Biology subjects

Llimos, G.

Publications and source records attributed to Llimos, G..

3 recordsLinked to original sources

bioRxiv2020

Reduced NCOR2 expression accelerates androgen deprivation therapy failure in prostate cancer

NCOR2 is frequently and significantly mutated in late stage androgen deprivation therapy resistant prostate cancer (ADT-RPCa). NCOR2 has been characterized as a transcriptional corepressor and has mechanistic links to DNA methylation, but its global functions and overall contributions to PCa progression remain enigmatic. In the current study, we utilize immunohistochemical staining of samples from over 700 PCa patients and reveal associations of reduced NCOR2 expression with correlates of aggressive primary PCa and recurrence in patients who received adjuvant androgen deprivation therapy. We mapped the dihydrotestosterone (DHT) dependent and independent effects of NCOR2 on the transcriptome, cistrome and DNA methylome in androgen sensitive (AS) and ADT-RPCa cells using the isogenic LNCaP and LNCaP-C4-2 (C4-2) cell models. Transcriptional profiling identified androgen dependent and independent regulatory roles of NCOR2, the latter of which was enhanced in the ADT-RPCa state and included neuronal differentiation. Interestingly, reduced expression of NCOR2 resulted in a striking global DNA hypermethylation pattern that significantly enriched at enhancer regions. ChIP-seq revealed that NCOR2 was more clearly associated with promoters in AS LNCaP cells, which was modestly enhanced by DHT treatment. However, in ADT-RPCa C4-2 cells, the NCOR2 cistrome was larger and more distal. Motif analyses and integration of large-scale public cistrome data revealed strong enrichment for FOXA1 in mediating NCOR2 binding, and included additional factors such as AR, E2F, TET2, MED1 and MBD2. Utilizing the CWR22 xenograft model, we demonstrate a direct role for NCOR2 in PCa progression as reduced NCOR2 expression attenuated the impact of ADT, and significantly accelerated recurrence of disease. Transcriptomic analyses in recurrent CWR22 tumors indicated NCOR2-dependent gene expression profiles during ADT that were enriched for neuroendocrine associated genes and also associated with worse survival in human patients with ADT-RPCa. DNA methylation profiles in CWR22 tumors with reduced NCOR2 expression recapitulated the hypermethylation observed in vitro, and further revealed that hypermethylation patterns are commonly associated with ADT-RPCa disease, which was also confirmed in human samples. These studies reveal robust roles for NCOR2 in regulating the PCa transcriptome and epigenome and underscore recent mutational studies linking NCOR2 loss of function to PCa disease progression.Competing Interest StatementThe authors have declared no competing interest.View Full Text

cancer biology↗

bioRxiv2019

A highly parallel, automated platform enabling individual or sequential ChIP of histone marks and transcription factors

Despite its popularity, chromatin immunoprecipitation followed by sequencing (ChIP-seq) remains a tedious (>2d), manually intensive, low-sensitivity and low-throughput approach. Here, we combine principles of microengineering, surface chemistry and molecular biology to address the major limitations of standard ChIP-seq. The resulting approach, FloChIP, automates and miniaturizes ChIP in a beadless fashion while facilitating the downstream library preparation process through on-chip chromatin tagmentation. FloChIP is fast (<2h), has a wide dynamic range (from 106 to 500 cells), is high-throughput (up to 64 parallel, antibody- or sample-multiplexed experiments) and is compatible with both histone mark and transcription factor ChIP. In addition, FloChIPs interconnected design allows for straightforward chromatin re-immunoprecipitation, thus constituting the first example of a microfluidic sequential ChIP-seq system. Finally, we demonstrate FloChIPs high-throughput capacity by performing ChIP-seq of the transcription factor MEF2A in 32 distinct human lymphoblastoid cell lines, providing novel insights into the main factors driving collaborative DNA binding of MEF2A and into its role in B-cell-specific gene regulation. Together, our results validate FloChIP as a flexible and reproducible automated solution for individual or sequential ChIP-seq.

bioengineering↗

bioRxiv2017

The miR-96/RARγ signaling axis governs androgen signaling and PCa progression

Expression levels of retinoic acid receptor gamma (NR1B3/RARG, encodes RAR{gamma}), are commonly reduced in prostate cancer (PCa). Therefore we sought to establish the cellular and gene regulatory consequences of reduced RAR{gamma} expression, and determine RAR{gamma} regulatory mechanisms. RARG shRNA approaches in non-malignant (RWPE-1 and HPr1-AR) and malignant (LNCaP) prostate models revealed that reducing RAR{gamma} levels, rather than adding exogenous retinoid ligand, had the greatest impact on prostate cell viability and gene expression. ChIP-Seq defined the RAR{gamma} cistrome which was significantly enriched at active enhancers associated with AR binding sites. Reflecting a significant genomic role for RAR{gamma} to regulate androgen signaling, RAR{gamma} knockdown in HPr1-AR cells significantly regulated the magnitude of the AR transcriptome. RAR{gamma} down-regulation was explained by increased miR-96 in PCa cell and mouse models, and TCGA PCa cohorts. Biochemical approaches confirmed that miR-96 directly regulated RAR{gamma} expression and function Capture of the miR-96 targetome by biotin-miR96 identified that RAR{gamma} and a number of RAR{gamma} interacting co-factors including TACC1 were all targeted by miR-96, and expression of these genes were prominently altered, positively and negatively, in the TCGA-PRAD cohort. Differential gene expression analyses between tumors in the TCGA-PRAD cohort with lower quartile expression levels of RARG and TACC1 and upper quartile miR-96, compared to the reverse, identified a gene network including several RAR{gamma} target genes (e.g. SOX15) that significantly associated with worse disease free survival (hazard ratio 2.23, 95% CI 1.58 to 2.88, p=0.015). In summary, miR-96 targets a RAR{gamma} network to govern AR signaling, PCa progression and disease outcome.\n\nConflict of interestThe authors certify that they have NO affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript.\n\nFUNDINGLESC acknowledges support, in part, of Roswell Park Comprehensive Cancer Center-University of Pittsburg Cancer Institute Ovarian Cancer Specialized Program of Research Excellence National Institutes of Health [P50CA159981-01A1].\n\nMDL acknowledges support of Molecular Pharmacology and Experimental Therapeutics NRSA T32 program [T32CA009072] held at Roswell Park Comprehensive Cancer Center.\n\nMJC and DJS acknowledges support in part from the Prostate program of the Department of Defense Congressionally Directed Medical Research Programs [W81XWH-14-1-0608, W81XWH-11-2-0033] and the National Cancer Institute (NCI) grant P30CA016056 involving the use of Roswell Park Comprehensive Cancer Centers Genomic Shared Resource.\n\nMJC, GL, AR, HW and PvdB acknowledges support from the European Union-United States Atlantis Program [P116J090011].\n\nMJC and LESC acknowledge support from the National Cancer Institute (NCI) grant P30CA016056 involving the use of OSUCCC The James, CCSG P30CA016058

cancer biology↗