N-Myc-mediated epigenetic reprogramming drives lineage plasticity in advanced prostate cancer [ChIP-seq]

Despite recent advances in highly effective androgen receptor (AR)-directed therapies for the treatment of prostate cancer, a significant subset of patients with resistant disease develop AR-null, androgen signaling-indifferent neuroendocrine prostate cancer (NEPC). A majority of these NEPC cases that arise following anti-androgen therapy are driven by the aberrant expression of the transcription factor N-Myc. To define the cell lineage states associated with the development of prostate cancer resistance phenotypes, we analyzed whole transcriptome data from a cohort of primary and metastatic tumors compared to benign tissues. NEPC tumors are significantly enriched for stem cell genes associated with embryonic and neural crest lineages, as well as for neural lineage-defining genes. Analysis of the N-Myc transcriptome, cistrome and chromatin-bound interactome using in vivo (GEMM and human xenografts), in vitro (human prostate cancer cell lines) and ex vivo models (NEPC-patient-derived organoids) revealed that the N-Myc cistrome is androgen-dependent and drives a transcriptional program that leads to epithelial plasticity and the acquisition of clinically-relevant neural lineage markers. Moreover, we show that histone marks specifically associated with lineage-defining genes are epigenetically reprogrammed by N-Myc. Finally, we demonstrate how N-Myc-induced gene expression and epigenetic changes can accurately classify patients with advanced prostate cancer which may provide a molecular signature to inform future therapeutic strategies.