Effects of exon-deleted estrogen receptor β transcript variants on growth, apoptosis and gene expression of human breast cancer cell lines

Estrogen receptor β gene codes for a variety of transcript isoforms resulting from alternative splicing, which are expressed both in mammary gland and in breast cancer cells. We studied the function of two exon-deleted ERβ isoforms recently identified by our group in comparison to ERβ1 in regulation of growth, apoptosis and gene expression of two breast cancer cell lines with different ERα status. Overexpression of ERβ1, but not of the exon-deleted variants exerted strong antitumoral effects both on ERα-positive MCF-7 and ERα-negative SK-BR-3 cells. ERβ1 overexpression slowed growth of MCF-7 and SK-BR-3 cells in…