title: Enhanced expression of the stemness-related factors OCT4, SOX15 and TWIST1 in ectopic endometrium of endometriosis patients.
abstract: BACKGROUND
  Current evidence suggests that endometrial-derived stem cells, spilled in the peritoneal cavity via retrograde menstruation, are key players in the establishment of endometriotic lesions. The aim of this study was to determine the presence and distribution of the stemness-related factors OCT4, SOX15, TWIST1 and DCAMLK1 in women with and without endometriosis.
  
  
  METHODS
  Immunohistochemical analysis was used to determine stromal and epithelial expression of OCT4, SOX15, TWIST1 and DCAMLK1 in endometriosis patient (EP) endometrium (n = 69) and endometriotic tissue (n = 90) and in control endometrium (n = 50). Quantitative Real-Time PCR of OCT4, SOX15 TWIST1 and DCAMLK1 was performed in paired samples of EP endometrium and endometriotic tissue. Co-immunofluorescence staining was performed for OCT4 and SOX15. For statistical analyses we used unpaired t-test, Fisher combination test and Spearman test. For paired analyses, paired t-test and McNemar test were used.
  
  
  RESULTS
  We detected a significant correlation between the expression of the established stem cell marker OCT4 and the stemness-related markers SOX15 (p < 0.001) and TWIST1 (p = 0.002) but not DCAMLK1. We showed a colocalization of SOX15 and OCT4 in epithelial and stromal cells of endometriotic tissue by coimmunofluorescence. A concordant expression of OCT4 and SOX15 in the same sample was observed in epithelial cells of the endometriotic tissue (71.7%). The expression of stemness-related factors was not associated with proliferative or secretory phase of the menstrual cycle in endometriosis patients but was found to be differentially expressed during the menstrual cycle in the control group. Increased expression of epithelial OCT4, SOX15 and TWIST1 was detected in endometriotic tissue compared to EP endometrium in paired (p = 0.021, p < 0.001 and p < 0.001) and unpaired analysis (p = 0.040, p < 0.001 and p = 0.001).
  
  
  CONCLUSIONS
  Our findings support the hypothesis that upregulation of stem cell-related factors contribute to the establishment of endometriotic lesions.
  
  
  BACKGROUND
  The study was approved by the institutional review board (545/2010 on 6th of May 2014) of the Medical University of Vienna ( http://ethikkommission.meduniwien.ac.at/fileadmin/ethik/media/dokumente/register/alle_2010.pdf ).
authors.affiliation: Department of Obstetrics and Gynecology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.
authors.forename: Katharina
authors.initials: K
authors.lastname: Proestling
authors.affiliation: Department of Pathology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Birner
authors.affiliation: Department of Pathology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.
authors.forename: Sukirthini
authors.initials: S
authors.lastname: Balendran
authors.affiliation: Department of Obstetrics and Gynecology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.
authors.forename: Nadine
authors.initials: N
authors.lastname: Nirtl
authors.affiliation: Department of Obstetrics and Gynecology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.
authors.forename: Erika
authors.initials: E
authors.lastname: Marton
authors.affiliation: Fetal Medicine Research Institute, King's College Hospital, 16-20 Windsor Walk, Denmark Hill, SE58BB, London, UK.
authors.forename: Gülen
authors.initials: G
authors.lastname: Yerlikaya
authors.affiliation: Department of Obstetrics and Gynecology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.
authors.forename: Lorenz
authors.initials: L
authors.lastname: Kuessel
authors.affiliation: Department of Obstetrics and Gynecology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.
authors.forename: Theresa
authors.initials: T
authors.lastname: Reischer
authors.affiliation: Department of Obstetrics and Gynecology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.
authors.forename: Rene
authors.initials: R
authors.lastname: Wenzl
authors.affiliation: Department of Pathology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria. berthold.streubel@meduniwien.ac.at.
authors.forename: Berthold
authors.identifier: http://orcid.org/0000-0001-6985-7406
authors.initials: B
authors.lastname: Streubel
authors.affiliation: Department of Obstetrics and Gynecology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.
authors.forename: Heinrich
authors.initials: H
authors.lastname: Husslein
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D000089742:Doublecortin-Like Kinases; D004715:Endometriosis / Q000235:genetics* / Q000378:metabolism; D004717:Endometrium / Q000378:metabolism*; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism; D010535:Laparoscopy; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D050814:Octamer Transcription Factor-3 / Q000235:genetics* / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D055747:SOX Transcription Factors / Q000235:genetics* / Q000378:metabolism; D051879:Twist-Related Protein 1 / Q000235:genetics* / Q000378:metabolism
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D050814:Octamer Transcription Factor-3; C494173:POU5F1 protein, human; D012333:RNA, Messenger; D055747:SOX Transcription Factors; C102810:SOX15 protein, human; C103173:TWIST1 protein, human; D051879:Twist-Related Protein 1; C117347:DCLK1 protein, human; D000089742:Doublecortin-Like Kinases; D017346:Protein Serine-Threonine Kinases
keywords: Endometriosis; OCT4; SOX15; Stem cells; TWIST1