The transcriptional co-repressor Runx1t1 is essential for N-Myc-driven neuroblastoma tumorigenesis [ChIP-Seq]

Changes in epigenetic regulation are believed to be a major contributing factor to neuroblastoma development. Using a large-scale in vivo mutagenesis screen in Th-MYCN transgenic mice, we identified a single point mutation in the transcriptional corepressor Runx1t1, that can block N-Myc-driven neuroblastoma tumorigenesis. The loss of function mutation disrupts a highly conserved zinc finger domain (NHR4) within Runx1t1. Crossing an independent Runx1t1 knockout model with Th-MYCN mice, demonstrated that Runx1t1 haploinsufficiency is enough to prevent neuroblastoma development and reverse ganglia hyperplasia. Silencing RUNX1T1 in human neuroblastoma cells resulted in decreased colony formation in vitro, and significant inhibition of tumor growth in vivo. Our results show that RUNX1T1 forms part of a transcriptional LSD1-CoREST3-HDAC repressive complex that regulates the epigenomic landscape and chromatin accessibility, to control neuron-specific pathway genes and maintain an undifferentiated state. Runx1t1 thus represents an entirely novel and highly promising target not previously described in neuroblastoma. KELLY cells containing doxycycline-inducible shRNA to Runx1t1 were cultured with and without treatment. After 72 hours, 12 × 106 cells were fixed per condition to perform ChIP assays and sequencing for K4 monomethyl-histone H3 (H4K4me1), K4 dimethyl-histone H3 (H3K4me2), K4 trimethyl-histone H3 (H3K4me3), k27 acetyl-histone H3 (H3K27AC), and K27 trimethyl-histone H3 (H3K27me3) based on ChIP-seq method as previously described ( Valdés-Mora F et, al, 2017).