Tissue Selective Androgen Receptor Modulators (SARMs) Increase Pelvic Floor Muscle Mass in Ovariectomized Mice

Stress urinary incontinence (SUI), a prevalent condition, is represented by an involuntary leakage of urine that results, at least in part, from weakened or damaged pelvic floor muscles and is triggered by physical stress. Current treatment options are limited with no oral therapies available. The pelvic floor is rich in androgen receptor and molecules with anabolic activity including selective androgen receptor modulators (SARMs) may serve as therapeutic options for individuals with SUI. In this study, two SARMs (GTx-024 and GTx-027) were evaluated in a post-menopausal animal model in order to determine their effect on pelvic floor muscles. Female C57BL/6 mice were ovariectomized and their pelvic muscles allowed to regress. The animals were then treated with vehicle or doses of GTx-024 or GTx-027. Animal total body weight, lean body mass, and pelvic floor muscle weights were measured along with the expression of genes associated with muscle catabolism. Treatment with the SARMs resulted in a restoration of the pelvic muscles to the sham-operated weight. Coordinately, the induction of genes associated with muscle catabolism was inhibited. Although a trend was observed towards an increase in total lean body mass in the SARM-treated groups, no significant differences were detected. Treatment of an ovariectomized mouse model with SARMs resulted in an increase in pelvic floor muscles, which may translate to an improvement of symptoms associated with SUI and serves as the basis for evaluating their clinical use. J. Cell. Biochem. 118: 640-646, 2017. © 2016 Wiley Periodicals, Inc.

Activity of ABCG2 Is Regulated by Its Expression and Localization in DHT and Cyclopamine-Treated Breast Cancer Cells

Elevated expression of the efflux transporter, ATP-binding cassette subfamily G isoform 2 (ABCG2) on the plasma membrane of cancer cells contributes to the development of drug resistance and is a key characteristic of cancer stem cells. In this study, gene expression analysis identified that treatment of the MCF-7 and T-47D breast cancer cell lines with the androgen, 5α-dihydrotestosterone (DHT), and the Hedgehog signaling inhibitor, cyclopamine downregulated ABCG2 mRNA levels. In MCF-7 cells, and in Hoechst 33342(lo) /CD44(hi) /CD24(lo) breast cancer stem-like cells isolated from MCF-7 cultures, ABCG2 was accumulated in cell-to-cell junction complexes and in large cytoplasmic aggresome-like vesicles. DHT treatments, which decreased cellular ABCG2 protein levels, led to diminished ABCG2 localization in both cell-to-cell junction complexes and in cytoplasmic vesicles. In contrast, cyclopamine, which did not alter ABCG2 protein levels, induced accumulation of ABCG2 in cytoplasmic vesicles, reducing its localization in cell-to-cell junction complexes. The reduced localization of ABCG2 at the plasma membrane of MCF-7 cells was associated with decreased efflux of the ABCG2 substrate, mitoxantrone, and increased sensitivity of cyclopamine-treated cultures to the cytotoxic effects of mitoxantrone. Together, these findings indicate that DHT and cyclopamine reduce ABCG2 activity in breast cancer cells by distinct mechanisms, providing evidence to advocate the adjunct use of analogous pharmaceutics to increase or prolong the efficacy of breast cancer treatments. J. Cell. Biochem. 117: 2249-2259, 2016. © 2016 Wiley Periodicals, Inc.