HYPERMETHYLATION OF HPAII RECOGNITION SEQUENCES WITHIN THE 5'-CODING REGION OF THE ESTROGEN-RECEPTOR GENE IS NOT ASSOCIATED WITH ESTROGEN-RECEPTOR NEGATIVITY IN PRIMARY BREAST-TUMORS

Estrogen receptor negative tumours nle unable to respond to antiestrog en therapy. The underlying molecular mechanisms of estrogen receptor n egativity are poorly understood. Cytosine mechylation is one of the me chanisms of gene control and previous studies, particularly on breast tumour derived cell lines have suggested that hypermethylation of HpaI I recognition sequences within the 5' coding region of estrogen recept or may be responsible for gene inactivity. This study has examined the methylation status of HpaII recognition sequences in estrogen recepto r positive and negative breast tumours taking into account a polymorph ic HpaII site in the 5' coding region of the estrogen receptor gene. I t is concluded that hypermethylation of one or more of the 4 or 5 HpaI I recognition sequences in the 5' coding region of estrogen receptor i s not associated with ER negativity in primary breast armours.