TRIM28 interacts with EZH2 and SWI/SNF to activate genes that promote mammosphere formation

EZH2 is generally associated with H3K27 methylation and gene silencing. Mass spectrometry of the EZH2-interactome in MCF7 cells revealed EZH2-interactions with SWI/SNF subunits and TRIM28, which formed a complex with EZH2 distinct from PRC2. Transcriptome profiling showed that EZH2 primarily activates transcription in MCF7 cells and with TRIM28 co-regulates a set of genes associated with stem cell maintenance and poor survival of breast cancer patients. TRIM28 depletion repressed EZH2 recruitment and expression of this gene set, in parallel with decreased CD44hi/CD24lo mammosphere formation. These results support PRC2-independent functions of EZH2 and TRIM28 in mammary stem cell enrichment and maintenance. TRIM28 ChIP-seq, EZH2 KD RNA-seq and TRIM28 KD RNA-seq in MCF7 cells