A Novel Function of the Fe65 Neuronal Adaptor in Estrogen Receptor Action in Breast Cancer Cells [Molecular Bases of Disease]

March 11th, 2014 by Sun, Y., Kasiappan, R., Tang, J., Webb, P. L., Quarni, W., Zhang, X., Bai, W.

Fe65 is a multidomain adaptor with established functions in neuronal cells and neuro-degeneration diseases. It binds to the carboxyl terminus of the Aβ amyloid precursor protein (APP) and is involved in regulating gene transcription. The present studies show that Fe65 is expressed in breast cancer (BCa) cells and acts as an ERα transcriptional coregulator that is recruited by 17β-estradiol to the promoters of estrogen target genes. Deletion analyses mapped the ERα binding domain to the phosphotyrosine binding domain 2 (PTB2). Ectopic Fe65 increased the transcriptional activity of the ERα in a PTB2-dependent manner in reporter assays. Fe65 knockdown decreased, whereas its stable expression increased, the transcriptional activity of endogenous ERα in BCa cells and the ability of estrogens to stimulate target gene expression, ERα and coactivator recruitment to target gene promoters and cell growth. Furthermore, Fe65 expression decreased the antagonistic activity of tamoxifen (TAM), suggesting a role for Fe65 in TAM resistance. Overall, the studies define a novel role for the neuronal adaptor in estrogen actions in BCa cells.