Autoclave antigen retrieval technique for immunohistochemical staining of androgen receptor in formalin-fixed paraffin sections of human prostate

Although information on the states of androgen receptor (AR) expression at the individual cell level is essential in understanding the human diseased prostate, histological approaches are often hampered by the artifactual loss of AR or AR antigenicity. Here we examined the effects of various antigen retrieval methods, including microwave irradiation and autoclave treatment, for immunohistochemical detection of AR in cultured LNCaP cells and paraffin embedded sections of human prostate, and found beneficial effects of autoclave treatment over microwave treatment. Staining results were consistent with that of AR messenger RNA expression assessed by the reverse transcriptase-polymerase chain reaction method. The procedures described in this article provided intense and reproducible immunostaining for AR, estrogen receptor and progesterone receptor in paraffin sections of the human diseased prostate. Finally, 0.01 M EDTA (pH 7.4) gave us the most intense nuclear signal for the steroid hormone receptors, though the best soaking solution was 0.01 M citrate buffer (pH 6.0) considering the lost of tissue morphology.