An unusual nicotinamide derivative, 4-pyridone-3-carboxamide ribonucleoside (4PYR), is a novel endothelial toxin and oncometabolite

Abstract

Our recent studies identified a novel pathway of nicotinamide metabolism that involves 4-pyridone-3-carboxamide-1-β-D-ribonucleoside (4PYR) and demonstrated its endothelial cytotoxic effect. This study tested the effects of 4PYR and its metabolites in experimental models of breast cancer. Mice were divided into groups: 4T1 (injected with mammary 4T1 cancer cells), 4T1 + 4PYR (4PYR-treated 4T1 mice), and control, maintained for 2 or 21 days. Lung metastasis and endothelial function were analyzed together with blood nucleotides (including 4PYR), plasma amino acids, nicotinamide metabolites, and vascular ectoenzymes of nucleotide catabolism. 4PYR metabolism was also evaluated in cultured 4T1, MDA-MB-231, MCF-7, and T47D cells. An increase in blood 4PYR in 4T1 mice was observed at 2 days. 4PYR and its metabolites were noticed after 21 days in 4T1 only. Higher blood 4PYR was linked with more lung metastases in 4T1 + 4PYR vs. 4T1. Decreased L-arginine, higher asymmetric dimethyl-L-arginine, and higher vascular ecto-adenosine deaminase were observed in 4T1 + 4PYR vs. 4T1 and control. Vascular relaxation caused by flow-dependent endothelial activation in 4PYR-treated mice was significantly lower than in control. The permeability of 4PYR-treated endothelial cells was increased. Decreased nicotinamide but enhanced nicotinamide metabolites were noticed in 4T1 vs. control. Reduced N-methylnicotinamide and a further increase in Met2PY were observed in 4T1 + 4PYR vs. 4T1 and control. In cultured breast cancer cells, estrogen and progesterone receptor antagonists inhibited the production of 4PYR metabolites. 4PYR formation is accelerated in cancer and induces metabolic disturbances that may affect cancer progression and, especially, metastasis, probably through impaired endothelial homeostasis. 4PYR may be considered a new oncometabolite.

4-Pyridone-3-carboxamide-1-β-D-ribonucleoside (4PYR)—A Novel Oncometabolite Modulating Cancer-Endothelial Interactions in Breast Cancer Metastasis

“…An external calibration with pure compounds obtained through chemical synthesis was used for the quantitative analysis. Protein precipitates were dissolved in 0.5 mL 0.5 M NaOH and analyzed using the Bradford method for protein concentration (nmol/min/mg of protein) [ 19 , 70 , 71 , 72 ].…”

Synthesis, Detection, and Metabolism of Pyridone Ribosides, Products of NAD Overoxidation

“…Other catabolites of nicotinamide include nicotinamide N -oxide and 6-hydroxynicotinamide, also known as 6-oxopyridine-3-carboxamide (6-PY, Figure ), the nonmethylated form of N -Me-6-PY. Additional NAD + urinary metabolites include the ribosylated forms of these PY nucleobases, the pyridone ribosides (Figure , PYRs). − While less abundant than N -Me-PYs, carboxamide pyridone ribosides (PYRs) have been detected numerous times in mammalian urine since the 1970s . Yet, the metabolomics literature often only reports on the 1-ribosylpyridin-4-one-3-carboxamide (4-PYR; Figure ) species (e.g., ref ).…”

Conformational Preferences of Pyridone Adenine Dinucleotides from Molecular Dynamics Simulations

“…These aberrant forms of NAD(P) accumulate in cells under stress conditions when cells build up an overabundance of electrons, in turn causing an abnormally high ratio of NADH to NAD + and the generation of reactive oxygen species [ 15 , 16 , 17 ]. Pyridone adenine dinucleotides can be detected at concentrations within the nmol/mg of protein range of NAD(P)(H) concentrations in tissues and cultured cells [ 18 , 19 ]. There, they have the potential to inhibit NAD(P)-dependent enzymes, causing further metabolic dysfunction and pathogenic oxidative damage.…”