title: BMP and TGFbeta pathways in human central chondrosarcoma: enhanced endoglin and Smad 1 signaling in high grade tumors.
abstract: BACKGROUND
  As major regulators of normal chondrogenesis, the bone morphogenic protein (BMP) and transforming growth factor β (TGFB) signaling pathways may be involved in the development and progression of central chondrosarcoma. In order to uncover their possible implication, the aim of this study was to perform a systematic quantitative study of the expression of BMPs, TGFBs and their receptors and to assess activity of the corresponding pathways in central chondrosarcoma.
  
  
  METHODS
  Gene expression analysis was performed by quantitative RT-PCR in 26 central chondrosarcoma and 6 healthy articular cartilage samples. Expression of endoglin and nuclear localization of phosphorylated Smad1/5/8 and Smad2 was assessed by immunohistochemical analysis.
  
  
  RESULTS
  The expression of TGFB3 and of the activin receptor-like kinase ALK2 was found to be significantly higher in grade III compared to grade I chondrosarcoma. Nuclear phosphorylated Smad1/5/8 and Smad2 were found in all tumors analyzed and the activity of both signaling pathways was confirmed by functional reporter assays in 2 chondrosarcoma cell lines. Immunohistochemical analysis furthermore revealed that phosphorylated Smad1/5/8 and endoglin expression were significantly higher in high-grade compared to low-grade chondrosarcoma and correlated to each other.
  
  
  CONCLUSIONS
  The BMP and TGFβ signaling pathways were found to be active in central chondrosarcoma cells. The correlation of Smad1/5/8 activity to endoglin expression suggests that, as described in other cell types, endoglin could enhance Smad1/5/8 signaling in high-grade chondrosarcoma cells. Endoglin expression coupled to Smad1/5/8 activation could thus represent a functionally important signaling axis for the progression of chondrosarcoma and a regulator of the undifferentiated phenotype of high-grade tumor cells.
authors.affiliation: Research Centre for Experimental Orthopaedics, Department of Orthopaedics, Trauma Surgery and Paraplegiology, Heidelberg University Hospital, Schlierbacher Landstrasse 200a, 69118, Heidelberg, Germany.
authors.forename: Stephane
authors.initials: S
authors.lastname: Boeuf
authors.forename: Judith V M G
authors.initials: JV
authors.lastname: Bovée
authors.forename: Burkhard
authors.initials: B
authors.lastname: Lehner
authors.forename: Brendy
authors.initials: B
authors.lastname: van den Akker
authors.forename: Maayke
authors.initials: M
authors.lastname: van Ruler
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Cleton-Jansen
authors.forename: Wiltrud
authors.initials: W
authors.lastname: Richter
mesh_terms: D015703:Antigens, CD / Q000378:metabolism*; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000378:metabolism*; D001859:Bone Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002813:Chondrosarcoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D000071063:Endoglin; D020869:Gene Expression Profiling; D006801:Humans; D007150:Immunohistochemistry; D053208:Kaplan-Meier Estimate; D011956:Receptors, Cell Surface / Q000378:metabolism*; D015398:Signal Transduction; D051898:Smad1 Protein / Q000378:metabolism*; D051899:Smad2 Protein / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*
chemical_list: D015703:Antigens, CD; D019485:Bone Morphogenetic Proteins; C064206:ENG protein, human; D000071063:Endoglin; D011956:Receptors, Cell Surface; C497399:SMAD1 protein, human; C497782:SMAD2 protein, human; D051898:Smad1 Protein; D051899:Smad2 Protein; D016212:Transforming Growth Factor beta