Aims: The amplified in breast cancer 1 (AIB1), steroid receptor co-activator family member, acts as an oestrogen receptor (ER) co-activator. Acting with HER-2, it is thought to play a role in endocrine resistance by facilitating ER-growth factor crosstalk. The aim was to analyse AIB1 expression by immunohistochemistry and study its correlations with other prognostic variables in breast cancer and its effect on survival. Methods: A tissue microarray comprising tumours from 438 patients with 15.4 years' median follow-up was used. Interpretable AIB1 expression obtained in 395 patients was analysed along with other prognostic factors in breast cancer. Results: AIB1 expression scores ranged from 0 to 30; positive AIB1 expression (score > 14) was seen in 146/395 breast cancers; it correlated negatively with ER (P = 0.003) and progesterone receptor (PR) (P = 0.007), and positively with HER-2 (P = 0.005) and tumour grade (P = 0.014). It did not correlate with nodal status (P = 0.437). Among ER+ patients, AIB1 expression showed a trend towards loss of PR expression (29% versus 20%; P = 0.14). AIB1 did not predict survival on univariate or multivariate analysis. Conclusions: AIB1 expression correlates with HER-2 expression in breast cancer and shows a trend of association with loss of PR expression in ER+ tumours. Our study supports the postulated role of AIB1 in ER-growth factor interactions.
- Amplified in breast cancer 1
- Breast cancer
- Human epidermal growth factor receptor 2
- Oestrogen receptor
- Steroid receptor co-activator 3
ASJC Scopus subject areas
- Pathology and Forensic Medicine