Effect of Period 2 on the proliferation, apoptosis and migration of osteosarcoma cells, and the corresponding mechanisms.

Period 2 (per2) is a core circadian clock gene. Dysregulation of the per2 gene has been identified in a number of types of human cancer and may be associated with a poor prognosis. To confirm the influence of per2 gene on MNNG/HOS human osteosarcoma cells, small interfering (si)RNA against per2 or plasmids containing per2 were transfected into MNNG/HOS cells, and the proliferation, apoptosis and migration were observed. The present study demonstrated that per2 knockdown significantly enhanced MNNG/HOS cell proliferation and migration and protected MNNG/HOS cells from apoptosis. Per2 overexpression inhibited MNNG/HOS cell proliferation and migration and promoted apoptosis. Furthermore, the protein expression of phosphorylated (p)-protein kinase B (Akt) and Bcl-2 were inhibited in per2-overexpressing cells, while the expression of p27, p21 and cleaved caspase-3 was promoted. In contrast, the expression of p-Akt and Bcl-2 was promoted in per2-knockdown cells, and p27, p21 and cleaved caspase-3 were decreased. This initial study may provide an alternative therapeutic strategy for the treatment of osteosarcoma.