Bufalin inhibited the growth of human osteosarcoma MG-63 cells via down-regulation of Bcl-2/Bax and triggering of the mitochondrial pathway

Cinobufacini (Huachansu), a Chinese medicine prepared from the skin of Bufo bufo gargarizans Cantor (Bufonidae), has potent anti-tumor activity in vitro and in vivo. However, the molecular mechanism of cell apoptosis induced by Bufalin remains elusive. Here, we investigated the apoptosis in Bufalin-treated human osteosarcoma MG-63 cells. The results showed that Bufalin could inhibit cell proliferation and induce apoptosis in a dose- and time-dependent manner. Further investigation revealed that a disruption of mitochondrial transmembrane potential (MMP) and an up-regulation of reactive oxygen species (ROS) in Bufalin-treated cells. By western blot analysis, we found that the up-regulation of Apaf-1, cleaved PARP, cleaved caspase-3, cleaved caspase-9, and Bax/Bcl-2, varies with different concentration of Bufalin. These protein interactions may play a pivotal role in the regulation of apoptosis. Taken together, these results overall indicate that Bufalin could be used as an effective anti-tumor agent in therapy of osteosarcoma targets the mitochondrial-dependent signaling pathway.