Androgen receptor coactivator p44/Mep50 in breast cancer growth and invasion.
Bottom Line: Furthermore, nuclear expression of p44 inhibits prostate cancer growth.In addition to being an AR coactivator, p44 also functions as an ER coactivator.In contrast to findings in prostate cancer, the expression of p44 shows strong cytoplasmic expression in morphologically normal terminal ductal lobular units, while nuclear p44 is observed in both ductal carcinoma in situ and invasive carcinoma.
Affiliation: Department of Pathology, New York University School of Medicine, New York, NY 10010, USA.Show MeSH
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Mentions: We examined the expression profile of p44 in benign and malignant breast ductal cells by immunohistochemical studies (IHC). IHC was performed on formalin-fixed paraffin-embedded breast cancer sections and the staining patterns were measured semi quantitatively (0 as negative, 1+ as weak staining, 2+ as moderate staining, 3+ as strong staining) for its intensity in cytoplasm and nuclei. A value 1+ is considered a positive value. Of 33 cases with invasive carcinoma evaluated, 22 had morphologically normal glandular elements and in situ carcinoma (DCIS) on the same section. In these 22 cases with benign terminal ductal lobular units, p44 was expressed as cytoplasmic protein in all cases from weak (n = 2, 9%), to moderate (n = 9, 41%) to strong (n = 11, 50%) cytoplasmic staining (Fig. 1A), but nuclear localization of p44 observed in rare benign cells. In contrast to benign ductal epithelium, p44 was localized in nuclei of DCIS lesions (Fig. 1B) in 18 of 22 (82%) cases and invasive carcinoma in 28 of 31 (90%) cases. Interestingly, nuclear localization of p44 (Fig. 1C) was more frequently seen in invasive rather than in situ components of the ductal carcinoma of the same patient in 17 of 21 (81%) cases. These findings suggest an association of translocation of p44 from the cytoplasm to nucleus in benign to malignant breast epithelia.
Affiliation: Department of Pathology, New York University School of Medicine, New York, NY 10010, USA.