SIRT1-ZEB1-positive feedback promotes epithelial-mesenchymal transition process and metastasis of osteosarcoma.

Osteosarcoma is the most common malignant bone cancer that mainly affects children and young adults. Recently, the NAD -dependent deacetylase, sirtuin 1 (SIRT1), has been reported to play a key role in the development of malignant tumors. The study aimed to investigate the role of SIRT1 in osteosarcoma and explore its underlying oncogenic mechanisms. The prognostic value of SIRT1 in osteosarcoma was assessed through detection of SIRT1 expression based on osteosarcoma biopsy tissue. Then, to further investigate the effect of SIRT1 in osteosarcoma, osteosarcoma cells were treated with small interfering RNA SIRT1 and overexpressed SIRT1 to detect the cell migration, invasion, and epithelial-mesenchymal transition (EMT). The levels of SIRT1 expression were significantly higher in osteosarcoma tissues than those in adjacent normal tissues, and the SIRT1 protein level may be coupled with metastatic and poor prognosis risk in patients with osteosarcoma. Moreover, SIRT1 silencing inhibited the migration as well as invasion ability of osteosarcoma cells in vitro, and SIRT1 upregulation reversed those effects. Finally, we found that SIRT1-ZEB1-positive feedback enhanced the EMT process and metastasis of osteosarcoma. Altogether, the results of the current study revealed that high levels of SIRT1 might be a biomarker for a high metastatic rate in patients with osteosarcoma, which suggested that inhibition of SIRT1 might be promising for the therapeutics of osteosarcoma.