Unknown,Transcriptomics,Genomics,Proteomics

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Convergence of oncogenic and hormone receptor pathways promotes pro-metastatic phenotypes.

ABSTRACT: Cyclin D1b is a splice variant of the cell cycle regulator Cyclin D1 and is known to harbor divergent and highly oncogenic functions in human disease. While Cyclin D1b is induced during disease progression in many cancer types, the mechanisms underlying Cyclin D1b function remain poorly understood. Herein, models of human disease were utilized to resolve the downstream pathways requisite for the pro-tumorigenic functions of Cyclin D1b. Specifically, it was shown that Cyclin D1b modulates the expression of a large transcriptional network that cooperates with AR signaling to enhance tumor cell growth and invasive potential. Notably, Cyclin D1b promoted AR-dependent activation of genes associated with metastatic phenotypes. Further exploration determined that transcriptional induction of SNAI2 (Slug) was essential for Cyclin D1b- mediated proliferative and invasive properties, implicating Slug as a critical driver of disease progression. Importantly, Cyclin D1b expression highly correlated with that of Slug in clinical samples of advanced disease. Further, in vivo analyses provided strong evidence that Slug enhances both tumor growth and homing to distal soft tissues. Collectively, these findings reveal the underpinning mechanisms behind the pro-tumorigenic functions of Cyclin D1b, and demonstrate that the convergence of the Cyclin D1b-AR and Slug pathways results in the activation of processes critical for the promotion of lethal tumor phenotypes. Analysis of transcriptomes under the control of individual D-type cyclin isoforms in the hormone dependent prostate cancer cell line LNCaP in the presence and absence of androgen. LNCaP cells cultured in charcoal dextran treated media were transduced with virus encoding Cyclin D1a, Cyclin D1b, or control GFP for 24 hours in biological triplicate. Cells were then stimulated with either 1nM DHT or 0.01% EtOH (vehicle control) for 16 hours and harvested for RNA

ORGANISM(S): Homo sapiens

SUBMITTER: Adam Ertel

PROVIDER: E-GEOD-40794 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Enzalutamide (ENZ) is a potent androgen receptor (AR) antagonist with activity in castration-resistant prostate cancer (CRPC); however, progression to ENZ-resistant (ENZ-R) CRPC frequently occurs with rising serum PSA levels, implicating AR full length (ARFL) or variants (AR-Vs) in disease progression. To define functional roles of ARFL and AR-Vs in ENZ-R CRPC, we designed 3 antisense oligonucleotides (ASO) targeting exon 1, intron 1, and exon 8 in AR pre-mRNA to knockdown either ARFL alone, or ARFL plus AR-Vs, and examined their respective effects in LNCaP-derived ENZ-R, as well as M12 and 22Rv1, cells. ENZ-R LNCaP xenografts express high levels of both ARFL and AR-V7 compared to CRPC LNCaP xenografts. In particular, ARFL levels were ~20-fold higher than AR-V7. ENZ-R LNCaP sub-lines, derived by selection from the ENZ xenografts, also expressed uniformly high levels of ARFL and AR-V7 compared to CRPC LNCaP cells. In addition, both ARFL and AR-V7 are highly expressed in the nuclear fractions of ENZ-R-LNCaP. In ENZ-R LNCaP cells, knockdown of ARFL alone, or ARFL plus AR-Vs, similarly induced apoptosis, suppressed cell growth and AR-regulated gene expression in vitro, and delayed tumour growth in vivo. In 22Rv1 cells that are inherently resistant to ENZ, knockdown of both ARFL and AR-Vs more potently suppressed cell growth, AR transcriptional activity and AR-regulated gene expression than knockdown of ARFL alone. These data indicate the AR is an important driver of ENZ resistance, and while the contributions of ARFL and AR-Vs can vary across cell systems, ARFL is the key driver in the ENZ-R LNCaP model. AR targeting strategies against both ARFL and AR-Vs is a rational approach for AR-dependent CRPC. CRPC and ENZ-R LNCaP xenografts were generated as described in: Gleave, M.E., et al., Serum prostate specific antigen levels in mice bearing human prostate LNCaP tumors are determined by tumor volume and endocrine and growth factors. Cancer Res, 1992. 52(6): p. 1598-605.

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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Convergence of oncogenic and hormone receptor pathways promotes pro-metastatic phenotypes.

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