Project description:Tumor cell heterogeneity defines therapy responsiveness in neuroblastoma (NB), a cancer derived from immature nerve cells which consists of two primary subtypes: adrenergic and mesenchymal. Adrenergic traits predominate in NB tumors, while mesenchymal features becomes enriched post-chemotherapy or after relapse. The interconversion between these subtypes contributes to NB lineage plasticity, but the underlying mechanisms driving this phenotypic switching remain unclear. Here, we demonstrate that SWI/SNF chromatin remodeling complex ATPases are essential in establishing an mesenchymal gene-permissive chromatin state in adrenergic-type NB, facilitating lineage plasticity. Targeting SWI/SNF ATPases with SMARCA2/4 dual degraders effectively inhibits NB cell proliferation, invasion, and notably, cellular plasticity, thereby preventing chemotherapy resistance. Mechanistically, depletion of SWI/SNF ATPases compacts cis-regulatory elements, diminishes enhancer activity, and displaces core transcription factors (MYCN, HAND2, PHOX2B, and GATA3) from DNA, thereby suppressing transcriptional programs associated with plasticity. These findings underscore the pivotal role of SWI/SNF ATPases in driving intrinsic plasticity and therapy resistance in neuroblastoma, highlighting an epigenetic target for combinational treatments in this cancer.
Project description:Neuroblastoma (NB) comprises mesenchymal (MES) and adrenergic (ADRN) subtypes, and the cell identity is determined by core transcription factors (TFs). However, the binding mechanism of these TFs to DNA and the epigenetic mechanisms governing NB plasticity remain unclear. In this study, we investigated the impact of targeting SWI/SNF ATPases with SMARCA2/4 dual degraders on NB cells. Our results revealed that depletion of SWI/SNF ATPases compacted cis-regulatory elements, diminished enhancer activity, and displaced core TFs (MYCN, HAND2, PHOX2B, and GATA3) from DNA, suppressing transcriptional programs linked to plasticity and invasiveness. These findings underscore the pivotal role of SWI/SNF ATPases in driving NB progression, positioning them as promising therapeutic targets.
Project description:Neuroblastoma (NB) comprises mesenchymal (MES) and adrenergic (ADRN) subtypes, and the cell identity is determined by core transcription factors (TFs). However, the binding mechanism of these TFs to DNA and the epigenetic mechanisms governing NB plasticity remain unclear. In this study, we investigated the impact of targeting SWI/SNF ATPases with SMARCA2/4 dual degraders on NB cells. Our results revealed that depletion of SWI/SNF ATPases compacted cis-regulatory elements, diminished enhancer activity, and displaced core TFs (MYCN, HAND2, PHOX2B, and GATA3) from DNA, suppressing transcriptional programs linked to plasticity and invasiveness. These findings underscore the pivotal role of SWI/SNF ATPases in driving NB progression, positioning them as promising therapeutic targets.
Project description:Neuroblastoma (NB) comprises mesenchymal (MES) and adrenergic (ADRN) subtypes, and the cell identity is determined by core transcription factors (TFs). However, the binding mechanism of these TFs to DNA and the epigenetic mechanisms governing NB plasticity remain unclear. In this study, we investigated the impact of targeting SWI/SNF ATPases with SMARCA2/4 dual degraders on NB cells. Our results revealed that depletion of SWI/SNF ATPases compacted cis-regulatory elements, diminished enhancer activity, and displaced core TFs (MYCN, HAND2, PHOX2B, and GATA3) from DNA, suppressing transcriptional programs linked to plasticity and invasiveness. These findings underscore the pivotal role of SWI/SNF ATPases in driving NB progression, positioning them as promising therapeutic targets.
Project description:Neuroblastoma (NB) comprises mesenchymal (MES) and adrenergic (ADRN) subtypes, and the cell identity is determined by core transcription factors (TFs). However, the binding mechanism of these TFs to DNA and the epigenetic mechanisms governing NB plasticity remain unclear. In this study, we investigated the impact of targeting SWI/SNF ATPases with SMARCA2/4 dual degraders on NB cells. Our results revealed that depletion of SWI/SNF ATPases compacted cis-regulatory elements, diminished enhancer activity, and displaced core TFs (MYCN, HAND2, PHOX2B, and GATA3) from DNA, suppressing transcriptional programs linked to plasticity and invasiveness. These findings underscore the pivotal role of SWI/SNF ATPases in driving NB progression, positioning them as promising therapeutic targets.
Project description:The switch/sucrose non-fermentable (SWI/SNF) complex has a crucial role in chromatin remodelling1 and is altered in over 20% of cancers2,3. Here we developed a proteolysis-targeting chimera (PROTAC) degrader of the SWI/SNF ATPase subunits, SMARCA2 and SMARCA4, called AU-15330. Androgen receptor (AR)+ forkhead box A1 (FOXA1)+ prostate cancer cells are exquisitely sensitive to dual SMARCA2 and SMARCA4 degradation relative to normal and other cancer cell lines. SWI/SNF ATPase degradation rapidly compacts cis-regulatory elements bound by transcription factors that drive prostate cancer cell proliferation, namely AR, FOXA1, ERG and MYC, which dislodges them from chromatin, disables their core enhancer circuitry, and abolishes the downstream oncogenic gene programs. SWI/SNF ATPase degradation also disrupts super-enhancer and promoter looping interactions that wire supra-physiologic expression of the AR, FOXA1 and MYC oncogenes themselves. AU-15330 induces potent inhibition of tumour growth in xenograft models of prostate cancer and synergizes with the AR antagonist enzalutamide, even inducing disease remission in castration-resistant prostate cancer (CRPC) models without toxicity. Thus, impeding SWI/SNF-mediated enhancer accessibility represents a promising therapeutic approach for enhancer-addicted cancers.
Project description:Diffuse midline gliomas (DMGs) including diffuse intrinsic pontine gliomas (DIPGs) bearing lysine-to-methionine mutations in histone H3 at lysine 27 (H3K27M) are lethal childhood brain cancers. These tumors harbor a global reduction in the transcriptional repressive mark H3K27me3 accompanied by an increase in the transcriptional activation mark H3K27ac. We postulated that H3K27M mutations, in addition to altering H3K27 modifications, reprogram the master chromatin remodeling switch/sucrose nonfermentable (SWI/SNF) complex. The SWI/SNF complex can exist in two main forms termed BAF and PBAF that play central roles in neurodevelopment and cancer. Moreover, BAF antagonizes PRC2, the main enzyme catalyzing H3K27me3. We demonstrate that H3K27M gliomas show increased protein levels of the SWI/SNF complex ATPase subunits SMARCA4 and SMARCA2, and the PBAF component PBRM1. Additionally, knockdown of mutant H3K27M lowered SMARCA4 protein levels. The proteolysis targeting chimera (PROTAC) AU-15330 that simultaneously targets SMARCA4, SMARCA2, and PBRM1 for degradation exhibits cytotoxicity in H3.3K27M but not H3 wild-type cells. AU-15330 lowered chromatin accessibility measured by ATAC-Seq at nonpromoter regions and reduced global H3K27ac levels. Integrated analysis of gene expression, proteomics, and chromatin accessibility in AU-15330-treated cells demonstrated reduction in the levels of FOXO1, a key member of the forkhead family of transcription factors. Moreover, genetic or pharmacologic targeting of FOXO1 resulted in cell death in H3K27M cells. Overall, our results suggest that H3K27M up-regulates SMARCA4 levels and combined targeting of SWI/SNF ATPases in H3.3K27M can serve as a potent therapeutic strategy for these deadly childhood brain tumors.