title: The bone morphogenetic protein pathway is inactivated in the majority of sporadic colorectal cancers.
abstract: OBJECTIVE
  The finding of bone morphogenetic protein (BMP) receptor 1a mutations in juvenile polyposis suggests that BMPs are important in colorectal cancer (CRC). We investigated the BMP pathway in sporadic CRC.
  
  
  METHODS
  We investigated BMP receptor (BMPR) expression using immunoblotting and sequenced BMPR2 in CRC cell lines. We assessed the expression of BMPRs, SMAD4, and pSMAD1/5/8 in 72 sporadic CRCs using a tissue microarray and immunohistochemistry. We assessed the effect of reintroduction of wild-type BMPR2 on BMP pathway activity and the effect of wild-type or mutated BMPR2 3' untranslated region (UTR) sequences on protein expression by attachment to pCMV-Luc.
  
  
  RESULTS
  BMPR2 and SMAD4 protein expression is abrogated in microsatellite unstable (MSI) and microsatellite stable (MSS) cell lines, respectively. BMPR2 3'UTR is mutated in all MSI and in none of the MSS cell lines. Mutant BMPR2 3'UTR sequences reduced luciferase expression 10-fold compared with wild-type BMPR2 3'UTR. BMPR2 expression is impaired more frequently in MSI CRCs than MSS (85% vs 29%; P < .0001) and shows a mutually exclusive pattern of impaired expression compared with SMAD4. Nine of 11 MSI cancers with impaired expression of BMPR2 have microsatellite mutations. The BMP pathway is inactivated, as judged by nuclear pSMAD1/5/8 expression, in 70% of CRCs, and this correlates with BMPR and SMAD4 loss.
  
  
  CONCLUSIONS
  Our data suggest that the BMP pathway is inactivated in the majority of sporadic CRCs. In MSI CRC this is associated predominantly with impaired BMPR2 expression and in MSS CRC with impaired SMAD4 expression.
authors.affiliation: Department of Gastroenterology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Liudmila L
authors.initials: LL
authors.lastname: Kodach
authors.forename: Eliza
authors.initials: E
authors.lastname: Wiercinska
authors.forename: Noel F C C
authors.initials: NF
authors.lastname: de Miranda
authors.forename: Sylvia A
authors.initials: SA
authors.lastname: Bleuming
authors.forename: Alex R
authors.initials: AR
authors.lastname: Musler
authors.forename: Maikel P
authors.initials: MP
authors.lastname: Peppelenbosch
authors.forename: Evelien
authors.initials: E
authors.lastname: Dekker
authors.forename: Gijs R
authors.initials: GR
authors.lastname: van den Brink
authors.forename: Carel J M
authors.initials: CJ
authors.lastname: van Noesel
authors.forename: Hans
authors.initials: H
authors.lastname: Morreau
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Hommes
authors.forename: Peter
authors.initials: P
authors.lastname: Ten Dijke
authors.forename: G Johan A
authors.initials: GJ
authors.lastname: Offerhaus
authors.forename: James C H
authors.initials: JC
authors.lastname: Hardwick
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000096:biosynthesis / Q000235:genetics; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000096:biosynthesis / Q000235:genetics*; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D008297:Male; D053842:Microsatellite Instability; D018895:Microsatellite Repeats / Q000235:genetics; D008875:Middle Aged; D009154:Mutation; D012334:RNA, Neoplasm / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051901:Smad4 Protein / Q000096:biosynthesis / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000096:biosynthesis / Q000235:genetics*
chemical_list: C525718:BMP2 protein, human; D014408:Biomarkers, Tumor; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D012334:RNA, Neoplasm; C497796:SMAD4 protein, human; D051901:Smad4 Protein; D016212:Transforming Growth Factor beta