Identification of an NKX3.1-G9a-UTY transcriptional regulatory network that controls prostate differentiation

Transcriptional Regulation in Prostate Cancer

Prostate cancer development involves corruption of the normal prostate transcriptional network, following deregulated expression or mutation of key transcription factors. Here, we provide an overview of the transcription factors that are important in normal prostate homeostasis (NKX3-1, p63, androgen receptor [AR]), primary prostate cancer (ETS family members, c-MYC), castration-resistant prostate cancer (AR, FOXA1), and AR-independent castration-resistant neuroendocrine prostate cancer (RB1, p53, N-MYC). We use functional (in vitro and in vivo) as well as clinical data to discuss evidence that unveils their roles in the initiation and progression of prostate cancer, with an emphasis on results of chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq).

Downregulation of C-Terminal Tensin-Like Protein (CTEN) Suppresses Prostate Cell Proliferation and Contributes to Acinar Morphogenesis

C-terminal tensin-like protein (CTEN) is a member of tensin family, which is crucial for the assembly of cell-matrix adhesome. Unlike other tensins, CTEN is selectively expressed only in a few tissues such as the prostate. However, the biological relevance of CTEN in normal prostate is poorly understood. In this study, we revealed that CTEN is selectively expressed in the prostate epithelial cells and enriched in the basal compartment. Knockdown of CTEN in RWPE-1 cells suppresses cell proliferation and results in G1/S cell cycle arrest as well as the accumulation of cyclin-dependent kinase (CDK) inhibitors, p21 and p27. Moreover, the expression of CTEN is decreased during acinar morphogenesis using Matrigel-based three-dimensional (3D) culture. In the course of acinar formation, induction of CTEN reactivates focal adhesion kinase (FAK) Y³⁹⁷ phosphorylation and disrupts the acini structure. This study, to our knowledge, is the first report demonstrating that downregulation of CTEN is required for luminal differentiation and acinar formation.

Long noncoding RNA lncHand2 promotes liver repopulation via c-Met signaling

BACKGROUND & AIMS

Long noncoding RNAs (lncRNAs) play important roles in various biological processes, regulating gene expression by diverse mechanisms. However, how lncRNAs regulate liver repopulation is unknown. Herein, we aimed to identify lncRNAs that regulate liver repopulation and elucidate the signaling pathways involved.

METHODS

Herein, we performed 70% partial hepatectomy in wild-type and gene knockout mice. We then performed transcriptomic analyses to identify a divergent lncRNA termed lncHand2 that is highly expressed during liver regeneration.

RESULTS

LncHand2 is constitutively expressed in the nuclei of pericentral hepatocytes in mouse and human livers. LncHand2 knockout abrogates liver regeneration and repopulation capacity. Mechanistically, lncHand2 recruits the Ino80 remodeling complex to initiate expression of Nkx1-2 in trans, which triggers c-Met (Met) expression in hepatocytes. Finally, knockout of both Nkx1-2 and c-Met causes more severe liver injury and poorer repopulation ability. Thus, lncHand2 promotes liver repopulation via initiating Nkx1-2-induced c-Met signaling.

CONCLUSIONS

Our findings reveal that lncHand2 acts as a critical mediator regulating liver repopulation. It does this by inducing Nkx1-2 expression, which in turn triggers c-Met signaling.

LAY SUMMARY

Long noncoding RNAs play important roles in various biological processes. While long noncoding RNAs do not directly code proteins, they can regulate gene expression by diverse mechanisms. We identified the long noncoding RNA, termed lncHand2 because of its proximity to the gene Hand2, to be an important determinant of liver regeneration through c-Met signaling.

Transcriptional network analysis on brains reveals a potential regulatory role of PPP1R3F in autism spectrum disorders

OBJECTIVE

This study aims at identifying master regulators of transcriptional networks in autism spectrum disorders (ASDs).

RESULTS

With two sets of independent RNA-Seq data generated on cerebellum from patients with ASDs and control subjects (N = 39 and 45 for set 1, N = 24 and 38 for set 2, respectively), we carried out a network deconvolution of transcriptomic data, followed by virtual protein activity analysis. We identified PPP1R3F (Protein Phosphatase 1 Regulatory Subunit 3F) as a candidate master regulator affecting a large body of downstream genes that are associated with the disease phenotype. Pathway analysis on the identified targets of PPP1R3F in both datasets indicated alteration of endocytosis pathway. Despite a limited sample size, our study represents one of the first applications of network deconvolution approach to brain transcriptomic data to generate hypotheses that may be further validated by large-scale studies.

