Decoding 3D chromatin architecture reveals distinct enhancer classes underlying hierarchical gene regulation in prostate cancer [ATAC-Seq]

Background: The transcription process is controlled by non-coding regulatory elements, more than 70% of which are putative enhancers. These enhancers comprise over 600,000 regions and are marked by histone modifications. However, the mechanisms by which altered enhancers in cancer cooperate within the three-dimensional chromatin architecture to drive oncogenic programs remain poorly understood. Results: By integrating 201 H3K27ac ChIP seq datasets from prostate, we identify 3,216 high confidence prostate cancer-specific putative enhancers. Ultra high resolution chromatin interaction profiling by Region Capture Micro-C at a representative chr6q24.1 locus reveals that these enhancers form cancer specific, highly nested interactions with promoters that coalesce into a multi connected hub absent in normal prostate cells. CRISPR/Cas9 perturbations of these enhancers, examined one by one, distinguish enhancer classes within the hub. Deletion of a central enhancer collapses hub-wide enhancer activities and architecture, leading to the downregulation of target genes, impaired proliferation, and reduced clonogenic growth. In contrast, deletion of a redundant enhancer results in minimal transcriptional changes, as neighboring enhancers rescue cancer signaling through compensatory architectural rewiring that strengthens alternative enhancer-promoter interactions. We also observe that FOXA1, a pioneer transcription factor activated in prostate cancer, directly binds to these enhancers and regulates distinct enhancer classes, leading to varying degrees of chromatin accessibility and gene expression changes. Conclusions: These findings suggest that enhancers function in a coordinated manner, forming multi-connected cancer-specific chromatin interaction hubs, with distinct enhancer classes contributing differently to gene regulation. This study advances our ability to modulate gene expression in a cell type-specific manner, opening new avenues for precision therapies.