title: BET bromodomains regulate transforming growth factor-β-induced proliferation and cytokine release in asthmatic airway smooth muscle.
abstract: Airway smooth muscle (ASM) mass is increased in asthma, and ASM cells from patients with asthma are hyperproliferative and release more IL-6 and CXCL8. The BET (bromo- and extra-terminal) family of proteins (Brd2, Brd3, and Brd4) govern the assembly of histone acetylation-dependent chromatin complexes. We have examined whether they modulate proliferation and cytokine expression in asthmatic ASM cells by studying the effect of BET bromodomain mimics JQ1/SGCBD01 and I-BET762. ASM cells from healthy individuals and nonsevere and severe asthmatics were pretreated with JQ1/SGCBD01 and I-BET762 prior to stimulation with FCS and TGF-β. Proliferation was measured by BrdU incorporation. IL-6 and CXCL8 release was measured by ELISA, and mRNA expression was measured by quantitative RT-PCR. ChIP using a specific anti-Brd4 antibody and PCR primers directed against the transcriptional start site of IL-6 and CXCL8 gene promoters was performed. Neither JQ1/SGCBD01 nor I-BET762 had any effect on ASM cell viability. JQ1/SGCBD01 and I-BET762 inhibited FCS+TGF-β-induced ASM cell proliferation and IL-6 and CXCL8 release in healthy individuals (≥ 30 nM) and in nonsevere and severe asthma patients (≥100 nM), with the latter requiring higher concentrations of these mimics. JQ1/SGCBD01 reduced Brd4 binding to IL8 and IL6 promoters induced by FCS+TGF-β. Mimics of BET bromodomains inhibit aberrant ASM cell proliferation and inflammation with lesser efficiency in those from asthmatic patients. They may be effective in reducing airway remodeling in asthma.
authors.affiliation: From the Experimental Studies, National Heart and Lung Institute, Imperial College London and Royal Brompton National Institute for Health Research Biomedical Research Unit, London SW3 6LY, United Kingdom m.perry@imperial.ac.uk.
authors.forename: Mark M
authors.initials: MM
authors.lastname: Perry
authors.affiliation: From the Experimental Studies, National Heart and Lung Institute, Imperial College London and Royal Brompton National Institute for Health Research Biomedical Research Unit, London SW3 6LY, United Kingdom.
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Durham
authors.affiliation: From the Experimental Studies, National Heart and Lung Institute, Imperial College London and Royal Brompton National Institute for Health Research Biomedical Research Unit, London SW3 6LY, United Kingdom.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Austin
authors.affiliation: From the Experimental Studies, National Heart and Lung Institute, Imperial College London and Royal Brompton National Institute for Health Research Biomedical Research Unit, London SW3 6LY, United Kingdom.
authors.forename: Ian M
authors.initials: IM
authors.lastname: Adcock
authors.affiliation: From the Experimental Studies, National Heart and Lung Institute, Imperial College London and Royal Brompton National Institute for Health Research Biomedical Research Unit, London SW3 6LY, United Kingdom.
authors.forename: Kian Fan
authors.initials: KF
authors.lastname: Chung
mesh_terms: D001249:Asthma / Q000378:metabolism*; D049109:Cell Proliferation / Q000502:physiology*; D002478:Cells, Cultured; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D006801:Humans; D012333:RNA, Messenger / Q000235:genetics; D014132:Trachea / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000502:physiology*
chemical_list: D016207:Cytokines; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta
keywords: Airway Smooth Muscle; Asthma; Bromodomain-containing Protein 4 (BRD4); CXCL8; Cell Proliferation; I-BET762; Interleukin 6 (IL-6); JQ1/SGCBD01; Myc (c-Myc)