Project description:The discovery that enhancers are regulated transcription units, encoding eRNAs, has raised new questions about the mechanisms of their activation. Here, we report an unexpected molecular mechanism that underlies ligand-dependent enhancer activation, based on DNA nicking to relieve torsional stress from eRNA synthesis. Using dihydrotestosterone (DHT)-induced binding of androgen receptor (AR) to prostate cancer cell enhancers as a model, we show rapid recruitment, within minutes, of DNA topoisomerase I (TOP1) to a large cohort of AR-regulated enhancers. Furthermore, we show that the DNA nicking activity of TOP1 is a prerequisite for robust eRNA synthesis and enhancer activation and is kinetically accompanied by the recruitment of ATR and the MRN complex, followed by additional components of DNA damage repair machinery to the AR-regulated enhancers. Together, our studies reveal a linkage between eRNA synthesis and ligand-dependent TOP1-mediated nicking - a strategy exerting quantitative effects on eRNA expression in regulating AR-bound enhancer-dependent transcriptional programs. Genome-wide binding analysis of AR, TOP1, MRE11 in prostate cancer cell line LNCaP with or without 5alpha-dihydrotestosterone (DHT) treatment. Nascent RNA analysis by global nuclear run-on (GRO-seq) in LNCaP cells transfected with siRNA with or without DHT treatment. Distribution of transcriptionally engaged RNA Pol II in LNCaP cells with or without DHT treatment by precision nuclear run-on and sequencing (PRO-seq).
Project description:We report the androgen receptor recruitment to the chromatin of androgen responsive prostate cancer cell lines, LNCaP-1F5 and VCaP in response to physiological androgen 5a-dihydrotestosterone (DHT) using ChIP-sequencing. We compare the AR recruitment by DHT to that by partial agonist/antagonist cyproterone acetate (CPA), mifepristone (RU486) and bicalutamide (Bica) in LNCaP-1F5 cells. We also report the role of glucocorticoid receptor recruitment in presence of dexamethasone (Dex) in androgen responsive prostate cancer cells. The AR and GR cistrome analysis is subsequently compared with gene expression data and RNA Pol II analysis. The ChIP-seq has been performed using AR, GR, RNA Pol II antibodies. Examination of AR and GR binding sites in LNCaP-1F5 and VCaP cells in presence of DHT and Dex respectively. Further analysis of AR binding sites in LNCaP-1F5 cells treated with partial agonist/antagonists, CPA, RU486 and Bica. Additionally RNA Pol II mapping is performed in cells treated with DHT and Dex.
Project description:We previously encountered regulatory processes where dihydrotestosterone (DHT) exerted its inhibitory effect on parathyroid hormone-related protein (PTHrP) gene repression through the estrogen receptor (ER)M-NM-1, but not the androgen receptor (AR) in breast cancer MCF-7 cells. Here, we investigated whether such an aberrant ligand-nuclear receptor (NR) interaction is present in prostate cancer LNCaP cells. First, we confirmed that LNCaP cells expressed a functional AR and at negligible levels of ERM-NM-1, and progesterone receptors. Both suppression of PTHrP and activation of the PSA genes were observed after treatment of E2, DHT and R5020. Consistent with the previous notion that the AR in LNCaP cells lost the ligand specificity due to a mutation AR (Thr-Ala877), our study using siRNA targeting each NR revealed that the AR, but not the other NRs, monopolized the role as the mediator of shared hormone-dependent regulation. These results were invariably associated with nuclear translocation of this mutant AR. Microarray of the genes regulated by either DHT, E2 or R5020 downstream of the AR (Thr-Ala877) revealed that more than half genes overlapped in LNCaP cells. Noticeably, AR (wild-type, wt) and AR (Thr-Ala877) were equally responsible for the E2-AR interactions. Fluorescent microscopic experiments demonstrated that both EGFP-AR (wt) and EGFP-AR (Thr-Ala877) were exclusively localized within the nucleus after E2 or DHT treatment. Further, a promoter assay revealed that breast cancer MCF-7 and Rv22 cells also exhibited such an aberrant E2-AR (wt) signaling. We postulate entangled interactions between the AR (wt) and E2 in a certain hormone-sensitive cancer cells. Total RNAs from the LNCaP cells transfected with control siRNA (siCT) or siRNA for AR (siAR) transfected LNCaP cells before 24 hr followed by exposed to 10-7M of DHT, E2 or R5020 exposure for another 24 h, respectively, were used.
