Role of deoxycytidine kinase in an in vitro model for AraC- and DAC-resistance: substrate-enzyme interactions with deoxycytidine, 1-beta-D-arabinofuranosylcytosine and 5-aza-2'-deoxycytidine. 1993

A P Stegmann, and M W Honders, and M G Kester, and J E Landegent, and R Willemze
Department of Hematology, University Hospital Leiden, The Netherlands.

Deoxycytidine kinase activity (dCk) was monitored in cell lines from a rat acute myeloid leukemia model of acquired resistance to cytosine arabinoside (AraC) and decitabine (DAC). In both AraC-resistant cell lines (RCL/A and its subclone RA/7), as well as in a DAC-resistant cell line (RCL/D) which we generated from the drug-sensitive RCL/0 cell line, a total deficiency of dCk activity and a cross-resistance for AraC and DAC was demonstrated. Furthermore, the metabolization of deoxycytidine (dC) was severely impaired in all these cell lines. Km values for dC (9.4 microM in RCL/0 cells) had increased 70- to 100-fold in RCL/D (Km = 673.2 microM), in RCL/A (Km = 947.2 microM) and in RA/7 (Km = 817.5 microM). Vmax values were unaltered in RCL/D and RA/7, and twofold increased in RCL/A. Addition of hydroxyurea (HU) to cell cultures stimulated dCk salvage pathway activity in RCL/0 cells for dC, AraC, and DAC by increasing Vmax values approximately 160% leaving Km constants unchanged. In all resistant cell lines, HU pre-incubation did not influence the level of dCk activity, leaving Km and Vmax values unaltered. These data indicate that deficiency of dCk activity is crucial in the mechanism of drug resistance in this model.

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D007951 Leukemia, Myeloid Form of leukemia characterized by an uncontrolled proliferation of the myeloid lineage and their precursors (MYELOID PROGENITOR CELLS) in the bone marrow and other sites. Granulocytic Leukemia,Leukemia, Granulocytic,Leukemia, Myelocytic,Leukemia, Myelogenous,Myelocytic Leukemia,Myelogenous Leukemia,Myeloid Leukemia,Leukemia, Monocytic, Chronic,Monocytic Leukemia, Chronic,Chronic Monocytic Leukemia,Chronic Monocytic Leukemias,Granulocytic Leukemias,Leukemia, Chronic Monocytic,Leukemias, Chronic Monocytic,Leukemias, Granulocytic,Leukemias, Myelocytic,Leukemias, Myelogenous,Leukemias, Myeloid,Monocytic Leukemias, Chronic,Myelocytic Leukemias,Myelogenous Leukemias,Myeloid Leukemias
D011914 Rats, Inbred BN An inbred strain of rat that is widely used in a variety of research areas such as the study of ASTHMA; CARCINOGENESIS; AGING; and LEUKEMIA. Rats, Inbred Brown Norway,Rats, BN,BN Rat,BN Rat, Inbred,BN Rats,BN Rats, Inbred,Inbred BN Rat,Inbred BN Rats,Rat, BN,Rat, Inbred BN
D003561 Cytarabine A pyrimidine nucleoside analog that is used mainly in the treatment of leukemia, especially acute non-lymphoblastic leukemia. Cytarabine is an antimetabolite antineoplastic agent that inhibits the synthesis of DNA. Its actions are specific for the S phase of the cell cycle. It also has antiviral and immunosuppressant properties. (From Martindale, The Extra Pharmacopoeia, 30th ed, p472) Ara-C,Arabinofuranosylcytosine,Arabinosylcytosine,Cytosine Arabinoside,Aracytidine,Aracytine,Cytarabine Hydrochloride,Cytonal,Cytosar,Cytosar-U,beta-Ara C,Ara C,Arabinoside, Cytosine,Cytosar U,beta Ara C
D003841 Deoxycytidine A nucleoside component of DNA composed of CYTOSINE and DEOXYRIBOSE. Cytosine Deoxyribonucleoside,Cytosine Deoxyriboside,Deoxyribonucleoside, Cytosine,Deoxyriboside, Cytosine
D003842 Deoxycytidine Kinase An enzyme that catalyzes reversibly the phosphorylation of deoxycytidine with the formation of a nucleoside diphosphate and deoxycytidine monophosphate. Cytosine arabinoside can also act as an acceptor. All natural nucleoside triphosphates, except deoxycytidine triphosphate, can act as donors. The enzyme is induced by some viruses, particularly the herpes simplex virus (HERPESVIRUS HOMINIS). EC 2.7.1.74. Kinase, Deoxycytidine
D004351 Drug Resistance Diminished or failed response of an organism, disease or tissue to the intended effectiveness of a chemical or drug. It should be differentiated from DRUG TOLERANCE which is the progressive diminution of the susceptibility of a human or animal to the effects of a drug, as a result of continued administration. Resistance, Drug
D000077209 Decitabine An azacitidine derivative and antineoplastic antimetabolite. It inhibits DNA methyltransferase to re-activate silent genes, limiting METASTASIS and NEOPLASM DRUG RESISTANCE. Decitabine is used in the treatment of MYELODISPLASTIC SYNDROMES, and ACUTE MYELOID LEUKEMIA. 2'-Deoxy-5-azacytidine,5-Aza-2'-deoxycytidine,5-AzadC,5-Azadeoxycytidine,5-Deoxyazacytidine,5AzadC,AzadC Compound,Dacogen,Decitabine Mesylate,NSC 127716,NSC-127716,2' Deoxy 5 azacytidine,5 Aza 2' deoxycytidine,5 Azadeoxycytidine,5 Deoxyazacytidine,Compound, AzadC,Mesylate, Decitabine,NSC127716
D000208 Acute Disease Disease having a short and relatively severe course. Acute Diseases,Disease, Acute,Diseases, Acute
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia

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