Abstract
BACKGROUND: The development of novel therapies for sarcoma is urgently required because most sarcomas are refractory to adjuvant therapy and the treatment options are limited. Although antitumor effects of blue light (BL) have been reported for several malignant tumors, its impact on various sarcomas remains unknown. In this study, we examined the antitumor effects of BL on several kinds of bone and soft tissue sarcomas. METHODS: We used human osteosarcoma, undifferentiated pleomorphic sarcoma, liposarcoma, and myxofibrosarcoma cell lines, as well as a human dermal fibroblast cell line as normal cells. We continuously irradiated these cells with BL in an incubator. RESULTS: BL inhibited cell proliferation in sarcoma cells, but hardly affected normal cells. BL increased intracellular reactive oxygen species (ROS) levels in sarcoma cells, but not in normal cells. Interestingly, oxidative stress occurred after BL irradiation in both sarcoma and normal cells. In addition, apoptosis, autophagy, and mitochondrial dysfunction, which were induced by ROS, occurred in sarcoma cells. In undifferentiated pleomorphic sarcoma cells, BL caused cell death through activation of the endogenous apoptotic pathway, and autophagy counteracted the apoptosis. CONCLUSION: Our results indicate that BL might specifically kill sarcoma cells without injuring normal cells and may become a new treatment option for sarcoma.