Abstract
It has been reported that the presence of a small group of cancer stem‑like 'side population (SP)' cells is responsible for therapy failure and tumor recurrence. The present study demonstrated that primary human osteosarcoma samples contained a SP of about 3.9% which overexpressed ABC transporters, including ABCA1, ABCB1, ABCB2 and ABCG2, which are associated with drug resistance and may have contributed to multi‑drug resistance of SP cells. Furthermore, these SP cells displayed increased expression of endosialin (CD248) and other stem cell surface proteins, including CD133, octamer‑binding transcription factor 3/4A, Nanog and Nestin, which are ultimately responsible for high self‑renewal and deregulated cell proliferation. In addition, it was shown that endosialin‑overexpressing SP cells were able to regenerate the tumor population and had a high invasive potential. Therefore, the present study suggested that osteosarcoma SP cells were cancer stem cells, as they displayed stem‑like properties; furthermore, endosialin may be a potential target to prevent osteosarcoma recurrence following chemotherapy.