Nicotinamide N-methyltransferase enhances the capacity of tumorigenesis associated with the promotion of cell cycle progression in human colorectal cancer cells

Investigation on the mechanisms of scorpion venom in hepatocellular carcinoma model mice via untargeted metabolomics profiling

Metabolic reprogramming is frequently accompanied by hepatocellular carcinoma (HCC) progression. Disrupted metabolites act as potential biomarkers and drug therapeutic targets for HCC. Peptide extract of scorpion venom (PESV) induces cytotoxic anti-proliferative effects and apoptosis in tumors. However, the action mechanisms of PESV remain unknown. This study aimed to explore the serum metabolic profiles of tumor-bearing mouse model. We generated an orthotopic HCC xenograft mouse model by implanting H22 cells into the left hepatic lobe of male C57BL/6 mice. After surgery, the mice were assigned to two groups randomly: PESV (PESV-treated 40 mg/kg daily, i.g.; n = 6) and control (treated with the solvent equally for 14 d, n = 6) groups. Based on an untargeted metabolomics approach using ultra-high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry, differential metabolites were screened via univariate and multivariate data analyses. A total of 48 differential metabolites in negative ion mode and 63 in positive ion mode were identified in the serum samples. Furthermore, metabolic pathway analysis revealed that aminoacyl-tRNA biosynthesis, amino acid pathway, glutathione metabolism, protein transports, protein digestion and absorption, and cAMP signaling pathways play vital roles in PESV-induced inhibition of tumors. These findings highlight the distinct changes in the metabolic profiles of HCC-bearing mice after PESV treatment, suggesting the potential of the identified metabolic molecules as therapeutic targets for HCC.

Nicotinamide N-Methyltransferase (NNMT): A New Hope for Treating Aging and Age-Related Conditions

The complex process of aging leads to a gradual deterioration in the function of cells, tissues, and the entire organism, thereby increasing the risk of disease and death. Nicotinamide N-methyltransferase (NNMT) has attracted attention as a potential target for combating aging and its related pathologies. Studies have shown that NNMT activity increases over time, which is closely associated with the onset and progression of age-related diseases. NNMT uses S-adenosylmethionine (SAM) as a methyl donor to facilitate the methylation of nicotinamide (NAM), converting NAM into S-adenosyl-L-homocysteine (SAH) and methylnicotinamide (MNA). This enzymatic action depletes NAM, a precursor of nicotinamide adenine dinucleotide (NAD+), and generates SAH, a precursor of homocysteine (Hcy). The reduction in the NAD+ levels and the increase in the Hcy levels are considered important factors in the aging process and age-related diseases. The efficacy of RNA interference (RNAi) therapies and small-molecule inhibitors targeting NNMT demonstrates the potential of NNMT as a therapeutic target. Despite these advances, the exact mechanisms by which NNMT influences aging and age-related diseases remain unclear, and there is a lack of clinical trials involving NNMT inhibitors and RNAi drugs. Therefore, more in-depth research is needed to elucidate the precise functions of NNMT in aging and promote the development of targeted pharmaceutical interventions. This paper aims to explore the specific role of NNMT in aging, and to evaluate its potential as a therapeutic target.

Nicotinamide N-methyltransferase (NNMT): a novel therapeutic target for metabolic syndrome

Metabolic syndrome (MetS) represents a constellation of metabolic abnormalities, typified by obesity, hypertension, hyperglycemia, and hyperlipidemia. It stems from intricate dysregulations in metabolic pathways governing energy and substrate metabolism. While comprehending the precise etiological mechanisms of MetS remains challenging, evidence underscores the pivotal roles of aberrations in lipid metabolism and insulin resistance (IR) in its pathogenesis. Notably, nicotinamide N-methyltransferase (NNMT) has recently surfaced as a promising therapeutic target for addressing MetS. Single nucleotide variants in the NNMT gene are significantly correlated with disturbances in energy metabolism, obesity, type 2 diabetes (T2D), hyperlipidemia, and hypertension. Elevated NNMT gene expression is notably observed in the liver and white adipose tissue (WAT) of individuals with diabetic mice, obesity, and rats afflicted with MetS. Knockdown of NNMT elicits heightened energy expenditure in adipose and hepatic tissues, mitigates lipid accumulation, and enhances insulin sensitivity. NNMT catalyzes the methylation of nicotinamide (NAM) using S-adenosyl-methionine (SAM) as the donor methyl group, resulting in the formation of S-adenosyl-l-homocysteine (SAH) and methylnicotinamide (MNAM). This enzymatic process results in the depletion of NAM, a precursor of nicotinamide adenine dinucleotide (NAD+), and the generation of SAH, a precursor of homocysteine (Hcy). Consequently, this cascade leads to reduced NAD+ levels and elevated Hcy levels, implicating NNMT in the pathogenesis of MetS. Moreover, experimental studies employing RNA interference (RNAi) strategies and small molecule inhibitors targeting NNMT have underscored its potential as a therapeutic target for preventing or treating MetS-related diseases. Nonetheless, the precise mechanistic underpinnings remain elusive, and as of yet, clinical trials focusing on NNMT have not been documented. Therefore, further investigations are warranted to elucidate the intricate roles of NNMT in MetS and to develop targeted therapeutic interventions.

Targeting nicotinamide N-methyltransferase decreased aggressiveness of osteosarcoma cells

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.

Knockdown of nicotinamide N-methyltransferase suppresses proliferation, migration, and chemoresistance of Merkel cell carcinoma cells in vitro

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.

NNMT/1-MNA Promote Cell-Cycle Progression of Breast Cancer by Targeting UBC12/Cullin-1-Mediated Degradation of P27 Proteins

Cell cycle dysregulation is a defining feature of breast cancer. Here, 1-methyl-nicotinamide (1-MNA), metabolite of nicotinamide N-methyltransferase(NNMT) is identified, as a novel driver of cell-cycle progression in breast cancer. NNMT, highly expressed in breast cancer tissues, positively correlates with tumor grade, TNM stage, Ki-67 index, and tumor size. Ablation of NNMT expression dramatically suppresses cell proliferation and causes cell-cycle arrest in G0/G1 phase. This phenomenon predominantly stems from the targeted action of 1-MNA, resulting in a specific down-regulation of p27 protein expression. Mechanistically, 1-MNA expedites the degradation of p27 proteins by enhancing cullin-1 neddylation, crucial for the activation of Cullin-1-RING E3 ubiquitin ligase(CRL1)-an E3 ubiquitin ligase targeting p27 proteins.  NNMT/1-MNA specifically up-regulates the expression of UBC12, an E2 NEDD8-conjugating enzyme required for cullin-1 neddylation. 1-MNA showes high binding affinity to UBC12, extending the half-life of UBC12 proteins via preventing their localization to lysosome for degradation. Therefore, 1-MNA is a bioactive metabolite that promotes breast cancer progression by reinforcing neddylation pathway-mediated p27 degradation. The study unveils the link between NNMT enzymatic activity with cell-cycle progression, indicating that 1-MNA may be involved in the remodeling of tumor microenvironment.

Inhibitors of NAD+ Production in Cancer Treatment: State of the Art and Perspectives

The addiction of tumors to elevated nicotinamide adenine dinucleotide (NAD+) levels is a hallmark of cancer metabolism. Obstructing NAD+ biosynthesis in tumors is a new and promising antineoplastic strategy. Inhibitors developed against nicotinamide phosphoribosyltransferase (NAMPT), the main enzyme in NAD+ production from nicotinamide, elicited robust anticancer activity in preclinical models but not in patients, implying that other NAD+-biosynthetic pathways are also active in tumors and provide sufficient NAD+ amounts despite NAMPT obstruction. Recent studies show that NAD+ biosynthesis through the so-called "Preiss-Handler (PH) pathway", which utilizes nicotinate as a precursor, actively operates in many tumors and accounts for tumor resistance to NAMPT inhibitors. The PH pathway consists of three sequential enzymatic steps that are catalyzed by nicotinate phosphoribosyltransferase (NAPRT), nicotinamide mononucleotide adenylyltransferases (NMNATs), and NAD+ synthetase (NADSYN1). Here, we focus on these enzymes as emerging targets in cancer drug discovery, summarizing their reported inhibitors and describing their current or potential exploitation as anticancer agents. Finally, we also focus on additional NAD+-producing enzymes acting in alternative NAD+-producing routes that could also be relevant in tumors and thus become viable targets for drug discovery.

Multi-omics analyses reveal bacteria and catalase associated with keloid disease

BACKGROUND

The pathology of keloid and especially the roles of bacteria on it were not well understood.

