title: Aspirin exposure reveals novel genes associated with platelet function and cardiovascular events.
abstract: OBJECTIVE
  The aim of this study was to develop ribonucleic acid (RNA) profiles that could serve as novel biomarkers for the response to aspirin.
  
  
  BACKGROUND
  Aspirin reduces death and myocardial infarction (MI), suggesting that aspirin interacts with biological pathways that may underlie these events.
  
  
  METHODS
  Aspirin was administered, followed by whole-blood RNA microarray profiling, in a discovery cohort of healthy volunteers (HV1) (n = 50) and 2 validation cohorts of healthy volunteers (HV2) (n = 53) and outpatient cardiology patients (OPC) (n = 25). Platelet function was assessed using the platelet function score (PFS) in HV1 and HV2 and the VerifyNow Aspirin Test (Accumetrics, Inc., San Diego, California) in OPC. Bayesian sparse factor analysis identified sets of coexpressed transcripts, which were examined for associations with PFS in HV1 and validated in HV2 and OPC. Proteomic analysis confirmed the association of validated transcripts in platelet proteins. Validated gene sets were tested for association with death or MI in 2 patient cohorts (n = 587 total) from RNA samples collected at cardiac catheterization.
  
  
  RESULTS
  A set of 60 coexpressed genes named the "aspirin response signature" (ARS) was associated with PFS in HV1 (r = -0.31, p = 0.03), HV2 (r = -0.34, Bonferroni p = 0.03), and OPC (p = 0.046). Corresponding proteins for the 17 ARS genes were identified in the platelet proteome, of which 6 were associated with PFS. The ARS was associated with death or MI in both patient cohorts (odds ratio: 1.2 [p = 0.01]; hazard ratio: 1.5 [p = 0.001]), independent of cardiovascular risk factors. Compared with traditional risk factors, reclassification (net reclassification index = 31% to 37%, p ≤ 0.0002) was improved by including the ARS or 1 of its genes, ITGA2B.
  
  
  CONCLUSIONS
  RNA profiles of platelet-specific genes are novel biomarkers for identifying patients who do not respond adequately to aspirin and who are at risk for death or MI.
authors.affiliation: Institute for Genome Sciences & Policy, Duke University, Durham, North Carolina; Department of Medicine, Duke University, Durham, North Carolina. Electronic address: deepak.voora@duke.edu.
authors.forename: Deepak
authors.initials: D
authors.lastname: Voora
authors.affiliation: Institute for Genome Sciences & Policy, Duke University, Durham, North Carolina.
authors.forename: Derek
authors.initials: D
authors.lastname: Cyr
authors.affiliation: Institute for Genome Sciences & Policy, Duke University, Durham, North Carolina.
authors.forename: Joseph
authors.initials: J
authors.lastname: Lucas
authors.affiliation: Institute for Genome Sciences & Policy, Duke University, Durham, North Carolina.
authors.forename: Jen-Tsan
authors.initials: JT
authors.lastname: Chi
authors.affiliation: Department of Medicine, Duke University, Durham, North Carolina.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Dungan
authors.affiliation: Division of Genomic Medicine, The George Washington University/Medical Faculty Associates, Washington, DC.
authors.forename: Timothy A
authors.initials: TA
authors.lastname: McCaffrey
authors.affiliation: Division of Cardiology, Department of Medicine, The George Washington University/Medical Faculty Associates, Washington, DC.
authors.forename: Richard
authors.initials: R
authors.lastname: Katz
authors.affiliation: Department of Medicine, Duke University, Durham, North Carolina.
authors.forename: L Kristin
authors.initials: LK
authors.lastname: Newby
authors.affiliation: Department of Medicine, Duke University, Durham, North Carolina.
authors.forename: William E
authors.initials: WE
authors.lastname: Kraus
authors.affiliation: Department of Medicine, Duke University, Durham, North Carolina.
authors.forename: Richard C
authors.initials: RC
authors.lastname: Becker
authors.affiliation: Department of Medicine, Duke University, Durham, North Carolina.
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Ortel
authors.affiliation: Institute for Genome Sciences & Policy, Duke University, Durham, North Carolina; Department of Medicine, Duke University, Durham, North Carolina. Electronic address: geoffrey.ginsburg@duke.edu.
authors.forename: Geoffrey S
authors.initials: GS
authors.lastname: Ginsburg
mesh_terms: D001241:Aspirin / Q000627:therapeutic use*; D001499:Bayes Theorem; D001792:Blood Platelets / Q000187:drug effects / Q000502:physiology*; D002318:Cardiovascular Diseases / Q000097:blood / Q000188:drug therapy / Q000235:genetics*; D005796:Genes / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D046228:Microarray Analysis; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use; D010979:Platelet Function Tests; D040901:Proteomics / Q000379:methods*; D012313:RNA / Q000032:analysis*; D060888:Real-Time Polymerase Chain Reaction; D012307:Risk Factors
chemical_list: D010975:Platelet Aggregation Inhibitors; D012313:RNA; D001241:Aspirin
keywords: ARS; CAD; CATHGEN; CI; Catheterization Genetics; DUMC; Duke University Medical Center; HV1; HV2; MI; MPV; OPC; OR; PCR; PFS; RNA; RT-PCR; aspirin; aspirin response signature; biomarkers; confidence interval; coronary artery disease; genes; healthy volunteer discovery cohort; healthy volunteer validation cohort; mean platelet volume; myocardial infarction; odds ratio; outpatient cardiology cohort; platelet function score; platelets; polymerase chain reaction; real-time polymerase chain reaction; ribonucleic acid