Introduction: Treatment-emergent neuroendocrine prostate cancer (NEPC) after androgen receptor (AR) targeted therapies has been an aggressive variant of prostate cancer with unfavorable prognosis and limited therapeutic options. This study aims to identify potential neural lineage signature genes and evaluate whether they could serve as early biomarkers to stratify patients for optimal treatment and potential therapeutic targets in advanced prostate cancer. Methods: We performed transcriptomic analysis on the enzalutamide-resistant prostate cancer cell lines and advanced prostate cancer patient databases to identify neural lineage signature (NLS) genes including ARHGEF2. The correlation of NLS genes with clinicopathologic features was determined. RNA sequencing analysis and viability of tumor organoids were performed on C4-2B MDVR and H660 cells with ARHGEF2 knocking down and gene set enrichment was analyzed. Results: We identified a 95-gene NLS representing the molecular landscape of neural precursor cell proliferation, embryonic stem cell pluripotency and neural stem cell differentiation, which may indicate a spectrum of early and intermediate stages of neuroendocrine differentiation. These NLS genes positively correlate with conventional neuroendocrine (NE) markers such as chromogranin and synaptophysin, and negatively correlate with AR and AR target genes. Differentially expressed NLS genes stratify small cell NEPC from prostate adenocarcinoma, which is closely associated with higher Gleason Score and metastasis status. Higher ARHGEF2 levels correlate with a shortened survival time in NEPC patients. ARHGEF2 regulates neuron differentiation and neural precursor cell proliferation which are significantly enriched in treatment-emergent NEPC patients and H660 cells. Upregulation of ARHGEF2 in both patient and experimental models positively correlates with NE markers. ARHGEF2 knocking down inhibited tumor organoids viability and NE markers in enzalutamide-resistant and NEPC cells. Conclusions: Our studies suggest that ARHGEF2 activation promotes neural lineage plasticity contributing to the survival and proliferation of enzalutamide-resistance and NEPC cells. ARHGEF2 could serve as a biomarker to stratify advanced prostate cancer patients for better treatment options and a potential therapeutic target in advanced prostate cancer. SOURCE OF Funding: NIH CA253605, CA 225836, CA250082, DOD PC180180.
