Gemcitabine Pharmacogenomics: Deoxycytidine Kinase and Cytidylate Kinase Gene Resequencing and Functional Genomics
Gemcitabine and other cytidine antimetabolites require metabolic activation by phosphorylation. Deoxycytidine kinase (DCK) and cytidine monophosphate kinase (CMPK) catalyze these reactions. We have applied a genotype-to-phenotype strategy to study DCK and CMPK pharmacogenomics. Specifically, we rese...
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Published in | Drug metabolism and disposition Vol. 36; no. 9; pp. 1951 - 1959 |
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Main Authors | , , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Bethesda, MD
American Society for Pharmacology and Experimental Therapeutics
01.09.2008
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Subjects | |
Online Access | Get full text |
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Summary: | Gemcitabine and other cytidine antimetabolites require metabolic activation by phosphorylation. Deoxycytidine kinase (DCK)
and cytidine monophosphate kinase (CMPK) catalyze these reactions. We have applied a genotype-to-phenotype strategy to study
DCK and CMPK pharmacogenomics. Specifically, we resequenced DCK and CMPK using 240 DNA samples, 60 each from African-American, Caucasian-American, Han Chinese-American, and Mexican-American subjects.
We observed 28 DCK polymorphisms and 28 polymorphisms in CMPK , 33 of which were novel. Expression in COS-1 cells showed that variant allozyme enzyme activities ranged from 32 to 105%
of the wild type (WT) for DCK and from 78 to 112% of WT for CMPKâwith no significant differences in apparent K m values for either enzyme except for a DCK Val24/Ser122 double variant allozyme. Relative levels of DCK and CMPK immunoreactive
protein in the COS-1 cells paralleled relative levels of enzyme activity and were significantly correlated for DCK ( R p = 0.89, P = 0.0004) but not for CMPK ( R p = 0.82, P = 0.095). The results of an analysis of DCK and CMPK structural models were compatible with the observed functional consequences
of sequence alterations in variant allozymes. We also confirmed that the CMPK protein expressed in COS-1 cells and in a rabbit
reticulocyte lysate was 196 rather than 228 amino acids in length. In summary, we determined common sequence variations in
DCK and CMPK and systematically evaluated their functional implications. These gene sequence differences may contribute to variations
in the metabolic activation of gemcitabine and other cytidine antimetabolites. |
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Bibliography: | These two authors contributed equally to this manuscript. Dr. Aksoy is on leave of absence from Istanbul University, Pharmacy Faculty, Department of Biochemistry, Istanbul, Turkey. Present address: Inha University Hospital, Incheon, South Korea Present address: Roswell Park Cancer Institute, Buffalo NY Present address: University of Gazi, Faculty of Pharmacy, Department of Toxicology, Ankara, Turkey (NAK) |
ISSN: | 0090-9556 1521-009X |
DOI: | 10.1124/dmd.108.020925 |