NKX3-1 is required for induced pluripotent stem cell reprogramming and can replace OCT4 in mouse and human iPSC induction

Reprogramming somatic cells to induced pluripotent stem cells (iPSCs) is now routinely accomplished by overexpression of the four Yamanaka factors (OCT4, SOX2, KLF4, MYC (or OSKM))¹. These iPSCs can be derived from patients' somatic cells and differentiated toward diverse fates, serving as a resource for basic and translational research. However, mechanistic insights into regulators and pathways that initiate the pluripotency network remain to be resolved. In particular, naturally occurring molecules that activate endogenous OCT4 and replace exogenous OCT4 in human iPSC reprogramming have yet to be found. Using a heterokaryon reprogramming system we identified NKX3-1 as an early and transiently expressed homeobox transcription factor. Following knockdown of NKX3-1, iPSC reprogramming is abrogated. NKX3-1 functions downstream of the IL-6-STAT3 regulatory network to activate endogenous OCT4. Importantly, NKX3-1 substitutes for exogenous OCT4 to reprogram both mouse and human fibroblasts at comparable efficiencies and generate fully pluripotent stem cells. Our findings establish an essential role for NKX3-1, a prostate-specific tumour suppressor, in iPSC reprogramming.

Prostate Organogenesis

The prostate is a male exocrine gland that secretes components of the seminal fluid. In men, prostate tumors are one of the most prevalent cancers. Studies on the development of the prostate have given a better understanding of the processes and genes that are important in the formation of this organ and have provided insights into the mechanisms of prostate tumorigenesis. These developmental studies have provided evidence that some of the genes and signaling pathways involved in development are reactivated or deregulated during prostate cancer. The prostate goes through a number of different stages during organogenesis, which include organ specification, epithelial budding, branching morphogenesis, canalization, and cytodifferentiation. During development, these processes are tightly regulated, many of which are controlled by the male hormone androgens. The majority of prostate tumors remain hormone regulated, and antiandrogen therapy is a first-line therapy, highlighting the important link between prostate organogenesis and cancer. In this review, we describe some of the data on genes that have important roles during prostate development that also have strong evidence linking them to prostate cancer.

Aberrant activity of NKL homeobox gene NKX3-2 in a T-ALL subset

T-cell acute lymphoblastic leukemia (T-ALL) is a hematopoietic malignancy originating from T-cell progenitors in which differentiation is blocked at early stages. Physiological expression of specific NKL homeobox genes obeys a hematopoietic NKL-code implicated in the process of lymphopoiesis while in differentiated T-cells these genes are silenced. We propose that this developmental expression pattern underlies the observation that NKL homeobox genes are the most ubiquitous group of transcription factors deregulated in T-ALL, including TLX1, TLX3, NKX2-5 and NKX3-1. Here, we describe a novel member of the NKL homeobox gene subclass, NKX3-2 (BAPX1), which is aberrantly activated in 18% of pediatric T-ALL patients analyzed while being normally expressed in developing spleen. Identification of NKX3-2 expression in T-ALL cell line CCRF-CEM qualified these cells to model its deregulation and function in a leukemic context. Genomic and chromosomal analyses demonstrated normal configuration of the NKX3-2 locus at chromosome 4p15, thus excluding cytogenetic dysregulation. Comparative expression profiling analysis of NKX3-2 patient data revealed deregulated activity of BMP- and MAPK-signalling. These candidate pathways were experimentally confirmed to mediate aberrant NKX3-2 expression. We also show that homeobox gene SIX6, plus MIR17HG and GATA3 are downstream targets of NKX3-2 and plausibly contribute to the pathogenesis of this malignancy by suppressing T-cell differentiation. Finally, NKL homeobox gene NKX2-5 was activated by NKX3-2 in CCRF-CEM and by FOXG1 in PEER, representing mutually inhibitory activators of this translocated oncogene. Together, our findings reveal a novel oncogenic NKL homeobox gene subclass member which is aberrantly expressed in a large subset of T-ALL patients and participates in a deregulated gene network likely to arise in developing spleen.