METHODS

In this study, multi-omics analyses including microbiome, metaproteomics, metabolomic, single-cell transcriptome and cell-derived xenograft (CDX) mice model were used to explore the roles of bacteria on keloid disease.

FINDINGS

We found that the types of bacteria are significantly different between keloid and healthy skin. The 16S rRNA sequencing and metaproteomics showed that more catalase (CAT) negative bacteria, Clostridium and Roseburia existed in keloid compared with the adjacent healthy skin. In addition, protein mass spectrometry shows that CAT is one of the differentially expressed proteins (DEPs). Overexpression of CAT inhibited the proliferation, migration and invasion of keloid fibroblasts, and these characteristics were opposite when CAT was knocked down. Furthermore, the CDX model showed that Clostridium butyricum promote the growth of patient's keloid fibroblasts in BALB/c female nude mice, while CAT positive bacteria Bacillus subtilis inhibited it. Single-cell RNA sequencing verified that oxidative stress was up-regulated and CAT was down-regulated in mesenchymal-like fibroblasts of keloid.

INTERPRETATION

In conclusion, our findings suggest that bacteria and CAT contribute to keloid disease.

FUNDING

A full list of funding bodies that contributed to this study can be found in the Acknowledgements section.

Metabolomic Signatures of Exposure to Nitrate and Trihalomethanes in Drinking Water and Colorectal Cancer Risk in a Spanish Multicentric Study (MCC-Spain)

We investigated the metabolomic profile associated with exposure to trihalomethanes (THMs) and nitrate in drinking water and with colorectal cancer risk in 296 cases and 295 controls from the Multi Case-Control Spain project. Untargeted metabolomic analysis was conducted in blood samples using ultrahigh-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. A variety of univariate and multivariate association analyses were conducted after data quality control, normalization, and imputation. Linear regression and partial least-squares analyses were conducted for chloroform, brominated THMs, total THMs, and nitrate among controls and for case-control status, together with a N-integration model discriminating colorectal cancer cases from controls through interrogation of correlations between the exposure variables and the metabolomic features. Results revealed a total of 568 metabolomic features associated with at least one water contaminant or colorectal cancer. Annotated metabolites and pathway analysis suggest a number of pathways as potentially involved in the link between exposure to these water contaminants and colorectal cancer, including nicotinamide, cytochrome P-450, and tyrosine metabolism. These findings provide insights into the underlying biological mechanisms and potential biomarkers associated with water contaminant exposure and colorectal cancer risk. Further research in this area is needed to better understand the causal relationship and the public health implications.

NAD+ Metabolism and Immune Regulation: New Approaches to Inflammatory Bowel Disease Therapies

Inflammatory bowel disease (IBD), which includes Crohn's disease (CD) and ulcerative colitis (UC), is a multifactorial systemic inflammatory immune response. Nicotinamide adenine dinucleotide (NAD⁺) is a co-enzyme involved in cell signaling and energy metabolism. Calcium homeostasis, gene transcription, DNA repair, and cell communication involve NAD⁺ and its degradation products. There is a growing recognition of the intricate relationship between inflammatory diseases and NAD⁺ metabolism. In the case of IBD, the maintenance of intestinal homeostasis relies on a delicate balance between NAD⁺ biosynthesis and consumption. Consequently, therapeutics designed to target the NAD⁺ pathway are promising for the management of IBD. This review discusses the metabolic and immunoregulatory processes of NAD⁺ in IBD to examine the molecular biology and pathophysiology of the immune regulation of IBD and to provide evidence and theoretical support for the clinical use of NAD⁺ in IBD.

Systematic pan-cancer analysis of the nicotinamide n-methyltransferase in human cancer

In several tumors, Nicotinamide N-Methyltransferase (NNMT) was identified as a bridge between methylation metabolism and tumorigenesis and was associated with a poor prognosis. This research aims is to study the prognostic value of NNMT in cancer, its relationship with DNA methylation, and the immune microenvironment. On the basis of the Cancer Genome Atlas and the Cancer Cell Line Encyclopedia, Genotype Tissue-Expression, cBioPortal, Cellminer, Gene Expression Profiling Interactive Analysis, Human Protein Atlas and Clinical Proteomic Tumor Analysis Consortium, we used a series of bioinformatics strategies to investigate the potential carcinogenicity of NNMT, including the relationship between NNMT expression and prognosis, tumor mutational burden, microsatellite instability, and sensitivity analysis of anticancer drugs. The GeneMANIA, STRING, and BioGRID databases were examined for protein-protein interactions, and Gene Ontology and the Kyoto Encyclopedia of Genes were used to infer the signal pathway. The results indicated that NNMT was significantly expressed in several tumor tissues compared to the matching non-tumor tissues. Increased NNMT expression was linked to reduced OS, DSS, and DFI. In addition, there was a link between NNMT expression and TMB and MSI in 18 cancer types, and between NNMT expression and DNA methylation in 23 cancer types. Further study of NNMT gene alteration data revealed that deletion was the most prevalent form of NNMT mutation, and that there was a significant negative association between NNMT expression and mismatch repair genes. In addition, there was a strong positive connection between NNMT and immune infiltration in 28 types of tumors, and the immune cells that infiltrated the tumors displayed a characteristic NNMT pattern. According to the enrichment study, cell migration, cell motility, and cell adhesion were highly enriched in biological processes, and NNMT may be associated with the PI3K-Akt signaling pathway. By downregulating gene methylation or impacting the immunological microenvironment widely, NNMT may drive carcinogenesis and cause a poor prognosis. Our research showed that NNMT could be used as a biomarker of tumor immune infiltration and poor prognosis, thus providing a unique strategy for cancer therapy.

Nicotinamide N-Methyltransferase Remodeled Cell Metabolism and Aggravated Proinflammatory Responses by Activating STAT3/IL1β/PGE2 Pathway

Nicotinamide N-methyltransferase (NNMT) is a cytosolic methyltransferase, catalyzing N-methylation of nicotinamide (NAM) to form 1-methylnicotinamide (1-MNAM), in which S-adenosyl-l-methionine (SAM) is the methyl donor. It has been well documented that NNMT is elevated in multiple cancers and promotes tumor aggressiveness. In the present study, we investigated the effects of NNMT overexpression on cellular metabolism and proinflammatory responses. We found that NNMT overexpression reduced NAD⁺ and SAM levels, and activated the STAT3 signaling pathway. Consequently, STAT3 activation upregulated interleukin 1β (IL1β) and cyclooxygenase-2 (COX2), leading to prostaglandin E2 (PGE₂) accumulation. On the other hand, NNMT downregulated 15-hydroxyprostaglandin dehydrogenase (15-PGDH) which catalyzes PGE₂ into inactive molecules. Moreover, secretomic data indicated that NNMT promoted secretion of collagens, pro-inflammatory cytokines, and extracellular matrix proteins, confirming NNMT aggravated inflammatory responses to promote cell growth, migration, epithelial-mesenchymal transition (EMT), and chemoresistance. Taken together, we showed that NNMT played a pro-inflammatory role in cancer cells by activating the STAT3/IL1β/PGE₂ axis and proposed that NNMT was a potential therapeutic target for cancer treatment.

Nicotinamide N-Methyltransferase as Promising Tool for Management of Gastrointestinal Neoplasms

Gastrointestinal (GI) neoplasms include esophageal, gastric, colorectal, hepatic, and pancreatic cancers. They are characterized by asymptomatic behavior, being responsible for diagnostic delay. Substantial refractoriness to chemo- and radiotherapy, exhibited by late-stage tumors, contribute to determine poor patient outcome. Therefore, it is of outmost importance to identify new molecular targets for the development of effective therapeutic strategies. In this study, we focused on the enzyme nicotinamide N-methyltransferase (NNMT), which catalyzes the N-methylation reaction of nicotinamide and whose overexpression has been reported in numerous neoplasms, including GI cancers. The aim of this review was to report data illustrating NNMT involvement in these tumors, highlighting its contribution to tumor cell phenotype. Cited works clearly demonstrate the interesting potential use of enzyme level determination for both diagnostic and prognostic purposes. NNMT was also found to positively affect cell viability, proliferation, migration, and invasiveness, contributing to sustain in vitro and in vivo tumor growth and metastatic spread. Moreover, enzyme upregulation featuring tumor cells was significantly associated with enhancement of resistance to treatment with chemotherapeutic drugs. Taken together, these results strongly suggest the possibility to target NNMT for setup of molecular-based strategies to effectively treat GI cancers.

