The role of GRHL2 and epigenetic remodeling in epithelial–mesenchymal plasticity in ovarian cancer cells

TLDR

Cancer cells exhibit phenotypic plasticity during EMT and MET, involving intermediate states. The study aims to investigate genome‑wide epigenetic remodeling associated with EMT plasticity in ovarian cancer cells. The authors integrated DNA methylation, ChIP‑seq of five histone marks, and transcriptome profiling on ovarian cancer cells of varying epithelial/mesenchymal states and on a GRHL2 knockdown model. Differentially methylated CpG sites at epithelial gene promoters and GRHL2 binding sites were identified, and GRHL2 knockdown induced CpG methylation gain and nucleosomal remodeling (loss of H3K4me3 and H3K27ac, gain of H3K27me3) mirroring progressive EMT; epigenetic modifiers further revealed cell‑state‑dependent plasticity upon GRHL2 overexpression, demonstrating that epithelial genes are epigenetically regulated during intermediate EMT/MET phases involving GRHL2.

Abstract

Abstract Cancer cells exhibit phenotypic plasticity during epithelial–mesenchymal transition (EMT) and mesenchymal–epithelial transition (MET) involving intermediate states. To study genome-wide epigenetic remodeling associated with EMT plasticity, we integrate the analyses of DNA methylation, ChIP-sequencing of five histone marks (H3K4me1, H3K4me3, H3K27Ac, H3K27me3 and H3K9me3) and transcriptome profiling performed on ovarian cancer cells with different epithelial/mesenchymal states and on a knockdown model of EMT suppressor Grainyhead-like 2 (GRHL2). We have identified differentially methylated CpG sites associated with EMT, found at promoters of epithelial genes and GRHL2 binding sites. GRHL2 knockdown results in CpG methylation gain and nucleosomal remodeling (reduction in permissive marks H3K4me3 and H3K27ac; elevated repressive mark H3K27me3), resembling the changes observed across progressive EMT states. Epigenetic-modifying agents such as 5-azacitidine, GSK126 and mocetinostat further reveal cell state-dependent plasticity upon GRHL2 overexpression. Overall, we demonstrate that epithelial genes are subject to epigenetic control during intermediate phases of EMT/MET involving GRHL2.