Abstract: Objective To isolate and identify cancer stem like cells (Sphere formed cells) from human osteosarcoma cell line MG-63, and study it’s invasion and metastasis ability. Methods Non-adherent culture was performed and PKH26 staining was used to identify cancer stem like cells in MG-63 spheres. Western blot was used to detect stemness associated protein expression in spheres cells. Self-renew and invasion of sphere formed cells were detected by methylcellulose semisolid culture and Transwell methods. The key proteins of epithelial to mesenchymal transition (EMT), invasion and metastasis in sphere cells were also detected by Western blot. Results The single PKH26 positive cell was observed in sphere formed cells after MG-63 cells were cultured for 11days. Compared with the monolayer cells, the sphere formed cells presented higher self-renewal ability (P<0.01), invasion ability enhanced 1.45 times (P<0.01) and increased expression of snail and MMP2 companied with decreased expression of E-cadherin. Conclusions Sphere formed cells in MG-63 show stemness characteristics and EMT, which are related with invasion and metastasis of osteosarcoma cells.

Key words: osteosarcoma, cancer stem cell, invasion, metastasis