Inhibition of histone H3K27 demethylases inactivates brachyury (TBXT) and promotes chordoma cell death (ChIP-seq)

ABSTRACT: Expression of the transcription factor brachyury (TBXT) is normally restricted to the embryo and its silencing is epigenetically regulated. TBXT promotes mesenchymal transition in a subset of common carcinomas, and in chordoma, a rare cancer showing notochordal differentiation, TBXT acts as a putative oncogene: we hypothesised that TBXT expression could be controlled through epigenetic inhibition to promote chordoma cell death. Screening of five human chordoma cell lines revealed that pharmacological inhibition of the histone 3 lysine 27 demethylases KDM6A (UTX) and KDM6B (JMJD3) leads to cell death. This effect was phenocopied by the dual genetic inactivation of KDM6A/B using CRISPR/Cas9. Inhibition of KDM6A/B using a novel compound, KDOBA67, led to a genome-wide increase in repressive H3K27me3 marks, with concomitant reduction in H3K27ac, H3K9ac and H3K4me3 active marks. We show that TBXT is a KDM6A/B target gene, and that changes in the chromatin at TBXT following KDOBA67 treatment were associated with a reduction in TBXT protein levels in all models tested, including primary patient-derived cultures. KDOBA67 downregulated also the expression of a network of transcription factors critical for chordoma survival, whereas upregulated pathways were dominated by ATF4-driven stress and pro-apoptotic responses in all models. Blocking the AFT4-stress response did not prevent the suppression of TBXT and induction of cell death, but viability was increased by ectopic overexpression of TBXT, therefore implicating TBXT as potential therapeutic target of H3K27 demethylases inhibitors. Our work highlights how knowledge of normal processes in fetal development can provide insight into tumourigenesis and identify novel therapeutic approaches.

ORGANISM(S): Homo sapiens

PROVIDER: GSE150600 | GEO | 2020/09/01

REPOSITORIES: GEO