Investigate FOXA2 regulated chromatin state program  during NEPC transformation by ATAC-seq.
Emerging evidence suggests that the epigenetic state, including the DNA methylation, chromatin accessibility and histone modification, is substantially remodeled, leading to transcriptional reprogramming during the transformation of castration resistant adenocarcinoma (CRPC-Adeno) to neuroendocrine (CRPC-NE) lineage and LUAD to LUAD-SCLC lineage . However, the underlying mechanism is largely unknown. Here, we found FOXA2 transdifferentiates prostate adenocarcinoma away from an AR+/AR gene signature positive (AR+/ARS+) luminal cell lineage to an embryonic and neuroendocrine-lineage by inducing a population of AR+/ARS- transient cells through NKX2-1. Mechanistically, as a pioneer factor, FOXA2 primes NE lineage enhancers by inducing regional chromatin accessibility and DNA demethylation at early stage of transformation. Whereas, once the expression of NKX2-1 is induced by FOXA2, FOXA2 interacts with NKX2-1, mediates gene promoter and enhancer looping and cooperatively recruits P300/CBP complex to NE lineage enhancers, thereby activates NE lineage gene transcription. Interestingly, similar mechanism is also observed in SCLC cancer, suggesting FOXA2 and NKX2-1 are general regulators orchestrating the epigenetic landscape of NE lineage cancer. Finally, therapeutic targeting P300/CBP with CCS1477 which is in clinical trial for lethal PCa significantly impairs NEPC tumor growth. Overall design: To examine  whether the chromatin state was regulated by FOXA2 during NEPC transformation.  We performed the Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) in LNCaP FOXA2 time course cells (FOXA2-D0, D2, D7, D14, D21 and D28).