GSE126003
IL6/STAT3 co-opts ER/FOXA1 regulatory elements to drive metastasis in breast cancer (RNA-Seq)
Interleukin 6 (IL6) signaling has been associated with an aggressive and metastatic phenotype in multiple solid tumors including breast cancer, but its mechanism of action in mediating tumor progression and treatment response is not clear. By exploiting a clinically relevant intraductal xenograft model of estrogen receptor a positive (ER+) breast cancer, we demonstrate that IL6 increases both primary tumor growth and distant metastases. In pre-clinical models and clinical specimens, signal transducer and activator of transcription 3 (STAT3) mediates IL6-induced activation of a metastatic gene program from enhancers shared with ER and its pioneer factor FOXA1. However, STAT3 drives transcription independent of ER and FOXA1 function from these enhancers, and the IL6/STAT3 pathway is therefore resistant to ER-targeted therapies, decoupling these two important oncogenic pathways. This demonstrates that ER/FOXA1 and IL6/STAT3 are two parallel, but functionally independent and actionable pathways controlling breast cancer progression. Overall design: RNA-seq in human breast cancer cell lines in response to short-term interleukin 6 (IL6) treatment