Fig. 3.

Prosaposin (PSAP), a known androgen receptor (AR) activator, is readily detectable in breast cancer cells that have high endogenous levels of HOXC11 and AR protein. a Secreted PSAP protein levels were evaluated in conditioned media harvested from a range of breast cancer cell lines that were designated endocrine-sensitive (MCF7, Aro) or endocrine-resistant (LY2, letrozole-resistant (LetR) and anastrozole-resistant (AnaR)). PSAP ELISA detected significant levels of protein in the endocrine-resistant cells. b (i) Protein levels of AR were determined by western blot analysis of nuclear protein cell lysate extracted from breast cancer cells (MCF7, LetR, MDA-MB-453, LY2 and SKBR3). (ii) Endocrine-resistant cells LY2 and LetR exhibited >2 fold increase in AR nuclear protein expression compared to their endocrine-sensitive MCF7 counterparts. Image representative of three experimental replicates. Error bars are representative of mean ± standard error of the mean (SEM) of three separate experiments. c (i) Transient overexpression of HOXC11 in MCF7 cells resulted in a significant increase in the level of nuclear AR. Image representative of three experimental replicates. Error bars are representative of mean ± SEM of three separate experiments. c (ii) Representative images of AR in MCF7 cells with transient overexpression of pSPORT empty vector versus pSPORT HOXC11. d Elevated levels of PSAP, HOXC11 and AR in endocrine-resistant cells. ^§McIlroy et al., 2010. *p <0.05 **p <0.001. Tam tamoxifen, AI aromatase inhibitor