Genome-wide analysis of PIAS1 on AR gene expression in MDA-MB453

The majority of breast cancer subtypes express androgen receptor (AR) in addition to estrogen receptor α (ERα). Depending on the breast cancer subtype androgen signaling has either stimulatory or inhibitory roles in breast cancer cell growth. We have mapped AR cistrome in ERα negative human molecular apocrine breast cancer MDA-MB453 cells and analyzed it in relation to the androgen-regulated transcriptome in the same cells. We have also examined the effect of silencing of the coregulator SUMO ligase PIAS1 on the androgen-regulated transcriptome and AR cistrome in MDA-MB453 cells. Our results show that the MDA-MB453 cells share with VCaP prostate cancer cells a core AR cistrome and target gene signature linked to cancer cell growth and that PIAS1 acts as an AR target gene-selective coregulator in MDA-MB453 cells. MDA-MB453 cells were transfected with control siRNA (siNON) or PIAS1 siRNA (siPIAS1) for 72 h and treated 16 h with 10 nM R1881 or vehicle (ethanol). Total RNA was isolated and biological triplicate samples were analyzed by microarray.