Substrate-specific deoxycytidine kinase deficiency in 1-beta-D-arabinofuranosylcytosine-resistant leukemic cells.
In this study we describe the establishment of a leukemic cell line (BNML-CL/ara-C), originating from the 1-beta-D-arabinofuranosylcytosine (ara-C)-resistant brown Norway rat myelocytic leukemia model (BNML/ara-C), that retains the in vivo generated ara-C resistance. Its biological and biochemical characteristics have been compared with a cell line, derived from the ara-C-sensitive BNML model (BNML-CL/O). Resistance to ara-C was attributed to a decrease in phosphorylation of ara-C. Deoxycytidine (dCyd) kinase activity in crude cell extracts with dCyd as substrate showed similar enzyme activities in both cell lines, whereas with ara-C as substrate no dCyd kinase activity was detectable in the ara-C-resistant cell line. Two isoenzymes of dCyd kinase with different substrate specificities have been described (Cheng, Y.C., Domin, B., and Lee, L.S. Biochim. Biophys. Acta, 481: 481-492, 1977), cytoplasmic (dCyd kinase I, substrates: dCyd and ara-C) and mitochondrial (dCyd kinase II, substrates: dCyd and thymidine). In the ara-C-sensitive BNML model, thymidine induced a reduction of dCyd kinase activity when dCyd was used as substrate. However, thymidine did not affect kinase activity with ara-C was used as substrate. In the BNML-CL/ara-C, thymidine even induces a dCyd kinase inhibition of 85% with dCyd as substrate. It is likely that the ara-C-specific dCyd kinase deficiency in BNML-CL/ara-C cells was due to a selective loss of dCyd kinase I, whereas dCyd kinase II activity remained intact.
Department of Hematology, Leiden University Medical Center, The Netherlands.
D J
DJ
Richel
L P
LP
Colly
G J
GJ
Arkesteijn
M W
MW
Arentsen-Honders
M G
MG
Kerster
P M
PM
ter Riet
R
R
Willemze
D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D002869:Chromosome Aberrations; D003561:Cytarabine / Q000378:metabolism* / Q000494:pharmacology; D003842:Deoxycytidine Kinase / Q000032:analysis / Q000172:deficiency*; D003854:Deoxyribonucleotides / Q000032:analysis; D004351:Drug Resistance; D007527:Isoenzymes / Q000032:analysis; D007951:Leukemia, Myeloid / Q000235:genetics / Q000473:pathology*; D051381:Rats; D011914:Rats, Inbred BN; D013379:Substrate Specificity; D014407:Tumor Cells, Cultured / Q000187:drug effects
D003854:Deoxyribonucleotides; D007527:Isoenzymes; D003561:Cytarabine; D003842:Deoxycytidine Kinase