It is demonstrated that INSM1 is consistently upregulated across NEPC patient tumors and experimental models, including both ASCL1⁺ and NEUROD1⁺ molecular subtypes, as revealed by integrated bulk and single-cell transcriptomic analyses.
Abstract
Neuroendocrine prostate cancer (NEPC) is a highly aggressive and therapy-resistant subtype that arises from adenocarcinoma through lineage plasticity; however, the molecular mechanisms driving this transition remain incompletely defined. Insulinoma-associated protein 1 (INSM1), a zinc-finger transcription factor and established neuroendocrine lineage marker, has been implicated in a variety of neuroendocrine malignancies, yet its functional contribution to NEPC progression is not well understood. In this study, we demonstrate that INSM1 is consistently upregulated across NEPC patient tumors and experimental models, including both ASCL1⁺ and NEUROD1⁺ molecular subtypes, as revealed by integrated bulk and single-cell transcriptomic analyses. Functional studies revealed that INSM1 is sufficient to induce and necessary to maintain neuroendocrine lineage programs in prostate cancer, as overexpression promoted and depletion suppressed neuroendocrine-associated transcriptional networks. Mechanistically, pro-neural transcription factors, including ASCL1, NEUROD1, NEUROG3, and MYCN, directly or indirectly activate INSM1 expression, positioning it as a critical downstream effector of neuroendocrine lineage specification. Therapeutically, we identify homo-harringtonine (HHT), an FDA-approved protein synthesis inhibitor, as a potent suppressor of INSM1. HHT selectively reduces viability of INSM1-high NEPC cells at nanomolar concentrations, promotes ubiquitin-mediated degradation of INSM1, and significantly inhibits tumor growth in vivo. Notably, INSM1 depletion further enhances cellular sensitivity to HHT treatment. Collectively, our findings establish INSM1 as a key regulator of neuroendocrine plasticity and a promising therapeutic vulnerability in NEPC, providing a rationale for targeting INSM1 to suppress tumor progression.
It is demonstrated that DNMT3B is required for both the initiation and maintenance of the NEPC phenotype, and its inhibition suppresses NEPC growth and differentiation, highlighting it as a promising therapeutic target for treatment-resistant disease.
Yunsol Jo, H. Jung, Zi-Qin Wang et al.· Molecular Cancer Research· 0 citations
Neuroendocrine prostate cancer (NEPC) or small-cell neuroendocrine prostate cancer (SCNPC) is increasingly recognized as a treatment-resistant disease arising among prostate adenocarcinoma (PRAD) patients. It has no effective therapy due to incomplete understanding of the mechanisms underlying treatment-induced cancer cell identity switching. Here, we identified RUNX1 Partner Transcriptional Co-Repressor 1 (RUNX1T1) as a frequently amplified gene in prostate cancer patients, associated with a poorer prognosis. RUNX1T1 is highly expressed and progression-correlated in NEPC and SCNPC. We found that RUNX1T1 is essential for SCNPC survival, as its knockdown induced apoptotic cell death and the acquisition of PRAD-like identity, including alterations in genes involved in cell-cell adhesion and epithelial cell polarity. Functional assays in prostate cancer cell lines revealed that RUNX1T1 regulates genes associated with stemness and the maintenance of neuroendocrine identity in SCNPC. Using our human cell reprogramming assay, which mimics the development of PRAD or SCNPC in vivo, we further demonstrated that RUNX1T1 is required to initiate neuroendocrine differentiation (NED), histological feature changes, and stemness. Its knockout abolished expression of NED and stemness markers and induced loss of SCNPC histological features during SCNPC development. Collectively, these findings establish RUNX1T1 as a critical driver of the cell identity of stem-like SCNPC. Understanding the mechanisms by which RUNX1T1 exerts its versatile regulation of proliferation, stemness, and SCNPC differentiation will in turn pave the way for the discovery of new, specific therapeutic targets to prevent SCNPC progression.
