c-myc gene inactivation during induced maturation of HL-60 cells. Transcriptional repression and loss of a specific DNAse I hypersensitive site

The c-myc proto-oncogene is amplified and expressed at high levels in HL-60 cells, a cell line derived from a patient with acute promyelocytic leukemia. Upon induction to terminal maturation, expression of c-myc is greatly reduced. We have studied the level of gene expression at which the change in c-myc expression is controlled and the changes in chromatin configuration that accompany the repression of myc expression. We report here that the repression of myc expression with induced maturation is controlled at the level of transcription, and that reduced expression is accompanied by the loss of a single DNAse I hypersensitive site 0.9 kilobase pair upstream from the gene.