Dynamics of the Trypanosoma cruzi infection in adipose tissue: Assessing gene expression of PNPLA2, FASN, and ACAT1 under Benzonidazole treatment and indirect mononuclear immune cells interaction.

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.

The m6A modification mediated-lncRNA POU6F2-AS1 reprograms fatty acid metabolism and facilitates the growth of colorectal cancer via upregulation of FASN.

BACKGROUND: Long noncoding RNAs (lncRNAs) have emerged as key players in tumorigenesis and tumour progression. However, the biological functions and potential mechanisms of lncRNAs in colorectal cancer (CRC) are unclear. METHODS: The novel lncRNA POU6F2-AS1 was identified through bioinformatics analysis, and its expression in CRC patients was verified via qRT-PCR and FISH. In vitro and in vivo experiments, such as BODIPY staining, Oil Red O staining, triglyceride (TAG) assays, and liquid chromatography mass spectrometry (LC-MS) were subsequently performed with CRC specimens and cells to determine the clinical significance, and functional roles of POU6F2-AS1. Biotinylated RNA pull-down, RIP, Me-RIP, ChIP, and patient-derived organoid (PDO) culture assays were performed to confirm the underlying mechanism of POU6F2-AS1. RESULTS: The lncRNA POU6F2-AS1 is markedly upregulated in CRC and associated with adverse clinicopathological features and poor overall survival in CRC patients. Functionally, POU6F2-AS1 promotes the growth and lipogenesis of CRC cells both in vitro and in vivo. Mechanistically, METTL3-induced m6A modification is involved in the upregulation of POU6F2-AS1. Furthermore, upregulated POU6F2-AS1 could tether YBX1 to the FASN promoter to induce transcriptional activation, thus facilitating the growth and lipogenesis of CRC cells. CONCLUSIONS: Our data revealed that the upregulation of POU6F2-AS1 plays a critical role in CRC fatty acid metabolism and might provide a novel promising biomarker and therapeutic target for CRC.

Targeting ZDHHC21/FASN axis for the treatment of diffuse large B-cell lymphoma.

S-palmitoylation is essential for cancer development via regulating protein stability, function and subcellular location, yet the roles S-palmitoylation plays in diffuse large B-cell lymphoma (DLBCL) progression remain enigmatic. In this study, we uncovered a novel function of the palmitoyltransferase ZDHHC21 as a tumor suppressor in DLBCL and identified ZDHHC21 as a key regulator of fatty acid synthetase (FASN) S-palmitoylation for the first time. Specifically, ZDHHC21 was downregulated in DLBCL, and its expression level was associated with the clinical prognosis of patients with DLBCL. In vitro and in vivo experiments suggested that ZDHHC21 suppressed DLBCL cell proliferation. Mechanistically, ZDHHC21 interacted with FASN and mediated its palmitoylation at Cys1317, resulting in a decrease in FASN protein stability and fatty acid synthesis, consequently leading to the inhibition of DLBCL cell growth. Of note, an FDA-approved small-molecule compound lanatoside C interacted with ZDHHC21, increased ZDHHC21 protein stability and decreased FASN expression, which contributed to the suppression of DLBCL growth in vitro and in vivo. Our results demonstrate that ZDHHC21 strongly represses DLBCL cell proliferation by mediating FASN palmitoylation, and suggest that targeting ZDHHC21/FASN axis is a potential therapeutic strategy against DLBCL.

Metabolic reprogramming based on RNA sequencing of gemcitabine-resistant cells reveals the FASN gene as a therapeutic for bladder cancer.

Bladder cancer (BLCA) is the most frequent malignant tumor of the genitourinary system. Postoperative chemotherapy drug perfusion and chemotherapy are important means for the treatment of BLCA. However, once drug resistance occurs, BLCA develops rapidly after recurrence. BLCA cells rely on unique metabolic rewriting to maintain their growth and proliferation. However, the relationship between the metabolic pattern changes and drug resistance in BLCA is unclear. At present, this problem lacks systematic research. In our research, we identified and analyzed resistance- and metabolism-related differentially expressed genes (RM-DEGs) based on RNA sequencing of a gemcitabine-resistant BLCA cell line and metabolic-related genes (MRGs). Then, we established a drug resistance- and metabolism-related model (RM-RM) through regression analysis to predict the overall survival of BLCA. We also confirmed that RM-RM had a significant correlation with tumor metabolism, gene mutations, tumor microenvironment, and adverse drug reactions. Patients with a high drug resistance- and metabolism-related risk score (RM-RS) showed more active lipid synthesis than those with a low RM-RS. Further in vitro and in vivo studies were implemented using Fatty Acid Synthase (FASN), a representative gene, which promotes gemcitabine resistance, and its inhibitor (TVB-3166) that can reverse this resistance effect.

