ABSTRACT
Objectives: This study investigates the role of Nicotinamide N-methyltransferase (NNMT) in immune infiltration modulation through amino acid metabolism in gastric adenocarcinoma (STAD). Methods: Utilizing data from The Cancer Genome Atlas (TCGA) and validated with clinical samples, we analyzed NNMT expression and its prognostic implications in STAD. Differential amino acid profiles between cancerous and adjacent normal tissues were assessed, along with their associations with NNMT. Results: NNMT exhibits heightened expression in STAD cancer tissues, positively correlating with tumor immune infiltration. Additionally, twenty-eight amino acids display differential expression in gastric tissue, with their metabolic enzymes showing connections to NNMT. Conclusions: Elevated NNMT expression in STAD tissues potentially influences amino acid metabolism, thereby affecting immune infiltration dynamics and tumorigenesis in gastric adenocarcinoma.
Subject(s)
Adenocarcinoma , Amino Acids , Nicotinamide N-Methyltransferase , Stomach Neoplasms , Nicotinamide N-Methyltransferase/metabolism , Nicotinamide N-Methyltransferase/genetics , Humans , Stomach Neoplasms/immunology , Stomach Neoplasms/pathology , Stomach Neoplasms/genetics , Stomach Neoplasms/metabolism , Adenocarcinoma/genetics , Adenocarcinoma/pathology , Adenocarcinoma/immunology , Adenocarcinoma/metabolism , Amino Acids/metabolism , Prognosis , Male , Female , Gene Expression Regulation, Neoplastic , Middle AgedABSTRACT
Merkel cell carcinoma (MCC) is an aggressive skin cancer, with a propensity for early metastasis. Therefore, early diagnosis and the identification of novel targets become fundamental. The enzyme nicotinamide N-methyltransferase (NNMT) catalyzes the reaction of N-methylation of nicotinamide and other analogous compounds. Although NNMT overexpression was reported in many malignancies, the significance of its dysregulation in cancer cell phenotype was partly clarified. Several works demonstrated that NNMT promotes cancer cell proliferation, migration, and chemoresistance. In this study, we investigated the possible involvement of this enzyme in MCC. Preliminary immunohistochemical analyses were performed to evaluate NNMT expression in MCC tissue specimens. To explore the enzyme function in tumor cell metabolism, MCC cell lines have been transfected with plasmids encoding for short hairpin RNAs (shRNAs) targeting NNMT mRNA. Preliminary immunohistochemical analyses showed elevated NNMT expression in MCC tissue specimens. The effect of enzyme downregulation on cell proliferation, migration, and chemosensitivity was then evaluated through MTT, trypan blue, and wound healing assays. Data obtained clearly demonstrated that NNMT knockdown is associated with a decrease of cell proliferation, viability, and migration, as well as with enhanced sensitivity to treatment with chemotherapeutic drugs. Taken together, these results suggest that NNMT could represent an interesting MCC biomarker and a promising target for targeted anti-cancer therapy.
Subject(s)
Carcinoma, Merkel Cell , Skin Neoplasms , Humans , Nicotinamide N-Methyltransferase/genetics , Nicotinamide N-Methyltransferase/metabolism , Carcinoma, Merkel Cell/genetics , Drug Resistance, Neoplasm/genetics , Cell Proliferation/genetics , Skin Neoplasms/drug therapy , Skin Neoplasms/genetics , RNA, Small Interfering/geneticsABSTRACT
BACKGROUND: Osteosarcoma (OS) is a primary bone malignancy that mostly affects young people, characterized by high metastatic potential, and a marked chemoresistance that is responsible for disease relapse in most patients. Therefore, it is necessary to identify novel molecules to setup targeted strategies to improve the clinical outcome. The enzyme nicotinamide N-methyltransferase (NNMT) catalyses the N-methylation of nicotinamide and other analogs, playing a crucial role in the biotransformation of drugs and xenobiotics. NNMT overexpression was reported in a wide variety of cancers, and several studies demonstrated that is able to promote cell proliferation, migration and resistance to chemotherapy. The aim of this study was to explore the potential involvement of NNMT in OS. METHODS: Immunohistochemical analyses have been performed to evaluate NNMT expression in selected OS and healthy bone tissue samples. Subsequently, OS cell lines have been transfected with vectors targeting NNMT mRNA (shRNAs) and the impact of this downregulation on migration, cell proliferation, and response to chemotherapeutic treatment was also analysed by wound healing, MTT, SRB and Trypan blue assays, respectively. RESULTS: Results showed that OS samples display a significantly higher NNMT expression compared with healthy tissue. Preliminary results suggest that NNMT silencing in OS cell lines is associated to a decrease of cell proliferation and migration, as well as to enhanced sensitivity to chemotherapy. Data obtained showed that NNMT may represent an interesting marker for OS detection and a promising target for effective anti-cancer therapy.