NNMT contributes to high metastasis of triple negative breast cancer by enhancing PP2A/MEK/ERK/c-Jun/ABCA1 pathway mediated membrane fluidity

Elucidating the mechanism for high metastasis capacity of triple negative breast cancers (TNBC) is crucial to improve treatment outcomes of TNBC. We have recently reported that nicotinamide N-methyltransferase (NNMT) is overexpressed in breast cancer, especially in TNBC, and predicts poor survival of patients undergoing chemotherapy. Here, we aimed to determine the function and mechanism of NNMT on metastasis of TNBC. Additionally, analysis of public datasets indicated that NNMT is involved in cholesterol metabolism. In vitro, NNMT overexpression promoted migration and invasion of TNBCs by reducing cholesterol levels in the cytoplasm and cell membrane. Mechanistically, NNMT activated MEK/ERK/c-Jun/ABCA1 pathway by repressing protein phosphatase 2A (PP2A) activity leading to cholesterol efflux and membrane fluidity enhancement, thereby promoting the epithelial-mesenchymal transition (EMT) of TNBCs. In vivo, the metastasis capacity of TNBCs was weakened by targeting NNMT. Collectively, our findings suggest a new molecular mechanism involving NNMT in metastasis and poor survival of TNBC mediated by PP2A and affecting cholesterol metabolism.

NNMT promotes the progression of intrahepatic cholangiocarcinoma by regulating aerobic glycolysis via the EGFR-STAT3 axis

Nicotinamide N-methyltransferase (NNMT), a member of the N-methyltransferase family, plays an important role in tumorigenesis. However, its expression and biological functions in intrahepatic cholangiocarcinoma (iCCA) remain to be established. In our study, we identified NNMT as an oncogene in iCCA and provided mechanistic insights into the roles of NNMT in iCCA progression. High NNMT expression in iCCA tissues was identified using western blotting and immunohistochemistry (IHC). We identified a significantly higher NNMT expression level in human iCCA tissues than that in adjacent normal tissues. Increased NNMT expression promoted iCCA cell proliferation and metastasis in vitro and in vivo. Mechanistically, NNMT inhibited the level of histone methylation in iCCA cells by consuming the methyl donor S-adenosyl methionine (SAM), thereby promoting the expression of epidermal growth factor receptor (EGFR). EGFR may activate the aerobic glycolysis pathway in iCCA cells by activating the STAT3 signaling pathway. In conclusion, we identified NNMT as an oncogene in iCCA and provided mechanistic insights into the roles of NNMT in iCCA progression.

Nicotinamide N-Methyltransferase: A Promising Biomarker and Target for Human Cancer Therapy

Cancer cells typically exhibit a tightly regulated program of metabolic plasticity and epigenetic remodeling to meet the demand of uncontrolled cell proliferation. The metabolic-epigenetic axis has recently become an increasingly hot topic in carcinogenesis and offers new avenues for innovative and personalized cancer treatment strategies. Nicotinamide N-methyltransferase (NNMT) is a metabolic enzyme involved in controlling methylation potential, impacting DNA and histone epigenetic modification. NNMT overexpression has been described in various solid cancer tissues and even body fluids, including serum, urine, and saliva. Furthermore, accumulating evidence has shown that NNMT knockdown significantly decreases tumorigenesis and chemoresistance capacity. Most importantly, the natural NNMT inhibitor yuanhuadine can reverse epidermal growth factor receptor tyrosine kinase inhibitor resistance in lung cancer cells. In this review, we evaluate the possibility of NNMT as a diagnostic biomarker and molecular target for effective anticancer treatment. We also reveal the exact mechanisms of how NNMT affects epigenetics and the development of more potent and selective inhibitors.

Nicotinamide-N-methyltransferase is a promising metabolic drug target for primary and metastatic clear cell renal cell carcinoma

Background

The metabolic enzyme nicotinamide‐N‐methyltransferase (NNMT) is highly expressed in various cancer entities, suggesting tumour‐promoting functions. We systematically investigated NNMT expression and its metabolic interactions in clear cell renal cell carcinoma (ccRCC), a prominent RCC subtype with metabolic alterations, to elucidate its role as a drug target.

Methods

NNMT expression was assessed in primary ccRCC (n = 134), non‐tumour tissue and ccRCC‐derived metastases (n = 145) by microarray analysis and/or immunohistochemistry. Findings were validated in The Cancer Genome Atlas (kidney renal clear cell carcinoma [KIRC], n = 452) and by single‐cell analysis. Expression was correlated with clinicopathological data and survival. Metabolic alterations in NNMT‐depleted cells were assessed by nontargeted/targeted metabolomics and extracellular flux analysis. The NNMT inhibitor (NNMTi) alone and in combination with the inhibitor 2‐deoxy‐D‐glucose for glycolysis and BPTES (bis‐2‐(5‐phenylacetamido‐1,3,4‐thiadiazol‐2‐yl)ethyl‐sulfide) for glutamine metabolism was investigated in RCC cell lines (786‐O, A498) and in two 2D ccRCC‐derived primary cultures and three 3D ccRCC air–liquid interface models.

Results

NNMT protein was overexpressed in primary ccRCC (p = 1.32 × 10^–16) and ccRCC‐derived metastases (p = 3.92 × 10^–20), irrespective of metastatic location, versus non‐tumour tissue. Single‐cell data showed predominant NNMT expression in ccRCC and not in the tumour microenvironment. High NNMT expression in primary ccRCC correlated with worse survival in independent cohorts (primary RCC—hazard ratio [HR] = 4.3, 95% confidence interval [CI]: 1.5–12.4; KIRC—HR = 3.3, 95% CI: 2.0–5.4). NNMT depletion leads to intracellular glutamine accumulation, with negative effects on mitochondrial function and cell survival, while not affecting glycolysis or glutathione metabolism. At the gene level, NNMT‐depleted cells upregulate glycolysis, oxidative phosphorylation and apoptosis pathways. NNMTi alone or in combination with 2‐deoxy‐D‐glucose and BPTES resulted in inhibition of cell viability in ccRCC cell lines and primary tumour and metastasis‐derived models. In two out of three patient‐derived ccRCC air–liquid interface models, NNMTi treatment induced cytotoxicity.

Conclusions

Since efficient glutamine utilisation, which is essential for ccRCC tumours, depends on NNMT, small‐molecule NNMT inhibitors provide a novel therapeutic strategy for ccRCC and act as sensitizers for combination therapies.

Complex roles of nicotinamide N-methyltransferase in cancer progression

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.

Prognostic value of nicotinamide N-methyltransferase in human cancers: Evidence from a meta-analysis and database validation

Background

Previous studies indicated that dysregulated expression of nicotinamide N-methyltransferase (NNMT) contributed to the tumor progression and predicted poor prognosis in various cancers. However, there was no exact conclusion on account of the contradictory results across studies.

Methods

The relevant studies up to December 7, 2020 were searched in PubMed, Web of Science, and Embase. The association between NNMT expression and prognostic outcomes was explored, including overall survival (OS), disease-free survival (DFS), and clinicopathological features. The bioinformatics database was used to validate the findings.

Results

Thirteen retrospective studies containing 2,591 patients with cancers were included in this analysis. High NNMT expression was significantly associated with shorter OS (hazard ratio [HR] = 2.01, 95% confidence interval [CI] = 1.42–2.86, and P < 0.01) and DFS (HR = 1.59, 95% CI = 1.23–2.05, and P < 0.01) compared to low NNMT expression in cancers. Compared to patients with low NNMT expression, patients with high NNMT expression tended to have worse tumor differentiation (P = 0.03), earlier lymph node metastasis (P = 0.01), earlier distant metastasis (P = 0.02), and more advanced clinical stage (P < 0.01).

Conclusion

High NNMT expression is an unfavorable factor of various cancers. NNMT is a promising indicator to predict the prognosis of various cancers and can serve as a potential therapeutic target in various cancers.

Nicotinamide N-Methyltransferase in Head and Neck Tumors: A Comprehensive Review

The head and neck tumors (HNT) are a heterogeneous group of diseases ranging from benign to malignant lesions, with distinctive molecular and clinical behaviors. Several studies have highlighted the presence of an altered metabolic phenotype in HNT, such as the upregulation of nicotinamide N-methyltransferase (NNMT). However, its biological effects have not been completely disclosed and the role of NNMT in cancer cell metabolism remains unclear. Therefore, this comprehensive review aims to evaluate the available literature regarding the biological, diagnostic, and prognostic role of NNMT in HNT. NNMT was shown to be significantly overexpressed in all of the evaluated HNT types. Moreover, its upregulation has been correlated with cancer cell migration and adverse clinical outcomes, such as high-pathological stage, lymph node metastasis, and locoregional recurrences. However, in oral squamous cell carcinoma (OSCC) these associations are still debated, and several studies have failed to demonstrate the prognostic significance of NNMT. The shRNA-mediated gene silencing efficiently suppressed the NNMT gene expression and exhibited a clear inhibitory effect on cell proliferation, promoting the expression of apoptosis-related proteins and modulating the cell cycle. NNMT could represent a new molecular biomarker and a new target of molecular-based therapy, although further studies on larger patient cohorts are needed to explore its biological role in HNT.

