title: Methylation of the estrogen receptor gene CpG island marks loss of estrogen receptor expression in human breast cancer cells.
abstract: Breast cancer is the most common malignancy in women and hormone resistance is a challenging problem in its treatment. Loss of estrogen receptor expression is an important means of hormone resistance, but the mechanisms involved are poorly understood. We now demonstrate a potential role for abnormal DNA methylation in transcriptional inactivation of the estrogen receptor gene. Estrogen receptor-negative human breast cancer cells growing in culture lack estrogen receptor mRNA, have a higher capacity to methylate DNA, and display extensive methylation of the CpG island in the 5' promoter region of the estrogen receptor gene, which would correlate with silencing of expression. These results suggest that abnormal methylation could account for transcriptional inactivation of the estrogen receptor gene and subsequent hormone resistance in some human breast cancers.
authors.affiliation: Oncology Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231.
authors.forename: Y L
authors.initials: YL
authors.lastname: Ottaviano
authors.forename: J P
authors.initials: JP
authors.lastname: Issa
authors.forename: F F
authors.initials: FF
authors.lastname: Parl
authors.forename: H S
authors.initials: HS
authors.lastname: Smith
authors.forename: S B
authors.initials: SB
authors.lastname: Baylin
authors.forename: N E
authors.initials: NE
authors.lastname: Davidson
mesh_terms: D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics / Q000378:metabolism; D004273:DNA, Neoplasm / Q000378:metabolism*; D005260:Female; D006801:Humans; D008745:Methylation; D012333:RNA, Messenger / Q000378:metabolism; D011960:Receptors, Estrogen / Q000235:genetics* / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D004273:DNA, Neoplasm; D012333:RNA, Messenger; D011960:Receptors, Estrogen; D004248:DNA (Cytosine-5-)-Methyltransferases