Subject(s)
Bone Neoplasms , Nicotinamide N-Methyltransferase , Osteosarcoma , Adolescent , Adult , Child , Female , Humans , Male , Young Adult , Bone Neoplasms/genetics , Bone Neoplasms/metabolism , Bone Neoplasms/pathology , Bone Neoplasms/drug therapy , Cell Line, Tumor , Cell Movement , Cell Proliferation , Drug Resistance, Neoplasm/genetics , Nicotinamide N-Methyltransferase/metabolism , Nicotinamide N-Methyltransferase/genetics , Osteosarcoma/genetics , Osteosarcoma/pathology , Osteosarcoma/metabolism , Osteosarcoma/drug therapy , RNA, Small Interfering/geneticsABSTRACT
Background: Chronic kidney disease (CKD) is a significant global health issue characterized by progressive loss of kidney function. Renal interstitial fibrosis (TIF) is a common feature of CKD, but current treatments are seldom effective in reversing TIF. Nicotinamide N-methyltransferase (NNMT) has been found to increase in kidneys with TIF, but its role in renal fibrosis is unclear. Methods: Using mice with unilateral ureteral obstruction (UUO) and cultured renal interstitial fibroblast cells (NRK-49F) stimulated with transforming growth factor-ß1 (TGF-ß1), we investigated the function of NNMT in vivo and in vitro. Results: We performed single-cell transcriptome sequencing (scRNA-seq) on the kidneys of mice and found that NNMT increased mainly in fibroblasts of UUO mice compared to sham mice. Additionally, NNMT was positively correlated with the expression of renal fibrosis-related genes after UUO injury. Knocking down NNMT expression reduced fibroblast activation and was accompanied by an increase in DNA methylation of p53 and a decrease in its phosphorylation. Conclusions: Our findings suggest that chronic kidney injury leads to an accumulation of NNMT, which might decrease p53 methylation, and increase the expression and activity of p53. We propose that NNMT promotes fibroblast activation and renal fibrosis, making NNMT a novel target for preventing and treating renal fibrosis.
Subject(s)
Nicotinamide N-Methyltransferase , Renal Insufficiency, Chronic , Ureteral Obstruction , Fibrosis , Kidney/metabolism , Nicotinamide N-Methyltransferase/genetics , Renal Insufficiency, Chronic/genetics , Tumor Suppressor Protein p53/metabolism , Ureteral Obstruction/genetics , Animals , MiceABSTRACT
INTRODUCTION: Nicotinamide N-methyltransferase (NNMT) catalyzes the N-methylation of nicotinamide with S-adenosine-L-methionine (SAM) as the methyl donor. Abnormal expression of NNMT is associated with many diseases (such as multiple cancers and metabolic and liver diseases), making NNMT a potential therapeutic target. Limited studies concerning the enzymesubstrate/ inhibitor interactions could be found to fully understand the detailed reaction mechanism. METHODS: The binding affinity and ligand binding epitopes of nicotinamide or SAH for binding NNMT and its mutants were determined using saturated transfer difference (STD) nuclear magnetic resonance (NMR) techniques combined with site-directed mutagenesis. RESULTS: The average dissociation constant of WT NNMT with nicotinamide and S-adenosine homocysteine (SAH) was 5.5 ± 0.9 mM and 1.2 ± 0.3 mM, respectively, while the mutants Y20F and Y20G with nicotinamide were up to nearly 4 times and 20 times that of WT and with SAH nearly 2 times and 5 times that of WT. The data suggested that WT had the highest binding affinity for nicotinamide or SAH, followed by Y20F and Y20G, which was consistent with its catalytic activity. CONCLUSION: The binding affinity of nicotinamide and SAH to NNMT and its mutants were obtained by STD NMR in this study. It was found that nicotinamide and SAH bind to WT in a particular orientation, and Y20 is critical for their binding orientation and affinity to NNMT.
Subject(s)
Niacinamide , Nicotinamide N-Methyltransferase , Nicotinamide N-Methyltransferase/genetics , Nicotinamide N-Methyltransferase/chemistry , Ligands , Niacinamide/chemistry , Niacinamide/metabolism , Adenosine , Magnetic Resonance SpectroscopyABSTRACT
Metastatic colonization of distant organs accounts for over 90% of deaths related to solid cancers, yet the molecular determinants of metastasis remain poorly understood. Here, we unveil a mechanism of colonization in the aggressive basal-like subtype of breast cancer that is driven by the NAD+ metabolic enzyme nicotinamide N-methyltransferase (NNMT). We demonstrate that NNMT imprints a basal genetic program into cancer cells, enhancing their plasticity. In line, NNMT expression is associated with poor clinical outcomes in patients with breast cancer. Accordingly, ablation of NNMT dramatically suppresses metastasis formation in pre-clinical mouse models. Mechanistically, NNMT depletion results in a methyl overflow that increases histone H3K9 trimethylation (H3K9me3) and DNA methylation at the promoters of PR/SET Domain-5 (PRDM5) and extracellular matrix-related genes. PRDM5 emerged in this study as a pro-metastatic gene acting via induction of cancer-cell intrinsic transcription of collagens. Depletion of PRDM5 in tumor cells decreases COL1A1 deposition and impairs metastatic colonization of the lungs. These findings reveal a critical activity of the NNMT-PRDM5-COL1A1 axis for cancer cell plasticity and metastasis in basal-like breast cancer.
