NOVEL DNASE-I HYPERSENSITIVE SITES IN THE 3'-FLANKING REGION OF THE HUMAN C-MYC GENE

DNase I hypersensitivity regions correlate with genetic regulatory loc i and binding sites for sequence-specific DNA-binding proteins. We pre sent data supporting the presence of novel DNase 1 hypersensitive site s (which we have designated sites VI-IX) in both the body of the human c-myc gene downstream from exon 2 and the 3'-flanking region of the c -myc gene in HL-60 cells. All of these novel DH sites are markedly dec reased when HL-60 cells are treated with either dimethyl sulfoxide (DM SO) or retinoic acid. Moreover, a similar pattern of DNase I hypersens itive sites in this region of c-myc was present in MCF-7 human breast cancer cells growing in culture. Our results suggest a potential role for these sites in transcriptional regulation of the human c-myc gene.