Nicotinamide N‐methyltransferase decreases 5‐fluorouracil sensitivity in human esophageal squamous cell carcinoma through metabolic reprogramming and promoting the Warburg effect

Abstract

Esophageal squamous cell carcinoma (ESCC) is a common malignant tumor with poor prognosis. And different individuals respond to the same drug differently. Increasing evidence has confirmed that metabolism reprogramming was involved in the drug sensitivity of tumor cells. However, the potential molecular mechanism of 5‐fluorouracil (5‐FU) sensitivity remains to be elucidated in ESCC cells. In this study, we found that the 5‐FU sensitivity of TE1 cells was lower than that of EC1 and Eca109 cells. Gas chromatography‐mass spectrometry analysis results showed that nicotinate and nicotinamide metabolism and tricarboxylic acid cycle were significantly different in these three cell lines. Nicotinamide N‐methyltransferase (NNMT), a key enzyme of nicotinate and nicotinamide metabolism, was significantly higher expressed in TE1 cells than that in EC1 and Eca109 cells. Therefore, the function of NNMT on 5‐FU sensitivity was analyzed in vitro and in vivo. NNMT downregulation significantly increased 5‐FU sensitivity in TE1 cells. Meanwhile, the glucose consumption and lactate production were decreased, and the expression of glycolysis‐related enzymes hexokinase 2, lactate dehydrogenase A, and phosphoglycerate mutase 1 were downregulated in NNMT knockdown TE1 cells. Besides, overexpression of NNMT in EC1 and Eca109 cells caused the opposite effects. Moreover, when glycolysis was inhibited by 2‐deoxyglucose, the roles of NNMT on 5‐FU sensitivity was weakened. In vivo experiments showed that NNMT knockdown significantly increased the sensitivity of xenografts to 5‐FU and suppressed the Warburg effect. Overall, these results demonstrated that NNMT decreases 5‐FU sensitivity in human ESCC cells through promoting the Warburg effect, suggesting that NNMT may contribute to predict the treatment effects of the clinical chemotherapy in ESCC.

HPV Infection Leaves a DNA Methylation Signature in Oropharyngeal Cancer Affecting Both Coding Genes and Transposable Elements

“…Therefore, TCEAL7 downregulation was proposed as an alternative mechanism for the activation of MYC and NF-κB target genes [73,74]. NNMT upregulation was already reported in oral squamous cell carcinoma [75], but its downregulation was associated with increased sensitivity to 5-fluorouracil in esophageal squamous cell carcinoma cells [76]. In contrast, MFAP2 upregulation was reported in head and neck cancer [77] and associated with poor prognosis in gastric and hepatocellular carcinomas [78,79].…”

Detection of oncometabolites 1-methylnicotinamide, nicotine imine and N-Methylnicotinium in nails of oral cancer patients and prediction of them as modulators of DNMT1

“…In these cells, intracellular metabolic adaptations including activation of NNMT, methylation of nicotine are linked with the consumption of methyl group from SAM to methylate nicotinamide and nicotine derived products. Due to these changes, cancer cells achieve altered epigenetic state as global hypomethylation to promote expression of pro-tumorigenic genes (Feinberg and Vogelstein, 1983; Christmane et al., 2002; Lopez-Serra and Esteller, 2008; Palii et al, 2008; Wu et al, 2008; Ulanovskaya et al, 2013; Kraus et al, 2014; Cui et al, 2020; Gissi et al, 2020). However, there is a significant gap on the suitability and availability of the nicotine metabolites and 1-MNA that influence the global DNA methylation and in turn pro-tumor microenvironment.…”

“…Among plethora of detoxifying systems, there are reports on the overexpression of NNMT in OSCC and this cytoplasmic methyltransferase family of protein is known to consume SAM to produce 1-MNA from nicotinamide (Feinberg and Vogelstein, 1983; Christmane et al., 2002; Lopez-Serra and Esteller, 2008; Palii et al, 2008; Wu et al, 2008; Ulanovskaya et al, 2013; Kraus et al, 2014; Cui et al, 2020; Gissi et al, 2020). Interestingly, the utilization of SAM by NNMT is suggested to lead to the DNA hypomethylation as a pro-tumor epigenetic landscape.…”

“…Among various metabolic adaptations in cancer cells, involvement of various classes of methyltransferases including cytoplasmic nicotine methyltransferase (NNMT) and nuclear methyltransferases that include DNA methyltransferase and histone methyltransferase is imperative (Feinberg and Vogelstein, 1983; Christmane et al., 2002; Lopez-Serra and Esteller, 2008; Palii et al, 2008; Wu et al, 2008; Ulanovskaya et al, 2013; Kraus et al, 2014; Cui et al, 2020; Gissi et al, 2020). There are limited attempts that show the connection between metabolic and epigenetic landscape including the use of SAM to drive the need of NNMT enzyme that leads to the less availability of SAM for methylation activity of DNMT1 upon the DNA (Wu et al, 2008; Ulanovskaya et al, 2013; Kraus et al, 2014; Cui et al, 2020). Data support that inhibition of DNMT1 is linked with the global hypomethylation and associated with the pro-tumor transcriptional state in cancer cells (Feinberg and Vogelstein, 1983; Christmane et al., 2002; Lopez-Serra and Esteller, 2008; Palii et al, 2008; Gissi et al, 2020).…”

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

“…However, the bulk of scientific literature on NNMT is greatly focused on speculating and clarifying the role played by the enzyme in cancer. In fact, NNMT overexpression has been reported for many solid tumors, including gastrointestinal neoplasms [40][41][42][43][44][45][46][47][48], lung [49][50][51][52], oral [53][54][55][56][57][58][59], esophageal [60,61], nasopharyngeal [62] and thyroid [63][64][65] cancers, as well as ameloblastoma [66] and glioblastoma multiforme [67]. Significant NNMT upregulation was recently found in epithelial neoplasms [68][69][70][71][72][73] and in association with cancer stem cells (CSCs) [74][75][76][77][78].…”