Subject(s)
Neoplasms , Nicotinamide N-Methyltransferase , Animals , Mice , Nicotinamide N-Methyltransferase/genetics , Nicotinamide N-Methyltransferase/metabolism , Neoplasms/metabolism , DNA Methylation , Epigenesis, GeneticABSTRACT
Peroxisome proliferator-activated receptor γ (PPARγ) plays a pivotal role in regulating lipid metabolism and hepatic PPARγ transactivation contributes to fatty liver development. Fatty acids (FAs) are well-known endogenous ligands for PPARγ. Palmitate, a 16-C saturated FA (SFA) and the most abundant SFA in human circulation, is a strong inducer of hepatic lipotoxicity, a central pathogenic factor for various fatty liver diseases. In this study, using both alpha mouse liver 12 (AML12) and primary mouse hepatocytes, we investigated the effects of palmitate on hepatic PPARγ transactivation and underlying mechanisms, as well as the role of PPARγ transactivation in palmitate-induced hepatic lipotoxicity, all of which remain ambiguous currently. Our data revealed that palmitate exposure was concomitant with both PPARγ transactivation and upregulation of nicotinamide N-methyltransferase (NNMT), a methyltransferase catalyzing the degradation of nicotinamide, the predominant precursor for cellular NAD+ biosynthesis. Importantly, we discovered that PPARγ transactivation by palmitate was blunted by NNMT inhibition, suggesting that NNMT upregulation plays a mechanistic role in PPARγ transactivation. Further investigations uncovered that palmitate exposure is associated with intracellular NAD+ decline and NAD+ replenishment with NAD+-enhancing agents, nicotinamide and nicotinamide riboside, obstructed palmitate-induced PPARγ transactivation, implying that cellular NAD+ decline resulted from NNMT upregulation represents a potential mechanism behind palmitate-elicited PPARγ transactivation. At last, our data showed that the PPARγ transactivation marginally ameliorated palmitate-induced intracellular triacylglycerol accumulation and cell death. Collectively, our data provided the first-line evidence supporting that NNMT upregulation plays a mechanistic role in palmitate-elicited PPARγ transactivation, potentially through reducing cellular NAD+ contents.NEW & NOTEWORTHY Hepatic PPARγ transactivation contributes to fatty liver development. Saturated fatty acids (SFAs) induce hepatic lipotoxicity. Here, we investigated whether and how palmitate, the most abundant SFA in the human blood, affects PPARγ transactivation in hepatocytes. We reported for the first time that upregulation of nicotinamide N-methyltransferase (NNMT), a methyltransferase catalyzing the degradation of nicotinamide, the predominant precursor for cellular NAD+ biosynthesis, plays a mechanistic role in regulating palmitate-elicited PPARγ transactivation through reducing intracellular NAD+ contents.
Subject(s)
Fatty Liver , Palmitates , Mice , Animals , Humans , Palmitates/toxicity , Nicotinamide N-Methyltransferase/genetics , Nicotinamide N-Methyltransferase/metabolism , Up-Regulation , NAD/metabolism , Transcriptional Activation , PPAR gamma/genetics , PPAR gamma/metabolism , Hepatocytes/metabolism , Niacinamide/metabolism , Niacinamide/pharmacology , Fatty Acids/metabolismABSTRACT
Nicotinamide metabolism is important in carcinogenesis. Nicotinamide affects the cellular methyl pool, thus affecting DNA and histone methylation and gene expression. Cancer cells have increased expression of nicotinamide N-methyl transferase (NNMT), the key enzyme in nicotinamide metabolism. NNMT contributes to tumor angiogenesis. Overexpression of NNMT is associated with poorer prognosis in cancers. Additionally, NNMT can contribute to cancer-associated morbidities, such as cancer-associated thrombosis. 1-methylnicotinamide (1-MNA), a metabolite of nicotinamide, has anti-inflammatory and antithrombotic effects. Therefore, targeting NNMT can affect both carcinogenesis and cancer-associated morbidities. Several antitumor drugs have been shown to inhibit NNMT expression in cancer cells. Implementing these drugs to reverse NNMT effects in addition to 1-MNA supplementation has the potential to prevent cancer-associated thrombosis through various mechanisms.