FASN Gene Methylation is Associated with Fatty Acid Synthase Expression and Clinical-genomic Features of Prostate Cancer.

Fatty acid synthase (FASN) catalyzes the synthesis of long-chain saturated fatty acids and is overexpressed during prostatic tumorigenesis, where it is the therapeutic target in several ongoing trials. However, the mechanism of FASN upregulation in prostate cancer remains unclear. Here, we examine FASN gene CpG methylation pattern by InfiniumEPIC profiling and whole-genome bisulfite sequencing across multiple racially diverse primary and metastatic prostate cancer cohorts, comparing with FASN protein expression as measured by digitally quantified IHC assay and reverse phase protein array analysis or FASN gene expression. We demonstrate that the FASN gene body is hypomethylated and overexpressed in primary prostate tumors compared with benign tissue, and FASN gene methylation is significantly inversely correlated with FASN protein or gene expression in both primary and metastatic prostate cancer. Primary prostate tumors with ERG gene rearrangement have increased FASN expression and we find evidence of FASN hypomethylation in this context. FASN expression is also significantly increased in prostate tumors from carriers of the germline HOXB13 G84E mutation compared with matched controls, consistent with a report that HOXB13 may contribute to epigenetic regulation of FASN in vitro. However, in contrast to previous studies, we find no significant association of FASN expression or methylation with self-identified race in models that include ERG status across two independent primary tumor cohorts. Taken together, these data support a potential epigenetic mechanism for FASN regulation in the prostate which may be relevant for selecting patients responsive to FASN inhibitors. SIGNIFICANCE: Here, we leverage multiple independent primary and metastatic prostate cancer cohorts to demonstrate that FASN gene body methylation is highly inversely correlated with FASN gene and protein expression. This finding may shed light on epigenetic mechanisms of FASN regulation in prostate cancer and provides a potentially useful biomarker for selecting patients in future trials of FASN inhibitors.

Fatty acid synthase (FASN) signalome: A molecular guide for precision oncology.

The initial excitement generated more than two decades ago by the discovery of drugs targeting fatty acid synthase (FASN)-catalyzed de novo lipogenesis for cancer therapy was short-lived. However, the advent of the first clinical-grade FASN inhibitor (TVB-2640; denifanstat), which is currently being studied in various phase II trials, and the exciting advances in understanding the FASN signalome are fueling a renewed interest in FASN-targeted strategies for the treatment and prevention of cancer. Here, we provide a detailed overview of how FASN can drive phenotypic plasticity and cell fate decisions, mitochondrial regulation of cell death, immune escape and organ-specific metastatic potential. We then present a variety of FASN-targeted therapeutic approaches that address the major challenges facing FASN therapy. These include limitations of current FASN inhibitors and the lack of precision tools to maximize the therapeutic potential of FASN inhibitors in the clinic. Rethinking the role of FASN as a signal transducer in cancer pathogenesis may provide molecularly driven strategies to optimize FASN as a long-awaited target for cancer therapeutics.

Sex differences in FASN protein concentrations in urinary exosomes related to serum triglycerides levels in healthy adults.