Project description:The aim of the study is to identify AR target gens in LNCaP cells 5 samples corresponding to LSD1 K114me2 or CHD1 genome-binding in DHT-treated and control LNCaP cells. 6 samples corresponding to LSD1 K114me2 or CHD1 genome-binding in LNCaP cells knocked-down for LSD1 or CHD1 and treated with DHT.
Project description:We previously encountered regulatory processes where dihydrotestosterone (DHT) exerted its inhibitory effect on parathyroid hormone-related protein (PTHrP) gene repression through the estrogen receptor (ER)α, but not the androgen receptor (AR) in breast cancer MCF-7 cells. Here, we investigated whether such an aberrant ligand-nuclear receptor (NR) interaction is present in prostate cancer LNCaP cells. First, we confirmed that LNCaP cells expressed a functional AR and at negligible levels of ERα, and progesterone receptors. Both suppression of PTHrP and activation of the PSA genes were observed after treatment of E2, DHT and R5020. Consistent with the previous notion that the AR in LNCaP cells lost the ligand specificity due to a mutation AR (Thr-Ala877), our study using siRNA targeting each NR revealed that the AR, but not the other NRs, monopolized the role as the mediator of shared hormone-dependent regulation. These results were invariably associated with nuclear translocation of this mutant AR. Microarray of the genes regulated by either DHT, E2 or R5020 downstream of the AR (Thr-Ala877) revealed that more than half genes overlapped in LNCaP cells. Noticeably, AR (wild-type, wt) and AR (Thr-Ala877) were equally responsible for the E2-AR interactions. Fluorescent microscopic experiments demonstrated that both EGFP-AR (wt) and EGFP-AR (Thr-Ala877) were exclusively localized within the nucleus after E2 or DHT treatment. Further, a promoter assay revealed that breast cancer MCF-7 and Rv22 cells also exhibited such an aberrant E2-AR (wt) signaling. We postulate entangled interactions between the AR (wt) and E2 in a certain hormone-sensitive cancer cells.
Project description:The major pioneer factor activity of FOXA1 in PCa is to facilitate AR recruitment to androgen-regulated enhancers. Therefore, we hypothesized that the decreased FOXA1 binding and enhancer availability by LSD1 inhibition may result in the impairment of subsequent AR recruitment to enhancers. To globally test this hypothesis, we performed AR ChIP-seq in LNCaP cells treated with an LSD1 inhibitors. Consistent with previous reports, DHT treatment can dramatically induce AR binding to chromatin. Significantly, LSD1 inhibitor treatment in presence of DHT stimulation markedly decreased the total number of AR binding peaks and their intensity. We further assessed the impact of LSD1 inhibition on overall AR transcriptional output using RNA-seq data.
Project description:Analyze the transcriptomic changes of LNCaP upon DMSO, DHT, Enzalutamide(ENZ), ET516 treatment. The DHT treatment induced robust androgen receptor (AR) signaling up-regulation, wheras ENZ and ET516 can significantly restore DHT-induced AR signaling changes.
Project description:We report the androgen receptor recruitment to the chromatin of androgen responsive prostate cancer cell lines, LNCaP-1F5 and VCaP in response to physiological androgen 5a-dihydrotestosterone (DHT) using ChIP-sequencing. We compare the AR recruitment by DHT to that by partial agonist/antagonist cyproterone acetate (CPA), mifepristone (RU486) and bicalutamide (Bica) in LNCaP-1F5 cells. We also report the role of glucocorticoid receptor recruitment in presence of dexamethasone (Dex) in androgen responsive prostate cancer cells. The AR and GR cistrome analysis is subsequently compared with gene expression data and RNA Pol II analysis. The ChIP-seq has been performed using AR, GR, RNA Pol II antibodies.
Project description:Androgen receptor (AR) is a ligand-dependent transcription factor that plays a key role in the onset and progression of prostate cancer. We investigated AR-induced gene expression in prostate cancer cells LNCaP and abl by transfecting siAR / siControl or treating cells with androgen (DHT) over a time course. Keywords: siRNA transfection and androgen stimulation time course