Quantitative assessment of protein activity in orphan tissues and single cells using the metaVIPER algorithm

We and others have shown that transition and maintenance of biological states is controlled by master regulator proteins, which can be inferred by interrogating tissue-specific regulatory models (interactomes) with transcriptional signatures, using the VIPER algorithm. Yet, some tissues may lack molecular profiles necessary for interactome inference (orphan tissues), or, as for single cells isolated from heterogeneous samples, their tissue context may be undetermined. To address this problem, we introduce metaVIPER, an algorithm designed to assess protein activity in tissue-independent fashion by integrative analysis of multiple, non-tissue-matched interactomes. This assumes that transcriptional targets of each protein will be recapitulated by one or more available interactomes. We confirm the algorithm's value in assessing protein dysregulation induced by somatic mutations, as well as in assessing protein activity in orphan tissues and, most critically, in single cells, thus allowing transformation of noisy and potentially biased RNA-Seq signatures into reproducible protein-activity signatures.

Maternal protein malnutrition: effects on prostate development and adult disease

Well-controlled intrauterine development is an essential condition for many aspects of normal adult physiology and health. This process is disrupted by poor maternal nutrition status during pregnancy. Indeed, physiological adaptations occur in the fetus to ensure nutrient supply to the most vital organs at the expense of the others, leading to irreversible consequences in tissue formation and differentiation. Evidence indicates that maternal undernutrition in early life promotes changes in key hormones, such as glucocorticoids, growth hormones, insulin-like growth factors, estrogens and androgens, during fetal development. These alterations can directly or indirectly affect hormone release, hormone receptor expression/distribution, cellular function or tissue organization, and impair tissue growth, differentiation and maturation to exert profound long-term effects on the offspring. Within the male reproductive system, maternal protein malnutrition alters development, structure, and function of the gonads, testes and prostate gland. Consequently, these changes impair the reproductive capacity of the male offspring. Further, permanent alterations in the prostate gland occur at the molecular and cellular level and thereby affect the onset of late life diseases such as prostatitis, hyperplasia and even prostate cancer. This review assembles current thoughts on the concepts and mechanisms behind the developmental origins of health and disease as they relate to protein malnutrition, and highlights the effects of maternal protein malnutrition on rat prostate development and homeostasis. Such insights on developmental trajectories of adult-onset prostate disease may help provide a foundation for future studies in this field.

Lineage Plasticity in Cancer Progression and Treatment

Historically, it has been widely presumed that differentiated cells are determined during development and become irreversibly committed to their designated fates. In certain circumstances, however, differentiated cells can display plasticity by changing their identity, either by dedifferentiation to a progenitor-like state or by transdifferentiation to an alternative differentiated cell type. Such cellular plasticity can be triggered by physiological or oncogenic stress, or it can be experimentally induced through cellular reprogramming. Notably, physiological stresses that promote plasticity, such as severe tissue damage, inflammation, or senescence, also represent hallmarks of cancer. Furthermore, key drivers of cellular plasticity include major oncogenic and tumor suppressor pathways and can be exacerbated by drug treatment. Thus, plasticity may help cancer cells evade detection and treatment. We propose that cancer can be considered as a disease of excess plasticity, a notion that has important implications for intervention and treatment.

Genetics of the human Y chromosome and its association with male infertility

The human Y chromosome harbors genes that are responsible for testis development and also for initiation and maintenance of spermatogenesis in adulthood. The long arm of the Y chromosome (Yq) contains many ampliconic and palindromic sequences making it predisposed to self-recombination during spermatogenesis and hence susceptible to intra-chromosomal deletions. Such deletions lead to copy number variation in genes of the Y chromosome resulting in male infertility. Three common Yq deletions that recur in infertile males are termed as AZF (Azoospermia Factor) microdeletions viz. AZFa, AZFb and AZFc. As estimated from data of nearly 40,000 Y chromosomes, the global prevalence of Yq microdeletions is 7.5% in infertile males; however the European infertile men are less susceptible to Yq microdeletions, the highest prevalence is in Americans and East Asian infertile men. In addition, partial deletions of the AZFc locus have been associated with infertility but the effect seems to be ethnicity dependent. Analysis of > 17,000 Y chromosomes from fertile and infertile men has revealed an association of gr/gr deletion with male infertility in Caucasians and Mongolian men, while the b2/b3 deletion is associated with male infertility in African and Dravidian men. Clinically, the screening for Yq microdeletions would aid the clinician in determining the cause of male infertility and decide a rational management strategy for the patient. As these deletions are transmitted to 100% of male offspring born through assisted reproduction, testing of Yq deletions will allow the couples to make an informed choice regarding the perpetuation of male infertility in future generations. With the emerging data on association of Yq deletions with testicular cancers and neuropsychiatric conditions long term follow-up data is urgently needed for infertile men harboring Yq deletions. If found so, the information will change the current the perspective of androgenetics from infertility and might have broad implication in men health.