BACKGROUND: Dysregulation of lipid metabolism is the most prominent metabolic alteration observed in obesity, cancer, and cardiovascular diseases. The present study aimed to explore the sex differences associated with lipid metabolism in urinary exosome proteins, and evaluate the correlation of urinary exosome proteins with serum lipid biomarkers. METHODS: The key enzymes regulating lipid metabolism in healthy adults were screened using urinary exosome data. Urinary exosomes were isolated from 120 healthy subjects and the expression of urinary proteins was assessed by Western blotting and ELISA. The correlation between urinary protein concentrations and the levels of serum lipid biomarkers was analyzed using correlation analysis. RESULTS: Three urinary exosome proteins, namely fatty acid synthase (FASN), phosphoenolpyruvate carboxykinase (PCK1), and ATP-citrate synthase (ACLY) were identified, and only FASN showed sex differences. Sex differences were also observed in the serum triglyceride (TG) levels. Healthy males had higher FASN levels than females, and a moderate positive correlation was found between FASN concentrations and serum TG levels in healthy males (r = 0.479, P < 0.05). FASN concentrations in different age groups were positively correlated with the level of serum TG (18 ~ 30 years, r = 0.502; 31 ~ 44 years, r = 0.587; 45 ~ 59 years, r = 0.654; all P < 0.05). In addition, FASN concentrations was positively related to the increase in serum TG levels (range:1.0 ~ 1.7 mmol/L; r = 0.574, P < 0.05). CONCLUSIONS: Sex differences were observed in urinary exosome FASN protein levels in healthy adults. FASN protein levels positively correlated with increased serum TG levels. FASN may serve as a novel biomarker to evaluate fatty acid synthesis in the human body.

BCAT2 promotes melanoma progression by activating lipogenesis via the epigenetic regulation of FASN and ACLY expressions.

Melanoma is the most lethal skin cancer originating from the malignant transformation of epidermal melanocyte. The dysregulation of cellular metabolism is a hallmark of cancer, including in melanoma. Aberrant branched-chain amino acids (BCAA) metabolism and related enzymes has been greatly implicated in the progression of multiple types of cancer, whereas remains far from understood in melanoma. Herein, we reported that the critical BCAA metabolism enzyme branched-chain amino acid transaminase 2 (BCAT2) is an oncogenic factor in melanoma by activating lipogenesis via the epigenetic regulation of fatty acid synthase (FASN) and ATP-citrate lyase (ACLY) expressions. Firstly, we found that BCAT2 expression was prominently increased in melanoma, and highly associated with clinical stage. Then, it was proved that the deficiency of BCAT2 led to impaired tumor cell proliferation, invasion and migration in vitro, and tumor growth and metastasis in vivo. Further, RNA sequencing technology and a panel of biochemical assays demonstrated that BCAT2 regulated de novo lipogenesis via the regulation of the expressions of both FASN and ACLY. Mechanistically, the inhibition of BCAT2 suppressed the generation of intracellular acetyl-CoA, mitigating P300-dependent histone acetylation at the promoter of FASN and ACLY, and thereby their transcription. Ultimately, zinc finger E-box binding homeobox 1 (ZEB1) was identified as the upstream transcriptional factor responsible for BCAT2 up-regulation in melanoma. Our results demonstrate that BCAT2 promotes melanoma progression by epigenetically regulating FASN and ACLY expressions via P300-dependent histone acetylation. Targeting BCAT2 could be exploited as a promising strategy to restrain tumor progression in melanoma.

FASN promotes gallbladder cancer progression and reduces cancer cell sensitivity to gemcitabine through PI3K/AKT signaling.

Lipid metabolism plays an important role in the growth and development of tumors. However, the role of lipid metabolism in gallbladder cancer (GBC) has not been clearly clarified. Here, we demonstrated that fatty acid synthase (FASN), a key enzyme in de novo fatty acid biosynthesis, had upregulated expression in GBC samples both at protein and mRNA levels. Analysis of clinical data indicated the association between elevated FASN expression and poorer histology grades. Furthermore, FASN activity impairment through FASN knockdown or treatment with orlistat resulted in the inhibition of cell proliferation and migration, as well as increased sensitivity to gemcitabine. Both FASN knockdown and orlistat treatment induced cell apoptosis. Mechanistically, impairment of FASN activity suppressed the activation of the PI3K/AKT signaling pathway, which led to increased cell apoptosis and sensitivity to gemcitabine. These findings were also validated through nude mouse xenograft models, thus highlighting the potential of targeting FASN as a clinical treatment strategy. Collectively, the present study underscores the crucial role of FASN in the progression of gallbladder cancer via the PI3K/AKT pathway.

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.

The m6A modification-mediated OGDHL exerts a tumor suppressor role in ccRCC by downregulating FASN to inhibit lipid synthesis and ERK signaling.

