GSE118407
Grainyhead-like 2 (GRHL2) and epigenetic remodeling in the intermediate states of epithelial-mesenchymal transition [RNA-seq]
Ovarian cancer (OC) cells exhibit varying extents of epithelial/mesenchymal phenotype, forming an EMT spectrum based on their EMT scores. Combining 450K DNA methylation array, ChIP-sequencing of five histone H3 marks (H3K4me1, H3K4me3, H3K27Ac, H3K27me3 and H3K9me3) and transcriptomic analyses, we examined the genome-wide epigenetic profiles of OC cell lines with progressive EMT phenotypes, including a knockdown model of EMT suppressor Grainyhead-like 2 (GRHL2) which showed intermediate state transition. We identified differentially methylated CpG sites (DMCs) associated with EMT genes, found mainly at the promoters of epithelial genes including CDH1, GRHL2 and genes with GRHL2 binding sites. This prompted us to further study the epigenetic role of GRHL2. GRHL2-knockdown resulted in CpG methylation gain at GRHL2 binding sites and at DMCs associated with epithelial genes. Importantly, the changes of histone modifications occurred in GRHL2-knockdown cells are also more prominent among epithelial genes and at GRHL2 binding sites—reduction in permissive marks H3K4me3 and H3K27ac; elevated repressive mark H3K27me3—similar to the transitions observed in a four-cell-line model representing the EMT spectrum. We tested the effects of GRHL2 overexpression in conjunction with epigenetic drugs 5-azacitidine, GSK126 and mocetinostat, all of which exerted MET effects to different extents, depending on the existing cell state. Overall, GRHL2 is required for the epigenetic and chromatin remodeling of epithelial genes during EMT/MET that control intermediate phenotype switching. Overall design: Total RNA of OVCA4209 control and GRHL2 knockdown (shGRHL2#12) cells were analyzed.