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PURPOSE: Colorectal cancer (CRC) is recognized as the third most common form of malignancy, with the liver frequently serving as the main site for metastasis. Anoikis resistance (AR) is critical in colorectal cancer liver metastases (CRLM). Fatty acid synthase (FASN), essential in lipid synthesis, mediates AR in many cancers. The present research examines the function of FASN in ERK1/2-mediated AR in CRLM and evaluates its therapeutic potential. METHODS: We performed scratch and migration experiment to evaluate the migration capacity of the LoVo cells. Flow cytometry was employed to identify cell apoptosis. The levels of FASN, p-ERK1/2, and proteins related to apoptosis was analyzed by Western blot. The mRNA level of FASN was determined by q-PCR after FASN silencing. In addition, we used an intrasplenic liver metastasis model of nude to assess the effect of FASN on CRLM. RESULTS: In vitro experiments showed that after FASN silencing, the cell apoptosis rate was increased, migration capability was notably decreased, the expression of p-ERK1/2, the proteins related to anti-apoptotic were significantly decreased, and the proteins related to apoptosis were significantly increased. In vivo experiments showed that AR significantly increased the number of liver metastatic foci, whereas FASN silencing significantly inhibited CRLM. CONCLUSION: These results suggest that FASN silencing suppressed AR through the ERK 1/2 pathway, which in turn suppressed CRLM.

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Fatty acid synthase (FASN) is a metabolic enzyme responsible for the synthesis of fatty acids in milk and meat. The SNPs g.841G/C and g.17924A/G of the FASN gene significantly influence the fat and fatty acid content of milk from cows of various breeds. Therefore, these SNPs were selected for this study. This study aimed to analyze the relationship of SNPs and their genotypes with the fat content and fatty acid profile of milk from Polish Red-and-White (ZR), Polish Red (RP), and Polish Holstein-Friesian Red-and-White (RW) cows. Milk samples were obtained during a milking trial. SNP genotyping was performed using the real-time PCR (HRM) method. It was shown that SNPs (with specific genotypes) were significantly associated with the presence of fatty acids such as C18:1n9t and C18:2n6c in milk. In addition, it was found that the milk fat from the ZR (genotypic variant A/G, AA) and RP (genotypic variant GG, A/G) breeds often exhibited a more attractive fatty acids profile than the milk fat from RW cows. This information can be used by both cattle breeders and people interested in consuming functional foods.

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Non-Alcoholic Fatty Liver Disease (NAFLD) prevalence is rising and can lead to detrimental health outcomes such as Non-Alcoholic Steatohepatitis (NASH), cirrhosis, and cancer. Recent studies have indicated that Cytochrome P450 2B6 (CYP2B6) is an anti-obesity CYP in humans and mice. Cyp2b-null mice are diet-induced obese, and human CYP2B6-transgenic (hCYP2B6-Tg) mice reverse the obesity or diabetes progression, but with increased liver triglyceride accumulation in association with an increase of several oxylipins. Notably, 9-hydroxyoctadecadienoic acid (9-HODE) produced from linoleic acid (LA, 18:2, ω-6) is the most prominent of these and 9-hydroxyoctadecatrienoic acid (9-HOTrE) from alpha-linolenic acid (ALA, 18:3, ω-3) is the most preferentially produced when controlling for substrate concentrations in vitro. Transactivation assays indicate that 9-HODE and 9-HOTrE activate PPARα and PPARγ. In Seahorse assays performed in HepG2 cells, 9-HOTrE increased spare respiratory capacity, slightly decreased palmitate metabolism, and increased non-glycolytic acidification in a manner consistent with slightly increased glutamine utilization; however, 9-HODE exhibited no effect on metabolism. Both compounds increased triglyceride and pyruvate concentrations, most strongly by 9-HOTrE, consistent with increased spare respiratory capacity. qPCR analysis revealed several perturbations in fatty acid uptake and metabolism gene expression. 9-HODE increased expression of CD36, FASN, PPARγ, and FoxA2 that are involved in lipid uptake and production. 9-HOTrE decreased ANGPTL4 expression and increased FASN expression consistent with increased fatty acid uptake, fatty acid production, and AMPK activation. Our findings support the hypothesis that 9-HODE and 9-HOTrE promote steatosis, but through different mechanisms as 9-HODE is directly involved in fatty acid uptake and synthesis; 9-HOTrE weakly inhibits mitochondrial fatty acid metabolism while increasing glutamine use.

