In Vivo Footprinting of the Progesterone Receptor Gene in Human Breast CancerCells

摘要

We have used in vivo genomic footprinting to examine the interaction of proteinswith the 5' flanking region of the progesterone receptor gene in human MCF-7 breast cancer cells. DMS footprinting of the PR gene demonstrates that Spisites in the A promoter are protected in the absence of hormone, but are more extensively protected in the presence of estrogen. In contrast, an adjacent ERE half site is not protected in the presence or in the absence of hormone. DNase I footprinting demonstrates that regions flanking the ERE/Sp1 sites are more extensively protected after estrogen treatment and that two antiestrogens elicit different footprinting patterns. While the partial agonist, 4-hydroxytamoxifen, produce a footprinting pattern that was similar to that of in vitro-cleaved, naked genomic DNA, the pure antagonist, ICI 182,780, produced a footprinting pattern that was distinct from all other footprints observed.