title: Epigenetic changes in Basal Cell Carcinoma affect SHH and WNT signaling components.
abstract: BACKGROUND
  The genetic background of Basal Cell Carcinoma (BCC) has been studied extensively, while its epigenetic makeup has received comparatively little attention. Epigenetic alterations such as promoter hypermethylation silence tumor suppressor genes (TSG) in several malignancies.
  
  
  OBJECTIVE
  We sought to analyze the promoter methylation status of ten putative (tumor suppressor) genes that are associated with Sonic Hedgehog (SHH), WNT signaling and (hair follicle) tumors in a large series of 112 BCC and 124 healthy control samples by methylation-specific PCR.
  
  
  RESULTS
  Gene promoters of SHH (P = 0.016), adenomatous polyposis coli (APC) (P = 0.003), secreted frizzled-related protein 5 (SFRP5) (P = 0.004) and Ras association domain family 1A (RASSF1A) (P = 0.023) showed significantly more methylation in BCC versus normal skin. mRNA levels of these four genes were reduced for APC and SFRP5 in BCC (n = 6) vs normal skin (n = 6). Down regulation of SHH, APC and RASSF1A could be confirmed on protein level as well (P<0.001 for all genes) by immunohistochemical staining. Increased canonical WNT activity was visualized by β-catenin staining, showing nuclear β-catenin in only 28/101 (27.7%) of BCC. Absence of nuclear β-catenin in some samples may be due to high levels of membranous E-cadherin (in 94.1% of the samples).
  
  
  CONCLUSIONS
  We provide evidence that promoter hypermethylation of key players within the SHH and WNT pathways is frequent in BCC, consistent with their known constitutive activation in BCC. Epigenetic gene silencing putatively contributes to BCC tumorigenesis, indicating new venues for treatment.
authors.affiliation: Department of Dermatology, Maastricht University Medical Center, Maastricht, The Netherlands. t.brinkhuizen@mumc.nl
authors.forename: Tjinta
authors.initials: T
authors.lastname: Brinkhuizen
authors.forename: Karin
authors.initials: K
authors.lastname: van den Hurk
authors.forename: Véronique J L
authors.initials: VJ
authors.lastname: Winnepenninckx
authors.forename: Joep P
authors.initials: JP
authors.lastname: de Hoon
authors.forename: Ariënne M
authors.initials: AM
authors.lastname: van Marion
authors.forename: Jürgen
authors.initials: J
authors.lastname: Veeck
authors.forename: Manon
authors.initials: M
authors.lastname: van Engeland
authors.forename: Maurice A M
authors.initials: MA
authors.lastname: van Steensel
mesh_terms: D000368:Aged; D002280:Basal Cell Carcinoma / Q000235:genetics*; D016022:Case-Control Studies; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D053823:Hedgehog Proteins / Q000235:genetics*; D006801:Humans; D008297:Male; D011401:Promoter Regions, Genetic / Q000235:genetics; D012867:Skin / Q000378:metabolism*; D012878:Skin Neoplasms / Q000235:genetics*; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins / Q000235:genetics; D051153:Wnt Proteins / Q000235:genetics*
chemical_list: D053823:Hedgehog Proteins; C509239:SHH protein, human; D025521:Tumor Suppressor Proteins; D051153:Wnt Proteins