EC-8042 disrupts both the primary SP/KLF transcription regulatory network and the secondary network induced by HDACi treatment. [SP1&H3K27me3 CUT&Tag]

Diffuse intrinsic pontine gliomas (DIPGs), frequently harboring H3K27M mutations, are lethal pediatric brain tumors within no effective treatment. The DIPG-opened chromatin regions are proved to be highly enriched for SP/KLF motifs. Using CUT&Tag of SP1 and H3K27me3 in human pontine progenitor cells (hPPCs) and H3K27M-mutated DIPG cells, we detected the gain of SP1 occupancy correlates with the loss of H3K27me3. Here our epigenomic analyses uncover a marked enrichment of the SP/KLF transcription factors in open chromatin regions specifically in H3K27M-mutated DIPG cells compared to normal pontine neural progenitor cells. We show that SP1 depletion or inhibition of SP/KLF DNA binding with EC-8042, an optimized Mithramycin analog, significantly suppresses the proliferation and invasiveness of H3K27M-DIPG cells. In a screen of epigenetic drugs, we find that histone deacetylase inhibitors (HDACi) synergize with EC-8042 to suppress H3K27M-DIPG cell growth. CUT&Tag of SP1 in SU-DIPG-XVII cells after treated with DMSO, EC-8042, vorinostat and combination vorinostat with EC-8042 revealed that HDACi treatment enhances chromatin accessibility to SP/KLF factors, while EC-8042 disrupts both the primary SP/KLF transcription regulatory network and the secondary network induced by HDACi treatment.