Notch signaling suppresses neuroendocrine differentiation and alters the tumor immune microenvironment in advanced prostate cancer

Neuroendocrine prostate cancer (NEPC) is an aggressive, androgen-independent variant of prostate cancer (PCa) that most commonly develops in patients as a mechanism of therapeutic resistance. The underlying mechanisms driving PCa lineage plasticity and trans-differentiation to a neuroendocrine lineage are not fully understood. Here, we identify Notch signaling as a key suppressor of neuroendocrine differentiation in PCa. Restoration of Notch signaling in NEPC models results in phenotypic conversion towards a non-neuroendocrine state with expression of prostate luminal cell markers and immunologic changes including up-regulation of MHC Class I and II and type I interferon signaling that correlate with changes in the tumor immune microenvironment. Overall, these data provide new insights into how Notch signaling influences PCa lineage plasticity and points to new therapeutic avenues to modulate it. To investigate the role of ASCL1 in neuroendocrine prostate cancer, we knocked out ASCL1 using CRISPR-Cas9 in NEPC organoids, WCM154, and inoculated organoids in vivo to investigate the tumor phenotype. We performed RNA-seq on control (sgGFP) and ASCL1 knockout (sgASCL1) tumors from three independent mice per condition. Differential expresesion analysis was then performed to illuminate gene expression.