title: Differential expression of stem cell markers and ABCG2 in recurrent prostate cancer.
abstract: BACKGROUND
  Prostate cancer (PCa) is the second most common tumor type related to mortality in males in the developed countries. Studies have demonstrated that therapeutic tools mostly ineffective to give positive outcome especially for PCa. Cancer stem cells are composed of a small cell population, which are supposed to have roles in tumorigenesis, metastasis, and tumor recurrence after chemo-radiotherapy. The aim of this research is to investigate expressions of stem cell markers in recurrent PCa and non-recurrent PCa tumors as well as in adjacent normal prostate tissues.
  
  
  METHODS
  We compared the expression of important stemness regulators like SOX2, OCT4, KLF4, and ABCG2 in recurrent, non-recurrent PCa and adjacent normal tissue samples using quantitative real-time polymerase chain reaction (qRT-PCR).
  
  
  RESULTS
  Our results demonstrated that SOX2 and OCT4 are strongly overexpressed in PCa samples. Recurrent PCa samples are markedly positive for stem cell markers SOX2, OCT4, and KLF4. Furthermore, non-recurrent PCa samples presented low levels of ABCG2, a multidrug resistance protein, compared to both normal and recurrent samples, which might be associated with chemo-sensitivity.
  
  
  CONCLUSIONS
  Enhanced expression of ABCG2 and stem cell markers including SOX2, OCT4, and KLF4 in the recurrent PCa tissues postulates the suggestion that enrichment for cells with stem cell characteristics in these tissues might be playing a critical role for chemoresistance and recurrence of cancer.
authors.affiliation: Department of Medical Genetics, Istanbul University, Cerrahpasa Medical School, Istanbul, Turkey; Biruni University, Istanbul, Turkey.
authors.forename: Esra
authors.initials: E
authors.lastname: Guzel
authors.forename: Omer F
authors.initials: OF
authors.lastname: Karatas
authors.forename: Mehmet B
authors.initials: MB
authors.lastname: Duz
authors.forename: Mustafa
authors.initials: M
authors.lastname: Solak
authors.forename: Michael
authors.initials: M
authors.lastname: Ittmann
authors.forename: Mustafa
authors.initials: M
authors.lastname: Ozen
mesh_terms: D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000378:metabolism*; D009364:Neoplasm Recurrence, Local / Q000378:metabolism* / Q000473:pathology; D014411:Neoplastic Stem Cells / Q000378:metabolism*; D050814:Octamer Transcription Factor-3 / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000378:metabolism* / Q000473:pathology; D060888:Real-Time Polymerase Chain Reaction; D055748:SOXB1 Transcription Factors / Q000378:metabolism
chemical_list: C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D014408:Biomarkers, Tumor; C000715467:KLF4 protein, human; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; D009363:Neoplasm Proteins; D050814:Octamer Transcription Factor-3; C494173:POU5F1 protein, human; C527782:SOX2 protein, human; D055748:SOXB1 Transcription Factors
keywords: chemoresistance; prostate cancer; recurrence; stem cell markers