title: BIRC5 expression is a poor prognostic marker in Ewing sarcoma.
abstract: BACKGROUND
  BIRC5 (Survivin), an inhibitor of apoptosis protein (IAP), is over-expressed in several human cancers and increased expression is associated with poor prognosis. The goal of the current study was to evaluate the role of BIRC5 in Ewing sarcoma (ES), the second most common pediatric bone sarcoma.
  
  
  METHODS
  BIRC5 protein expression was determined in ES cell lines using Western Blot analysis. Functional role of survivin on growth and viability of ES cells was assessed by siRNA knockdown of BIRC5 and by using a small molecule inhibitor YM155. Immunohistochemical analysis for BIRC5 protein was performed on patient tumor samples using an anti-survivin antibody. The degree of BIRC5 protein expression was correlated with clinical parameters and patient outcome.
  
  
  RESULTS
  BIRC5 is over-expressed in a panel of ES cell lines. Gene silencing of BIRC5 in the ES cell line TC-71 decreases cell growth by more than 50% for each BIRC5 siRNA construct compared to non-silencing siRNA control constructs. YM155 also reduces ES cell growth and viability with an EC(50) ranging from 2.8 to 6.2 nM. BIRC5 protein is expressed in majority of the ES tumor samples with minimal expression in normal tissue (P < 0.005). Tumors with more than 50% expression are associated with worse overall survival than tumors with less than 50% expression (Hazard Ratio: 6.05; CI: 1.7-21.4; P = 0.04).
  
  
  CONCLUSIONS
  BIRC5 is over-expressed in ES cell lines and tumor samples. Further, it plays an important role in cell growth and viability in vitro. Higher degree of expression in patients is an independent poor prognostic factor.
authors.affiliation: Center for Cancer and Blood Disorders, Phoenix Children's Hospital, Phoenix, AZ 85016, USA. phingorani@phoenixchildrens.com
authors.forename: Pooja
authors.initials: P
authors.lastname: Hingorani
authors.forename: Paul
authors.initials: P
authors.lastname: Dickman
authors.forename: Pamela
authors.initials: P
authors.lastname: Garcia-Filion
authors.forename: Andrea
authors.initials: A
authors.lastname: White-Collins
authors.forename: Edward A
authors.initials: EA
authors.lastname: Kolb
authors.forename: David O
authors.initials: DO
authors.lastname: Azorsa
mesh_terms: D000293:Adolescent; D000328:Adult; D017209:Apoptosis; D015415:Biomarkers; D001859:Bone Neoplasms / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D051034:Inhibitor of Apoptosis Proteins / Q000032:analysis / Q000502:physiology*; D008297:Male; D009285:Naphthoquinones / Q000494:pharmacology; D011379:Prognosis; D012512:Sarcoma, Ewing / Q000473:pathology*; D000077022:Survivin
chemical_list: C107489:BIRC5 protein, human; D015415:Biomarkers; D007093:Imidazoles; D051034:Inhibitor of Apoptosis Proteins; D009285:Naphthoquinones; D000077022:Survivin; C523798:sepantronium