Fig. 6: KDM4B binds to the MYCN promoter and promotes MYCN expression.

A The results of ChIP-seq targeting KDM4B reveal gene regions directly bound by KDM4B. B Venn diagram illustrating the overlap between genes directly bound by KDM4B and those that are differentially expressed following KDM4B knockdown. The results of qPCR confirmed that protein-coding genes were directly bound by KDM4B and differentially expressed after KDM4B knockdown, including genes whose expression increased (C) or decreased (D), after KDM4B knockdown. E Snapshot from the IGV program displaying the KDM4B peaks at the MYCN genomic loci (bottom), from which 3 pairs of specific primers were designed (top). F, G ChIP–PCR assay in H69AR and H446DDP cells demonstrated that a specific antibody against KDM4B, but not isotype IgG, could capture the fragment containing the KDM4B binding site in the MYCN promoter, which was amplified by specific primers using qPCR. H Immunoblot illustrating the relationship between KDM4B and MYCN expression in H69 and H446 cells. I Immunoblot showing the relationship between KDM4B downregulation and MYCN expression in H69AR and H446DDP cells. J Immunoblotting was performed to evaluate the levels of Flag and MYCN after transduction of wild-type or mutant KDM4B in H69 and H446 cells. ***, p < 0.001; **, p < 0.01. *, p < 0.05.