C- myc gene chromatin of estrogen receptor positive and negative breast cancer cells

• Published in: Molecular and cellular endocrinology Vol. 91; no. 1; pp. 83 - 89
• Main Authors: Miller, Teresa L., Huzel, Norman J., Davie, James R., Murphy, Leigh C.
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 01.02.1993; Elsevier
• Subjects: Binding Sites; Biological and medical sciences; Breast cancer (human); Breast Neoplasms - genetics; c- myc gene; Chromatin - chemistry; Chromatin - metabolism; Chromatin structure; Deoxyribonuclease I - metabolism; DNA, Neoplasm - metabolism; Estrogens - pharmacology; Gene Expression; Genes, myc - genetics; Gynecology. Andrology. Obstetrics; Humans; Male genital diseases; Medical sciences; Promoter Regions, Genetic; Receptors, Estrogen - analysis; RNA, Messenger - metabolism; Tumor Cells, Cultured; Tumors; c- myc gene; Breast cancer (human); ER; DHS; Chromatin structure; Human; Mammary gland diseases; Chromatin; Hormonodependence; C-Onc gene; Established cell line; Estrogen; Mammary gland; Malignant tumor; Sex steroid hormone; Protooncogene; Hormonal receptor
• ISSN: 0303-7207; 1872-8057
• DOI: 10.1016/0303-7207(93)90258-L

Expression of the c- myc protooncogene is estrogen regulated in estrogen receptor (ER) positive, hormone-dependent human breast cancer cells, but it is constitutively active in ER negative, hormone-independent breast cancer cells. To determine whether these differences are reflected in c- myc chromatin, DNase I hypersensitive sites (DHS) were mapped. Six DHS were detected in all cell lines studied, with DHS 3 2 being more prominent than DHS 3 1. The accessibility of DHS 2 was markedly greater in ER negative cells than in ER positive cells, and this relative accessibility remained unchanged when cells were grown in estrogen free medium. DHS 2, 3 1 and 3 2 map near the P0, P1 and P2 promoters, respectively. An analysis of promoter usage demonstrated that P2 was the preferred promoter. Thus, the differences in the accessibility of DHS 2 in c- myc chromatin of ER positive and negative cells likely reflects alterations in DNA-protein interactions in this region.