Nicotinamide N-Methyltransferase: An Emerging Protagonist in Cancer Macro(r)evolution

Nicotinamide N-methyltransferase (NNMT) has progressed from being considered merely a Phase II metabolic enzyme to one with a central role in cell function and energy metabolism. Over the last three decades, a significant body of evidence has accumulated which clearly demonstrates a central role for NNMT in cancer survival, metastasis, and drug resistance. In this review, we discuss the evidence supporting a role for NNMT in the progression of the cancer phenotype and how it achieves this by driving the activity of pro-oncogenic NAD+-consuming enzymes. We also describe how increased NNMT activity supports the Warburg effect and how it promotes oncogenic changes in gene expression. We discuss the regulation of NNMT activity in cancer cells by both post-translational modification of the enzyme and transcription factor binding to the NNMT gene, and describe for the first time three long non-coding RNAs which may play a role in the regulation of NNMT transcription. We complete the review by discussing the development of novel anti-cancer therapeutics which target NNMT and provide insight into how NNMT-based therapies may be best employed clinically.

Overexpression of Nicotinamide N-methyltransferase mainly covers stroma of colorectal cancer and correlates with unfavorable survival by its product 1-MNA

Background: Accumulating evidence indicates that Nicotinamide N-methyltransferase (NNMT) is abnormally expressed in tumor tissues of several cancers including colorectal cancer (CRC) and associated with cancer progression. However, the distribution characteristics and the clinical value of each part of NNMT expression in CRC are still not fully understood. The purpose of this study is to determine the distribution of NNMT expression and its association with survival in CRC. Methods: By using the cancer genome atlas (TCGA) and clinical proteomic tumor analysis consortium (CPTAC), we firstly analyzed the difference of gene and protein levels of NNMT between CRC and normal colorectal tissue. Then, NNMT protein expressions were detected in 18 intraepithelial neoplastic samples and 177 CRC tumor samples through immunohistochemistry in our study cohort. Furthermore, the relationship between NNMT expression and clinicopathological characteristics, overall survival (OS) and disease-free survival (DFS) of CRC patients were analyzed by Pearson χ2 test and log-rank test, respectively, in public datasets and our study cohort. Lastly, the function of NNMT and its product 1-methyl-nicotinamide (1-MNA) on migration and invasion in colorectal cancer cells was analyzed by wound healing assay and transwell assay. Results: We determined that higher NNMT expression in CRC tissues than normal tissues in both gene and protein level in TCGA and CPTAC datasets (all p < 0.05). In addition, the strong relationships of NNMT expression with stromal cells were found in the TCGA cohort. Fortunately, our cohort could validate that the expression of NNMT in tumor stroma cell was significantly higher than that in tumor cell (p < 0.0001), and both of them were significantly higher than that in adjacent normal tissue (ANT) (p < 0.0001 and p < 0.0001, respectively). Furthermore, the positive NNMT expression in tumor cell and stromal cell were associated with series of unfavorable clinical characteristics, including advanced TNM stage, lymph node metastasis, distant metastasis (all p < 0.05). Also, higher NNMT was associated with unfavorable survival both in our study and public datasets, including TCGA and two Gene Expression Omnibus (GEO) datasets (GSE33113 and GSE17538). Moreover, the functional experiments showed that stromal cells with high NNMT expression can secret 1-MAN to promote migration and invasion of CRC cells in vitro. Conclusions: In CRC, NNMT is overexpressed in tumor cells and stroma cells, and then mainly expressed in tumor stroma cells. Overexpression of NNMT in tumor cell and stroma cell both are associated with metastasis and unfavorable survival. Besides, stromal cells with high NNMT expression secrets 1-MAN to promote migration and invasion of CRC cells. Therefore, NNMT may be a potential prognostic indicator in CRC patients.

Potent Inhibition of Nicotinamide N-Methyltransferase by Alkene-Linked Bisubstrate Mimics Bearing Electron Deficient Aromatics

Nicotinamide N-methyltransferase (NNMT) methylates nicotinamide (vitamin B3) to generate 1-methylnicotinamide (MNA). NNMT overexpression has been linked to a variety of diseases, most prominently human cancers, indicating its potential as a therapeutic target. The development of small-molecule NNMT inhibitors has gained interest in recent years, with the most potent inhibitors sharing structural features based on elements of the nicotinamide substrate and the S-adenosyl-l-methionine (SAM) cofactor. We here report the development of new bisubstrate inhibitors that include electron-deficient aromatic groups to mimic the nicotinamide moiety. In addition, a trans-alkene linker was found to be optimal for connecting the substrate and cofactor mimics in these inhibitors. The most potent NNMT inhibitor identified exhibits an IC₅₀ value of 3.7 nM, placing it among the most active NNMT inhibitors reported to date. Complementary analytical techniques, modeling studies, and cell-based assays provide insights into the binding mode, affinity, and selectivity of these inhibitors.

Curcumin Reverses NNMT-Induced 5-Fluorouracil Resistance via Increasing ROS and Cell Cycle Arrest in Colorectal Cancer Cells

Nicotinamide N-methyltransferase (NNMT) plays multiple roles in improving the aggressiveness of colorectal cancer (CRC) and enhancing resistance to 5-Fluorouracil (5-FU), making it an attractive therapeutic target. Curcumin (Cur) is a promising natural compound, exhibiting multiple antitumor effects and potentiating the effect of 5-FU. The aim of the present study is to explore the effect of Cur on attenuating NNMT-induced resistance to 5-FU in CRC. A panel of CRC cell lines with different NNMT expressions are used to characterize the effect of Cur. Herein, it is observed that Cur can depress the expression of NNMT and p-STAT3 in CRC cells. Furthermore, Cur can induce inhibition of cell proliferation, G2/M phase cell cycle arrest, and reactive oxygen species (ROS) generation, especially in high-NNMT-expression CRC cell lines. Cur can also re-sensitize high-NNMT-expression CRC cells to 5-FU both in vitro and in vivo. In summary, it is proposed that Cur can reverse NNMT-induced cell proliferation and 5-FU resistance through ROS generation and cell cycle arrest. Given that Cur has long been used, we suppose that Cur is a promising anticancer drug candidate with minimal side effects for human CRC therapy and can attenuate NNMT-induced resistance to 5-FU.

The Utility of Nicotinamide N-Methyltransferase as a Potential Biomarker to Predict the Oncological Outcomes for Urological Cancers: An Update

Nicotinamide N-methyltransferase (NNMT) catalyzes the N-methylation reaction of nicotinamide, using S-adenosyl-L-methionine as the methyl donor. Enzyme overexpression has been described in many non-neoplastic diseases, as well as in a wide range of solid malignancies. This review aims to report and discuss evidence available in scientific literature, dealing with NNMT expression and the potential involvement in main urologic neoplasms, namely, renal, bladder and prostate cancers. Data illustrated in the cited studies clearly demonstrated NNMT upregulation (pathological vs. normal tissue) in association with these aforementioned tumors. In addition to this, enzyme levels were also found to correlate with key prognostic parameters and patient survival. Interestingly, NNMT overexpression also emerged in peripheral body fluids, such as blood and urine, thus leading to candidate the enzyme as promising biomarker for the early and non-invasive detection of these cancers. Examined results undoubtedly showed NNMT as having the capacity to promote cell proliferation, migration and invasiveness, as well as its potential participation in fundamental events highlighting cancer progression, metastasis and resistance to chemo- and radiotherapy. In the light of this evidence, it is reasonable to attribute to NNMT a promising role as a potential biomarker for the diagnosis and prognosis of urologic neoplasms, as well as a molecular target for effective anti-cancer treatment.

