Enhancer Transcription Reveals Subtype-Specific Transcription Programs Controlling Breast Cancer Pathogenesis [GRO-Seq]

Noncoding transcription is a defining feature of active enhancers, linking transcription factor (TF) binding to the molecular mechanisms controlling gene expression. To determine the relationship between enhancer activity and biological outcomes in breast cancers, we profiled the transcriptomes (using GRO-seq and RNA-seq) and epigenomes (using ChIP-seq) of 13 different breast cancer cell lines representing the five major molecular subtypes of breast cancer. In addition, we developed a robust and unbiased computational pipeline that simultaneously identifies putative subtype-specific enhancers and their cognate TFs by integrating the magnitude of enhancer transcription, TF mRNA expression levels, TF motif p-values, and enrichment of H3K4me1 and H3KK27. When applied across the 13 different breast cancer cell lines, the Total Functional Score of Enhancer Elements (TFSEE) identified key breast cancer subtype specific transcription factors that act at transcribed enhancers to dictate gene expression patterns determining growth outcomes. To determine the relationship between enhancer activity and biological outcomes in breast cancers, we profiled the transcriptomes (using GRO-seq and RNA-seq) and epigenomes (using ChIP-seq) of 13 different breast cancer cell lines representing the five major molecular subtypes of breast cancer.