Fig. 7

Bone tissue culture supernatants generated in the presence of testosterone have elevated estrogen levels and increased capacity to promote estrogen receptor-positive (ER+) breast cancer cell proliferation. a Experimental design in which bone tissue fragments are cultured in the presence of phenol red-free medium with 10% charcoal-stripped FBS containing testosterone in the presence vs. absence of letrozole. Supernatants were harvested and used to culture breast cancer cells growing on plastic and analyzed for estradiol levels via ELISA. b Bioluminescence imaging (BLI) signal (non-log) detected for ER+ MCF-7, and ER- SK-BR-3 and MDA-MB-231 cells cultured with supernatants generated by bone fragments isolated from total hip replacement (THR) specimen 147 in the presence of 10 nM testosterone +/− 100 nM letrozole, vs. 0 nM testosterone/letrozole. Each cell line was also cultured in control medium (phenol red-free medium with 10% charcoal-stripped FBS) in the presence vs. absence of 10 nM testosterone. c Averaged triplicate BLI signal detected on plate shown in b. BLI signal was significantly increased for ER+ MCF-7 cells, but not ER- SK-BR-3 or MDA-MB-231 breast cancer cells cultured with bone tissue-conditioned medium generated in the presence of 10 nM testosterone, as determined by t test (n = 3, error bars represent standard deviation). Although signal was reduced in the presence of 100 nM letrozole, the reduction was not significant. d ELISA analysis of triplicate aliquots of conditioned media collected from cultures of bone tissue fragments, showing elevated levels of estradiol in supernatants generated in the presence of 10 nM vs. 0 nM, or 10 nM testosterone + 100 nM letrozole (56.8 vs. 30.8 and 10.6 pg/mL, respectively) (*p = 0.047), as determined by analysis of variance, where n = 3 and error bars represent standard deviation