title: Frequent overexpression of Aurora Kinase A in upper gastrointestinal adenocarcinomas correlates with potent antiapoptotic functions.
abstract: BACKGROUND
  Upper gastrointestinal adenocarcinomas are a common cause of cancer-related deaths. In this study, the authors investigated the prevalence and biological significance of Aurora Kinase A (AURKA) overexpression in upper gastrointestinal adenocarcinomas.
  
  
  METHODS
  Quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemical staining on tumor tissue microarrays (TMA) were used to study the expression of AURKA in upper gastrointestinal adenocarcinomas. To investigate the biological and signaling impact of AURKA, the authors used multiple in vitro assays that included 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT), TUNEL (terminal deoxynucleotidyl transferase-mediated nick-end labeling), cytochrome C release, flow cytometry, luciferase reporter, and Western blot analysis.
  
  
  RESULTS
  Frequent overexpression of AURKA transcript in upper gastrointestinal adenocarcinomas was detected compared with normal samples (47%; P= .001). The immunohistochemical analysis of 130 tumors demonstrated moderate-to-strong immunostaining of AURKA in >50% of upper gastrointestinal adenocarcinomas. By using camptothecin as a drug-induced apoptosis in vitro model, the authors demonstrated that the expression of AURKA provided protection against apoptosis to gastrointestinal cancer cells (AGS and RKO) (P= .006) and RIE-1 primary intestinal epithelial cells (P= .001). The AURKA overexpression mediated an increase in phosphorylation of AKT(Ser473) with an increase in HDM2 level. The shRNA-knockdown of AKT in AURKA-overexpressing cells reversed this effect and showed a significant increase in the p53 protein level, indicating a possible nexus of AURKA/AKT/p53. Indeed, overexpression of AURKA led to a remarkable reduction in the transcription activity of p53, with subsequent reductions in transcript and protein levels of its downstream proapoptotic transcription targets (p21, BAX, NOXA, and PUMA).
  
  
  CONCLUSIONS
  Study results indicated that AURKA provides potent antiapoptotic properties to gastrointestinal cells by regulating levels of p53 through the AKT/HDM2 axis.
authors.affiliation: Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA.
authors.forename: Altaf A
authors.initials: AA
authors.lastname: Dar
authors.forename: Alexander
authors.initials: A
authors.lastname: Zaika
authors.forename: Maria B
authors.initials: MB
authors.lastname: Piazuelo
authors.forename: Pelayo
authors.initials: P
authors.lastname: Correa
authors.forename: Tatsuki
authors.initials: T
authors.lastname: Koyama
authors.forename: Abbes
authors.initials: A
authors.lastname: Belkhiri
authors.forename: Kay
authors.initials: K
authors.lastname: Washington
authors.forename: Antoni
authors.initials: A
authors.lastname: Castells
authors.forename: Manuel
authors.initials: M
authors.lastname: Pera
authors.forename: Wael
authors.initials: W
authors.lastname: El-Rifai
mesh_terms: D000230:Adenocarcinoma / Q000201:enzymology*; D017209:Apoptosis / Q000235:genetics / Q000502:physiology*; D064096:Aurora Kinase A; D064127:Aurora Kinases; D014408:Biomarkers, Tumor / Q000032:analysis; D015153:Blotting, Western; D002166:Camptothecin / Q000494:pharmacology; D004396:Coloring Agents; D045304:Cytochromes c / Q000032:analysis; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004938:Esophageal Neoplasms / Q000201:enzymology*; D005434:Flow Cytometry; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008156:Luciferases; D049408:Luminescent Agents; D016133:Polymerase Chain Reaction; D040081:Protein Array Analysis; D017346:Protein Serine-Threonine Kinases / Q000032:analysis*; D013274:Stomach Neoplasms / Q000201:enzymology*; D013778:Tetrazolium Salts; D013844:Thiazoles; D016159:Tumor Suppressor Protein p53 / Q000032:analysis
chemical_list: D014408:Biomarkers, Tumor; D004396:Coloring Agents; D004791:Enzyme Inhibitors; D049408:Luminescent Agents; D013778:Tetrazolium Salts; D013844:Thiazoles; D016159:Tumor Suppressor Protein p53; D045304:Cytochromes c; D008156:Luciferases; C576917:AURKA protein, human; D064096:Aurora Kinase A; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases; C022616:thiazolyl blue; D002166:Camptothecin