title: Loss of the NKX3.1 tumorsuppressor promotes the TMPRSS2-ERG fusion gene expression in prostate cancer.
abstract: BACKGROUND
  In normal prostate epithelium the TMPRSS2 gene encoding a type II serine protease is directly regulated by male hormones through the androgen receptor. In prostate cancer ERG protooncogene frequently gains hormonal control by seizing gene regulatory elements of TMPRSS2 through genomic fusion events. Although, the androgenic activation of TMPRSS2 gene has been established, little is known about other elements that may interact with TMPRSS2 promoter sequences to modulate ERG expression in TMPRSS2-ERG gene fusion context.
  
  
  METHODS
  Comparative genomic analyses of the TMPRSS2 promoter upstream sequences and pathway analyses were performed by the Genomatix Software. NKX3.1 and ERG genes expressions were evaluated by immunoblot or by quantitative Real-Time PCR (qRT-PCR) assays in response to siRNA knockdown or heterologous expression. QRT-PCR assay was used for monitoring the gene expression levels of NKX3.1-regulated genes. Transcriptional regulatory function of NKX3.1 was assessed by luciferase assay. Recruitment of NKX3.1 to its cognate elements was monitored by Chromatin Immunoprecipitation assay.
  
  
  RESULTS
  Comparative analysis of the TMPRSS2 promoter upstream sequences among different species revealed the conservation of binding sites for the androgen inducible NKX3.1 tumor suppressor. Defects of NKX3.1, such as, allelic loss, haploinsufficiency, attenuated expression or decreased protein stability represent established pathways in prostate tumorigenesis. We found that NKX3.1 directly binds to TMPRSS2 upstream sequences and negatively regulates the expression of the ERG protooncogene through the TMPRSS2-ERG gene fusion.
  
  
  CONCLUSIONS
  These observations imply that the frequently noted loss-of-function of NKX3.1 cooperates with the activation of TMPRSS2-ERG fusions in prostate tumorigenesis.
authors.forename: Rajesh
authors.initials: R
authors.lastname: Thangapazham
authors.forename: Francisco
authors.initials: F
authors.lastname: Saenz
authors.forename: Shilpa
authors.initials: S
authors.lastname: Katta
authors.forename: Ahmed A
authors.initials: AA
authors.lastname: Mohamed
authors.forename: Shyh-Han
authors.initials: SH
authors.lastname: Tan
authors.forename: Gyorgy
authors.initials: G
authors.lastname: Petrovics
authors.forename: Shiv
authors.initials: S
authors.lastname: Srivastava
authors.affiliation: Center for Prostate Disease Research, Uniform Services University of the Health Sciences, 1530 East Jefferson Street, Rockville, Maryland 20852, USA. adobi@cpdr.org.
authors.forename: Albert
authors.initials: A
authors.lastname: Dobi
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D045744:Cell Line, Tumor; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic; D050939:Gene Fusion; D055785:Gene Knockdown Techniques; D057809:HEK293 Cells; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D015514:Oncogene Proteins, Fusion / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D034622:RNA Interference; D013045:Species Specificity; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D018398:Homeodomain Proteins; D016328:NF-kappa B; C491178:NKX3-1 protein, human; D015514:Oncogene Proteins, Fusion; C515553:TMPRSS2-ERG fusion protein, human; D014157:Transcription Factors