Androgen receptor status in female breast cancer: RT-PCR and Western blot studies

Abstract

Purpose: Although the androgen receptor (AR) has been found to be expressed in female breast tumours, its role in breast cancer remains unclear. In addition to the oestrogen receptor (OR) and progesterone receptor (PR), AR functional status may be important in the control of female breast cancer growth.

Methods: In order to define AR in breast cancer, 67 primary breast tumours and 8 normal breast samples as control tissue were analysed for AR expression at the mRNA and protein levels using RT-PCR and Western blotting, respectively. The association of AR expression with tumour size and axillary lymph node status was investigated. Expression of AR mRNA was compared with that of OR and PR.

Results: AR expression was identified in 66% (44/67) and 51% (34/67) of the cancers studied by RT-PCR and Western blotting, respectively. The number of positive samples and the level of AR mRNA were significantly higher among the cancer samples than among normal samples. No expression of AR protein was detected in normal breast tissue. A significant correlation between AR gene expression and its protein level in nuclei of carcinoma samples was demonstrated. The expression level of both AR gene and AR protein in nuclei was found to be positively correlated with tumour invasiveness. Of the breast carcinoma specimens, 44.8% (30/67) were OR-, PR- and AR-positive, while 14.9% (10/67) were steroid receptor-negative. However, 18% (12/67) of the primary breast tumours negative for OR and PR were positive for AR.

Conclusions: The high incidence of AR expression in female breast tumours suggests a potential role of AR in breast cancer, in addition to OR and PR.