Nicotinamide N-methyltransferase gene silencing enhances chemosensitivity of melanoma cell lines

Melanoma accounts for less than 5% of all cutaneous neoplasms but is responsible for the greater part of skin cancer-related deaths. Therefore, the identification of molecules that could serve as the therapeutic target is urgent. This study focused on the enzyme nicotinamide N-methyltransferase (NNMT). The effect of NNMT knockdown on cell proliferation and migration of A375 melanoma cells was evaluated by MTT and wound healing assays, respectively. Viability of A375 cells downregulating NNMT was also explored under treatment with dacarbazine, a chemotherapeutic drug approved for advanced melanoma treatment. The impact of enzyme knockdown on cell proliferation and chemosensitivity was also investigated in WM-115 melanoma cells. Results obtained demonstrated that NNMT silencing led to a significant reduction of cell proliferation and migration of A375 cells. Moreover, enzyme downregulation was associated with an increase of melanoma cells sensitivity to treatment with dacarbazine. Analogous effects induced by enzyme knockdown on cell proliferation and chemosensitivity were also found in the WM-115 cell line. Our data seem to demonstrate that NNMT could represent a promising molecular target for the effective treatment of this form of skin cancer.

Vanillin downregulates NNMT and attenuates NNMT‑related resistance to 5‑fluorouracil via ROS‑induced cell apoptosis in colorectal cancer cells

Chemoresistance is the main cause of poor prognosis in colorectal cancer (CRC). Nicotinamide N-methyltransferase (NNMT) is a metabolic enzyme that is upregulated in various tumor types. It has been reported that NNMT inhibits apoptosis and enhances resistance to 5-fluorouracil (5-Fu) via inhibition of the apoptosis signal regulating kinase 1 (ASK1)-p38 MAPK pathway in CRC cells. A natural product library was screened, and it was found that vanillin, also known as 4-hydroxy-3-methoxybenzaldehyde, a plant secondary metabolite found in several essential plant oils, mainly Vanilla planifolia, Vanilla tahitensis, and Vanilla pompon, may be a promising anticancer compound targeted to NNMT. The aim of the present study was to explore the effect of vanillin on promoting apoptosis and attenuating NNMT-induced resistance to 5-Fu in CRC. Lentiviral vectors of short hairpin RNA and small interfering RNA were transfected into HT-29 cells to construct NNMT-knockdown HT-29 cell lines. Vectors containing an open reading frame of NNMT were stably transfected into SW480 cells to induce NNMT overexpression in SW480 cell lines. Vanillin was found to inhibit the mRNA and protein expression levels of NNMT following the inhibition of NNMT activity in HT-29 cell lines. Vanillin was able to reverse NNMT-induced increased cell proliferation, decreased cell apoptosis and resistance to 5-Fu by inhibiting NNMT expression. Furthermore, it increased cell apoptosis by activating the ASK1-p38 MAPK pathway, which could be inhibited by NNMT. In addition, vanillin increased cell apoptosis by promoting mitochondrial damage and reactive oxygen species. In vivo, the combination of vanillin with 5-Fu yielded a notable synergy in inhibiting tumor growth and inducing apoptosis. Considering that vanillin is an important flavor and aromatic component used in foods worldwide, vanillin is deemed to be a promising anticancer candidate by inhibiting NNMT and may attenuate NNMT-induced resistance to 5-Fu in human CRC therapy with few side effects.

Screening and Identification of Key Microenvironment-Related Genes in Non-functioning Pituitary Adenoma

Purpose

Non-functioning pituitary adenoma (NFPA) is a very common type of intracranial tumor, which can be locally invasive and can have a high recurrence rate. The tumor microenvironment (TME) shows a high correlation with tumor pathogenesis and prognosis. The current study aimed to identify microenvironment-related genes in NFPAs and assess their prognostic value.

Methods

73 NFPA tumor samples were collected from Beijing Tiantan Hospital and transcriptional expression profiles were obtained through microarray analysis. The immune and stromal scores of each sample were calculated through the ESTIMATE algorithm, and the patients were divided into high and low immune/stromal score groups. Intersection differentially expressed genes (DEGs) were then obtained to construct a protein–protein interaction (PPI) network. Potential functions and pathways of intersection DEGs were then analyzed through Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes. The prognostic value of these genes was evaluated. The quantitative real-time polymerase chain reaction in another set of NFPA samples was used to confirm the credibility of the bioinformatics analysis.

Results

The immune/stromal scores were significantly correlated with cavernous sinus (CS) invasion. The Kaplan–Meier curve indicated that the high immune score group was significantly related to poor recurrence-free survival. We identified 497 intersection DEGs based on the high vs. low immune/stromal score groups. Function enrichment analyses of 497 DEGs and hub genes from the PPI network showed that these genes are mainly involved in the immune/inflammatory response, T cell activation, and the phosphatidylinositol 3 kinase-protein kinase B signaling pathway. Among the intersection DEGs, 88 genes were further verified as significantly expressed between the CS invasive group and the non-invasive group, and five genes were highly associated with NFPA prognosis.

Conclusion

We screened out a series of critical genes associated with the TME in NFPAs. These genes may play a fundamental role in the development and prognosis of NFPA and may yield new therapeutic targets.

Exosomal NNMT from peritoneum lavage fluid promotes peritoneal metastasis in gastric cancer

Peritoneal metastasis (PM) is the major cause of recurrence in patients with gastric cancer (GC) and is associated with poor prognosis. The oncogenic role of Nicotinamide N-methyltransferase (NNMT) in GC has been reported, but the role of secreted NNMT that is transported by exosomes remains unknown. In this study, exosomes were isolated from GC patients with or without PM and from GC cell line, including GC-114, GC-026, MKN45, and SNU-16 cells. The contents of NNMT were significantly enhanced in exosomes isolated from GC patients with PM compared with those from GC patients without PM. Furthermore, the levels of NNMT were significantly enhanced in exosomes from GC cell lines relative to those from normal human gastric epithelial cell line GES-1 cells. These data indicate that NNMT may be involved in intercellular communication for peritoneal dissemination. Moreover, colocalization of GC-derived exosomal NNMT was found in human peritoneal mesothelial cell line HMrSV5 cells. Additionally, relative to GES-1 exosomes, SNU-16 exosomes significantly activated TGF-β/smad2 signaling in HMrSV5 cells. However, when NNMT was silenced, the activation of TGF-β/smad2 by SNU-16 exosomes was abolished in HMrSV5 cells. We propose that NNMT-containing exosomes derived from GC cells could promote peritoneal metastasis via TGF-β/smad2 signaling.

Patients with low nicotinamide N-methyltransferase expression benefit significantly from bevacizumab treatment in ovarian cancer

BACKGROUND

The role of nicotinamide N-methyltransferase (NNMT) in ovarian cancer is still elusive. Our aim is to explore the expression of NNMT in ovarian cancer and to assess its association with patient prognosis and treatment response.

METHODS

We first analyzed the differential expression of NNMT among fallopian tube epithelium, primary ovarian cancers, metastatic ovarian cancers, and recurrent ovarian cancers using Gene Expression Ominus (GEO) database (GSE10971, GSE30587, GSE44104 and TCGA datasets). Then, we assessed the association of NNMT expression with clinical and molecular parameters using CSIOVDB database and GSE28739 dataset. Next, we evaluate the association of NNMT expression with the prognosis of ovarian cancer patients in both GSE9891 dataset and TCGA dataset. Finally, GSE140082 dataset was used to explore the association of NNMT expression with bevacizumab response.

RESULTS

NNMT expression was significantly elevated in lymphovascular space invasion (LVSI)-positive ovarian cancers compared with that in LVSI-negative ovarian cancers (TCGA dataset, P < 0.05), Moreover, increased expression of NNMT was associated with increased tumor stage, grade, and mesenchymal molecular subtype (CSIOVDB database). Survival analysis indicated that increased expression of NNMT was associated with a reduced OS in both GSE9891 dataset (HR: 2.28, 95%CI: 1.51-3.43, Log-rank P < 0.001) and TCGA dataset (HR: 1.55, 95%CI: 1.02-2.36, Log-rank P = 0.039). Multivariate analysis further confirmed the negative impact of NNMT expression on OS in ovarian cancer patients in those two datasets. Furthermore, the NNMT-related nomogram showed that NNMT shared a larger contribution to OS, compared with debulking status. More interestingly, bevacizumab conferred significant improvements in OS for patients with low NNMT expression (HR: 0.56, 95%CI: 0.31-0.99, Log-rank P = 0.049). In contrast, patients with high NNMT expression didn't benefit from bevacizumab treatment significantly (HR: 0.85, 95%CI: 0.48-1.49, Log-rank P = 0.561). NNMT expression was positively correlated with the expression of genes, LDHA and PGAM1, involved in Warburg effect.

CONCLUSIONS

In conclusion, NNMT expression is associated with the aggressive behavior of ovarian cancer, correlates with a poor prognosis, and is predictive of sensitivity to bevacizumab treatment.

