Cantharidin decreased viable cell number in human osteosarcoma U-2 OS cells through G2/M phase arrest and induction of cell apoptosis.

Cantharidin (CTD), a sesquiterpenoid bioactive substance, has been reported to exhibit anticancer activity against various types of cancer cells. The aim of the present study was to investigate the apoptosis effects and the underlying mechanisms of CTD on osteosarcoma U-2 OS cells. Results showed that CTD induced cell morphologic changes, reduced total viable cells, induced DNA damage, and G2/M phase arrest. CTD increased the production of reactive oxygen species and Ca2+, and elevated the activities of caspase-3 and -9, but decreased the level of mitochondrial membrane potential. Furthermore, CTD increased the ROS- and ER stress-associated protein expressions and increased the levels of pro-apoptosis-associated proteins, but decreased that of anti-apoptosis-associated proteins. Based on these observations, we suggested that CTD decreased cell number through G2/M phase arrest and the induction of cell apoptosis in U-2 OS cells and CTD could be a potential candidate for osteosarcoma treatments.