Metabolic reprogramming is a hallmark of cancer, and the impact of lipid metabolism as a crucial aspect of metabolic reprogramming on clear cell renal cell carcinoma (ccRCC) progression has been established. However, the regulatory mechanisms underlying the relationship between metabolic abnormalities and ccRCC progression remain unclear. Therefore, this study aimed to identify key regulatory factors of metabolic reprogramming in ccRCC and provide potential therapeutic targets for ccRCC patients. Potential metabolic regulatory factors in ccRCC were screened using bioinformatics analysis. Public databases and patient samples were used to investigate the aberrant expression of Oxoglutarate dehydrogenase-like (OGDHL) in ccRCC. The function of OGDHL in ccRCC growth and metastasis was evaluated through in vitro and in vivo functional experiments. Mechanistic insights were obtained through luciferase reporter assays, chromatin immunoprecipitation, RNA methylation immunoprecipitation, and mutagenesis studies. OGDHL mRNA and protein levels were significantly downregulated in ccRCC tissues. Upregulation of OGDHL expression effectively inhibited ccRCC growth and metastasis both in vitro and in vivo. Furthermore, FTO-mediated OGDHL m6A demethylation suppressed its expression in ccRCC. Mechanistically, low levels of OGDHL promoted TFAP2A expression by inhibiting ubiquitination levels, which then bound to the FASN promoter region and transcriptionally activated FASN expression, thereby promoting lipid accumulation and ERK pathway activation. Our findings demonstrate the impact of OGDHL on ccRCC progression and highlight the role of the FTO/OGDHL/TFAP2A/FASN axis in regulating ccRCC lipid metabolism and progression, providing new targets for ccRCC therapy.

FABP5 suppresses colorectal cancer progression via mTOR-mediated autophagy by decreasing FASN expression.

Lipid metabolism plays an important role in the occurrence and development of cancer, in particular, digestive system tumors such as colon cancer. Here, we investigated the role of the fatty acid-binding protein 5 (FABP5) in colorectal cancer (CRC). We observed marked down-regulation of FABP5 in CRC. Data from functional assays revealed inhibitory effects of FABP5 on cell proliferation, colony formation, migration, invasion as well as tumor growth in vivo. In terms of mechanistic insights, FABP5 interacted with fatty acid synthase (FASN) and activated the ubiquitin proteasome pathway, leading to a decrease in FASN expression and lipid accumulation, moreover, suppressing mTOR signaling and facilitating cell autophagy. Orlistat, a FASN inhibitor, exerted anti-cancer effects both in vivo and in vitro. Furthermore, the upstream RNA demethylase ALKBH5 positively regulated FABP5 expression via an m6A-independent mechanism. Overall, our collective findings offer valuable insights into the critical role of the ALKBH5/FABP5/FASN/mTOR axis in tumor progression and uncover a potential mechanism linking lipid metabolism to development of CRC, providing novel therapeutic targets for future interventions.

Overexpression of fatty acid synthase attenuates bleomycin induced lung fibrosis by restoring mitochondrial dysfunction in mice.

Proper lipid metabolism is crucial to maintain alveolar epithelial cell (AEC) function, and excessive AEC death plays a role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). The mRNA expression of fatty acid synthase (FASN), a key enzyme in the production of palmitate and other fatty acids, is downregulated in the lungs of IPF patients. However, the precise role of FASN in IPF and its mechanism of action remain unclear. In this study, we showed that FASN expression is significantly reduced in the lungs of IPF patients and bleomycin (BLM)-treated mice. Overexpression of FASN significantly inhibited BLM-induced AEC death, which was significantly potentiated by FASN knockdown. Moreover, FASN overexpression reduced BLM-induced loss of mitochondrial membrane potential and the production of mitochondrial reactive oxygen species (ROS). Oleic acid, a fatty acid component increased by FASN overexpression, inhibited BLM-induced cell death in primary murine AECs and rescue BLM induced mouse lung injury/fibrosis. FASN transgenic mice exposed to BLM exhibited attenuated lung inflammation and collagen deposition compared to controls. Our findings suggest that defects in FASN production may be associated with the pathogenesis of IPF, especially mitochondrial dysfunction, and augmentation of FASN in the lung may have therapeutic potential in preventing lung fibrosis.

FABP5 regulates lipid metabolism to facilitate pancreatic neuroendocrine neoplasms progression via FASN mediated Wnt/ß-catenin pathway.

