

ATP Citrate Lyase is a General Tumour Biomarker and Contributes to the Development of Cutaneous Squamous Cell Carcinoma

ATP citrate lyase, the first rate-limiting enzyme in de novo lipogenesis, plays a crucial role in tumour progression. This study explores ATP citrate lyase's potential as a tumour biomarker and its role in cutaneous squamous cell carcinoma. ATP citrate lyase expression patterns were analysed using TCGA and TIMER databases, and patient skin specimens were collected for immunohistochemistry to determine ATP citrate lyase levels. Cell proliferation, cell cycle, apoptosis, and c-Myc expression were assessed in A431 and SCL-1 cells. Stable cell lines with reduced ATP citrate lyase expression were obtained and subcutaneously implanted into nude mice to evaluate in vivo tumour growth. Ki67, c-Myc expression and TUNEL staining were analysed in subcutaneous tumours. ATP citrate lyase exhibited upregulation in various tumours, and showed significant associations with prognosis and immune infiltrate. Moreover, ATP citrate lyase was highly expressed in cutaneous squamous cell carcinoma. After ATP citrate lyase silencing, cutaneous squamous cell carcinoma cell growth decelerated, the cell cycle halted, cell apoptosis increased, and c-Myc expression decreased. Animal experiments revealed that, following ATP citrate lyase knockdown, tumour tissue growth slowed down, and there was a reduction in Ki-67 and c-Myc expression, accompanied by enhanced TUNEL staining. In conclusion, ATP citrate lyase may serve as a tumour biomarker. It is highly expressed in cutaneous squamous cell carcinoma and may serve as a therapeutic target.

Checkmate: Metabolic flexibility with a STING in its tail

Inhibiting a key metabolic enzyme, ACLY, in cancer cells impacts T cell function in immunotherapy-resistant tumors and may offer a target for therapeutic treatment.