GSE162057
Epigenetic biomarkers for EZH2 inhibitor sensitivity in neuroblastoma [ChIP-seq]
EZH2 is a H3K27 methylase and a target of cancer epigenetic treatments. We recently reported the oncogenic roles and NTRK1 (TRKA) epigenetic regulation by EZH2 in the MYCN-amplified aggressive neuroblastomas (NB) (L. Here, we investigated the effects and function of small molecule EZH2 inhibitor (EZH2i) on aggressive NB model cell lines. We examined the antitumor effects of EZH2i using WST assay and colony formation assay. By EZH2i treatments, suppression of proliferation, G0/G1 cell cycle arrest, and apoptosis were observed in sensitive NB cells dose-dependently, whereas they were not observed in resistant NB cells. Transcriptome analysis and GSEA indicated significant changes were observed in the gene set related to differentiation and cell cycle arrest in the sensitive cells. We selected genes induced at mRNA level by EZH2i only in the sensitive cells and confirmed tumor suppressor function in NB cells. Almost of the EZH2i-induced gene promoters were marked by H3K27me3 in the sensitive NB cell line. Interestingly, a part of the EZH2i-induced gene promoters have CpG islands and methylated in NB tumor samples registered in databases and the EZH2i-resistant NB cells. Further, combination of EPZ-6438 and 5-aza-deoxycitide, resulted in effective suppression of proliferation in the EPZ-6438-resistant 3 NB cell lines. Transcriptome/methylome analysis of the EPZ-6438 and 5-aza-deoxycitide-treated NB cells revealed the combinational epigenetic regulation of the tumor suppressors and oncogene expression. Finally, we found that methylome analysis of the promoter regions, e.g. VSTM2L, GPNMB, and TIMP3 CpG islands can be biomarkers of EPZ-6438-registancy in unfavorable NB patients. These responsible CpG island methylation appears to be biomarkers for the application of EZH2i/DNMTi combination therapy. Overall design: We performed EZH2, H3K3me3, H3K27ac, H3K27me3 and MYCN for neuroblastoma cell, IMR32.