Subject(s)
Antineoplastic Agents , Neoplasms , Humans , Neoplasms/complications , Neoplasms/drug therapy , Neoplasms/genetics , Antineoplastic Agents/pharmacology , Carcinogenesis , Niacinamide/pharmacology , Niacinamide/therapeutic use , Transferases , Nicotinamide N-Methyltransferase/genetics , Nicotinamide N-Methyltransferase/metabolismABSTRACT
OBJECTIVE: Early gastric cardia adenocarcinoma (EGCA) is a highly heterogeneous cancer, and the understanding of its classification and malignant progression is limited. This study explored the cellular and molecular heterogeneity in EGCA using single-cell RNA sequencing (scRNA-seq). DESIGN: scRNA-seq was conducted on 95 551 cells from endoscopic biopsies of low-grade intraepithelial neoplasia, well/moderately/poorly differentiated EGCA and their paired adjacent nonmalignant biopsy samples. Large-scale clinical samples and functional experiments were employed. RESULTS: Integrative analysis of epithelial cells revealed that chief cells, parietal cells and enteroendocrine cells were rarely detected in the malignant epithelial subpopulation, whereas gland and pit mucous cells and AQP5+ stem cells were predominant during malignant progression. Pseudotime and functional enrichment analyses showed that the WNT and NF-κB signalling pathways were activated during the transition. Cluster analysis of heterogeneous malignant cells revealed that NNMT-mediated nicotinamide metabolism was enriched in gastric mucin phenotype cell population, which was associated with tumour initiation and inflammation-induced angiogenesis. Furthermore, the expression level of NNMT was gradually increased during the malignant progression and associated with poor prognosis in cardia adenocarcinoma. Mechanistically, NNMT catalysed the conversion of nicotinamide to 1-methyl nicotinamide via depleting S-adenosyl methionine, which led to a reduction in H3K27 trimethylation (H3K27me3) and then activated the WNT signalling pathway to maintain the stemness of AQP5+ stem cells during EGCA malignant progression. CONCLUSION: Our study extends the understanding of the heterogeneity of EGCA and identifies a functional NNMT+/AQP5+ population that may drive malignant progression in EGCA and could be used for early diagnosis and therapy.
Subject(s)
Adenocarcinoma , Stomach Neoplasms , Humans , Cardia/metabolism , S-Adenosylmethionine , Neoplastic Stem Cells/metabolism , Niacinamide , Nicotinamide N-Methyltransferase/genetics , Nicotinamide N-Methyltransferase/metabolism , Aquaporin 5ABSTRACT
Nicotinamide N-methyltransferase (NNMT) has been reported to be linked to methylation reprogramming in cancer cells. However, the role of NNMT in the tumour microenvironment (TME) remains elusive. Here, we found that the expression of NNMT was elevated in the stroma of oral squamous cell carcinoma (OSCC). Using a fibroblast-attached organoids (FAOs) model, we confirmed that stromal NNMT expression contributed to the generation of assembled tumour organoids. In a tumour regeneration assay with co-implanted OSCC cells and cancer-associated fibroblasts (CAFs), the tumour-initiating activity was reduced when NNMT was silenced in CAFs. In contrast, overexpression of NNMT in paracancerous fibroblasts (PFs) accelerated tumour growth in co-inoculation experiments. Notably, fibroblast-specific NNMT can regulate type I collagen deposition in both FAOs and xenografts. Further investigations confirmed that the stromal NNMT-aggravated oncogenic activities were attenuated by treatment with inhibitors of either collagen synthesis (e.g. losartan, tranilast, and halofuginone) in fibroblasts, or the focal adhesion kinase (FAK) signal (i.e. defactinib) in cancer cells. Mechanistically, overexpression of NNMT reduced the enrichment of H3K27me3 at the promoter of the gene encoding lysyl oxidase (LOX), a key enzyme that regulates the cross-linking of collagen I. Overall, we propose that the NNMT-LOX-FAK cascade contributes to the crosstalk between cancer cells and fibroblasts during OSCC development, and that NNMT-centric extracellular matrix remodelling is a novel therapeutic target for patients with OSCC.
