Re-programing chromatin with a bifunctional LSD1/HDAC inhibitor induces therapeutic differentiation in DIPG [ChIP-seq]

Histone H3 lysine 27 to methionine mutations (H3K27M) resulting in aberrant chromatin regulation are frequently observed in Diffuse Intrinsic Pontine Glioma (DIPG), a pediatric brain tumor with no cure. We conducted a CRISPR screen to determine if various chromatin regulators might be targeted to treat DIPG. Excitingly, this genetic screen reveals that co-targeting lysine specific demethylase 1 (LSD1) and histone deacetylases (HDACs) results in an enhanced growth suppressive effect in patient DIPG cells. Consistent with the genetic screen, a bifunctional inhibitor of HDACs and LSD1, Corin, inhibits DIPG growth in vitro and in xenografts. Mechanistically, Corin rescues H3K27me3 levels typically suppressed by the dominant effects of H3K27M mutations in DIPG and simultaneously increases HDAC-targeted H3K27ac and LSD1-targeted H3K4me1 at enhancers. Further studies reveal that Corin de-regulates DIPG transcription resulting in cell death, cell cycle arrest, and the induction of neuronal differentiation. These data suggest that co-targeting LSD1 and HDACs may represent a novel strategy for treating DIPG. We performed ChIP-seq using antibodies to H3K27me3, H3K27ac, and H3K4me1 modified histones in SU-DIPGXIII diffuse intrinsic pontine glioma cells after one week of treatment with either DMSO (control) or a dual inhibitor of LSD1 and HDACs 1-3 (Corin).