title: Absence of Canonical WNT Signaling in Adult Renal Cell Tumors of Embryonal Origin.
abstract: OBJECTIVE
  The canonical β-catenin pathway is involved in the development of Wilms' tumor, but its role in adult renal cell tumors (RCT) of embryonal origin is not yet known.
  
  
  METHODS
  We sequenced the catenin beta 1 (CTNNB1) gene in papillary RCTs, applied the TOPflash/FOPflash reporter plasmid system on cell lines, and examined the β-catenin protein expression by immunohistochemistry.
  
  
  RESULTS
  The absence of mutations in CTNNB1 and low TOPflash/FOPflash ratio in tumor cell lines indicated the absence of active Wingless-type MMTV integration site family (WNT) signaling in RCTs. The weakly cytoplasmic tending towards membranous expression of β-catenin in RCT is analogous to cellular differentiation in the embryonal kidney rather than tumorigenic activation of WNT signaling.
  
  
  CONCLUSIONS
  The localization of β-catenin in papillary RCT, metanephric adenoma and mucinous tubular and spindle-cell carcinoma corresponds to that of emerging tubules of kidney at distinct stage of maturation, indicating their embryonal origin.
authors.affiliation: Medical Faculty, Ruprecht-Karls-University, Heidelberg, Germany.
authors.forename: Nina Kaerger
authors.initials: NK
authors.lastname: Billfeldt
authors.affiliation: Department of Urology, Medical School, University of Pecs, Pecs, Hungary.
authors.forename: Daniel
authors.initials: D
authors.lastname: Banyai
authors.affiliation: Medical Faculty, Ruprecht-Karls-University, Heidelberg, Germany Department of Urology, Medical School, University of Pecs, Pecs, Hungary gyula.kovacs@urz.uni-heidelberg.de.
authors.forename: Gyula
authors.initials: G
authors.lastname: Kovacs
mesh_terms: D002292:Carcinoma, Renal Cell / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D057809:HEK293 Cells; D006801:Humans; D007680:Kidney Neoplasms / Q000378:metabolism* / Q000473:pathology; D009373:Neoplasms, Germ Cell and Embryonal / Q000378:metabolism* / Q000473:pathology; D015398:Signal Transduction; D051153:Wnt Proteins / Q000378:metabolism*
chemical_list: D051153:Wnt Proteins
keywords: CTNNB1; TOPflash/FOPflash; WNT signaling; papillary renal cell tumor; β-catenin