title: Tumourigenic canine osteosarcoma cell lines associated with frizzled-6 up-regulation and enhanced side population cell frequency.
abstract: An increased serum alkaline phosphatase concentration is known to be associated with a negative prognosis in canine and human osteosarcoma. To expand upon previous studies regarding the biological relevance of increased serum alkaline phosphatase as a negative prognostic factor, xenogeneic heterotopic transplants were performed using six canine primary osteosarcoma cell lines generated from patients with differing serum alkaline phosphatase concentrations (three normal and three increased). Three of the six cell lines were capable of generating tumours and tumour formation was independent of the serum alkaline phosphatase status of the cell line. Microarray analysis identified 379 genes as being differentially expressed between the tumourigenic and non-tumourigenic cell lines. Frizzled-6 was upregulated to the greatest extent (7.78-fold) in tumourigenic cell lines compared with non-tumourigenic cell lines. Frizzled-6, a co-receptor for Wnt ligands has been associated with enhanced tumour-initiating cells and poor prognosis for other tumours. The increased expression of frizzled-6 was confirmed by quantitative reverse transcription polymerase chain reaction (QPCR) and Western blot analysis. Additionally, the tumourigenic cell lines also had an increase in the percentage of side population cells compared with non-tumourigenic cell lines (5.89% versus 1.58%, respectively). There were no differences in tumourigenicity, frizzled-6 or percentage of side population cells noted between osteosarcoma cell lines generated from patients of differing serum alkaline phosphatase concentration. However, to our knowledge this is the first study to identified frizzled-6 as a possible marker of osteosarcoma cell populations with enhanced tumourigenicity and side population cells. Future work will focus on defining the role of frizzled-6 in osteosarcoma tumourigenesis and tumour-initiating cells.
authors.affiliation: Department of Medical Sciences, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: L C
authors.initials: LC
authors.lastname: de Sá Rodrigues
authors.affiliation: Department of Medical Sciences, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: K E
authors.initials: KE
authors.lastname: Holmes
authors.affiliation: Department of Medical Sciences, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: V
authors.initials: V
authors.lastname: Thompson
authors.affiliation: Departments of Statistics and of Biostatistics and Medical Informatics, University of Wisconsin-Madison, Madison, WI, USA.|Carbone Comprehensive Cancer Center, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Newton
authors.affiliation: Department of Medical Sciences, University of Wisconsin-Madison, Madison, WI, USA.|Carbone Comprehensive Cancer Center, University of Wisconsin-Madison, Madison, WI, USA.|Institute for Clinical & Translational Research, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: T J
authors.initials: TJ
authors.lastname: Stein
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D014408:Biomarkers, Tumor / Q000235:genetics; D001859:Bone Neoplasms / Q000235:genetics / Q000378:metabolism / Q000662:veterinary*; D045744:Cell Line, Tumor; D004283:Dog Diseases / Q000235:genetics* / Q000378:metabolism; D004285:Dogs; D015870:Gene Expression; D051379:Mice; D008819:Mice, Nude; D046228:Microarray Analysis / Q000662:veterinary; D012516:Osteosarcoma / Q000235:genetics / Q000378:metabolism / Q000662:veterinary*; D011379:Prognosis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D058985:Side-Population Cells
chemical_list: D014408:Biomarkers, Tumor; D000469:Alkaline Phosphatase
keywords: cell signalling; comparative oncology; mouse models; oncology; tumour biology