Pancreatic neuroendocrine neoplasms (pNENs) are among the most frequently occurring neuroendocrine neoplasms (NENs) and require targeted therapy. High levels of fatty acid binding protein 5 (FABP5) are involved in tumor progression, but its role in pNENs remains unclear. We investigated the mRNA and protein levels of FABP5 in pNEN tissues and cell lines and found them to be upregulated. We evaluated changes in cell proliferation using CCK-8, colony formation, and 5-ethynyl-2'-deoxyuridine assays and examined the effects on cell migration and invasion using transwell assays. We found that knockdown of FABP5 suppressed the proliferation, migration, and invasion of pNEN cell lines, while overexpression of FABP5 had the opposite effect. Co-immunoprecipitation experiments were performed to clarify the interaction between FABP5 and fatty acid synthase (FASN). We further showed that FABP5 regulates the expression of FASN via the ubiquitin proteasome pathway and both proteins facilitate the progression of pNENs. Our study demonstrated that FABP5 acts as an oncogene by promoting lipid droplet deposition and activating the WNT/ß-catenin signaling pathway. Moreover, the carcinogenic effects of FABP5 can be reversed by orlistat, providing a novel therapeutic intervention option.

EIF4A3-induced circZFAND6 promotes breast cancer proliferation and metastasis through the miR-647/FASN axis.

AIMS: Circular RNAs (circRNAs) are important regulators in breast cancer progression. However, the underlying mechanism of circRNAs functions in breast cancer remain largely unclear. MAIN METHODS: To investigate the circRNAs expression pattern in breast cancer, high-throughput circRNA microarray assay was used. The top up-regulated circRNA, circZFAND6, was submitted to further experiments, including cell counting kit-8 (CCK-8) assay, colony formation assay, transwell assay and mouse xenograft assay. To investigate the underlying mechanism of circZFAND6 function in breast cancer progression, luciferase reporter assay and RNA immunoprecipitation (RIP) assay were conducted. KEY FINDINGS: We found a novel circRNA, circZFAND6, was up-regulated in breast cancer tissues and cell lines. Inhibition of circZFAND6 reduced proliferation and metastasis of breast cancer. Mechanically, circZFAND6 acted as a competing endogenous RNA (ceRNA) to sponge miR-647 and increase fatty acid synthase (FASN) expression. And eukaryotic translation initiation factor 4A3 (EIF4A3) was found to bind to circZFAND6 pre-mRNA transcript upstream region, leading to the high expression of circZFAND6 in breast cancer. Inhibition of EIF4A3 also suppressed proliferation and metastasis of breast cancer. SIGNIFICANCE: EIF4A3-induced circZFAND6 up-regulation promoted proliferation and metastasis of breast cancer through the miR-647/FASN axis. Our results uncovered a possible mechanism underlying breast cancer progression and might provide a breast cancer treatment target.

FBXW7ß 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 FBXW7ß, a FBXW7 isoform located in the cytoplasm and frequently mutated in CRC, is an E3 ligase of fatty acid synthase (FASN). Cancer-specific FBXW7ß 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 FBXW7ß and FASN, and antagonizes FBXW7ß's activity by enhancing FBXW7ß autoubiquitination and degradation, which in turn prevents FBXW7ß-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.

CircRNA MBOAT2 promotes intrahepatic cholangiocarcinoma progression and lipid metabolism reprogramming by stabilizing PTBP1 to facilitate FASN mRNA cytoplasmic export.

The carcinogenic role of FASN by regulating lipid metabolism reprogramming has been well-established in multiple tumors. However, whether mechanisms during intrahepatic cholangiocarcinoma (ICC) progression, such as circRNAs, regulate FASN expression remains unknown. Here we demonstrate a lipid metabolism-related circRNA, circMBOAT2 (hsa_circ_0007334 in circBase), frequently upregulated in ICC tissues, and positively correlated with ICC malignant features. CircMBOAT2 knockdown inhibits the growth and metastasis of ICC cells. Mechanistically, circMBOAT2 combines with PTBP1 and protects PTBP1 from ubiquitin/proteasome-dependent degradation, impairing the function of PTBP1 to transfer FASN mRNA from the nucleus to the cytoplasm. Moreover, circMBOAT2 and FASN have the same effect on fatty acid profile, unsaturated fatty acids instead of saturated fatty acids are primarily regulated and associated with malignant behaviors of ICC cells. The levels of lipid peroxidation and ROS were significantly higher when FASN was knocked down and recovered when circMBOAT2 was overexpressed. Our results identified that circMBOAT2 was upregulated in ICC and promoted progression by stabilizing PTBP1 to facilitate FASN mRNA cytoplasmic export, which altered lipid metabolic profile and regulated redox homeostasis in ICC, suggesting that circMBOAT2 may serve as an available therapeutic target for ICC with active lipid metabolism.

