Cluster of differentiation 44- and octamer-binding transcription factor-4-positive stem-like osteosarcoma cells involved in tumor development.

Osteosarcoma (OS) is an aggressive primary bone cancer that usually affects children and young adolescents. Previous studies have demonstrated the implications of a small sub-population of cancer stem cells on treatment failure and tumor recurrence. The present study analyzed the characteristic features of the stem-like cells within the human OS-55 cell line. It was identified that 2.3% of the OS-55 cells were cancer stem-like side population (SP) cells. Following treatment with verapamil, the population of SP cells was reduced to 0.7%. The sphere formation assay revealed that the OS cells were able to rapidly form tumor spheres (also known as sarcospheres). Immunofluorescence analysis identified that the OS-55 cells expressed the cluster of differentiation 44, octamer-binding transcription factor-3/4A and Nanog stem cell surface markers. The results of the present study suggest that, as with other tumors, OS also contains a sub-population of cancer stem-like cells, which may have important implications in cancer diagnosis and treatment.