Androgen and Vitamin D Receptor Expression in Archival Human Breast Tumors

Background: The present study was undertaken for quantitation of androgen (AR) and vitamin D (VDR) receptor expression in human male and female breast tumors by flow cytometry. Methods: Nuclei isolated from sections of paraffin-embedded tumors by pepsin digestion were treated for antigen unmasking and incubated with antibodies to AR and VDR. Flow cytometric analysis was used to determine the percentage of receptor-positive nuclei with fluorescence greater than 95% of the isotype nuclei. Mean log fluorescence channel values were used for comparing antigen density of the isotype and the antibody-treated nuclei. Results. Six of 23 female breast tumors had aneuploid DNA content. Nineteen of 20 estrogen receptor-positive female tumors by immunohistochemical analysis (IHC) were also AR positive by flow analysis. Aneuploid subpopulations had higher percentages of AR-positive nuclei than did diploid populations. Eight of 33 male breast tumors had aneuploid DNA content. Twenty-three of 33 male breast tumors were AR positive by flow analysis compared with six that were AR positive by IHC. Six AR-positive (IHC) male tumors were also AR positive by flow analysis. VDR expression was higher in diploid female tumors than in aneuploid tumors. Conclusions: Lack of a strong correlation between IHC and flow analysis may be due to differences in criteria used for identification of receptor-positive and -negative tumors by the two methods.