Defined cellular reprogramming of androgen receptor-active prostate cancer to neuroendocrine prostate cancer

Reviewer #1 (Public review):

Summary:

In their manuscript, Li and colleagues introduce a pioneering investigation into the molecular and epigenetic foundations of neuroendocrine transdifferentiation in prostate cancer. By employing a genetically engineered cellular reprogramming approach, they elucidate the pivotal roles of ASCL1 and NeuroD1 as pioneer transcription factors that suppress AR signaling and orchestrate lineage plasticity toward NEPC. Their integrative multi-omics methodology delineates dynamic transcriptional and chromatin reorganization processes, offering profound insights into mechanisms of therapeutic resistance.

Strengths:

(1) The development of a reproducible in vitro reprogramming platform to transition ARPC cells into NEPC represents a significant technical achievement. This model enables high-resolution temporal analysis of NEtD, addressing constraints inherent in traditional PDX systems.

(2) The authors reveal that ASCL1 and NeuroD1 suppress AR signaling through chromatin structural modifications at somatically amplified AR enhancers, a significant discovery that clarifies the longstanding ambiguity surrounding AR pathway inactivation during lineage plasticity.

(3) The integration of RNA sequencing, CUT&RUN, and single-cell multiomic profiling delivers a holistic perspective on dynamic epigenetic and transcriptional reprogramming during NEtD. Their observation that AR suppression precedes NE marker activation provides chronological insights into this process.

(4) By delineating the distinct roles of ASCL1/NeuroD1-driven NE lineage programs versus REST inactivation, the study critiques the excessive dependence on limited immunohistochemical indicators for NEPC classification, directly informing improvements in molecular diagnostics.

(5) The association of ASCL1/NeuroD1 with MHC class I suppression mediated by PRC2 unveils opportunities for combining agents targeting epigenetic modifiers with immune-based therapies to counteract immune evasion in NEPC.

Weaknesses:

While the study is methodologically robust, a modest limitation lies in its primary reliance on established cell lines for mechanistic exploration. Although key observations are corroborated with clinical samples, additional validation in PDX models or organoid systems could enhance translational applicability. Furthermore, while the role of ASCL1/NeuroD1 in AR enhancer silencing is convincingly demonstrated, the upstream regulatory mechanisms governing ASCL1/NeuroD1 induction under therapeutic stress remain unaddressed, a compelling avenue for future research.

Reviewer #2 (Public review):

Summary:

This manuscript reported that the pioneer factors ASCL1 and NeuroD1 in neuroendocrine transdifferentiation of Neuroendocrine prostate cancer (NEPC) and uncovered their abilities to silence AR expression by remodeling chromatin at the somatically acquired AR enhancer and global AR binding sites with enhancer activity. It also elucidated the dynamic temporal changes in the transcriptomic and epigenomic landscapes of cells undergoing acute lineage conversion from AR-active prostate cancer to NEPC which should inform future therapeutic development.

Strengths:

Data from cell lines is great and solid.

Weaknesses:

The paper would be better if some clinical data could be added.

Reviewer #3 (Public review):

Summary:

This study investigates the molecular mechanisms underlying the transdifferentiation of androgen receptor-active prostate cancer (ARPC) to neuroendocrine prostate cancer (NEPC) in prostate cancer (PC). Using a cellular reprogramming strategy, the research team successfully converted ARPC cell lines into NEPC cell lines and explored key molecular mechanisms driving this transformation. The work demonstrates the pivotal role of neurogenic pioneer transcription factors ASCL1 and NeuroD1 in NEPC transdifferentiation, which silence AR expression and signaling by remodeling chromatin architecture while inducing NEPC-associated gene programs. Additionally, the study reveals dynamic transcriptomic and epigenomic changes during NEPC transformation, as well as downregulation of the MHC class I antigen processing and presentation pathway in NEPC cell lines.

Strengths:

(1) The study introduces a novel genetically defined cellular reprogramming strategy to directly convert ARPC to NEPC. This approach circumvents previous limitations by starting from AR-active cells, thereby addressing a critical gap in the field.
(2) The study provides a comprehensive characterization of the dynamic changes in the transcriptomic and epigenomic landscapes during the NEPC transdifferentiation process.

Weaknesses:

(1) What was the rationale for selecting these specific candidate factors (e.g., ASCL1, NeuroD1) to drive neuroendocrine transdifferentiation (NEtD)? Was a comprehensive screening process conducted to identify additional potential drivers of this phenotypic shift?

(‌2) The AR bypass assay employed an AR response element-driven FKBP-Casp8 fusion protein for negative selection. How was the specificity and efficiency of this system validated? Are there additional validation experiments (e.g., orthogonal AR activity assays) to confirm the complete bypass of AR signaling?

(3‌) While extensive omics data (RNA-seq, ATAC-seq, CUT&RUN) are presented, have these datasets been deposited in public repositories (e.g., GEO, SRA) to enable validation and reuse by the scientific community?

(‌4) What criteria guided the selection of time points for analyzing dynamic changes during NEtD? Would denser time-point sampling (e.g., intermediate time courses) enhance resolution of critical transitional events?

(5‌) Were multiple hypothesis testing corrections (e.g., Benjamini-Hochberg) applied during differential expression and pathway enrichment analyses? How was the statistical significance of chromatin accessibility changes and super-enhancer reconfiguration rigorously validated?