Change in transcriptome upon G9a knockdown in RD ERMS (Embryonal Rhabdomyosarcoma) cells

The Wnt signaling pathway is down-regulated in embryonal rhabdomyosarcoma (ERMS) and contributes to the block of myogenic differentiation. Epigenetic mechanisms leading to its suppression are unknown and could pave the way towards novel therapeutic modalities. In this study, we demonstrate that the lysine methyltransferase G9a suppresses the canonical Wnt signalling pathway by activating expression of the Wnt antagonist DKK1. Inhibition of G9a expression or activity reduced DKK1 expression and elevated canonical Wnt signalling resulting in myogenic differentiation in vitro and in vivo. Mechanistically, G9a impacted Sp1 and p300 enrichment at the DKK1 promoter in a methylation-dependent manner. The reduced tumor growth upon G9a deficiency was reversed by recombinant DKK1 or LGK974, which also inhibits Wnt signaling. Consistently, among thirteen drugs targeting chromatin modifiers, G9a inhibitors were highly effective in reducing ERMS cell viability. Together, our study demonstrates that ERMS cells are vulnerable to G9a inhibitors and suggest that targeting the G9a-DKK1--catenin node holds promise for differentiation therapy. We report the transcriptomic changes through RNA sequencing analysis upon transient knockdown of G9a in RD Embryonal Rhabdomyosarcoma cell line Three biological replicates for control RD cells (siscm) and three biological replicates for siG9a knockdown RD cells were analyzed .