TRAF6 regulates proliferation of stromal cells in the transition and peripheral zones of benign prostatic hyperplasia via Akt/mTOR signaling

BACKGROUND

Increased prostatic smooth muscle tone and hyperplastic growth contribute to urethral obstruction and voiding symptoms in benign prostatic hyperplasia (BPH). It has been suggested that different proliferative potential of stromal cells between transition zone (TZ) and adjoining regions of the prostate plays a significant role in the development of BPH. However, the molecular mechanisms of this hyperplastic process remain unclear. We found tumor necrosis factor receptor-associated factor 6 (TRAF6) highly expressed in TZ stromal cells compared to peripheral zone (PZ) stromal cells by gene array analyzes. Therefore, we aim to study the potential mechanisms of stromal TRAF6 in promoting BPH progression.

METHODS

Stromal cells obtained from BPH-derived primary cultures. The TRAF6-siRNA vector were constructed and transfected into cultured human BPH primary TZ stromal cells, and TRAF6-overexpressing vector were constructed and transfected into cultured human BPH primary PZ stromal cells. Stromal cells were recombined with BPH-1 cells then subcutaneously inoculated into the kidney capsule of male nude mice. Cell proliferation was evaluated by CCK-8 assay. Multiple proteins in the Akt/mTOR pathway were assessed using western blot.

RESULTS

TRAF6 levels were increased in TZ stroma compared with PZ stroma of BPH. The in vitro cell culture and in vivo cell recombination revealed that selective downregulation of TRAF6 in TZ stromal cells led to suppression of the proliferation, while upregulation of TRAF6 in PZ stromal cells enhanced the proliferation. We found that the Phosphorylation and Ubiquitination of Akt as well as the Phosphorylation of mTOR, P70^S6K were decreased when TRAF6 was downregulated in primary cultured TZ stromal cells of BPH.

CONCLUSIONS

TRAF6 can promote the proliferation of stromal cells of BPH via Akt/mTOR signaling. Our results may make stromal TRAF6 responsible for zonal characteristic of BPH and as a promising therapeutic strategy for BPH treatment.

Androgen receptor (AR) cistrome in prostate differentiation and cancer progression

Despite the progress in development of better AR-targeted therapies for prostate cancer (PCa), there is no curative therapy for castration-resistant prostate cancer (CRPC). Therapeutic resistance in PCa can be characterized in two broad categories of AR therapy resistance: the first and most prevalent one involves restoration of AR activity despite AR targeted therapy, and the second one involves tumor progression despite blockade of AR activity. As such AR remains the most attractive drug target for CRPC. Despite its oncogenic role, AR signaling also contributes to the maturation and differentiation of prostate luminal cells during development. Recent evidence suggests that AR cistrome is altered in advanced PCa. Alteration in AR may result from AR amplification, alternative splicing, mutations, post-translational modification of AR, and altered expression of AR co-factors. We reasoned that such alterations would result in the transcription of disparate AR target genes and as such may contribute to the emergence of castration-resistance. In the present study, we evaluated the expression of genes associated with canonical or non-canonical AR cistrome in relationship with PCa progression and prostate development by analyzing publicly available datasets. We discovered a transcription switch from canonical AR cistrome target genes to the non-canonical AR cistrome target genes during PCa progression. Using Gene Set Enrichment Analysis (GSEA), we discovered that canonical AR cistrome target genes are enriched in indolent PCa patients and the loss of canonical AR cistrome is associated with tumor metastasis and poor clinical outcome. Analysis of the datasets involving prostate development, revealed that canonical AR cistrome target genes are significantly enriched in prostate luminal cells and can distinguish luminal cells from basal cells, suggesting a pivotal role for canonical AR cistrome driven genes in prostate development. These data suggest that the expression of canonical AR cistrome related genes play an important role in maintaining the prostate luminal cell identity and might restrict the lineage plasticity observed in lethal PCa. Understanding the molecular mechanisms that dictate AR cistrome may lead to development of new therapeutic strategies aimed at restoring canonical AR cistrome, rewiring the oncogenic AR signaling and overcome resistance to AR targeted therapies.