Nicotinamide N-Methyltransferase Is a Prognostic Biomarker and Correlated With Immune Infiltrates in Gastric Cancer

Gastric cancer (GC) is the third most common cause of cancer-related death in the word. Immunotherapy is a promising treatment of cancer. However, it is unclear which GC subpopulation would benefit most from immunotherapy and it is necessary to develop effective biomarkers for predicting immunotherapy response. Nicotinamide N-methyltransferase (NNMT) is a metabolic regulator of cancer-associated fibroblast (CAF) differentiation and cancer progression. In this study, we explored the correlations of NNMT to tumor-infiltrating immune cells (TIICs) and immune marker sets in The Cancer Genome Atlas Stomach Adenocarcinoma STAD (TCGA-STAD). Subsequently, we screened the NNMT correlated genes and performed the enrichment analysis of these genes. We eventually predicted the 19 most potential small-molecule drugs using the connectivity map (CMap) and Comparative Toxicogenomics Database (CTD). Also, nadolol, tranexamic acid, felbinac and dapsone were considered the four most promising drugs for GC. In summary, NNMT can be used as a prognostic biomarker that reflect immune infiltration level and a novel therapeutic target in GC.

Targeted Metabolomics Analyses Reveal Specific Metabolic Alterations in High-Grade Prostate Cancer Patients

Prostate cancer (PCa) is a hormone-dependent tumor characterized by an extremely heterogeneous prognosis. Despite recent advances in partially uncovering some of the biological processes involved in its progression, there is still an urgent need for identifying more accurate and specific prognostic procedures to differentiate between disease stages. In this context, targeted approaches, focused on mapping dysregulated metabolic pathways, could play a critical role in identifying the mechanisms driving tumorigenesis and metastasis. In this study, a targeted analysis of the nuclear magnetic resonance-based metabolomic profile of PCa patients with different tumor grades, guided by transcriptomics profiles associated with their stages, was performed. Serum and urine samples were collected from 73 PCa patients. Samples were classified according to their Gleason score (GS) into low-GS (GS < 7) and high-GS PCa (GS ≥ 7) groups. A total of 36 metabolic pathways were found to be dysregulated in the comparison between different PCa grades. Particularly, the levels of glucose, glycine and 1-methlynicotinamide, metabolites involved in energy metabolism and nucleotide synthesis were significantly altered between both groups of patients. These results underscore the potential of targeted metabolomic profiling to characterize relevant metabolic changes involved in the progression of this neoplastic process.

Development of fluorescence polarization-based competition assay for nicotinamide N-methyltransferase

Methylation-mediated pathways play important roles in the progression of various diseases. Thus, targeting methyltransferases has proven to be a promising strategy for developing novel therapies. Nicotinamide N-methyltransferase (NNMT) is a major metabolic enzyme involved in epigenetic regulation through catalysis of methyl transfer from the cofactor S-adenosyl-l-methionine onto nicotinamide and other pyridines. Accumulating evidence infers that NNMT is a novel therapeutic target for a variety of diseases such as cancer, diabetes, obesity, cardiovascular and neurodegenerative diseases. Therefore, there is an urgent need to discover potent and specific inhibitors for NNMT to assess its therapeutical potential. Herein, we reported the design and synthesis of a fluorescent probe II138, exhibiting a K_d value of 369 ± 14 nM for NNMT. We also established a fluorescence polarization (FP)-based competition assay for evaluation of NNMT inhibitors. Importantly, the unique feature of this FP competition assay is its capability to identify inhibitors that interfere with the interaction of the NNMT active site directly or allosterically. In addition, this assay performance is robust with a Z'factor of 0.76, indicating its applicability in high-throughput screening for NNMT inhibitors.

Genome wide meta-analysis of cDNA datasets reveals new target gene signatures of colorectal cancer based on systems biology approach

Background

Colorectal cancer is known to be the most common type of cancer worldwide with high disease-related mortality. It is the third most common cancer in men and women and is the second major cause of death globally due to cancer. It is a complicated and fatal disease comprising of a group of molecular heterogeneous disorders.

Results

This study identifies the potential biomarkers of CRC through differentially expressed analysis, system biology, and proteomic analysis. Ten publicly available microarray datasets were analyzed and seven potential biomarkers were identified from the list of differentially expressed genes having a p value < 0.05. The expression profiling and the functional enrichment analysis revealed the role of these genes in cell communication, signal transduction, and immune response. The protein-protein interaction showed the functional association of the source genes (CTNNB1, NNMT, PTCH1, CALD1, CXCL14, CXCL8, and TNFAIP3) with the target proteins, such as AXIN, MAPK, IL6, STAT, APC, GSK3B, and SHH.

Conclusion

The integrated pathway analysis indicated the role of these genes in important physiological responses, such as cell cycle regulation, WNT, hedgehog, MAPK, and calcium signaling pathways during colorectal cancer. These pathways are involved in cell proliferation, chemotaxis, cellular growth, differentiation, tissue patterning, and cytokine production. The study shows the regulatory role of these genes in colorectal cancer and the pathways that can be effected after the dysregulation of these genes.

PGRMC1 effects on metabolism, genomic mutation and CpG methylation imply crucial roles in animal biology and disease

Background

Progesterone receptor membrane component 1 (PGRMC1) is often elevated in cancers, and exists in alternative states of phosphorylation. A motif centered on PGRMC1 Y180 was evolutionarily acquired concurrently with the embryological gastrulation organizer that orchestrates vertebrate tissue differentiation.

Results

Here, we show that mutagenic manipulation of PGRMC1 phosphorylation alters cell metabolism, genomic stability, and CpG methylation. Each of several mutants elicited distinct patterns of genomic CpG methylation. Mutation of S57A/Y180/S181A led to increased net hypermethylation, reminiscent of embryonic stem cells. Pathways enrichment analysis suggested modulation of processes related to animal cell differentiation status and tissue identity, as well as cell cycle control and ATM/ATR DNA damage repair regulation. We detected different genomic mutation rates in culture.

Conclusions

A companion manuscript shows that these cell states dramatically affect protein abundances, cell and mitochondrial morphology, and glycolytic metabolism. We propose that PGRMC1 phosphorylation status modulates cellular plasticity mechanisms relevant to early embryological tissue differentiation.

Molecular signature of interleukin-22 in colon carcinoma cells and organoid models

Interleukin (IL)-22 activates STAT (signal transducer and activator of transcription) 3 and antiapoptotic and proproliferative pathways; but beyond this, the molecular mechanisms by which IL-22 promotes carcinogenesis are poorly understood. Characterizing the molecular signature of IL-22 in human DLD-1 colon carcinoma cells, we observed increased expression of 26 genes, including NNMT (nicotinamide N-methyltransferase, ≤10-fold) and CEA (carcinoembryonic antigen, ≤7-fold), both known to promote intestinal carcinogenesis. ERP27 (endoplasmic reticulum protein-27, function unknown, ≤5-fold) and the proinflammatory ICAM1 (intercellular adhesion molecule-1, ≤4-fold) were also increased. The effect on CEA was partly STAT3-mediated, as STAT3-silencing reduced IL-22-induced CEA by ≤56%. Silencing of CEA or NNMT inhibited IL-22-induced proliferation/migration of DLD-1, Caco-2, and SW480 colon carcinoma cells. To validate these results in primary tissues, we assessed IL-22-induced gene expression in organoids from human healthy colon and colon cancer patients, and from normal mouse small intestine and colon. Gene regulation by IL-22 was similar in DLD-1 cells and human and mouse healthy organoids. CEA was an exception with no induction by IL-22 in organoids, indicating the 3-dimensional organization of the tissue may produce signals absent in 2D cell culture. Importantly, augmentation of NNMT was 5-14-fold greater in human cancerous compared to normal organoids, supporting a role for NNMT in IL-22-mediated colon carcinogenesis. Thus, NNMT and CEA emerge as mediators of the tumor-promoting effects of IL-22 in the intestine. These data advance our understanding of the multifaceted role of IL-22 in the gut and suggest the IL-22 pathway may represent a therapeutic target in colon cancer.

High stromal nicotinamide N-methyltransferase (NNMT) indicates poor prognosis in colorectal cancer

PURPOSE

Nicotinamide n-methyltransferase (NNMT) has good biochemical activity and epigenetic regulation, and has been reported as a major metabolic regulator of cancer. The goal of this study was to investigate the significance of stromal NNMT expression in colorectal cancer (CRC).

PATIENTS AND METHODS

Stromal expression of NNMT in primary CRC, metastasis CRC, and their non-cancerous tissues from 1088 CRC patients was examined by immunohistochemistry. The associations between stromal NNMT expression and survival outcomes in 967 patients with stage I-III CRC were further evaluated with Kaplan-Meier curve and Cox model analyses.

