Overexpression of the steroid receptor coactivator AIB1 in breast cancer correlates with the absence of estrogen and progesterone receptors and positivity for p53and HER2h/neu

Abstract

The gene for the steroid receptor coactivator amplified in breast cancer 1 (AIB1), located on chromosome 20q12, is overexpressed at the mRNA level in up to 60% of primary breast carcinomas; however, only 5% of these tumors show DNA amplification. The transcription factors and signaling pathways relevant to breast cancer, which in the absence of DNA amplification are responsible for and targeted by elevated levels of AIB1 mRNA, are unknown. In the present study, in situ hybridization was used to examine AIB1 mRNA expression in 93 breast carcinomas of varying histological grade and immunohistochemical profile. AIB1 mRNA was overexpressed relative to normal breast tissue in 26 of 83 (31%) invas..