EXPRESSION OF THE ANDROGEN RECEPTOR AND AN ANDROGEN-RESPONSIVE PROTEIN, APOLIPOPROTEIN-D, IN HUMAN BREAST-CANCER

Little is known regarding the activity and function of the androgen re ceptor (AR) in human breast cancer. In the present study AR was evalua ted in untreated primary breast cancers using antisera to the amino- a nd carboxy-termini of the receptor and quantitated using colour video image analysis. A strong correlation between tissue concentration and percentage AR-positive cells was observed for each antiserum. However, comparison of percentage positive cells using the amino- and carboxy- terminal AR antisera in individual breast cancer specimens revealed a subset of tumours with discordantly increased staining for the carboxy terminus. These findings suggest the presence of amino-terminal-trunc ated AR in a proportion of breast cancer cells or presence of AR mutat ions or associated protein alterations that affect binding of the amin o-terminal AR antiserum. Immunohistochemical expression of the androge n-regulated glycoprotein, apolipoprotein D (apo-D), was also evaluated in the breast cancer specimens. Focal positivity of apo-D staining, w hich did not always co-localise with AR-positive cells, was observed w ithin breast tumours. Furthermore, no correlation was evident between percentage positive cells stained for AR and apo-D in breast cancer sp ecimens. These findings indicate that, although apo-D expression is an drogen regulated in human breast cancer cell lines in vitro, its expre ssion in primary breast cancers may be regulated by other factors. The expression of AR in primary breast cancers also suggests that the rec eptor may be involved in tumour responsiveness or in abnormal response s to endocrine therapies.