RESULTS

NNMT expression was mainly sourced from stromal compartments and also elevated in CRC. Patients with high stromal NNMT (IHC-score ≥ 106) have a worse survival than those patients with low stromal NNMT. In multiple Cox analyses, high expression of stromal NNMT remained as an independent risk factor in CRC for disease-free survival with a hazard ratio (HR) of 1.415 (95% confidence interval [CI], 1.015-1.972) and disease-specific survival with a HR of 5.004 (95% CI, 2.301-10.883). In addition, high stromal NNMT expression in CRC also indicates the poor survival outcomes in patients with early stage CRC (stage I and II) and in patients who undergo chemotherapy.

CONCLUSION

NNMT is mainly located in CRC stromal compartment. High stromal NNMT expression predicts an unfavorable postoperative prognosis.

Novel Propargyl-Linked Bisubstrate Analogues as Tight-Binding Inhibitors for Nicotinamide N-Methyltransferase

Nicotinamide N-methyltransferase (NNMT) catalyzes the methyl transfer from the cofactor S-adenosylmethionine to nicotinamide and other pyridine-containing compounds. NNMT is an important regulator for nicotinamide metabolism and methylation potential. Aberrant expression levels of NNMT have been implicated in cancer, metabolic, and neurodegenerative diseases, which makes NNMT a potential therapeutic target. Therefore, potent and selective NNMT inhibitors can serve as valuable tools to investigate the roles of NNMT in its mediated diseases. Here, we applied a rational strategy to design and synthesize the tight-binding bisubstrate inhibitor LL320 through a novel propargyl linker. LL320 demonstrates a Ki value of 1.6 ± 0.3 nM, which is the most potent inhibitor to date. The cocrystal structure of LL320 confirms its interaction with both the substrate and cofactor binding sites on NNMT. Importantly, this is the first example of using the propargyl linker to construct potent methyltransferase inhibitors, which will expand our understanding of the transition state of methyl transfer.

Nicotinamide N-methyltransferase in nonmelanoma skin cancers

BACKGROUND

Squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) represent the most common forms of nonmelanoma skin cancers (NMSCs). Although successful treatment of these neoplasms is based on surgical excision, an increasing number of BCCs relapses and many SCCs display high rates of recurrence and metastasis. Nicotinamide N-methyltransferase (NNMT) is a cytosolic enzyme, which was found to be upregulated in different solid tumours. However, there are no data regarding enzyme expression in NMSCs. The aim of this study was therefore to evaluate the potential involvement of NNMT in BCCs and SCCs.

MATERIALS AND METHODS

Immunohistochemical analyses were carried out on 40 BCC cases and 39 SCC cases, to evaluate enzyme expression in tumour and surrounding healthy margins. Moreover, the relationship between NNMT intratumour levels and clinico-pathological parameters were explored.

RESULTS

Nicotinamide N-methyltransferase was found to be overexpressed in BCCs compared with control tissues, while a significant enzyme downregulation was detected in SCCs with respect to corresponding healthy margins. In addition, NNMT levels were negatively related to aggressiveness of both BCCs (distinguishing between infiltrative and nodular tumours) and SCCs (considering head and neck forms and tumours of the extremities and trunk).

CONCLUSIONS

These evidences seem to demonstrate that the different NNMT dysregulation detected in BCC and SCC may be the result of important biological traits distinctively characterizing these two forms within NMSCs. In addition, enzyme levels seem to be inversely correlated with tumour aggressiveness, thus suggesting the potential suitability of the enzyme as a prognostic biomarker for both neoplasms.

Nicotinamide N-methyltransferase enhances chemoresistance in breast cancer through SIRT1 protein stabilization

Background

Nicotinamide N-methyltransferase (NNMT) is overexpressed in various human tumors and involved in the development and progression of several carcinomas. In breast cancer, NNMT was found to be overexpressed in several cell lines. However, the clinical relevance of NNMT in breast cancer is not yet clear.

Methods

NNMT expression in breast carcinoma was examined by immunohistochemistry, and then, its relationship with patient clinicopathological characteristics was analyzed. The effects of NNMT on chemoresistance in breast cancer cells were assessed by cell viability, colony formation, and apoptosis assay. The NNMT, SIRT1, p53, and acetyl-p53 proteins, which are involved in NNMT-related chemoresistance, were examined by Western blotting. The SIRT1 mRNA was examined by real-time PCR, and its activity was measured by using the SIRT1 deacetylase fluorometric reagent kit.

Results

NNMT expression was significantly higher (53.9%) in breast carcinoma than in paracancerous tissues (10.0%) and breast hyperplasia (13.3%). A high level of NNMT expression correlated with poor survival and chemotherapy response in breast cancer patients who received chemotherapy. Ectopic overexpression of NNMT significantly inhibited the apoptotic cell death and suppression of colony formation induced by adriamycin and paclitaxel. Mechanistic studies revealed that NNMT overexpression increased SIRT1 expression and promoted its activity. Either inhibition of SIRT1 by EX527 or knockdown of SIRT1 by siRNA could reverse NNMT-mediated resistance to adriamycin and paclitaxel, which suggests that SIRT1 plays a critical role in NNMT-related chemoresistance in breast cancer.

Conclusions

The results of this study demonstrate a novel correlation between the NNMT expression level and patient survival, suggesting that NNMT has the potential to become a new prognostic biomarker to predict the treatment outcomes of the clinical chemotherapy in breast cancer. Moreover, targeting NNMT or downstream SIRT1 may represent a new therapeutic approach to improve the efficacy of breast cancer chemotherapy.

Electronic supplementary material

The online version of this article (10.1186/s13058-019-1150-z) contains supplementary material, which is available to authorized users.

Overexpression of nicotinamide N-methyltransferase in HSC-2 OSCC cell line: effect on apoptosis and cell proliferation

OBJECTIVES

Oral squamous cell carcinoma (OSCC) is the most common malignancy of oral cavity. Despite advances in therapeutic approaches, the 5-year survival rate for oral cancer has not improved in the last three decades. Therefore, new molecular targets for early diagnosis and treatment of OSCC are needed. In the present study, we focused on the enzyme nicotinamide N-methyltransferase (NNMT). We have previously shown that enzyme expression is upregulated in OSCC and NNMT knockdown in PE/CA PJ-15 cells significantly decreased cell growth in vitro and tumorigenicity in vivo.

MATERIAL AND METHODS

To further explore the role of the enzyme in oral cancer cell metabolism, HSC-2 cells were transfected with the NNMT expression vector (pcDNA3-NNMT) and the effect of enzyme upregulation on cell proliferation was evaluated by MTT assay. Subsequently, we investigated at molecular level the role of NNMT on apoptosis and cell proliferation, by exploring the expression of β-catenin, survivin, and Ki-67 by real-time PCR. Moreover, we performed immunohistochemistry on 20 OSCC tissue samples to explore the expression level of NNMT and survivin ΔEx3 isoform.

RESULTS

Enzyme upregulation significantly increased cell growth in vitro. Moreover, a positive correlation between NNMT and survivin ΔEx3 isoform expression levels was found both in HSC-2 cells and in OSCC tissue samples.

CONCLUSION

Taken together, our results indicate a possible involvement of NNMT in the proliferation and tumorigenic capacity of OSCC cells and seem to suggest that the enzyme could represent a potential target for the treatment of oral cancer.

CLINICAL RELEVANCE

The involvement of NNMT in cell growth and anti-apoptotic mechanisms seems to suggest that this enzyme could be a new therapeutic target to improve the survival of OSCC patients.

Nicotinamide N-methyltransferase: potential involvement in cutaneous malignant melanoma

Nicotinamide N-methyltransferase (NNMT) is an enzyme that catalyzes the N-methylation of nicotinamide and pyridine compounds, participating in xenobiotic and drug metabolism. Data on literature have evidenced a possible role of NNMT in many solid cancers, but no data are currently available in cutaneous melanoma. Recent important advances have been achieved in the treatment of advanced melanoma with targeted therapy and immunotherapy. However, the identification of biomarkers that can be used for the detection of early stage disease as well as for monitoring the therapeutic response during treatment is of utmost importance. The aim of this study was to study the possible role of NNMT in melanoma. In the present study, we carried out immunohistochemical analyses to evaluate the expression of the enzyme NNMT in 34 melanomas and 34 nevi. Moreover, we explored the relationship between NNMT levels and the prognostic parameters of patients with melanoma. The results obtained showed significantly (P<0.0001) higher NNMT expression in melanoma compared with that detected in nevi. In addition, a significant (P<0.05) inverse relationship was found between enzyme levels and Breslow thickness, Clark level, the presence/number of mitoses, and ulceration. Taken together, these data seem to suggest that NNMT could represent a molecular biomarker for melanoma, thus highlighting its potential for both diagnosis and prognosis of this neoplasm.