Subject(s)
Carcinoma, Squamous Cell , Head and Neck Neoplasms , Mouth Neoplasms , Humans , Carcinoma, Squamous Cell/pathology , Squamous Cell Carcinoma of Head and Neck/genetics , Mouth Neoplasms/genetics , Mouth Neoplasms/pathology , Nicotinamide N-Methyltransferase/genetics , Nicotinamide N-Methyltransferase/metabolism , Fibroblasts/metabolism , Organoids/pathology , Collagen , Tumor MicroenvironmentABSTRACT
BACKGROUND: Clear cell renal cell carcinoma (ccRCC), with its hallmark phenotype of high cytosolic lipid content, is considered a metabolic cancer. Despite the implication of this lipid-rich phenotype in ccRCC tumorigenesis, the roles and regulators of de novo lipid synthesis (DNL) in ccRCC remain largely unexplained. METHODS: Our bioinformatic screening focused on ccRCC-lipid phenotypes identified glutathione peroxidase 8 (GPX8), as a clinically relevant upstream regulator of DNL. GPX8 genetic silencing was performed with CRISPR-Cas9 or shRNA in ccRCC cell lines to dissect its roles. Untargeted metabolomics, RNA-seq analyses, and other biochemical assays (e.g., lipid droplets staining, fatty acid uptake, cell proliferation, xenograft, etc.) were carried out to investigate the GPX8's involvement in lipid metabolism and tumorigenesis in ccRCC. The lipid metabolic function of GPX8 and its downstream were also measured by isotope-tracing-based DNL flux measurement. RESULTS: GPX8 knockout or downregulation substantially reduced lipid droplet levels (independent of lipid uptake), fatty acid de novo synthesis, triglyceride esterification in vitro, and tumor growth in vivo. The downstream regulator was identified as nicotinamide N-methyltransferase (NNMT): its knockdown phenocopied, and its expression rescued, GPX8 silencing both in vitro and in vivo. Mechanically, GPX8 regulated NNMT via IL6-STAT3 signaling, and blocking this axis suppressed ccRCC survival by activating AMPK. Notably, neither the GPX8-NNMT axis nor the DNL flux was affected by the von Hippel Lindau (VHL) status, the conventional regulator of ccRCC high lipid content. CONCLUSIONS: Taken together, our findings unravel the roles of the VHL-independent GPX8-NNMT axis in ccRCC lipid metabolism as related to the phenotypes and growth of ccRCC, which may be targeted for therapeutic purposes.
Subject(s)
Carcinoma, Renal Cell , Carcinoma , Kidney Neoplasms , Humans , Carcinoma, Renal Cell/pathology , Lipogenesis , Cell Transformation, Neoplastic/genetics , Carcinogenesis/genetics , Carcinoma/genetics , Kidney Neoplasms/pathology , Lipids , Cell Line, Tumor , Gene Expression Regulation, Neoplastic , Nicotinamide N-Methyltransferase/genetics , Nicotinamide N-Methyltransferase/metabolism , Peroxidases/genetics , Peroxidases/metabolismABSTRACT
Nicotinamide N-methyltransferase (NNMT) is a protein coding gene, which methylates the nicotinamide (NA) (vitamin B3) to produce 1-methylnicotinamide (MNA). Several studies have suggested that the overexpression of NNMT is associated with different metabolic disorders like obesity and type-2 diabetes thereby making it an important therapeutic target for development of anti-diabetic agents. Here we describe a workflow for identification of new inhibitors of NNMT from a library of small molecules. In this study, we have hypothesized a four-point pharmacophore model based on the pharmacophoric features of reported NNMT inhibitors in the literature. The statistically significant pharmacophore hypothesis was used to explore the Maybridge compound library that resulted in mapping of 1330 hit compounds on the proposed hypothesis. Subsequently, a total of eight high scoring compounds, showing good protein-ligand interactions in the molecular docking study, were selected for biological evaluation of NNMT activity. Eventually, four compounds were found to show significant inhibitory activity for NNMT and can be further explored to design new derivatives around the identified scaffolds with improved activities as NNMT inhibitors.
