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.
Highlights
Osteosarcoma is the most common bone tumor in children and adolescents comprising 20% of all bone tumors and about 5% of pediatric tumors overall [1,2]
We have identified a subpopulation of cells with stem-like properties in canine osteosarcoma that is relatively resistant to conventional chemotherapy
Cells isolated from a primary canine osteosarcoma, KTOSA5, and human osteosarcoma cell lines, U2OS and SAOS2, were seeded as single cells at low-density into suspension cultures in serum-free growth factor supplemented media
Summary
Osteosarcoma is the most common bone tumor in children and adolescents comprising 20% of all bone tumors and about 5% of pediatric tumors overall [1,2]. Significant improvements in patient survival rates have been achieved through multimodal therapeutic approaches combining high-dose chemotherapy and surgical resection [5]. Despite these advances, the overall relapse free-survival rate over 5-years has remained at approximately 65% to 75% and the intensification of chemotherapy regimens has not improved survival [6,7]. Like the situation in children, osteosarcoma is the most commonly diagnosed primary bone tumour of dogs [8] It generally occurs on the limbs of middle-aged to older, large breed dogs, with the distal radius and proximal humerus as common locations [8]. 1-year survival times are ,20% despite surgery and chemotherapy [8]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call