title: Steroid receptor RNA activator protein (SRAP) expression as a prognostic factor in ER+ human breast tumors.
abstract: BACKGROUND
  The steroid receptor RNA activator protein (SRAP) is a newly described protein modulating the activity of multiple transcription factors including the estrogen receptor (ER). We have recently reported the immunodetection by Western blot of multiple SRAP peptides in breast tissue. High expression of these peptides, assessed by tissue micro-array (TMA) analysis, was associated with poor prognosis in patients whose primary tumors were ER positive (ER+). In such studies, it is recognized that intensity as well as specificity of the signal detected directly depends upon the antibody used as well as the position of the epitope recognized. To confirm the potential relevance of SRAP as a new prognostic factor, it is critical to establish whether similar results are obtained with independent antibodies.
  
  
  METHODS
  Two commercial anti-SRAP antibodies (742A and 743A), respectively, recognizing the N- and C-terminal extremity of the protein, were first used to analyze by Western blot SRAP expression in protein extracts from frozen breast tumor tissue sections. These antibodies were further used to investigate by immunohistochemistry (IHC) SRAP location in paraffin-embedded breast tumors. Comparative TMA analysis of 170 ER+ tumors was eventually performed in order to establish the potential associations existing between SRAP expression and clinical outcome.
  
  
  RESULTS
  Multiple SRAP peptides were differentially detected by Western blot. Both antibodies led to similar nuclear and cytoplasmic staining in breast tissue section. A solid correlation was found (Spearman r = 0.46, P < 0.001) between 742A and 743A IHC scores. Results from both antibodies independently showed that dividing expression levels into lower 25 percentile, 26-75 percentile, and highest 25 percentile demonstrated a hazard ratio (HR) of 1.82 (P = 0.0042) for 742A antibody and 1.35 (P = 0.14) for 743A antibody. When both scores are combined, double high expressor (by 742A and 743A) was associated with a poor prognosis of breast-cancer-specific survival (Mantel-Cox: P = 0.005, HR = 2.24).
  
  
  CONCLUSIONS
  Overall, our data suggest the existence in breast tumor tissue of multiple SRAP-like peptides. Assessing their expression in primary breast tumors can predict clinical outcome in ER+ breast cancer patients.
authors.affiliation: Manitoba Institute of Cell Biology, 675 McDermot Ave., Winnipeg, MB, R3E0V9, Canada, umyan9@cc.umanitoba.ca.
authors.forename: Yi
authors.initials: Y
authors.lastname: Yan
authors.forename: Carla C
authors.initials: CC
authors.lastname: Penner
authors.forename: George P
authors.initials: GP
authors.lastname: Skliris
authors.forename: Charlton
authors.initials: C
authors.lastname: Cooper
authors.forename: Zoann
authors.initials: Z
authors.lastname: Nugent
authors.forename: Anne
authors.initials: A
authors.lastname: Blanchard
authors.forename: Mohammad K
authors.initials: MK
authors.lastname: Hamedani
authors.forename: Xuemei
authors.initials: X
authors.lastname: Wang
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Myal
authors.forename: Leigh C
authors.initials: LC
authors.lastname: Murphy
authors.forename: Etienne
authors.initials: E
authors.lastname: Leygue
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000378:metabolism* / Q000401:mortality; D018270:Carcinoma, Ductal, Breast / Q000378:metabolism* / Q000401:mortality; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015870:Gene Expression; D006801:Humans; D053208:Kaplan-Meier Estimate; D061986:MCF-7 Cells; D015999:Multivariate Analysis; D010446:Peptide Fragments / Q000378:metabolism; D011379:Prognosis; D016016:Proportional Hazards Models; D011960:Receptors, Estrogen / Q000378:metabolism; D046888:Tissue Array Analysis
chemical_list: D002352:Carrier Proteins; D010446:Peptide Fragments; D011960:Receptors, Estrogen; C548898:steroid receptor RNA activator, human
references.citation: DNA Cell Biol. 2006 Jul;25(7):418-28
references.pmid: 16848684
references.citation: Mol Endocrinol. 2010 May;24(5):1090-105
references.pmid: 20219889
references.citation: Clin Cancer Res. 2009 Dec 15;15(24):7479-7491
references.pmid: 20008848
references.citation: Genes Dev. 2013 May 15;27(10):1179-97
references.pmid: 23699411
references.citation: FEBS Lett. 2004 May 21;566(1-3):43-7
references.pmid: 15147866
references.citation: Int J Cancer. 2006 Feb 15;118(4):1054-9
references.pmid: 16152589
references.citation: Biochimie. 2011 Nov;93(11):1966-72
references.pmid: 21807064
references.citation: Oncologist. 2003;8(4):307-25
references.pmid: 12897328
references.citation: BMC Genomics. 2006 Apr 27;7:96
references.pmid: 16643655
references.citation: Breast Cancer Res. 2009;11(5):R67
references.pmid: 19740422
references.citation: FEBS Lett. 2010 Mar 19;584(6):1174-80
references.pmid: 20153324
references.citation: Proc Natl Acad Sci U S A. 2003 Jul 8;100(14):8418-23
references.pmid: 12829800
references.citation: Int J Cancer. 2005 Sep 1;116(3):340-50
references.pmid: 15818618
references.citation: FEBS Lett. 2010 Jun 3;584(11):2218-24
references.pmid: 20398657
references.citation: Nature. 2000 Aug 17;406(6797):747-52
references.pmid: 10963602
references.citation: J Steroid Biochem Mol Biol. 2010 Mar;119(1-2):89-95
references.pmid: 20079837
references.citation: J Natl Cancer Inst. 2009 May 20;101(10):736-50
references.pmid: 19436038
references.citation: Br J Cancer. 2006 Sep 4;95(5):616-26
references.pmid: 16880783
references.citation: Nucl Recept Signal. 2007 Aug 03;5:e006
references.pmid: 17710122
references.citation: Ann Oncol. 2013 Aug;24(8):1986-93
references.pmid: 23579816
references.citation: Biochimie. 2011 Nov;93(11):1973-80
references.pmid: 21771633
references.citation: Proc Natl Acad Sci U S A. 2001 Sep 11;98(19):10869-74
references.pmid: 11553815
references.citation: Prostate Cancer Prostatic Dis. 2006;9(2):173-8
references.pmid: 16607388
references.citation: Nucleic Acids Res. 2009 Jul;37(13):4518-31
references.pmid: 19483093
references.citation: Endocr Relat Cancer. 2004 Dec;11(4):643-58
references.pmid: 15613444