Nicotinamide N-methyltransferase enhances resistance to 5-fluorouracil in colorectal cancer cells through inhibition of the ASK1-p38 MAPK pathway

Nicotinamide N-methyltransferase (NNMT), which converts nicotinamide to 1-methylnicotinamide (1-MNA), is overexpressed in a variety of human cancers and serves as a potential anti-cancer target. In this study, we investigated the effect of NNMT on 5-fluorouracil (5-FU) sensitivity of colorectal cancer (CRC) cells, and the underlying mechanisms. Our results show that down-regulation of NNMT in CRC HT-29 cells diminishes 5-FU resistance, while over expression of NNMT in SW480 cells enhances it. NNMT reduces reactive oxygen species (ROS) production induced by 5-FU by increasing 1-MNA in CRC cells. The reduction in ROS leads to inactivation of the ASK1-p38 mitogen-activated protein kinase (MAPK) pathway, which reduces 5-FU-induced apoptosis. In vivo, NNMT attenuates 5-FU-induced inhibition of CRC tumor growth in nude mice. These observations suggest that NNMT and the 1-MNA it produces inhibit the ASK1-p38 MAPK pathway, resulting in increased CRC cell resistance to 5-FU.

Nicotinamide N-Methyltransferase in Health and Cancer

Over the past decade, the roles of nicotinamide N-methyltransferase and its product 1-methyl nicotinamide have emerged from playing merely minor roles in phase 2 xenobiotic metabolism as actors in some of the most important scenes of human life. In this review, the structures of the gene, messenger RNA, and protein are discussed, together with the role of the enzyme in many of the common cancers that afflict people today.

Aurora Kinase A is a Biomarker for Bladder Cancer Detection and Contributes to its Aggressive Behavior

The effects of AURKA overexpression associated with poor clinical outcomes have been attributed to increased cell cycle progression and the development of genomic instability with aneuploidy. We used RNA interference to examine the effects of AURKA overexpression in human bladder cancer cells. Knockdown had minimal effects on cell proliferation but blocked tumor cell invasion. Whole genome mRNA expression profiling identified nicotinamide N-methyltransferase (NNMT) as a downstream target that was repressed by AURKA. Chromatin immunoprecipitation and NNMT promoter luciferase assays revealed that AURKA’s effects on NNMT were caused by PAX3-mediated transcriptional repression and overexpression of NNMT blocked tumor cell invasion in vitro. Overexpression of AURKA and activation of its downstream pathway was enriched in the basal subtype in primary human tumors and was associated with poor clinical outcomes. We also show that the FISH test for the AURKA gene copy number in urine yielded a specificity of 79.7% (95% confidence interval [CI] = 74.2% to 84.1%), and a sensitivity of 79.6% (95% CI = 74.2% to 84.1%) with an AUC of 0.901 (95% CI = 0.872 to 0.928; P < 0.001). These results implicate AURKA as an effective biomarker for bladder cancer detection as well as therapeutic target especially for its basal type.

Up-regulation of GTPBP4 in colorectal carcinoma is responsible for tumor metastasis

GTP binding protein 4(GTPBP4), a member of GTP-binding protein family, was previously characterized as a tumor suppressor that regulates and requires merlin to suppress cell proliferation. However, the role of GTPBP4 in the metastasis of colorectal carcinoma (CRC) remains unelucidated. Here, we observed that GTPBP4 was detected at higher levels in CRC metastatic tissues than that in the primary tumor tissues. Notably, up-regulation of GTPBP4 was closely correlated with tumor metastasis in CRCs. Kaplan-Meier and multivariate Cox regression analysis indicated GTPBP4 as an independent prognostic factor for CRC patients (hazard ratio = 2.693, 95% confident interval: 1.193-6.083, p = 0.017). Functional studies established that knockdown of GTPBP4 impeded, whereas ectopic expression of GTPBP4 enhanced cell motility and tumor metastasis in CRC cells. Interestingly, mechanistic investigations suggested that GTPBP4 may disorganize actin cytoskeleton through repressing RhoA signaling. Taken together, our research uncovered that GTPBP4 promotes CRC metastasis by disrupting actin cytoskeleton, which is mediated by the reduced RhoA activity. Strategies targeting GTPBP4 will be promising for CRC patients with metastases.

1-Methylnicotinamide ameliorates lipotoxicity-induced oxidative stress and cell death in kidney proximal tubular cells

Free fatty acid-bound albumin (FFA-albumin)-related oxidative stress is involved in the pathogenesis of proximal tubular cell (PTC) damage and subsequent renal dysfunction in patients with refractory proteinuria. Nicotinamide adenine dinucleotide (NAD) metabolism has recently been focused on as a novel therapeutic target for several modern diseases, including diabetes. This study was designed to identify a novel molecule in NAD metabolism to protect PTCs from lipotoxicity-related oxidative stress. Among 19 candidate enzymes involved in mammalian NAD metabolism, the mRNA expression level of nicotinamide n-methyltransferase (NNMT) was significantly increased in both the kidneys of FFA-albumin-overloaded mice and cultured PTCs stimulated with palmitate-albumin. Knockdown of NNMT exacerbated palmitate-albumin-induced cell death in cultured PTCs, whereas overexpression of NNMT inhibited it. Intracellular concentration of 1-Methylnicotinamide (1-MNA), a metabolite of NNMT, increased and decreased in cultured NNMT-overexpressing and -knockdown PTCs, respectively. Treatment with 1-MNA inhibited palmitate-albumin-induced mitochondrial reactive oxygen species generation and cell death in cultured PTCs. Furthermore, oral administration of 1-MNA ameliorated oxidative stress, apoptosis, necrosis, inflammation, and fibrosis in the kidneys of FFA-albumin-overloaded mice. In conclusion, NNMT-derived 1-MNA can reduce lipotoxicity-mediated oxidative stress and cell damage in PTCs. Supplementation of 1-MNA may have potential as a new therapy in patients with refractory proteinuria.

Nicotinamide N-methyltransferase increases complex I activity in SH-SY5Y cells via sirtuin 3

Nicotinamide N-methyltransferase (NNMT, E.C. 2.1.1.1) N-methylates nicotinamide to 1-methylnicotinamide. We have previously shown that NNMT is significantly overexpressed in the brains of patients who have died of Parkinson's disease, and others have shown that NNMT is significantly overexpressed in a variety of diseases ranging from cancer to hepatic cirrhosis. In vitro overexpression has revealed many cytoprotective effects of NNMT, in particular increased complex I activity and ATP synthesis. Although this appears to be mediated by an increase in 1-methylnicotinamide production, the molecular mechanisms involved remain unclear. In the present study, we have investigated the role that sirtuins 1, 2 and 3, class III DNA deacetylase enzymes known to regulate mitochondrial energy production and cell cycle, have in mediating the effects of NNMT upon complex I activity. Expression of NNMT in SH-SY5Y human neuroblastoma cells, which have no endogenous expression of NNMT, significantly increased the expression of all three sirtuins. siRNA-mediated silencing of sirtuin 3 expression decreased complex I activity in NNMT-expressing SH-SY5Y cells to that observed in wild-type SH-SY5Y, and significantly reduced cellular ATP content also. These results demonstrate that sirtuin 3 is a key mediator of NNMT-induced complex I activity and ATP synthesis. These results further reinforce a central role for NNMT in the regulation of energy homeostasis and provide further mechanistic insight into the consequences of enhanced NNMT expression.

Design, Synthesis, and Biological Activity of Sulfonamide Analogues of Antofine and Cryptopleurine as Potent and Orally Active Antitumor Agents

Due to their profound antiproliferative activity and unique mode of action, phenanthroindolizidine and phenanthroquinolizidine alkaloids, represented by antofine and cryptopleurine, have attracted attention recently as potential therapeutic agents. We have designed, synthesized, and evaluated the methanesulfonamide analogues of these natural alkaloids with the hope of improving their druglikeness. The analogues showed enhanced growth inhibition of human cancer cells compared with the parent natural products. In particular, a methanesulfonamide analogue of cryptopleurine (5b) exhibited improved bioavailability and significant antitumor activity, which suggests that 5b is a promising new anticancer agent. Our studies suggest that the inhibition of cancer cell growth by 5b is associated with the induction of G0/G1 cell cycle arrest via nicotinamide N-methyltransferase-dependent JNK activation in Caki-1 renal cancer cells. In addition, compound 5b significantly inhibited the migration and invasion of Caki-1 cancer cells by modulating the p38 MAPK signaling pathway.