7-hydroxy-staurosporine, UCN-01, induces DNA damage response, and autophagy in human osteosarcoma U2-OS cells

Human osteosarcoma (bone cancer) is a highly malignant and the most prevalent bone tumor affecting children. Despite recent advances in the understanding of the molecular mechanism by which anticancer drugs kill osteosarcoma or block its growth, however, the mortality rate has declined only modestly. Thus, a new therapeutic approach is needed to be established. 7-hydroxystaurosporine, UCN-01, abrogates the G2 checkpoint thus enhancing the cytotoxicity of chemotherapeutic agents. In addition, it has been evaluated in clinical trials as a single antineoplastic agent in treating several cancers. However, the effects of UCN-01 on treating bone cancer has never been tested. In this study, we found that UCN-01 induced cell cycle arrest and apoptosis in the human osteosarcoma, U2-OS cells. In addition, the migration ability was also reduced, suggesting UCN-01 inhibited cell growth and migration. When U2-OS cells were treated with UCN-01, DNA damage response was triggered. The ataxia telangiectasia mutated (ATM) and the non-canonical downstream effector, ERK, was activated by UCN-01. In addition, depletion of ATM or inhibition of ERK deteriorated the cell viability in UCN-01-treated U2-OS cells. Furthermore, UCN-01 induced autophagy activation for protecting cells from apoptosis. Thus, UCN-01 might function as a single antineoplastic agent in treating human osteosarcoma.