SOX18 knockdown suppresses the proliferation and metastasis, and induces the apoptosis of osteosarcoma cells.

Sex determining region Y‑box 18 (SOX18) has been found to be overexpressed in several types of tumor. However, the molecular mechanism underlying the biological function of SOX18 in osteosarcoma remains to be elucidated. The present study aimed to elucidate the roles of SOX18 in regulating the biological behavior of osteosarcoma cells. First, SOX18 mRNA expression was analyzed in osteosarcoma tissues using reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR). The results demonstrated that the expression of SOX18 was elevated in osteosarcoma tissue, compared with normal bone tissue. In addition, the knockdown of SOX18 in U2OS or MG63 osteosarcoma cells inhibited cell proliferation and significantly increased the population of cells in the S‑phase of the cell cycle, as measured by the CCK‑8 assay and flow cytometric analysis, respectively. Additionally, suppression of the expression of SOX18 in the osteosarcoma cells significantly induced cell apoptosis as evaluated by annexin V/propidium iodide staining and flow cytometric analysis. The downregulation of SOX18 was found to significantly inhibit cell adhesion and invasion. The mRNA and protein expression levels of transforming growth factor‑β, platelet‑derived growth factor (PDGF)‑A, PDGF‑B and RhoA were also reduced by SOX18 silencing, as assessed by RT‑qPCR and western blot analysis, respectively. These results indicated that SOX18 may function as an oncogene, and may provide a novel and promising therapeutic strategy for osteosarcoma.