Long-range enhancers on 8q24 regulate c-Myc

Recent genomewide association studies have found multiple genetic variants on chromosome 8q24 that are significantly associated with an increased susceptibility to prostate, colorectal, and breast cancer. These risk loci are located in a "gene desert," a few hundred kilobases telomeric to the Myc gene. To date, the biological mechanism(s) underlying these associations remain unclear. It has been speculated that these 8q24 genetic variant(s) might affect Myc expression by altering its regulation or amplification status. Here, we show that multiple enhancer elements are present within this region and that they can regulate transcription of Myc. We also demonstrate that one such enhancer element physically interacts with the Myc promoter via transcription factor Tcf-4 binding and acts in an allele specific manner to regulate Myc expression.