Subject(s)
Diabetes Mellitus, Type 2 , Nicotinamide N-Methyltransferase , Humans , Molecular Docking Simulation , Nicotinamide N-Methyltransferase/genetics , Nicotinamide N-Methyltransferase/metabolism , Ligands , ObesityABSTRACT
BACKGROUND: Nicotinamide N-methyltransferase (NNMT) is a metabolic enzyme that catalyzes the methylation of nicotinamide (NAM) to generate 1-methyl nicotinamide (MNAM). Although previous studies have shown that NNMT is frequently dysregulated to promote the onset and progression of many malignancies, its expression profile, prognostic value and function in oral squamous cell carcinoma (OSCC) are still unknown. METHODS: We used untargeted metabolomics based on mass spectrometry to analyze potential metabolite differences between tumors and matched adjacent normal tissues in 40 OSCC patients. Immunohistochemistry (IHC) was used to analyze the NNMT expression profile in OSCC, and the diagnostic and prognostic values of NNMT were evaluated. Next, qPCR and Western blot were used to compare the expression of NNMT in five OSCC cell lines. Stable transfected cell lines were constructed, and functional experiments were carried out to elucidate the effects of NNMT on the proliferation and migration of OSCC cells. Finally, gene set enrichment analysis (GSEA) was performed using The Cancer Genome Atlas (TCGA) data to investigate the potential functional mechanisms of NNMT in OSCC. RESULTS: We found that the nicotinamide metabolic pathway was abnormally activated in OSCC tumor tissues compared with normal tissues. NNMT was expressed ubiquitously in tumor cells (TCs) and fibroblast-like cells (FLCs) but was absent in tumor-infiltrating lymphocytes (TILs). OSCC patients with highly expressed NNMT in TCs had higher risk of lymph node metastasis and showed a worse pattern of invasion (POI). Moreover, patients with highly expressed NNMT were also susceptible to postoperative recurrence. Highly expressed NNMT can independently predict shorter disease-free survival and recurrence-free survival. Functionally, we demonstrated that the ectopic expression of NNMT promoted OSCC tumor cell proliferation and migration in vitro. Conversely, silencing exerted significantly opposite effects in vitro. In addition, GSEA showed that highly expressed NNMT was mainly enriched in the epithelial-mesenchymal transformation (EMT) pathway, which displayed a significant positive correlation with the six classic EMT markers. CONCLUSIONS: Our study uncovered that NNMT may be a critical regulator of EMT in OSCC and may serve as a prognostic biomarker for OSCC patients. These findings might provide novel insights for future research in NNMT-targeted OSCC metastasis and recurrence therapy.
Subject(s)
Carcinoma, Squamous Cell , Head and Neck Neoplasms , Mouth Neoplasms , Humans , Carcinoma, Squamous Cell/genetics , Mouth Neoplasms/genetics , Mouth Neoplasms/pathology , Niacinamide , Nicotinamide N-Methyltransferase/genetics , Nicotinamide N-Methyltransferase/metabolism , Prognosis , Squamous Cell Carcinoma of Head and Neck/geneticsABSTRACT
This study aimed to investigate the putative role of nicotinamide N-methyltransferase in the metabolic response of human aortic endothelial cells. This enzyme catalyses S-adenosylmethionine-mediated methylation of nicotinamide to methylnicotinamide. This reaction is accompanied by the reduction of the intracellular nicotinamide and S-adenosylmethionine content. This may affect NAD+ synthesis and various processes of methylation, including epigenetic modifications of chromatin. Particularly high activity of nicotinamide N-methyltransferase is detected in liver, many neoplasms as well as in various cells in stressful conditions. The elevated nicotinamide N-methyltransferase content was also found in endothelial cells treated with statins. Although the exogenous methylnicotinamide has been postulated to induce a vasodilatory response, the specific metabolic role of nicotinamide N-methyltransferase in vascular endothelium is still unclear. Treatment of endothelial cells with bacterial lipopolysaccharide evokes several metabolic and functional consequences which built a multifaceted physiological response of endothelium to bacterial infection. Among the spectrum of biochemical changes substantially elevated protein level of nicotinamide N-methyltransferase was particularly intriguing. Here it has been shown that silencing of the nicotinamide N-methyltransferase gene influences several changes which are observed in cells treated with lipopolysaccharide. They include altered energy metabolism and rearrangement of the mitochondrial network. A complete explanation of the mechanisms behind the protective consequences of the nicotinamide N-methyltransferase deficiency in cells treated with lipopolysaccharide needs further investigation.
Subject(s)
Hydroxymethylglutaryl-CoA Reductase Inhibitors , Nicotinamide N-Methyltransferase , Chromatin/metabolism , Endothelial Cells/metabolism , Endothelium/metabolism , Energy Metabolism , Humans , Lipopolysaccharides/pharmacology , NAD/metabolism , Niacinamide/metabolism , Niacinamide/pharmacology , Nicotinamide N-Methyltransferase/genetics , Nicotinamide N-Methyltransferase/metabolism , S-Adenosylmethionine/metabolismABSTRACT
Cancers disrupt host homeostasis in various manners but the identity of host factors underlying such disruption remains largely unknown. Here we show that nicotinamide-N-methyltransferase (NNMT) is a host factor that mediates metabolic dysfunction in the livers of cancer-bearing mice. Multiple solid cancers distantly increase expression of Nnmt and its product 1-methylnicotinamide (MNAM) in the liver. Multi-omics analyses reveal suppression of the urea cycle accompanied by accumulation of amino acids, and enhancement of uracil biogenesis in the livers of cancer-bearing mice. Importantly, genetic deletion of Nnmt leads to alleviation of these metabolic abnormalities, and buffers cancer-dependent weight loss and reduction of the voluntary wheel-running activity. Our data also demonstrate that MNAM is capable of affecting urea cycle metabolites in the liver. These results suggest that cancers up-regulate the hepatic NNMT pathway to rewire liver metabolism towards uracil biogenesis rather than nitrogen disposal via the urea cycle, thereby disrupting host homeostasis.
