The ability of nicotinamide to inhibit the growth of a C3H mouse mammary carcinoma

Extension of use of nicotinamide riboside chloride as a novel food pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on the safety of an extension of use of the novel food (NF) nicotinamide riboside chloride (NRC) pursuant to Regulation (EU) 2015/2283. The assessment addresses the use of NRC in 'meal replacement products' and 'nutritional drink mixes' at levels up to 300 mg/day for the general population, and in food for special medical purposes (FSMP) and total diet replacement for weight control (TDRWC) (as per Regulation (EU) No 609/2013) at levels up to 500 mg/day in adults. Benchmark dose modelling was carried out on data from the 90-day oral toxicity studies in rats relevant to the safety assessment. Considering the lack of tolerable upper intake level (UL) for nicotinamide in infants and the narrow margin of exposure between the estimated intake in infants and the lower confidence bound of the benchmark doses (BMDL 05) estimated by the models, the Panel concludes that the safety of the NF has not been established for use in 'meal replacement products' and 'nutritional drink mixes' under the proposed conditions of use. For FSMP and TDRWC, the proposed maximum use level corresponds to an intake of 210 mg nicotinamide per day, which is below the current UL for nicotinamide of 900 mg/day for adults. The Panel considers that the NF is as safe as pure nicotinamide for use in FSMP and TDRWC. The Panel, however, notes experimental data which indicate several pathways by which intakes of nicotinamide (or its precursors), at levels that are substantially higher than the physiological requirement, might cause adverse effects. The Panel considers that further investigations are required and that a re-evaluation of the UL for nicotinamide may be warranted.

Screening for autosomal recessive and X-linked conditions during pregnancy and preconception: a practice resource of the American College of Medical Genetics and Genomics (ACMG)

Carrier screening began 50 years ago with screening for conditions that have a high prevalence in defined racial/ethnic groups (e.g., Tay-Sachs disease in the Ashkenazi Jewish population; sickle cell disease in Black individuals). Cystic fibrosis was the first medical condition for which panethnic screening was recommended, followed by spinal muscular atrophy. Next-generation sequencing allows low cost and high throughput identification of sequence variants across many genes simultaneously. Since the phrase "expanded carrier screening" is nonspecific, there is a need to define carrier screening processes in a way that will allow equitable opportunity for patients to learn their reproductive risks using next-generation sequencing technology. An improved understanding of this risk allows patients to make informed reproductive decisions. Reproductive decision making is the established metric for clinical utility of population-based carrier screening. Furthermore, standardization of the screening approach will facilitate testing consistency. This practice resource reviews the current status of carrier screening, provides answers to some of the emerging questions, and recommends a consistent and equitable approach for offering carrier screening to all individuals during pregnancy or preconception.

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

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.

The Role of Nicotinamide in Cancer Chemoprevention and Therapy

Nicotinamide (NAM) is a water-soluble form of Vitamin B3 (niacin) and a precursor of nicotinamide-adenine dinucleotide (NAD⁺) which regulates cellular energy metabolism. Except for its role in the production of adenosine triphosphate (ATP), NAD⁺ acts as a substrate for several enzymes including sirtuin 1 (SIRT1) and poly ADP-ribose polymerase 1 (PARP1). Notably, NAM is an inhibitor of both SIRT1 and PARP1. Accumulating evidence suggests that NAM plays a role in cancer prevention and therapy. Phase III clinical trials have confirmed its clinical efficacy for non-melanoma skin cancer chemoprevention or as an adjunct to radiotherapy against head and neck, laryngeal, and urinary bladder cancers. Evidence for other cancers has mostly been collected through preclinical research and, in its majority, is not yet evidence-based. NAM has potential as a safe, well-tolerated, and cost-effective agent to be used in cancer chemoprevention and therapy. However, more preclinical studies and clinical trials are needed to fully unravel its value.

Chemoprevention of Lung Carcinogenesis by Dietary Nicotinamide and Inhaled Budesonide

Nicotinamide, the amide form of vitamin B3, and budesonide, a synthetic glucocorticoid used in the treatment of asthma, were evaluated to determine their individual and combinational chemopreventive efficacy on benzo(a)pyrene-induced lung tumors in female A/J mice. Nicotinamide fed at a dietary concentration of 0.75% significantly inhibited tumor multiplicity. Nicotinamide by aerosol inhalation at doses up to 15 mg/kg/day did not result in a statistically significant reduction in tumor multiplicity. Finally, dietary nicotinamide was administered with aerosol budesonide and tumor multiplicity reduced by 90% at 1 week and 49% at 8 weeks post last carcinogen dose. We conclude nicotinamide is an effective and safe agent for lung cancer dietary prevention at both early- and late-stage carcinogenesis and that efficacy is increased with aerosol budesonide. Combination chemoprevention with these agents is a well-tolerated and effective strategy which could be clinically advanced to human studies.

