EFFECTS OF 3-DEAZAADENOSINE ON APOPTOSIS-RELATED GENE TRANSCRIPTS IN HL-60 CELLS

The effect of the transmethylation inhibitor 3-deazaadenosine on trans cription levels of genes associated with apoptosis was investigated in HL-60 cells. After incubation of HL-60 cells with 100 mu M 3-deazaade nosine for 45 min., a schedule known to perturb transmethylation metab olites and initiate apoptosis in these cells, a 50% decrease in c-myc and a 50% increase in bcl-2 RNA steady-slate levels compared to contro l cells were observed. Transcription levels of c-myc continued to decr ease after extended exposure to 3-deazaadenosine, while bcl-2 mRNA lev els dropped to 25% and 30% below those in control cells after 1.5 hr a nd 3 hr, respectively. The expression levels of the bcl-2 related bax gene, showed a similar pattern as bcl-2, a 60% increase was initially measured, but after 1.5 and 3 hr, bax transcripts were 80% and 70% res pectively, of those found in untreated cells. Another bcl-2 related ge ne, bcl-x, was previously reported to generate two transcripts in huma n cells. The long variant bcl-x(1) acts as bcl-2, while the short form bcl-x(s) induces apoptosis. We were unable to detect bcl-x(s) transcr ipts in untreated and 3-deazaadenosine treated cells by the highly sen sitive reverse transcriptase polymerase chain reaction method. This su ggests that this gene product may not be involved in 3-deazaadenosine induced apoptosis in HL-60 cells. Bcl-x(1) mRNA levels, however, slowl y decreased with about 50% after 1.5 or 3 hr 3-deazaadenosine treatmen t. It is concluded that 3-deazaadenosine initiated apoptosis affects c -myc, bcl-2, bax and bcl-x(1) mRNA levels.