The effect of edelfosine on CTP:cholinephosphate cytidylyltransferase activity in leukemic cell lines.
Analogs of ether phospholipids have been shown to have selective anti-neoplastic activity. The compounds are known to inhibit phospholipid biosynthesis. This paper examines the effect of the alkyl-lysophospholipid, edelfosine, on the rate-limiting enzyme, CTP:cholinephosphate cytidylyltransferase, in de novo phosphatidylcholine synthesis in sensitive and resistant leukemic cell lines. Enzyme activity was measured by the incorporation of 14C-phosphocholine into CDP-choline by lysates of HL60 and K562; cells demonstrated inhibition of incorporation of 14C-phosphocholine in HL60 cell lysates but no inhibition in K562 lysates. Partial purification of cytidylyltransferase by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting demonstrated similarity between the enzyme isolated from each cell line. Cloning and sequencing of cytidylyltransferase cDNA of HL60 cells was accomplished using a probe encoding the entire protein sequence of the K562 cytidylyltransferase gene. A substitution at nucleotide 751 from A in the HL60 cell cDNA clone to G in the K562 cDNA clone resulted in a change in amino acid number 251 from lysine (positively charged) in the HL60 enzyme to glutamic acid (negatively charged) in the K562 enzyme. This negative charge in the lipid-binding domain of the K562 enzyme may result in a weaker binding of edelfosine and the observed decrease in activity, as evidenced by resistance to edelfosine by K562 cells.
Vogler
W R
WR
Department of Medicine, Emory University, Atlanta, GA 30322, USA.
Shoji
M
M
Hayzer
D J
DJ
Xie
Y P
YP
Renshaw
M
M
D000970:Antineoplastic Agents / Q000494:pharmacology*; D019916:Choline-Phosphate Cytidylyltransferase; D018076:DNA, Complementary / Q000235:genetics; D004273:DNA, Neoplasm / Q000235:genetics; D019008:Drug Resistance, Neoplasm; D018922:HL-60 Cells / Q000187:drug effects; D006801:Humans; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000473:pathology; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009713:Nucleotidyltransferases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010742:Phospholipid Ethers / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D014407:Tumor Cells, Cultured / Q000187:drug effects
D000970:Antineoplastic Agents; D018076:DNA, Complementary; D004273:DNA, Neoplasm; D009363:Neoplasm Proteins; D010742:Phospholipid Ethers; C026659:edelfosine; D009713:Nucleotidyltransferases; D019916:Choline-Phosphate Cytidylyltransferase