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Background and Objectives: Aberrant upregulation of fatty acid synthase (FASN), catalyzing de novo synthesis of fatty acids, occurs in various tumor types, including human hepatocellular carcinoma (HCC). Although FASN oncogenic activity seems to reside in its pro-lipogenic function, cumulating evidence suggests that FASN's tumor-supporting role might also be metabolic-independent. Materials and Methods: In the present study, we show that FASN inactivation by specific small interfering RNA (siRNA) promoted the downregulation of the S-phase kinase associated-protein kinase 2 (SKP2) and the consequent induction of p27KIP1 in HCC cell lines. Results: Expression levels of FASN and SKP2 directly correlated in human HCC specimens and predicted a dismal outcome. In addition, forced overexpression of SKP2 rendered HCC cells resistant to the treatment with the FASN inhibitor C75. Furthermore, FASN deletion was paralleled by SKP2 downregulation and p27KIP1 induction in the AKT-driven HCC preclinical mouse model. Moreover, forced overexpression of an SKP2 dominant negative form or a p27KIP1 non-phosphorylatable (p27KIP1-T187A) construct completely abolished AKT-dependent hepatocarcinogenesis in vitro and in vivo. Conclusions: In conclusion, the present data indicate that SKP2 is a critical downstream effector of FASN and AKT-dependent hepatocarcinogenesis in liver cancer, envisaging the possibility of effectively targeting FASN-positive liver tumors with SKP2 inhibitors or p27KIP1 activators.

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Fatty acid synthase (FASN) is a critical enzyme essential for the production of fats in the body. The abnormal expression of FASN is associated with different types of malignancies, including ovarian cancer. FASN plays a crucial role in cell growth and survival as a metabolic oncogene, although the specific processes that cause its dysregulation are still unknown. FASN interacts with signaling pathways linked to the progression of cancer. Pharmacologically inhibiting or inactivating the FASN gene has shown potential in causing the death of cancer cells, offering a possible treatment approach. This review examines the function of FASN in ovarian cancer, namely its level of expression, influence on the advancement of the disease, and its potential as a target for therapeutic interventions.

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BACKGROUND: Breast cancer manifests as a heterogeneous pathology marked by complex metabolic reprogramming essential to satisfy its energy demands. Oncogenic signals boost the metabolism, modifying fatty acid synthesis and glucose use from the onset to progression and therapy resistant-forms. However, the exact contribution of metabolic dependencies during tumor evolution remains unclear. METHODS: In this study, we elucidate the connection between FASN and LDHA, pivotal metabolic genes, and their correlation with tumor grade and therapy response using datasets from public repositories. Subsequently, we evaluated the metabolic and proliferative functions upon FASN and LDHA inhibition in breast cancer models. Lastly, we integrated metabolomic and lipidomic analysis to define the contributions of metabolites, lipids, and precursors to the metabolic phenotypes. RESULTS: Collectively, our findings indicate metabolic shifts during breast cancer progression, unvealling two distinct functional energy phenotypes associated with aggressiveness and therapy response. Specifically, FASN exhibits reduced expression in advance-grade tumors and therapy-resistant forms, whereas LDHA demonstrates higher expression. Additionally, the biological and metabolic impact of blocking the enzymatic activity of FASN and LDHA was correlated with resistant conditions. CONCLUSIONS: These observations emphasize the intrinsic metabolic heterogeneity within breast cancer, thereby highlighting the relevance of metabolic interventions in the field of precision medicine.