Zi-Qin Wang, H. Jung, Changhyeon Hong et al.· Frontiers in Cell and Develo...· 0 citations
Introduction Neuroendocrine prostate cancer (NEPC) is an aggressive treatment-associated lineage state emerging with potent androgen receptor (AR) pathway inhibition. Although treatment-emergent NEPC is increasingly recognized, the transcriptional consequences of sustained AR suppression remain incompletely defined. It remains unclear to what extent AR-targeted therapies reshape cellular identity and engage neuroendocrine-associated transcriptional programs without full lineage-defining differentiation. Materials and methods Bulk RNA sequencing was performed in AR-dependent LNCaP and castration-resistant C4–2 prostate cancer cells under untreated conditions, androgen deprivation, first-generation AR antagonism with bicalutamide, and second-generation AR pathway inhibition with enzalutamide, using NCI-H660 as a NEPC reference. Transcriptomic organization and pathway-level changes were assessed using principal component analysis, comparative analyses, module score analysis of lineage-associated programs, and Gene Ontology–based functional enrichment. Results In LNCaP cells, AR suppression induced a progressive transcriptomic shift toward the NEPC reference cell line H660, with this trend being most pronounced in enzalutamide-treated cells. Canonical AR target genes (KLK3, TMPRSS2, NKX3-1, and FKBP5) were suppressed, whereas neuroendocrine-associated genes (NCAM1, ENO2, PEG10, and DLL3) showed partial induction. Canonical NEPC markers and lineage-defining transcription factors, including CHGA, INSM1, and SOX2, were not activated. Module score analysis demonstrated selective activation of lineage plasticity–associated programs corresponding to an intermediate Phase 2 state without engagement of canonical neuroendocrine differentiation programs. Gene-wise analyses further showed preferential induction of developmental and plasticity-associated transcriptional programs by enzalutamide compared with bicalutamide. In contrast, C4–2 cells exhibited context-dependent and incomplete neuroendocrine-associated transcriptional changes, consistent with modulation of a pre-existing permissive transcriptional state rather than stable neuroendocrine differentiation. Conclusions Potent AR pathway inhibition does not induce terminal neuroendocrine differentiation in vitro but promotes an adaptive plastic intermediate state characterized by partial activation of neuroendocrine-associated transcriptional programs. These findings suggest that enzalutamide preferentially enhances early lineage plasticity rather than bona fide NEPC differentiation and provide a framework for distinguishing adaptive transcriptional reprogramming from true neuroendocrine lineage conversion in treatment-emergent prostate cancer.
R. Watanabe, M. Chosei, Haruna Arai et al.· Frontiers in Oncology· 0 citations
Lineage plasticity is a major mechanism by which prostate cancer adapts to therapeutic pressure, particularly following sustained inhibition of androgen receptor signaling. A central mediator of this process is BRN2, a POU3F2 neural lineage transcription factor that is normally suppressed in AR-dependent luminal prostate epithelium but becomes aberrantly activated during progression to castration-resistant and neuroendocrine prostate cancer. This review examines how BRN2 connects developmental neurogenesis to therapy-induced tumor reprogramming. We integrate insights from neurodevelopment and direct lineage reprogramming to describe how BRN2 maintains stem-like and neuroendocrine transcriptional states. Mechanistically, we discuss how AR suppression, cooperating oncogenic drivers, epigenetic remodeling, and post-translational modification activate BRN2 and reshape transcriptional networks involving SOX2, Wnt signaling, N-Myc, and EZH2. We also evaluate strategies to target BRN2 and its associated dependencies, including direct inhibition of BRN2 DNA binding and pharmacologic disruption of cooperating epigenetic complexes such as BRD4, EZH2, and LSD1, though EZH2 inhibition may paradoxically promote further neuroendocrine differentiation. We additionally assess BRN2 as a potential circulating biomarker, detectable in extracellular vesicles, though no clinical-grade assay has been validated. This review highlights BRN2 as a key transcriptional regulator of lineage plasticity in prostate cancer, with important implications for overcoming therapy resistance in advanced prostate cancer.