Subject(s)
Neoplasms , Nicotinamide N-Methyltransferase , Nitrogen , Animals , Liver/metabolism , Mice , Neoplasms/genetics , Neoplasms/metabolism , Niacinamide/metabolism , Nicotinamide N-Methyltransferase/genetics , Nicotinamide N-Methyltransferase/metabolism , Nitrogen/metabolism , Uracil/metabolism , Urea/metabolismABSTRACT
Dysregulation of nicotinamide adenine dinucleotide (NAD +) metabolism contributes to the initiation and progression of age-associated diseases, including chronic kidney disease (CKD). Nicotinamide N-methyltransferase (NNMT), a nicotinamide (NAM) metabolizing enzyme, regulates both NAD + and methionine metabolism. Although NNMT is expressed abundantly in the kidney, its role in CKD and renal fibrosis remains unclear. We generated NNMT-deficient mice and a unilateral ureter obstruction (UUO) model and conducted two clinical studies on human CKD to investigate the role of NNMT in CKD and fibrosis. In UUO, renal NNMT expression and the degraded metabolites of NAM increased, while NAD + and NAD + precursors decreased. NNMT deficiency ameliorated renal fibrosis; mechanistically, it (1) increased the DNA methylation of connective tissue growth factor (CTGF), and (2) improved renal inflammation by increasing renal NAD + and Sirt1 and decreasing NF-κB acetylation. In humans, along with CKD progression, a trend toward a decrease in serum NAD + precursors was observed, while the final NAD + metabolites were accumulated, and the level of eGFR was an independent variable for serum NAM. In addition, NNMT was highly expressed in fibrotic areas of human kidney tissues. In conclusion, increased renal NNMT expression induces NAD + and methionine metabolism perturbation and contributes to renal fibrosis.
Subject(s)
NAD , Nicotinamide N-Methyltransferase , Renal Insufficiency, Chronic , Ureteral Obstruction , Animals , Female , Fibrosis , Humans , Male , Methionine , Mice , NAD/metabolism , Niacinamide/metabolism , Nicotinamide N-Methyltransferase/genetics , Nicotinamide N-Methyltransferase/metabolism , Renal Insufficiency, Chronic/genetics , Renal Insufficiency, Chronic/metabolism , Ureteral Obstruction/genetics , Ureteral Obstruction/metabolismABSTRACT
Nicotinamide N-methyltransferase (NNMT) is an intracellular methyltransferase, catalyzing the N-methylation of nicotinamide (NAM) to form 1-methylnicotinamide (1-MNAM), in which S-adenosyl-L-methionine (SAM) is the methyl donor. High expression of NNMT can alter cellular NAM and SAM levels, which in turn, affects nicotinamide adenine dinucleotide (NAD+)-dependent redox reactions and signaling pathways, and remodels cellular epigenetic states. Studies have revealed that NNMT plays critical roles in the occurrence and development of various cancers, and analysis of NNMT expression levels in different cancers from The Cancer Genome Atlas (TCGA) dataset indicated that NNMT might be a potential biomarker and therapeutic target for tumor diagnosis and treatment. This review provides a comprehensive understanding of recent advances on NNMT functions in different tumors and deciphers the complex roles of NNMT in cancer progression.
Subject(s)
Neoplasms , Nicotinamide N-Methyltransferase , Humans , Neoplasms/genetics , Niacinamide , Nicotinamide N-Methyltransferase/genetics , Nicotinamide N-Methyltransferase/metabolismABSTRACT
Hair loss is one of the most common skin problems experienced by more than half of the world's population. In East Asia, medicinal herbs have been used widely in clinical practice to treat hair loss. Recent studies, including systematic literature reviews, indicate that medicinal herbs may demonstrate potential effects for hair loss treatment. In a previous study, we identified medical herbs used frequently for alopecia treatment. Herein, we explored the potential novel therapeutic mechanisms of 20 vital medicinal herbs for alopecia treatment that could distinguish them from known mechanisms of conventional drugs using network pharmacology analysis methods. We determined the herb-ingredient-target protein networks and ingredient-associated protein (gene)-associated pathway networks and calculated the weighted degree centrality to define the strength of the connections. Data showed that 20 vital medicinal herbs could exert therapeutic effects on alopecia mainly mediated via regulation of various target genes and proteins, including acetylcholinesterase (AChE), phospholipase A2 (PLA2) subtypes, ecto-5-nucleotidase (NTE5), folate receptor (FR), nicotinamide N-methyltransferase (NNMT), and quinolinate phosphoribosyltransferase (QPRT). Findings regarding target genes/proteins and pathways of medicinal herbs associated with alopecia treatment offer insights for further research to better understand the pathogenesis and therapeutic mechanism of medicinal herbs for alopecia treatment with traditional herbal medicine.