Nicotinamide prohibits proliferation and enhances chemosensitivity of pancreatic cancer cells through deregulating SIRT1 and Ras/Akt pathways

BACKGROUND

Nicotinamide (NAM), the precursor for the synthesis of NAD(+) and also an inhibitor of SIRT1, has been discovered to inhibit some types of cancer. However, little is known about the effects of NAM on pancreatic cancer cells. Since previous research showed that SIRT1 and K-Ras/Akt signaling acted as a promoter in tumorigenesis of pancreatic cancer, our present research set out to explore whether NAM inhibits proliferation and facilitates chemosensitivity in pancreatic cancer cells as well as the potential mechanisms involving SIRT1 and K-Ras/Akt pathway.

METHODS

Cell viability was assessed by MTT assay, and apoptosis and cell cycle were measured by flow cytometry. Cell invasive ability was evaluated by matrigel invasion assays. The activity of SIRT1 was measured by the Fluor de Lys deacetylation assay. Expression levels of SIRT1, K-Ras, Phosphated Akt (P-Akt, Ser-473) and Akt were measured using western blot. In vivo tumor growth was performed in pancreatic cancer cells xenografts.

RESULTS

NAM inhibited the proliferation of pancreatic cancer cells in a dose-dependent manner, and significantly induced apoptosis and cell cycle arrest in G2/M phase. Moreover, NAM obviously restrained cell invasive ability and increased the chemosensitivity. NAM significantly inhibited the activity of SIRT1 and decreased expression of SIRT1, K-Ras and P-Akt. Further, NAM prohibited proliferation and enhanced GEM antitumor activity in vivo.

CONCLUSIONS

Our results implied that NAM might be a potential therapeutic agent for human pancreatic cancer treatment through downregulating SIRT1, K-Ras and P-Akt expression.

Role of nicotinamide in DNA damage, mutagenesis, and DNA repair

Nicotinamide is a water-soluble amide form of niacin (nicotinic acid or vitamin B3). Both niacin and nicotinamide are widely available in plant and animal foods, and niacin can also be endogenously synthesized in the liver from dietary tryptophan. Nicotinamide is also commercially available in vitamin supplements and in a range of cosmetic, hair, and skin preparations. Nicotinamide is the primary precursor of nicotinamide adenine dinucleotide (NAD⁺), an essential coenzyme in ATP production and the sole substrate of the nuclear enzyme poly-ADP-ribose polymerase-1 (PARP-1). Numerous in vitro and in vivo studies have clearly shown that PARP-1 and NAD⁺ status influence cellular responses to genotoxicity which can lead to mutagenesis and cancer formation. This paper will examine the role of nicotinamide in the protection from carcinogenesis, DNA repair, and maintenance of genomic stability.

Magnetic resonance imaging of perfusion in rat cerebral 9L tumor after nicotinamide administration

PURPOSE

To investigate the effect of nicotinamide on normal brain and 9L tumor blood flow in the rat using magnetic resonance imaging (MRI) and arterial spin tagging.

METHODS AND MATERIALS

Using MRI at 7 Tesla, measurements of blood perfusion were determined from two-dimensional maps of intracerebral 9L rat tumors and normal Fischer rat brains. The spatial and temporal influence of nicotinamide, 500 mg/kg i.p., on cerebral blood flow (CBF) was studied in normal brain and tumors between 5 and 21 days after tumor implantation. The MRI CBF measurements employed a variable tip-angle-gradient-recalled echo (VTA-GRE-CBF) readout of the magnetization of the tissue slice. The VTA-GRE-CBF required 8 minutes for a blood flow image with inplane resolution of 250 microm x 500 microm x 2 mm.

RESULTS

Normal brain blood flow decreased following the administration of nicotinamide. In contrast, tumor blood flow remained unaffected in the time following nicotinamide administration. Consequently, the blood flowing in the tumor relative to that in normal brain demonstrated a significant and selective increase in response to nicotinamide administration. Relative tumor blood flow increased at 10 minutes after nicotinamide injection compared with predrug levels and remained elevated for at least 1 hour.

CONCLUSION

The results suggest that nicotinamide will not enhance radiosensitivity of brain tumors. The results support the use of nicotinamide to improve delivery of anticancer therapeutics through its ability to selectively increase tumor blood flow relative to that in normal brain.