Alpha anomer of 5-aza-2'-deoxycytidine down-regulates hTERT mRNA expression in human leukemia HL-60 cells.
DNA methylation inhibitors are being extensively studied as potential anticancer agents. In the present study, we compared the capability of alpha anomer of 5-aza-2'-deoxycytidine (alpha-5-azadCyd) to induce down-regulation of hTERT expression in HL-60 cells with other nucleoside analogs that act as DNA methylation inhibitors: beta-5-azadCyd (decitabine), (S)-9-(2,3-dihydroxypropyl)adenine [(S)-DHPA], isobutyl ester of (R,S)-3-(adenin-9-yl)-2-hydroxypropanoic acid [(R,S)-AHPA-ibu] and prospective DNA methylation inhibitors (S)-1-[3-hydroxy-2-(phosphonomethoxy)propyl]-5-azacytosine [(S)-HPMPazaC] and 5-fluoro-zebularine (F-PymRf). Exposure to alpha-5-azadCyd induced the down-regulation of hTERT expression in low micromolar concentrations (0.05-50 microM). A more cytotoxic beta anomer caused a transient up-regulation of hTERT and a subsequent reduction in hTERT mRNA levels at concentrations more than 10 times below its GIC50 value. In this respect, (S)-DHPA and (R,S)-AHPA-ibu were less efficient, since a similar effect was achieved at concentrations above their GIC(50). In contrast, F-PymRf treatment resulted in up to a three-fold induction of hTERT expression within a broad range of concentrations. In all cases, the down-regulation of hTERT expression was concentration-dependent. The correlation was found between c-myc overexpression and transiently elevated hTERT expression after treatment with all tested compounds except for alpha-5-azadCyd and (S)-HPMPazaC. Although the primary task of hypomethylating agents in anticancer therapy lies in reactivation of silenced tumour-suppressor genes, the inhibition of hTERT expression might also be a fruitful clinical effect of this approach.
Hájek
Miroslav
M
Gilead Sciences Research Center, Institute of Organic Chemistry and Biochemistry v.v.i., AS CR, 166 10 Prague 6, Czech Republic. hajek@uochb.cas.cz
Votruba
Ivan
I
Holý
Antonín
A
Krecmerová
Marcela
M
Tloust'ová
Eva
E
D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D001374:Azacitidine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D019175:DNA Methylation / Q000187:drug effects; D000077209:Decitabine; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D018922:HL-60 Cells; D006801:Humans; D012333:RNA, Messenger / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012435:S-Adenosylhomocysteine / Q000378:metabolism; D012436:S-Adenosylmethionine / Q000378:metabolism; D013237:Stereoisomerism; D019098:Telomerase / Q000096:biosynthesis*
D000964:Antimetabolites, Antineoplastic; D012333:RNA, Messenger; D000077209:Decitabine; D012436:S-Adenosylmethionine; D004247:DNA; D012435:S-Adenosylhomocysteine; C509186:TERT protein, human; D019098:Telomerase; D001374:Azacitidine