NK3 homeobox 1 (NKX3.1) up-regulates forkhead box O1 expression in hepatocellular carcinoma and thereby suppresses tumor proliferation and invasion

Hepatocellular carcinoma (HCC) is the leading cause of cancer-related mortality in China, and the molecular mechanism of uncontrolled HCC progression remains to be explored. NK3 homeobox 1 (NKX3.1), an androgen-regulated prostate-specific transcription factor, suppresses tumors in prostate cancer, but its role in HCC is unknown, especially in hepatocellular carcinoma. In the present study, the differential expression analyses in HCC tissues and matched adjacent noncancerous liver tissues revealed that NKX3.1 is frequently down-regulated in human primary HCC tissues compared with matched adjacent noncancerous liver tissues. We also noted that NKX3.1 significantly inhibits proliferation and mobility of HCC cells both in vitro and in vivo Furthermore, NKX3.1 overexpression resulted in cell cycle arrest at the G₁/S phase via direct binding to the promoter of forkhead box O1 (FOXO1) and up-regulation of expression. Of note, FOXO1 silencing in NKX3.1-overexpressing cells reversed the inhibitory effects of NKX3.1 on HCC cell proliferation and invasion. Consistently, both FOXO1 and NKX3.1 were down-regulated in human HCC tissues, and their expression was significantly and positively correlated with each other. These results suggest that NKX3.1 functions as a tumor suppressor in HCC cells through directly up-regulating FOXO1 expression.

Prostate organogenesis: tissue induction, hormonal regulation and cell type specification

Prostate organogenesis is a complex process that is primarily mediated by the presence of androgens and subsequent mesenchyme-epithelial interactions. The investigation of prostate development is partly driven by its potential relevance to prostate cancer, in particular the apparent re-awakening of key developmental programs that occur during tumorigenesis. However, our current knowledge of the mechanisms that drive prostate organogenesis is far from complete. Here, we provide a comprehensive overview of prostate development, focusing on recent findings regarding sexual dimorphism, bud induction, branching morphogenesis and cellular differentiation.

Transcriptional regulation of the Nkx3.1 gene in prostate luminal stem cell specification and cancer initiation via its 3' genomic region

NK3 homeobox 1 (Nkx3.1), a transcription factor expressed in the prostate epithelium, is crucial for maintaining prostate cell fate and suppressing tumor initiation. Nkx3.1 is ubiquitously expressed in luminal cells of hormonally intact prostate but, upon androgen deprivation, exclusively labels a type of luminal stem cells named castration-resistant Nkx3.1-expressing cells (CARNs). During prostate cancer initiation, Nkx3.1 expression is frequently lost in both humans and mouse models. Therefore, investigating how Nkx3.1 expression is regulated in vivo is important for understanding the mechanisms of prostate stem cell specification and cancer initiation. Here, using a transgenic mouse line with destabilized GFP, we identified an 11-kb genomic region 3' of the Nkx3.1 transcription start site to be responsible for alterations in Nkx3.1 expression patterns under various physiological conditions. We found that androgen cell-autonomously activates Nkx3.1 expression through androgen receptor (AR) binding to the 11-kb region in both normal luminal cells and CARNs and discovered new androgen response elements in the Nkx3.1 3' UTR. In contrast, we found that, in Pten^-/- prostate tumors, loss of Nkx3.1 expression is mediated at the transcriptional level through the 11-kb region despite functional AR in the nucleus. Importantly, the GFP reporter specifically labeled CARNs in the regressed prostate only in the presence of cell-autonomous AR, supporting a facultative model for CARN specification.

Writing, erasing and reading histone lysine methylations

Histone modifications are key epigenetic regulatory features that have important roles in many cellular events. Lysine methylations mark various sites on the tail and globular domains of histones and their levels are precisely balanced by the action of methyltransferases ('writers') and demethylases ('erasers'). In addition, distinct effector proteins ('readers') recognize specific methyl-lysines in a manner that depends on the neighboring amino-acid sequence and methylation state. Misregulation of histone lysine methylation has been implicated in several cancers and developmental defects. Therefore, histone lysine methylation has been considered a potential therapeutic target, and clinical trials of several inhibitors of this process have shown promising results. A more detailed understanding of histone lysine methylation is necessary for elucidating complex biological processes and, ultimately, for developing and improving disease treatments. This review summarizes enzymes responsible for histone lysine methylation and demethylation and how histone lysine methylation contributes to various biological processes.

