13C and 31P NMR investigation of effect of 6-aminonicotinamide on metabolism of RIF-1 tumor cells in vitro.

Abstract

The effect of 6-aminonicotinamide on the metabolism of RIF-1 tumor cells was investigated using 13C and 31P NMR spectroscopy. 6-Aminonicotinamide can be metabolized to 6-amino-NAD(P), a competitive inhibitor of NAD(P)-requiring processes. 40 microM 6-aminonicotinamide led to an inhibition of 6-phosphogluconate dehydrogenase and an accumulation of 6-phosphogluconate. A subsequent accumulation of the 6-phosphogluconate precursor 6-phosphoglucono-delta-lactone was observed in the 13C NMR spectrum. These metabolites were shown to be intracellular, although a small amount of leakage of 6-phosphoglucono-delta-lactone occurred. The intracellular concentrations of 6-phosphogluconate and 6-phosphoglucono-delta-lactone were 1.9 +/- 0.8 micromol/108 cells (+/-1 standard deviation) and 0.8 +/- 0.4 micromol/10(8) cells, respectively, after 15 h. Glucose utilization and lactate production were significantly inhibited by 6-aminonicotinamide (both p < 0.05), indicating inhibition of glycolysis. 31P NMR data showed that phosphocreatine was significantly depleted in cells exposed to 6-aminonicotinamide (p < 0.05). Exposure of RIF-1 cells to 6-aminonicotinamide prior to 3- or 6-Gy x-irradiation induced a supra-additive cell kill, indicating that 6-aminonicotinamide is acting as a radiosensitizer. There was no effect of 6-aminonicotinamide alone or when the drug was given postradiation, suggesting that its mechanism of action may be by inhibition of radiation-induced repair.

• Authors: J C Street, U Mahmood, D Ballon, A A Alfieri, J A Koutcher
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 271 Issue 8 Pg. 4113-9 (Feb 23 1996) ISSN: 0021-9258 [Print] United States
• PMID: 8626749 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Carbon Isotopes
• Phosphorus
• 6-Aminonicotinamide
• Glucose

Topics

• 6-Aminonicotinamide (metabolism, pharmacology)
• Animals
• Carbon Isotopes
• Cell Line
• Cell Survival (drug effects)
• Dose-Response Relationship, Drug
• Fibrosarcoma
• Glucose (metabolism)
• Glycolysis (drug effects)
• Kinetics
• Magnetic Resonance Spectroscopy (methods)
• Neoplasms, Radiation-Induced
• Phosphorus
• Time Factors
• Tumor Cells, Cultured
• X-Rays