Proliferation, Apoptosis and Invasion effects of mistletoe alkali on human osteosarcoma U2OS in vitro.

OBJECTIVE: To evaluate the effects of mistletoe alkali on human Osteosarcoma cells (U2OS) in vitro.

SUMMARY OF BACKGROUND DATA: Osteosarcoma is the most common primary malignant tumor of bone tumor, although there are a lot of therapies such as surgery, radiotherapy and chemotherapy, its prognosis is still very poor. There is increasing interest in the protective biological function of natural antioxidants contained in Chinese medicinal herbs, which are candidates for the prevention of tumors. Mistletoe alkali is one of the compounds extracted from Viscum coloratum (Komar.) Nakai, one kind of mistletoe, whose extracts contribute to the improvement of the prognosis of patients with malignancies.

METHODS: The effect of mistletoe alkali on the growth of U2OS cells was compared with 5-FU, using a Cell Counting Kit-8 (CCK-8). The influence of mistletoe alkali on U2OS's proliferation and apoptosis were tested by TUNEL staining and immunocytochemical (ICC) staining of caspase 3 and proliferating cell nuclear antigen (PCNA). Additionally, the invasion ability of U2OS cells was detected using a Boyden chamber trans-well migration assay.

RESULTS: CCK-8 assays gave an IC50 of 7μg/ml for mistletoe alkali. Compared to 5-FU, mistletoe alkali inhibited U2OS proliferation and induced apoptosis more effectively. The invasion ability of U2OS was also weaker in mistletoe alkali than in 5-FU.

CONCLUSIONS: Mistletoe alkali significantly inhibited growth and invasion abilities of U2OS cells and induced their apoptosis in vitro. Mistletoe alkali may be a more effective drug for Human Osteosarcoma than the standard chemotherapeutic drug 5-FU.