A computational systems approach identifies synergistic specification genes that facilitate lineage conversion to prostate tissue

To date, reprogramming strategies for generating cell types of interest have been facilitated by detailed understanding of relevant developmental regulatory factors. However, identification of such regulatory drivers often represents a major challenge, as specific gene combinations may be required for reprogramming. Here we show that a computational systems approach can identify cell type specification genes (master regulators) that act synergistically, and demonstrate its application for reprogramming of fibroblasts to prostate tissue. We use three such master regulators (FOXA1, NKX3.1 and androgen receptor, AR) in a primed conversion strategy starting from mouse fibroblasts, resulting in prostate tissue grafts with appropriate histological and molecular properties that respond to androgen-deprivation. Moreover, generation of reprogrammed prostate does not require traversal of a pluripotent state. Thus, we describe a general strategy by which cell types and tissues can be generated even with limited knowledge of the developmental pathways required for their specification in vivo.

Co-clinical Analysis of a Genetically Engineered Mouse Model and Human Prostate Cancer Reveals Significance of NKX3.1 Expression for Response to 5α-reductase Inhibition

BACKGROUND

Although men on active surveillance for prostate cancer (PCa) may benefit from intervention with 5α-reductase inhibitors (5-ARIs), it has not been resolved whether 5-ARIs are effective for delaying disease progression and, if so, whether specific patients are more likely to benefit.

OBJECTIVE

To identify molecular features predictive of patient response to 5-ARIs.

DESIGN, SETTING, AND PARTICIPANTS

Nkx3.1 mutant mice, a model of early-stage PCa, were treated with the 5-ARI finasteride, and histopathological and molecular analyses were performed. Cross-species computational analyses were used to compare expression profiles for treated mice with those of patients who had received 5-ARIs before prostatectomy.

INTERVENTION

Finasteride administered to Nkx3.1 mutant mice. 5-ARI-treated patient specimens obtained retrospectively.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Endpoints in mice included histopathology, immunohistochemistry, and molecular profiling. GraphPad Prism software, R-studio, and Matlab were used for statistical and data analyses.

RESULTS AND LIMITATIONS

Finasteride treatment of Nkx3.1 mutant mice resulted in a significant reduction in prostatic intraepithelial neoplasia (PIN), as evident from histopathological and expression profiling analyses. Cross-species computational analysis comparing finasteride-treated mice with two independent 5-ARI-treated patient cohorts showed that reduced NKX3.1 expression is predictive of response to 5-ARI. A limitation of the study is that these retrospective human cohorts have relatively few patients with limited clinical outcome data. Future prospective clinical trials are needed to validate whether stratifying patients on the basis of NKX3.1 expression improves the benefit of 5-ARIs during active surveillance.

CONCLUSIONS

This co-clinical study implicates NKX3.1 status as a predictor of response to 5-ARIs, and suggests that molecular features, including NKX3.1 expression, may help to identify PCa patients most likely to benefit from 5-ARIs during active surveillance.

PATIENT SUMMARY

The aim of precision cancer prevention is to tailor interventions on the basis of individualized patient characteristics. We propose that patients with low NKX3.1 expression are optimal candidates for intervention with 5α-reductase inhibitors as an adjunct to active surveillance.

Dissecting cell-type-specific roles of androgen receptor in prostate homeostasis and regeneration through lineage tracing

Androgen signals through androgen receptor (AR) to influence prostate development and cancer. How stromal and epithelial AR regulate prostate homeostasis remains unclear. Using genetic lineage tracing, we systematically investigated the role of cell-autonomous AR in different prostate epithelial cell types. Here we show that AR is dispensable for basal cell maintenance, but is cell-autonomously required for the luminal differentiation of rare basal stem cells. In contrast, AR deletion in luminal cells alters cell morphology and induces transient over-proliferation, without affecting androgen-mediated luminal cell survival or regeneration. However, AR is selectively required for the maintenance of daughter cells produced by castration-resistant Nkx3.1-expressing luminal stem cells (CARNs). Notably, Pten loss can override AR-loss effects in both basal and luminal compartments to initiate tumours. Our data reveal distinct cell-type-specific roles of epithelial AR in orchestrating prostate homeostasis, and question the notion that epithelial AR serves as a tumour suppressor in early cancer initiation.

Androgen receptor is an important regulator of prostate development and cancer. In this study, the authors use genetic lineage tracing in mice to clarify the role of AR in different prostate epithelial cells.