title: N-[(11)C]-methyl-hydroxyfasudil is a potential biomarker of cardiac hypertrophy.
abstract: BACKGROUND
  Pathologic cardiac hypertrophy is one of the leading causes of sudden death from cardiac disease and involves a complex network of bio-signaling mechanisms. To date, the clinical detection and pathologic progression of hypertrophy remains elusive. Here we tested whether imaging Rho kinase activity would serve an accurate proxy for detecting hypertrophy. Specifically, we examine the use of the N-[(11)C]-methylated derivative of hydroxyfasudil, a Rho kinase inhibitor, as a biomarker for accurate identification of cardiomyocyte hypertrophy.
  
  
  METHODS
  Both transformed and primary neonatal cardiomyocytes were treated with isoproterenol to induce β-adrenergic receptor stimulation and hypertrophy. Phenotypic hypertrophy was verified using cytochemical evaluation of cell and nuclear size. Western blot and activity assays were used to detect ERK 1/2 mTOR and Rho kinase activation. N-[(11)C]-methyl-hydroxyfasudil binding was verified using in vitro binding assays with isoproterenol stimulated cells.
  
  
  RESULTS
  Isoproterenol induced a rapid and distinct activation of ERK 1/2, mTOR and Rho kinase with negligible cytotoxicity. Subsequent expansion in cell and nuclear size that is typically associated with hypertrophy was also observed. Enhanced retention of N-[(11)C]-methyl-hydroxyfasudil observed after ISO-induced Rho kinase activation in hypertrophic cells was prevented by pre-treatment with unlabeled hydroxyfasudil.
  
  
  CONCLUSIONS
  N-[(11)C]-methyl-hydroxyfasudil is able to measure increased Rho kinase activity via specific binding in hypertrophied cardiomyocytes and demonstrates the potential for molecular imaging of altered Rho kinase activity in diseases such as cardiac hypertrophy.
authors.affiliation: National Cardiac PET Centre, University of Ottawa Heart Institute, 40 Ruskin St., Ottawa, ON, Canada K1Y 4W7; Division of Cardiology and Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5.
authors.forename: Steven
authors.initials: S
authors.lastname: Moreau
authors.affiliation: National Cardiac PET Centre, University of Ottawa Heart Institute, 40 Ruskin St., Ottawa, ON, Canada K1Y 4W7; Division of Cardiology and Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5; Department of Radiology, Radio-Oncology and Nuclear Medicine, University of Montreal; University of Montreal Hospital Research Centre (CRCHUM), 900 rue Saint-Denis, Montréal, QC H2X 0A9.
authors.forename: Jean N
authors.initials: JN
authors.lastname: DaSilva
authors.affiliation: National Cardiac PET Centre, University of Ottawa Heart Institute, 40 Ruskin St., Ottawa, ON, Canada K1Y 4W7.
authors.forename: Ana
authors.initials: A
authors.lastname: Valdivia
authors.affiliation: Division of Cardiology and Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5; Canadian Molecular Imaging Center of Excellence (CMICE), University of Ottawa Heart Institute, Ottawa, ON K1Y 4W7; Nordion Inc., Ottawa, ON, K2K 1X8. Electronic address: pasan.fernando@nordion.com.
authors.forename: Pasan
authors.initials: P
authors.lastname: Fernando
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives* / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D006332:Cardiomegaly / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology; D002467:Cell Nucleus / Q000187:drug effects; D053145:Cell Nucleus Size / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D007545:Isoproterenol / Q000494:pharmacology; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D049268:Positron-Emission Tomography; D051381:Rats; D017207:Rats, Sprague-Dawley; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D054460:rho-Associated Kinases / Q000378:metabolism
chemical_list: D015415:Biomarkers; C547762:N-methyl-hydroxyfasudil; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D058570:TOR Serine-Threonine Kinases; D054460:rho-Associated Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D007545:Isoproterenol
keywords: Cardiomyocyte; ERK 1/2; Isoproterenol; ROCK; mTOR; β-adrenergic receptor stimulation