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Fat is an important energy and nutritional component of milk and consists of fatty acids. FASN (fatty acid synthase) is an enzyme that regulates the synthesis of fatty acids in the milk and meat of cattle. It was hypothesized that knowing the relationships between the genotypes of the tested single nucleotide polymorphisms (SNPs) and the content of fat and specific fatty acids would make it possible to improve milk quality in the selection process during cattle breeding. This study aimed to analyze the relationships of SNPs (g.16024A/G, g.16039T/C) of the FASN gene and their genotypes with the fat and fatty acid content of the milk of the following breeds: Polish Red-White (ZR), Polish Red (RP), and Polish Holstein-Friesian Red-White (RW). The SNP g.16060A/C was included in the study, although its effect on the fat composition of cow's milk has not yet been widely studied. Milk was obtained during test milkings. SNP genotyping was performed using the real-time PCR (HRM) method. The milk from ZR and RP cows was more often characterized by a more favorable fatty acid profile than the milk from RW cows. This information can be used by cattle breeders and consumers of so-called functional food.

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Despite its significance, the role of lipid metabolism in NLRP3 inflammasome remains elusive. Here, we reveal a critical role for fatty acid synthase (FASN) in NLRP3 inflammasome activation. We demonstrate that pharmacological or genetic depletion of FASN dampens NLRP3 activation in primary mouse and human macrophages and in mice. This disruption in NLRP3 activation is contingent upon FASN activity. Accordingly, abolishing cellular palmitoylation, a post-translational modification in which the FASN product palmitate is reversibly conjugated to cysteine residues of target proteins, blunts inflammasome signaling. Correspondingly, an acyl-biotin exchange assay corroborated NLRP3 palmitoylation. Mechanistically, Toll-like receptor (TLR) ligation introduces palmitoylation at NLRP3 Cys898, permitting NLRP3 translocation to dispersed trans-Golgi network (dTGN) vesicles, the site of inflammasome assembly, upon NLRP3 activation. Accordingly, the NLRP3 Cys898 mutant exhibits reduced palmitoylation, limited translocation to the dTGN compartment, and diminished inflammasome activation. These results underscore mechanistic insights through which lipid metabolism licenses NLRP3 inflammasome assembly and activation.

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Bladder cancer (BC) exhibits diversity in clinical outcomes and is characterized by heterogeneity. Anoikis, a form of programmed cell death, plays a crucial role in facilitating tumor invasion and metastasis. This study comprehensively investigated the genetic landscape of BC progression, identifying 300 differentially expressed Anoikis-related genes (DE-ARGs) through in-depth analysis of the GSE13507 datasets. Functional enrichment analysis revealed associations with diverse diseases and biological processes. Employing machine learning algorithms, a logistic regression model based on nine marker genes demonstrated superior accuracy in distinguishing BC from normal samples. Validation in TCGA datasets highlighted the prognostic significance of LRP1, FASN, and SIRT6, suggesting their potential as cancer biomarkers. Particularly, FASN emerged as an independent prognostic indicator, regulating BC cell proliferation and metastasis through the Wnt/ß-catenin pathway. The study provides crucial insights into altered genetic landscapes and potential therapeutic strategies for BC, emphasizing the significance of FASN in BC prognosis and progression.

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Gemcitabine plus cisplatin (GC) combination chemotherapy is the primary treatment for advanced bladder cancer (BC) with unresectable or metastatic disease. However, most cases develop resistance to this therapy. We investigated whether drug resistance could be targeted through metabolic reprogramming therapies. Metabolomics analyses in our lab's gemcitabine- and cisplatin-resistant cell lines revealed increased phosphoglycerate dehydrogenase (PHGDH) expression in gemcitabine-resistant cells compared with parental cells. Isocitrate dehydrogenase 2 (IDH2) gain of function stabilized hypoxia-inducible factor1α (HIF1α) expression, stimulating aerobic glycolysis. In gemcitabine-resistant cells, elevated fumaric acid suppressed prolyl hydroxylase domain-containing protein 2/Egl nine homolog 1 (PHD2) and stabilized HIF1α expression. PHGDH downregulation or inhibition in gemcitabine-resistant BC cells inhibited their proliferation, migration, and invasion. Cisplatin-resistant cells showed elevated fatty acid metabolism, upregulating fatty acid synthase (FASN) downstream of tyrosine kinase. Using the fibroblast growth factor receptor (FGFR) tyrosine kinase inhibitor erdafitinib, we inhibited malonyl-CoA production, which is crucial for fatty acid synthesis, and thereby suppressed upregulated HIF1α expression. Combination treatment with NCT503 and erdafitinib synergistically suppressed tumor cell proliferation and induced apoptosis in vitro and in vivo. Understanding these mechanisms could enable innovative BC therapeutic strategies to be developed.

