Participation of the peroxisomal beta-oxidation system in the chain-shortening of PCA16, a metabolite of the cytosine arabinoside prodrug, YNKO1, in rat liver.
When PCA16, a metabolite of the cytosine arabinoside prodrug YNKO1, was incubated with isolated rat hepatocytes, time-dependent H2O2 generation was found. When the hepatocytes obtained from clofibrate-treated rat liver were used as an enzyme source, PCA16-dependent production of H2O2 was increased by around 6-fold. The activity of peroxisomal beta-oxidation for PCA16 assayed by H2O2 generation was 3-fold higher than that for palmitic acid, whereas the activity of mitochondrial beta-oxidation for PCA16 assayed by ketone body production was much less than that for palmitic acid. A subcellular distribution study revealed that the distribution of the activities of beta-oxidation and fatty acyl-CoA oxidase for PCA16-CoA coincided with those of cyanide-insensitive palmitoyl-CoA-dependent beta-oxidation and catalase, a marker enzyme of peroxisomes. The profile of the cofactor requirement for beta-oxidation of PCA16-CoA in isolated peroxisomes was similar to that for palmitoyl-CoA oxidation, and the reaction was not inhibited by KCN. The formation of CoA derivative prior to beta-oxidation reaction was essential. HPLC analysis of metabolites after incubation of PCA16-CoA with isolated peroxisomes demonstrated the production of four metabolites, two of which were identified as PCA14 and PCA12 by fast atomic bombardment-mass spectrometry. These results indicate that peroxisomal beta-oxidation participates in the shortening of the alkyl-side chain of PCA16 and plays an important role in the formation of antileukemic cytosine arabinoside from YNKO1.
Yoshida
Y
Y
Department of Clinical Biochemistry, Tokyo College of Pharmacy, Japan.
Yamada
J
J
Watanabe
T
T
Suga
T
T
Takayama
H
H
D000818:Animals; D001088:Arabinonucleotides / Q000378:metabolism*; D002478:Cells, Cultured / Q000187:drug effects; D002994:Clofibrate / Q000494:pharmacology; D003066:Coenzyme A Ligases / Q000378:metabolism; D003561:Cytarabine / Q000378:metabolism; D003568:Cytidine Monophosphate / Q000031:analogs & derivatives / Q000378:metabolism*; D003597:Cytosine Nucleotides / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000032:analysis; D007657:Ketone Bodies / Q000032:analysis; D008099:Liver / Q000378:metabolism*; D008830:Microbodies / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000378:metabolism; D010168:Palmitates / Q000378:metabolism; D011355:Prodrugs / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D000098859:Long-Chain-Fatty-Acid-CoA Ligase
D001088:Arabinonucleotides; D003597:Cytosine Nucleotides; D007657:Ketone Bodies; D010168:Palmitates; D011355:Prodrugs; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D003561:Cytarabine; C064061:PCA 16; C061162:1-arabinofuranosylcytosine-5'-stearylphosphate; D006861:Hydrogen Peroxide; D003066:Coenzyme A Ligases; C090799:FAA2 protein, S cerevisiae; D000098859:Long-Chain-Fatty-Acid-CoA Ligase; D003568:Cytidine Monophosphate; D002994:Clofibrate