title: Estrogen receptor expression in sporadic vestibular schwannomas.
abstract: OBJECTIVE
  We hypothesize that vestibular schwannomas (VSs) exhibit up-regulation of estrogen receptor (ER) at the protein level compared with control great auricular nerve (GAN).
  
  
  BACKGROUND
  It has been reported in the literature that VS occur more commonly in women and tend to be larger and more vascular in women, and growth rate can accelerate during pregnancy. The literature contains widely divergent results on ER expression in VS, however, varying from no detectable levels to detection of ER in all samples.
  
  
  METHODS
  Sixteen sporadic VS specimens were immediately snap-frozen after microsurgical excision and analyzed for phosphorylated and total levels of ERα with Western blot analysis. ERα expression levels were normalized to actin; then, relative expression to GAN was determined.
  
  
  RESULTS
  All VS specimens exhibited expression of both phosphorylated and total ERα. Total ERα expression in VS is equivalent to or slightly up-regulated compared with GAN. VS specimens exhibited more pronounced up-regulation of phosphorylated (i.e., activated) levels of ERα compared with GAN.
  
  
  CONCLUSIONS
  We have demonstrated that ERα expression in VS is equivalent to GAN. The phosphorylated form of the receptor is up-regulated compared with GAN, however, indicating a higher level of ERα activation in sporadic VS compared with normal nerve. Further investigation into antiestrogen therapy for VS is warranted.
authors.affiliation: Department of Surgery, Division of Otolaryngology-Head and Neck Surgery, University of California, San Diego, California 92161, USA. cmaiorana@ucsd.edu
authors.forename: Carrie M
authors.initials: CM
authors.lastname: Brown
authors.forename: Zana K
authors.initials: ZK
authors.lastname: Ahmad
authors.forename: Allen F
authors.initials: AF
authors.lastname: Ryan
authors.forename: Joni K
authors.initials: JK
authors.lastname: Doherty
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015153:Blotting, Western; D047628:Estrogen Receptor alpha / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000378:metabolism*; D010766:Phosphorylation; D015854:Up-Regulation
chemical_list: D047628:Estrogen Receptor alpha