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To investigate the nucleotide variation sites (SNPs) and expression differences of the fatty acid synthase gene (FASN) in Guizhou white goats, the relationship between the variation and body size traits was investigated. In this study, DNA was extracted from the blood of 100 samples of white goats from different regions in Guizhou province, China, and the variation sites were screened using pooled sequencing by mixing DNA samples, and 242 blood samples with body size traits were used for association analysis. The allele frequency, genotype frequency, homozygosity, heterozygosity and effective gene number were calculated by using PopGene 32.0 software, the population polymorphism information content was calculated by using PIC software (Version 0.6), and the state of genetic balance of the genes was analyzed by using the chi-square test. The mRNA of FASN gene expression levels in male and female goats were investigated by using real-time fluorescence quantitative PCR (RT-qPCR). The general linear mixed model of MINTAB software (Version 16.0) was used to analyze the association between FASN gene nucleotide mutation sites and body size traits. The results showed that there was one nucleotide mutation site g.141 C/T in the target fragment of FASN gene amplification, and revealed two alleles, C and T, and three genotypes CC, CT and TT. The genotype frequencies for CC, CT and TT were 0.4308, 0.4205 and 0.1487, respectively. The allele frequencies for C and T were 0.6410 and 0.3590, respectively. The genetic homozygosity (Ho) was higher than the heterozygosity (He). The χ2 test showed that the mutation site was in the Hardy-Weinberg equilibrium state (p > 0.05). The RT-qPCR results showed that the FASN gene had different expression levels in the longissimus dorsi muscle of male and female goats, and its expression was significantly higher in male goats than in female goats. The association analysis results showed that the mutation of the FASN gene had different effects on body size traits of male and female goats, and the presence of the populations of the T allele and the TT genotype recorded higher body size traits (body weight, heart girth and wither height) in female populations. Therefore, the site of the FASN gene can be used as a candidate marker for the early selection of growth traits in Guizhou white goats.

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STING (stimulator of interferon genes) is a critical immunoregulatory protein in sepsis and is regulated by various mechanisms, especially palmitoylation. FASN (fatty acid synthase) is the rate-limiting enzyme to generate cellular palmitic acid (PA) via acetyl-CoA and malonyl-CoA and participates in protein palmitoylation. However, the mechanisms underlying the interaction between STING and FASN have not been completely understood. In this study, STING-knockout mice were used to confirm the pivotal role of STING in sepsis-induced liver injury. Metabolomics confirmed the dyslipidemia in septic mice and patients. The compounds library was screened, revealing that FASN inhibitors exerted a significant inhibitory effect on the STING pathway. Mechanically, the regulatory effect of FASN on the STING pathway was dependent on palmitoylation. Further experiments indicated that the upstream of FASN, malonyl-CoA inhibited STING pathway possibly due to C91 (palmitoylated residue) of STING. Overall, this study reveals a novel paradigm of STING regulation and provides a new perspective on immunity and metabolism.

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Aging affects lipid metabolism and can cause obesity as it is closely related to the disorder of many lipogenic regulatory factors. LncRNAs have been recognized as pivotal regulators across diverse biological processes, but their effects on lipogenesis in aging remain to be further studied. In this work, using RNA sequencing (RNA-Seq), we found that the expression of lncRNA AI504432 was significantly upregulated in the eWAT (epididymal white adipose tissue) of aging mice, and the knockdown of AI504432 notably reduced the expression of several adipogenic genes (e.g., Cebp/α, Srebp-1c, Fasn, Acaca, and Scd1) in senescent adipocytes. The bioinformatics investigation revealed that AI504432 possessed a binding site for miR-1a-3p, and the discovery was verified by the luciferase reporter assay. The expression of Fasn was increased upon the inhibition of miR-1a-3p but restored upon the simultaneous silencing of AI504432. Taken together, our results suggested that AI504432 controlled lipogenesis through the miR-1a-3p/Fasn signaling pathway. The findings may inspire new therapeutic approaches to target imbalanced lipid homeostasis due to aging.