Despite considerable progress in elucidating mechanisms leading to castration-resistant prostate cancer (CRPC), insight into the early stages of prostate cancer initiation and progression remains limited. Genomic drivers of prostate cancer initiation have been defined through patient tumor sequencing, but the subsequent events responsible for local tissue invasion are poorly understood. Here we leverage a well-studied genetically engineered mouse prostate cancer model (Hi-Myc) that, based on robust and reproducible kinetics for transitioning from pre-invasive prostatic intraepithelial neoplasia (PIN) to invasive prostate adenocarcinoma (PCa), provides an ideal system to systematically address this question using single-cell analysis. Surprisingly, the transcriptomic profiles of early PIN lesions are indistinguishable from those of late-stage, highly invasive tumor cells, suggesting that MYC activation at the PIN stage establishes a transcriptional program that is fully capable of driving invasion but is restrained by the local tumor microenvironment (TME). Indeed, we find that progression to PCa is associated with progressive infiltration of IL-1β+ tumor-infiltrating macrophages at the PIN stage that, based on immunodepletion and cytokine neutralization experiments, are required for the PIN-to-PCa transition. Mechanistically, IL-1β from macrophages acts directly on prostate fibroblasts, leading to the release of IL-6, which drives invasion by activating IL-6R in tumor cells. Collectively, these findings identify a pro-tumorigenic IL-1β/IL-6 signaling circuit mediated through local macrophages and fibroblasts that unleashes the full oncogenic potential of a cancer driver (MYC) activated at the PIN stage. We also find evidence of this circuit in other (non-MYC-driven) prostate cancer models as well as human prostate and lung adenocarcinoma, with implications for TME-specific targeted therapeutics in early-stage disease.
Young-Sun Lee, Jimmy L. Zhao, Agnieszka Chryplewicz et al.· bioRxiv· 0 citations
Neuroendocrine tumors (NETs), including aggressive subtypes such as neuroendocrine prostate cancer (NEPC) and small cell carcinomas, are characterized by marked heterogeneity, therapeutic resistance, and limited availability of clinically relevant models. The development of patient-derived systems that faithfully recapitulate tumor biology remains a major barrier to advancing precision oncology in this disease. Here, we applied conditional reprogramming (CR) technology to establish patient-derived neuroendocrine tumor cell cultures (CR-NETs) from primary and metastatic specimens. Using co-culture with irradiated feeder cells and ROCK inhibition, CR-NETs were rapidly expanded from small clinical samples, including biopsies and effusions, with high efficiency and short turnaround time. Comprehensive characterization demonstrated that CR-NETs retain key neuroendocrine features, including expression of canonical markers (e.g., CHGA, SYP), lineage plasticity signatures, and patient-specific genomic alterations. Functional assays revealed preserved tumor heterogeneity and differential responses to standard-of-care agents and targeted therapies. Notably, CR-NETs exhibited distinct vulnerabilities in epigenetic regulation and metabolic pathways, consistent with neuroendocrine differentiation states. Importantly, CR-NETs enabled real-time drug sensitivity testing, identifying patient-specific therapeutic susceptibilities. Collectively, our findings demonstrate that conditional reprogramming provides a robust and scalable approach to generate clinically relevant NET models, enabling functional precision oncology, biomarker discovery, and therapeutic optimization. This platform may facilitate rapid clinical decision-making and accelerate the development of targeted strategies for patients with neuroendocrine malignancies.
Jenny Li, Akshay Sood, Debasish Sundi, Timothy Gauntner, Shang-Jui Wang, Lingbin Meng, Qingqing Wu, Peng Wang, Eric Singer, Anil V. Parwani, Cheryl Lee, Xuefeng Liu. Conditional Reprogramming Enables Rapid Establishment of Patient-Derived Neuroendocrine Tumor Models for Functional Precision Oncology [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Breaking Barriers in the Fight against Rare Cancers; 2026 Jul 18-20; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2026;86(14_Suppl):Abstract nr PR005.
Jenny Li, Akshay Sood, Debasish Sundi et al.· Cancer Research· 0 citations
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