Fig. 2

HOXC11 is recruited to the prosaposin (PSAP) promoter when estrogen signalling is disrupted. a HOXC11 is present on the PSAP promoter in letrozole-resistant (LetR) cells cultured in androstenedione but not estrogen. HOXC11 is not present on the PSAP promoter in LY2 (tamoxifen (Tam) resistant) cell cultures in estrogen. Cycle threshold (ct) values were not detected for distal-promoter control reactions for any sample. Error bars are representative of mean ± standard error of the mean from three separate experiments (LetR) and two separate experiments (LY2). b In summary, HOXC11 is recruited to the PSAP promoter in endocrine-resistant breast cancer cells in which estrogen signalling has been disrupted. c (i) Expression of PSAP mRNA is significantly reduced in LY2 cells following silencing of HOXC11 by siRNA. (ii) Expression of PSAP mRNA is significantly reduced in LetR cells following silencing of HOXC11 by siRNA. Results are representative of three separate experimental replicates. d HOXC11 and PSAP mRNA levels were evaluated by qRT-PCR from RNA extracted from primary breast cancer specimens (n = 51). Spearman’s rank test was used to evaluate correlation between PSAP and HOXC11 transcripts (r = 0.7745: p <0.0001). *p <0.05, **p <0.001, ***p <0.0001). Andro androstenedione, HRE hormone response element