Subject(s)
Alopecia/drug therapy , Drugs, Chinese Herbal/therapeutic use , Network Pharmacology , Plants, Medicinal , Acetylcholinesterase/genetics , Alopecia/genetics , Alopecia/prevention & control , Asia, Eastern , Folate Receptor 1/genetics , Humans , Medicine, Chinese Traditional , Nicotinamide N-Methyltransferase/genetics , Nucleotidases/genetics , Pentosyltransferases/genetics , Phospholipases A2/genetics , Phytotherapy , Plant Preparations/chemistry , Plant Preparations/therapeutic useABSTRACT
Treatment with a nicotinamide N-methyltransferase inhibitor (NNMTi; 5-amino-1-methylquinolinium) combined with low-fat diet (LD) promoted dramatic whole-body adiposity and weight loss in diet-induced obese (DIO) mice, rapidly normalizing these measures to age-matched lean animals, while LD switch alone was unable to restore these measures to age-matched controls in the same time frame. Since mouse microbiome profiles often highly correlate with body weight and fat composition, this study was designed to test whether the cecal microbiomes of DIO mice treated with NNMTi and LD were comparable to the microbiomes of age-matched lean counterparts and distinct from microbiomes of DIO mice maintained on a high-fat Western diet (WD) or subjected to LD switch alone. There were minimal microbiome differences between lean and obese controls, suggesting that diet composition and adiposity had limited effects. However, DIO mice switched from an obesity-promoting WD to an LD (regardless of treatment status) displayed several genera and phyla differences compared to obese and lean controls. While alpha diversity measures did not significantly differ between groups, beta diversity principal coordinates analyses suggested that mice from the same treatment group were the most similar. K-means clustering analysis of amplicon sequence variants by animal demonstrated that NNMTi-treated DIO mice switched to LD had a distinct microbiome pattern that was highlighted by decreased Erysipelatoclostridium and increased Lactobacillus relative abundances compared to vehicle counterparts; these genera are tied to body weight and metabolic regulation. Additionally, Parasutterella relative abundance, which was increased in both the vehicle- and NNMTi-treated LD-switched groups relative to the controls, significantly correlated with several adipose tissue metabolites' abundances. Collectively, these results provide a novel foundation for future investigations.
Subject(s)
Enzyme Inhibitors/administration & dosage , Gastrointestinal Microbiome/drug effects , Nicotinamide N-Methyltransferase/antagonists & inhibitors , Nicotinamide N-Methyltransferase/metabolism , Obesity/diet therapy , Obesity/drug therapy , Adipose Tissue/drug effects , Adipose Tissue/metabolism , Adiposity/drug effects , Animals , Bacteria/classification , Bacteria/drug effects , Bacteria/genetics , Bacteria/isolation & purification , Body Weight/drug effects , Combined Modality Therapy , Diet, Fat-Restricted , Humans , Male , Mice , Mice, Inbred C57BL , Mice, Obese , Nicotinamide N-Methyltransferase/genetics , Obesity/metabolism , Obesity/microbiology , Quinolinium Compounds/administration & dosageABSTRACT
Osteoporosis (OP) is associated with a serious social and economic burden. Recent studies have shown that the differential expression of long non-coding RNAs (lncRNAs) is closely related to OP. However, the specific molecular mechanism of HOX transcript antisense intergenic RNA (HOTAIR) remains to be elucidated.The expression of HOTAIR and miR-378g in OP patients was detected using quantitative reverse transcription polymerase chain reaction (qRT-PCR). Bone marrow mesenchymal stem cells (BMSCs) were isolated and cultured, and osteogenic differentiation was induced. Alkaline phosphatase (ALP) and Runt-related transcription factor 2 (RUNX2) were detected by qRT-PCR, ELISA, and Western blotting. Calcium deposition was measured using Alizarin red s (ARS) staining. Molecular interactions between HOTAIR, miR-378g, and nicotinamide N-methyltransferase (NNMT) were detected using a dual-luciferase reporter assay.HOTAIR expression was upregulated and miR-378g level was downregulated in OP patients. HOTAIR expression decreased during the osteogenic differentiation of BMSCs. Silencing HOTAIR or NNMT reduced ALP and RUNX2 levels and promoted calcium deposition. The overexpression of HOTAIR or interference with miR-378g inhibited the osteogenic differentiation of BMSCs. HOTAIR negatively regulates miR-378g by targeting NNMT.HOTAIR is an miR-378g sponge that targets NNMT, inhibits the osteogenic differentiation of BMSCs, and provides a valuable target for the treatment of OP.