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SCAP plays a central role in controlling lipid homeostasis by activating SREBP-1, a master transcription factor in controlling fatty acid (FA) synthesis. However, how SCAP expression is regulated in human cancer cells remains unknown. Here, we revealed that STAT3 binds to the promoter of SCAP to activate its expression across multiple cancer cell types. Moreover, we identified that STAT3 also concurrently interacts with the promoter of SREBF1 gene (encoding SREBP-1), amplifying its expression. This dual action by STAT3 collaboratively heightens FA synthesis. Pharmacological inhibition of STAT3 significantly reduces the levels of unsaturated FAs and phospholipids bearing unsaturated FA chains by reducing the SCAP-SREBP-1 signaling axis and its downstream effector SCD1. Examination of clinical samples from patients with glioblastoma, the most lethal brain tumor, demonstrates a substantial co-expression of STAT3, SCAP, SREBP-1, and SCD1. These findings unveil STAT3 directly regulates the expression of SCAP and SREBP-1 to promote FA synthesis, ultimately fueling tumor progression.

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The aim of this study is to explore the function of USP14 on the sensitivity of retinoblastoma (RB) to cisplatin (DDP) and the underlying mechanism. USP14 was knockdown in Y79 cells by transfecting three siRNAs (si-USP14-1, si-USP14-2, and si-USP14-3), with si-USP14 NC as the negative control. si-USP14-3 was selected by results of Western blotting. The CCK-8 assay was used to detect the IC50 of Y79 cells and the growth curve. The cell cycle, cell apoptosis, and ROS level were measured by flow cytometry. The expression level of P-GP, ERCC1, survivin, GPX4, FTH1, ACSL4, NOX1, COX2, and FASN was determined by the Western blotting assay. CO-IP assay was utilized to evaluate the interaction between USP14 and FASN. The IC50 of DDP in Y79 cells and Y79/DDP cells was 7.83 µM and 24.67 µM, respectively. Compared to control and si-USP14 NC groups, increased apoptotic rate and ROS level, and arrested cell cycle in S phase were observed in USP14-knockdown Y79 cells. Compared to control and si-USP14 NC groups, increased apoptotic rate and arrested cell cycle in G0/G1 phase were observed in USP14-knockdown Y79/DDP cells. Compared to control, increased ROS level was observed in USP14-knockdown Y79/DDP cells. Compared to the si-USP14 NC groups, extremely downregulated P-GP, ERCC1, survivin, GPX4, FTH1, NOX1, COX2, and FASN were observed in USP14-knockdown Y79 cells or Y79/DDP cells, accompanied by the elevated expression of ACSL4. The interaction between USP14 and FASN was identified according to the result of CO-IP assay. By silencing USP14 in Y79 and Y79/DDP cells, levels of resistance-related proteins (P-GP, ERCC1, and survivin), ferroptosis-related proteins (FTH1 and GPX4), and lipid metabolism-related proteins (NOX1, COX2, and FASN) were dramatically reduced, accompanied by enhanced ROS level, increased apoptosis, and restrained DNA content, indicating that USP14 might suppress the DDP resistance in RB by mediating ferroptosis, which is an important target for treating RB.

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N-acetyltransferase 10 (NAT10) is acknowledged as a tumor promoter in various cancers due to its role as a regulator of acetylation modification. Tumor-associated macrophages (TAMs) play a pivotal role in the tumor microenvironment (TME). However, the intercellular communication between esophageal squamous cell carcinoma (ESCC) cells and TAMs involving NAT10 remains poorly understood. This study aimed to elucidate the regulatory mechanism of NAT10 in modulating macrophage lipid metabolism and polarization. Experimental evidence was derived from in vitro and in vivo analyses. We explored the association between upregulated NAT10 in ESCC tissues, macrophage polarization, and the therapeutic efficacy of PD-1. Furthermore, we investigated the impact of methyltransferase 3 (METTL3)-induced m6A modification on the increased expression of NAT10 in ESCC cells. Additionally, we examined the role of exosomal NAT10 in stabilizing the expression of fatty acid synthase (FASN) and promoting macrophage M2 polarization through mediating the ac4C modification of FASN. Results indicated that NAT10, packaged by exosomes derived from ESCC cells, promotes macrophage M2 polarization by facilitating lipid metabolism. In vivo animal studies demonstrated that targeting NAT10 could enhance the therapeutic effect of PD-1 on ESCC by mediating macrophage reprogramming. Our findings offer novel insights into improving ESCC treatment through NAT10 targeting.

