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ABI1 regulates transcriptional activity of Androgen Receptor by novel DNA and AR binding mechanism [RNA-seq]

ABSTRACT: Transcription regulates key functions of living organisms in normal and disease states, including cell growth and development, embryonic and adult tissue organization, and tumor progression. Here we identify a novel mechanism of transcriptional regulation by an actin regulatory and signaling protein, Abelson Interactor 1(ABI1). Using prostate cancer models, we uncover a reciprocal regulation between ABI1 and the Androgen Receptor (AR). ABI1 is a direct, androgen-regulated target; in turn, ABI1 interacts with AR and its splice variant ARv7, and co-regulates a subset of specific transcriptional targets. ABI1 directs transcription through transient yet well-defined interaction of its intrinsically disordered region with DNA. Clinical evaluation shows that both the ABI1-DNA binding (through Exon 4 splicing) and ABI1-AR interaction are regulated during androgen deprivation therapy and prostate cancer progression, thus controlling tumor plasticity through connecting actin cytoskeleton and cellular signaling to transcriptional regulation. We propose that ABI1 is an epigenetic regulator of transcriptional homeostasis in AR-driven cancers.

ORGANISM(S): Homo sapiens

PROVIDER: GSE238112 | GEO | 2024/07/18

REPOSITORIES: GEO

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Project description:Androgen receptor (AR) orchestrates an intricate transcriptional regulatory network that governs prostate cancer initiation, development and progression. To understand this network in detail, we generated genome-wide maps of AR occupancy by ChIP-seq in LNCaP cells. We found NKX3-1, an androgen-dependent homeobox protein well-characterized for its role in prostate development and differentiation, being recruited to AR binding sites (ARBS) in response to androgen signaling. We identified 6,359 NKX3-1 binding sites, most of which overlapped with AR. In addition to its novel collaborative transcriptional role at well-known prostate cancer model genes, our binding and knockdown studies further suggested that NKX3-1 potentially regulates AR in a feed-forward manner. Integrative analysis of Oncomine molecular concepts showed that these androgen-regulated AR and NKX3-1 associated genes are significantly overexpressed in prostate carcinoma as well as advanced and recurrent prostate tumors. From our transcriptomic profiling and Gene Ontology analysis, we observed that AR and NKX3-1 co-regulate genes involved in "protein trafficking" processes, which are mandatory events in the integration of oncogenic signaling pathways leading to prostate cancer development and progression. Interestingly, we found that AR and NKX3-1 co-regulate several members of the RAB GTPase family of secretory/trafficking proteins via the involvement of FoxA1 in a ternary complex and we believe that these AR/NKX3-1/FoxA1 co-regulated RAB genes could serve as expression signatures in prostate carcinogenesis. More specifically, through functional analyses, we showed that NKX3-1, together with AR and FoxA1, could promote prostate cancer cell survival through activation of RAB3B expression. Collectively, our study has provided important insights into the hierarchical transcriptional regulatory network established between AR and NKX3-1 and sought to elucidate the important genetic-molecular-phenotypic paradigm in androgen-dependent prostate cancer. Genome-wide binding analyses of AR, NKX3-1 and FoxA1 in LNCaP with or without DHT (5alpha-dihydrotestosterone) stimulation using ChIP-Seq.

Project description:Androgen receptor (AR) orchestrates an intricate transcriptional regulatory network that governs prostate cancer initiation, development and progression. To understand this network in detail, we generated genome-wide maps of AR occupancy by ChIP-seq in LNCaP cells. We found NKX3-1, an androgen-dependent homeobox protein well-characterized for its role in prostate development and differentiation, being recruited to AR binding sites (ARBS) in response to androgen signaling. We identified 6,359 NKX3-1 binding sites, most of which overlapped with AR. In addition to its novel collaborative transcriptional role at well-known prostate cancer model genes, our binding and knockdown studies further suggested that NKX3-1 potentially regulates AR in a feed-forward manner. Integrative analysis of Oncomine molecular concepts showed that these androgen-regulated AR and NKX3-1 associated genes are significantly overexpressed in prostate carcinoma as well as advanced and recurrent prostate tumors. From our transcriptomic profiling and Gene Ontology analysis, we observed that AR and NKX3-1 co-regulate genes involved in ‘protein trafficking’ processes, which are mandatory events in the integration of oncogenic signaling pathways leading to prostate cancer development and progression. Interestingly, we found that AR and NKX3-1 co-regulate several members of the RAB GTPase family of secretory/trafficking proteins via the involvement of FoxA1 in a ternary complex and we believe that these AR/NKX3-1/FoxA1 co-regulated RAB genes could serve as expression signatures in prostate carcinogenesis. More specifically, through functional analyses, we showed that NKX3-1, together with AR and FoxA1, could promote prostate cancer cell survival through activation of RAB3B expression. Collectively, our study has provided important insights into the hierarchical transcriptional regulatory network established between AR and NKX3-1 and sought to elucidate the important genetic-molecular-phenotypic paradigm in androgen-dependent prostate cancer. Gene expression profiling of LNCaP in response to ETOH (vehicle) or DHT (5α-dihydrotestosterone) stimulation across different treatment time-points using microarray.

Project description:Aberrant activation of androgen receptor (AR)-dependent transcriptional programs is a hallmark of human prostate cancers. At the molecular level, ligand-mediated AR activation is coordinated through spatial and temporal protein-protein interactions (PPIs) involving AR-interacting proteins, which we designate the “AR-interactome”. Despite many years of research, the ligand-sensitive protein complexes involved in ligand-mediated AR activation in prostate-tumor cells has not been clearly defined. Here, we describe the development, characterization, and utilization of a novel human LNCaP prostate-tumor cell line, N-AR, which stably expresses wild-type AR containing the streptavidin-binding peptide epitope tagged at its N-terminus (SBP-AR). A bioanalytical workflow involving streptavidin-chromatography and label-free quantitative mass spectrometry was used to identify SBP-AR and associated ligand-sensitive proteins/protein complexes functionally linked to AR activation in the cytosol of N-AR cells. Functional studies verified that ligand-sensitive streptavidin-copurified proteins encoded modulators of AR-mediated transcription, suggesting that these novel proteins were putative SBP-AR-interacting proteins in N-AR cells. This was supported by biochemical associations between recombinant SBP-AR and the ligand-sensitive COPI retrograde trafficking complex in vitro. Extensive biochemical and molecular experiments showed that the COPI-retrograde complex regulates ligand-mediated AR transcriptional activation through the mobilization of Golgi-localized ARA160 coactivator into the nuclear compartment of prostate-tumor cells. Collectively, this study provides a bioanalytical strategy to validate the AR-interactome and define novel AR-interacting proteins involved in ligand-mediated AR activation in prostate-tumor cells. Moreover, we describe a cellular system to study how compartment-specific AR-interacting proteins influence AR activation and contribute to aberrant AR-dependent transcription that underlies the majority of human prostate cancers.

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ABI1 regulates transcriptional activity of Androgen Receptor by novel DNA and AR binding mechanism [RNA-seq]

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