Effect of methylation inhibitors on gene expression in HL-60 cells.
The methylation inhibitors Neplanocin A (Nep A), 3'-deazaadenosine (dzAdo), and 3-deaza(+/-)aristeromycin (Dari) were tested for their effect on the expression of histone H2B, actin, and the protooncogenes c-myc, and v-fos. Nep A and Dari bind to the S-adenosylhomocysteine hydrolase resulting in the accumulation of S-adenosylhomocysteine, while dzAdo served as a substrate for the enzyme. With dzAdo, inordinant amounts of 3-deazaadenosylhomocysteine (dzAdoHcy) accumulated in the cell, provided L-homocysteine (Hcy) was present. When added at sublethal concentrations, the methylation inhibitors had little or no effect on c-myc, v-fos, histone H2B, or actin expression, nor did any significant number of the drug-treated cells demonstrate myeloid characteristics. However, growth and gene expression were markedly inhibited upon the addition of Hcy and dzAdo. One of the earliest effects of dzAdoHcy on HL-60 cells was the disappearance of c-myc mRNA. Within 1 h of the addition of dzAdo and Hcy, only trace amounts of c-myc mRNA were detectable. After 4-5 h v-fos, histone H2B, and actin mRNAs also decreased to about 40% of control levels. Differences in the stability of preexisting mRNAs would appear to account for these results. Within 1 h following the addition of dzAdo and Hcy, the synthesis of rRNA and mRNA were completely blocked as measured by the incorporation of [3H]uridine.
Department of Microbiology and Immunology, University of North Dakota School of Medicine, Grand Forks 58202.
J A
JA
Duerre
H R
HR
Buttz
J J
JJ
Ackerman
D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D016259:Genes, myc; D006801:Humans; D008745:Methylation / Q000187:drug effects; D011061:Poly A / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics; D014212:Tretinoin / Q000494:pharmacology; D014372:Tubercidin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D012333:RNA, Messenger; D012334:RNA, Neoplasm; C018258:3-deazaadenosine; D011061:Poly A; D014212:Tretinoin; C034583:3-deazaaristeromycin; C031096:neplanocin A; D000241:Adenosine; D014372:Tubercidin