title: Global gene expression analysis of canine osteosarcoma stem cells reveals a novel role for COX-2 in tumour initiation.
abstract: Osteosarcoma is the most common primary bone tumour of both children and dogs. It is an aggressive tumour in both species with a rapid clinical course leading ultimately to metastasis. In dogs and children distant metastasis occurs in >80% of individuals treated by surgery alone. Both canine and human osteosarcoma has been shown to contain a sub-population of cancer stem cells (CSCs), which may drive tumour growth, recurrence and metastasis, suggesting that naturally occurring canine osteosarcoma could act as a preclinical model for the human disease. Here we report the successful isolation of CSCs from primary canine osteosarcoma, as well as established cell lines. We show that these cells can form tumourspheres, and demonstrate relative resistance to chemotherapy. We demonstrate similar results for the human osteosarcma cell lines, U2OS and SAOS2. Utilizing the Affymetrix canine microarray, we are able to definitively show that there are significant differences in global gene expression profiles of isolated osteosarcoma stem cells and the daughter adherent cells. We identified 13,221 significant differences (p = 0.05), and significantly, COX-2 was expressed 141-fold more in CSC spheres than daughter adherent cells. To study the role of COX-2 expression in CSCs we utilized the COX-2 inhibitors meloxicam and mavacoxib. We found that COX-2 inhibition had no effect on CSC growth, or resistance to chemotherapy. However inhibition of COX-2 in daughter cells prevented sphere formation, indicating a potential significant role for COX-2 in tumour initiation.
authors.affiliation: Royal (Dick) School of Veterinary Studies and Roslin Institute, The University of Edinburgh, Easter Bush, Midlothian, United Kingdom.
authors.forename: Lisa Y
authors.initials: LY
authors.lastname: Pang
authors.affiliation: Royal (Dick) School of Veterinary Studies and Roslin Institute, The University of Edinburgh, Easter Bush, Midlothian, United Kingdom.
authors.forename: Emma L
authors.initials: EL
authors.lastname: Gatenby
authors.affiliation: Royal (Dick) School of Veterinary Studies and Roslin Institute, The University of Edinburgh, Easter Bush, Midlothian, United Kingdom.
authors.forename: Ayako
authors.initials: A
authors.lastname: Kamida
authors.affiliation: Royal (Dick) School of Veterinary Studies and Roslin Institute, The University of Edinburgh, Easter Bush, Midlothian, United Kingdom.
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Whitelaw
authors.affiliation: Edinburgh Cancer Research UK Centre, The University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Ted R
authors.initials: TR
authors.lastname: Hupp
authors.affiliation: Royal (Dick) School of Veterinary Studies and Roslin Institute, The University of Edinburgh, Easter Bush, Midlothian, United Kingdom.
authors.forename: David J
authors.initials: DJ
authors.lastname: Argyle
mesh_terms: D000818:Animals; D001859:Bone Neoplasms / Q000201:enzymology / Q000235:genetics / Q000473:pathology / Q000662:veterinary; D063646:Carcinogenesis / Q000235:genetics* / Q000473:pathology; D016923:Cell Death / Q000187:drug effects / Q000235:genetics; D002470:Cell Survival / Q000235:genetics; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism*; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology; D004283:Dog Diseases / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D004285:Dogs; D004317:Doxorubicin / Q000494:pharmacology / Q000627:therapeutic use; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D009361:Neoplasm Invasiveness; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology; D012516:Osteosarcoma / Q000201:enzymology / Q000235:genetics* / Q000473:pathology / Q000662:veterinary*; D018874:Spheroids, Cellular / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D014410:Tumor Stem Cell Assay
chemical_list: D052246:Cyclooxygenase 2 Inhibitors; D004317:Doxorubicin; D051546:Cyclooxygenase 2