FASN multi-omic characterization reveals metabolic heterogeneity in pancreatic and prostate adenocarcinoma.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) and prostate cancer (PCa) are among the most prevalent malignant tumors worldwide. There is now a comprehensive understanding of metabolic reprogramming as a hallmark of cancer. Fatty acid synthase (FASN) is a key regulator of the lipid metabolic network, providing energy to favor tumor proliferation and development. Whereas the biological role of FASN is known, its response and sensitivity to inhibition have not yet been fully established in these two cancer settings. METHODS: To evaluate the association between FASN expression, methylation, prognosis, and mutational profile in PDAC and PCa, we interrogated public databases and surveyed online platforms using TCGA data. The STRING database was used to investigate FASN interactors, and the Gene Set Enrichment Analysis platform Reactome database was used to perform an enrichment analysis using data from RNA sequencing public databases of PDAC and PCa. In vitro models using PDAC and PCa cell lines were used to corroborate the expression of FASN, as shown by Western blot, and the effects of FASN inhibition on cell proliferation/cell cycle progression and mitochondrial respiration were investigated with MTT, colony formation assay, cell cycle analysis and MitoStress Test. RESULTS: The expression of FASN was not modulated in PDAC compared to normal pancreatic tissues, while it was overexpressed in PCa, which also displayed a different level of promoter methylation. Based on tumor grade, FASN expression decreased in advanced stages of PDAC, but increased in PCa. A low incidence of FASN mutations was found for both tumors. FASN was overexpressed in PCa, despite not reaching statistical significance, and was associated with a worse prognosis than in PDAC. The biological role of FASN interactors correlated with lipid metabolism, and GSEA indicated that lipid-mediated mitochondrial respiration was enriched in PCa. Following validation of FASN overexpression in PCa compared to PDAC in vitro, we tested TVB-2640 as a FASN inhibitor. PCa proliferation arrest was modulated by FASN inhibition in a dose- and time-dependent manner, whereas PDAC proliferation was not altered. In line with this finding, mitochondrial respiration was found to be more affected in PCa than in PDAC. FASN inhibition interfered with metabolic signaling causing lipid accumulation and affecting cell viability with an impact on the replicative processes. CONCLUSIONS: FASN exhibited differential expression patterns in PDAC and PCa, suggesting a different evolution during cancer progression. This was corroborated by the fact that both tumors responded differently to FASN inhibition in terms of proliferative potential and mitochondrial respiration, indicating that its use should reflect context specificity.

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.

Comprehensive Analysis of FASN in Tumor Immune Infiltration and Prognostic Value for Immunotherapy and Promoter DNA Methylation.

Fatty acid synthase (FASN) promotes tumor progression in multiple cancers. In this study, we comprehensively examined the expression, prognostic significance, and promoter methylation of FASN, and its correlation with immune cell infiltration in pan-cancer. Our results demonstrated that elevated FASN expression was significantly associated with an unfavorable prognosis in many cancer types. Furthermore, FASN promoter DNA methylation can be used as a tumor prognosis marker. Importantly, high levels of FASN were significantly negatively correlated with tumor immune infiltration in 35 different cancers. Additionally, FASN was significantly associated with tumor mutational burden (TMB) and microsatellite instability (MSI) in multiple malignancies, suggesting that it may be essential for tumor immunity. We also investigated the effects of FASN expression on immunotherapy efficacy and prognosis. In up to 15 tumors, it was significantly negatively correlated with immunotherapy-related genes, such as PD-1, PD-L1, and CTLA-4. Moreover, we found that tumors with high FASN expression may be more sensitive to immunotherapy and have a good prognosis with PD-L1 treatment. Finally, we confirmed the tumor-suppressive effect of mir-195-5p through FASN. Altogether, our results suggested that FASN may serve as a novel prognostic indicator and immunotherapeutic target in various malignancies.