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Trypanosoma cruzi is a parasite with a high capacity to adapt to the host. Animal models have already demonstrated that the tropism of this parasite occurs not only in cardiac/digestive tissues but also in adipose tissue (AT). That said, the consequences ofT. cruziinfection for AT and the implications of treatment with Benzonidazole in this tissue are under discussion. Here, we tested the hypothesis that T. cruzi infection in adipose tissue upon treatment with Benzonidazole (Bz) and the interaction of mononuclear immune cells (PBMC) influences the relative expression of ACAT1, FASN, and PNPLA2 genes. Thus, stem cells derived from adipose tissue (ADSC) after adipogenic differentiation were indirectly cultivated with PBMC after infection with the T. cruzi Y strain and treatment with Bz. We use the TcSAT-IAM system and RT-qPCR to evaluate the parasite load and the relative quantification (ΔCt) of the ACAT1, FASN, and PNPLA2 genes. Our results demonstrate that treatment with Bz did not reduce adipocyte infection in the presence (p-value: 0.5796) or absence (p-value: 0.1854) of cultivation with PBMC. In addition, even though there is no statistical difference when compared to the control group (AT), T. cruzi induces the FASN expression (Rq: 14.00). However, treatment with Bz in AT suggests the increases of PNPLA2 expression levels (Rq: 12.58), even in the absence of T. cruzi infection. During indirect cultivation with PBMC, T. cruzi smooths the expression of PNPLA2 (Rq: 0.824) and instigates the expression of ACAT1 (Rq: 1.632) and FASN (Rq: 1.394). Furthermore, the treatment with Bz during infection induces PNPLA2 expression (Rq: 1.871), maintaining FASN expression levels (Rq: 1.334). Given this, our results indicate that treatment with Benzonidazole did not decrease T. cruzi infection in adipose tissue. However, treating the adipocyte cells with Bz during the interaction with PBMC cells influences the lipid pathways scenario, inducing lipolytic metabolism through the expression of PNPLA2.

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Vascular smooth muscle cells (VSMCs), in their contractile and differentiated state, are fundamental for maintaining vascular function. Upon exposure to cholesterol (CHO), VSMCs undergo dedifferentiation, adopting characteristics of foam cells-lipid-laden, macrophage-like cells pivotal in atherosclerotic plaque formation. CHO uptake by VSMCs leads to two primary pathways: ABCA1-mediated efflux or storage in lipid droplets as cholesterol esters (CEs). CE formation, involving the condensation of free CHO and fatty acids, is catalyzed by sterol O-acyltransferase 1 (SOAT1). The necessary fatty acids are synthesized by the lipogenic enzyme fatty acid synthase (FASN), which we found to be upregulated in atherosclerotic human coronary arteries. This observation led us to hypothesize that FASN-mediated fatty acid biosynthesis is crucial in the transformation of VSMCs into foam cells. Our study reveals that CHO treatment upregulates FASN in human aortic SMCs, concurrent with increased expression of CD68 and upregulation of KLF4, markers associated with the foam cell transition. Crucially, downregulation of FASN inhibits the CHO-induced upregulation of CD68 and KLF4 in VSMCs. Additionally, FASN-deficient VSMCs exhibit hindered lipid accumulation and an impaired transition to the foam cell phenotype following CHO exposure, while the addition of the fatty acid palmitate, the main FASN product, exacerbates this transition. FASN-deficient cells also show decreased SOAT1 expression and elevated ABCA1. Notably, similar effects are observed in KLF4-deficient cells. Our findings demonstrate that FASN plays an essential role in the CHO-induced upregulation of KLF4 and the VSMC to foam cell transition and suggest that targeting FASN could be a novel therapeutic strategy to regulate VSMC phenotypic modulation.

