RESUMO
According to the cancer stem cell theory, the presence of a small subpopulation of cancer cells, termed cancer stem cells (CSCs), have a significant implication on cancer treatment and are responsible for tumor recurrence. Previous studies have reported that alterations in the Wnt/ßcatenin signaling are crucial in the maintenance of CSCs. In the present study, the characteristic features and activation of Wnt/ßcatenin signaling in CSCs from osteosarcoma, an aggressive human bone tumor, were investigated. In total, ~2.1% of the cancer stemlike side population (SP) cells were identified in the osteosarcoma samples. The results of subsequent western blot and reverse transcriptionquantitative polymerase chain reaction analyses revealed that the protein levels of ßcatenin and cyclin D1 were markedly upregulated in the fluorescenceactivated cell sorted osteosarcoma SP cells. In addition, the elevated expression levels of stem cell proteins, including CD133, nestin Oct4, Sox2 and Nanog were significantly higher in the SP cells, which contributed to selfrenewal and enhanced the proliferation rate of the SP cells. Furthermore, the SP cells were found to be highly invasive and able to form tumors in vivo. Taken together, these data suggested that the identification of novel anticancer drugs, which suppress the Wnt/ßcatenin signaling and its downstream pathway may assist in eradicating osteosarcoma stem cells.