Decoding 3D chromatin architecture reveals distinct enhancer classes underlying hierarchical gene regulation in...

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.

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.

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.