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BACKGROUND & AIMS: Intrahepatic cholangiocarcinoma (iCCA) is the second most common primary liver cancer and is highly lethal. Clonorchis sinensis (C. sinensis) infection is an important risk factor for iCCA. Here we investigated the clinical impact and underlying molecular characteristics of C. sinensis infection-related iCCA. METHODS: We performed single-cell RNA sequencing, whole-exome sequencing, RNA sequencing, metabolomics and spatial transcriptomics in 251 patients with iCCA from three medical centers. Alterations in metabolism and the immune microenvironment of C. sinensis-related iCCAs were validated through an in vitro co-culture system and in a mouse model of iCCA. RESULTS: We revealed that C. sinensis infection was significantly associated with iCCA patients' overall survival and response to immunotherapy. Fatty acid biosynthesis and the expression of fatty acid synthase (FASN), a key enzyme catalyzing long-chain fatty acid synthesis, were significantly enriched in C. sinensis-related iCCAs. iCCA cell lines treated with excretory/secretory products of C. sinensis displayed elevated FASN and free fatty acids. The metabolic alteration of tumor cells was closely correlated with the enrichment of tumor-associated macrophage (TAM)-like macrophages and the impaired function of T cells, which led to formation of an immunosuppressive microenvironment and tumor progression. Spatial transcriptomics analysis revealed that malignant cells were in closer juxtaposition with TAM-like macrophages in C. sinensis-related iCCAs than non-C. sinensis-related iCCAs. Importantly, treatment with a FASN inhibitor significantly reversed the immunosuppressive microenvironment and enhanced anti-PD-1 efficacy in iCCA mouse models treated with excretory/secretory products from C. sinensis. CONCLUSIONS: We provide novel insights into metabolic alterations and the immune microenvironment in C. sinensis infection-related iCCAs. We also demonstrate that the combination of a FASN inhibitor with immunotherapy could be a promising strategy for the treatment of C. sinensis-related iCCAs. IMPACT AND IMPLICATIONS: Clonorchis sinensis (C. sinensis)-infected patients with intrahepatic cholangiocarcinoma (iCCA) have a worse prognosis and response to immunotherapy than non-C. sinensis-infected patients with iCCA. The underlying molecular characteristics of C. sinensis infection-related iCCAs remain unclear. Herein, we demonstrate that upregulation of FASN (fatty acid synthase) and free fatty acids in C. sinensis-related iCCAs leads to formation of an immunosuppressive microenvironment and tumor progression. Thus, administration of FASN inhibitors could significantly reverse the immunosuppressive microenvironment and further enhance the efficacy of anti-PD-1 against C. sinensis-related iCCAs.

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BACKGROUND: ß-Propeller protein-associated neurodegeneration (BPAN) is a genetic neurodegenerative disease caused by mutations in WDR45. The impairment of autophagy caused by WDR45 deficiency contributes to the pathogenesis of BPAN; however, the pathomechanism of this disease is largely unknown. Lipid dyshomeostasis is involved in neurogenerative diseases, but whether lipid metabolism is affected by Wdr45 deficiency and whether lipid dyshomeostasis contributes to the progression of BPAN are unclear. METHODS: We generated Wdr45 knockout SN4741 cell lines using CRISPR‒Cas9-mediated genome editing, then lipid droplets (LDs) were stained using BODIPY 493/503. Chaperone-mediated autophagy was determined by RT-qPCR and western blotting. The expression of fatty acid synthase (Fasn) was detected by western blot in the presence or absence of the lysosomal inhibitor NH4Cl and the CMA activator AR7. The interaction between Fasn and HSC70 was analyzed using coimmunoprecipitation (Co-IP) assay. Cell viability was measured by a CCK-8 kit after treatment with the Fasn inhibitor C75 or the CMA activator AR7. RESULTS: Deletion of Wdr45 impaired chaperone-mediated autophagy (CMA), thus leading to lipid droplet (LD) accumulation. Moreover, Fasn can be degraded via CMA, and that defective CMA leads to elevated Fasn, which promotes LD formation. LD accumulation is toxic to cells; however, cell viability was not rescued by Fasn inhibition or CMA activation. Inhibition of Fasn with a low concentration of C75 did not affect cell viability but decreases LD density. CONCLUSIONS: These results suggested that Fasn is essential for cell survival but that excessive Fasn leads to LD accumulation in Wdr45 knockout cells.

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