TY - JOUR
T1 - 13C and 31P NMR investigation of effect of 6-Aminonicotinamide on metabolism of RIF-1 tumor cells in vitro
AU - Street, James C.
AU - Mahmood, Umar
AU - Ballon, Douglas
AU - Alfieri, Alan A.
AU - Koutcher, Jason A.
PY - 1996/2/23
Y1 - 1996/2/23
N2 - 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 μM 6-aminonicotinamide led to an inhibition of 6-phosphogluconate dehy-drogenase and an accumulation of 6-phosphogluconate. A subsequent accumulation of the 6-phosphogluconate precursor 6-phosphoglucono-δ-lactone was observed in the 13C NMR spectrum. These metabolites were shown to be intracellular, although a small amount of leakage of 6-phosphoglucono-δ-lactone occurred. The intracellular concentrations of 6-phosphogluconate and 6-phosphoglucono-δ-lactone were 1.9 ± 0.8 μmol/108 cells (±1 standard deviation) and 0.8 ± 0.4 μmol/108 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.
AB - 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 μM 6-aminonicotinamide led to an inhibition of 6-phosphogluconate dehy-drogenase and an accumulation of 6-phosphogluconate. A subsequent accumulation of the 6-phosphogluconate precursor 6-phosphoglucono-δ-lactone was observed in the 13C NMR spectrum. These metabolites were shown to be intracellular, although a small amount of leakage of 6-phosphoglucono-δ-lactone occurred. The intracellular concentrations of 6-phosphogluconate and 6-phosphoglucono-δ-lactone were 1.9 ± 0.8 μmol/108 cells (±1 standard deviation) and 0.8 ± 0.4 μmol/108 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.
UR - http://www.scopus.com/inward/record.url?scp=0029671453&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0029671453&partnerID=8YFLogxK
U2 - 10.1074/jbc.271.8.4113
DO - 10.1074/jbc.271.8.4113
M3 - Article
C2 - 8626749
AN - SCOPUS:0029671453
SN - 0021-9258
VL - 271
SP - 4113
EP - 4119
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 8
ER -