1. Critical role of heat shock protein 27 in bufalin-induced apoptosis in human osteosarcomas: a proteomic-based research.
- Author
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Xie XB, Yin JQ, Wen LL, Gao ZH, Zou CY, Wang J, Huang G, Tang QL, Colombo C, He WL, Jia Q, and Shen JN
- Subjects
- Animals, Apoptosis genetics, Bone Neoplasms genetics, Cell Line, Tumor, Cytochromes c metabolism, Female, Gene Expression Regulation, Neoplastic drug effects, HSP27 Heat-Shock Proteins genetics, Humans, Mice, Osteosarcoma genetics, Proteome, Proteomics, Proto-Oncogene Proteins c-akt metabolism, Transcription Factor RelA metabolism, Xenograft Model Antitumor Assays, Antineoplastic Agents pharmacology, Apoptosis drug effects, Bone Neoplasms metabolism, Bufanolides pharmacology, HSP27 Heat-Shock Proteins metabolism, Osteosarcoma metabolism
- Abstract
Bufalin is the primary component of the traditional Chinese herb "Chan Su". Evidence suggests that this compound possesses potent anti-tumor activities, although the exact molecular mechanism(s) is unknown. Our previous study showed that bufalin inhibited growth of human osteosarcoma cell lines U2OS and U2OS/MTX300 in culture. Therefore, this study aims to further clarify the in vitro and in vivo anti-osteosarcoma effects of bufalin and its molecular mechanism of action. We found bufalin inhibited both methotrexate (MTX) sensitive and resistant human osteosarcoma cell growth and induced G2/M arrest and apoptosis. Using a comparative proteomics approach, 24 differentially expressed proteins following bufalin treatment were identified. In particular, the level of an anti-apoptotic protein, heat shock protein 27 (Hsp27), decreased remarkably. The down-regulation of Hsp27 and alterations of its partner signaling molecules (the decrease in p-Akt, nuclear NF-κB p65, and co-immunoprecipitated cytochrome c/Hsp27) were validated. Hsp27 over-expression protected against bufalin-induced apoptosis, reversed the dephosphorylation of Akt and preserved the level of nuclear NF-κB p65 and co-immunoprecipitated Hsp27/cytochrome c. Moreover, bufalin inhibited MTX-resistant osteosarcoma xenograft growth, and a down-regulation of Hsp27 in vivo was observed. Taken together, bufalin exerted potent anti-osteosarcoma effects in vitro and in vivo, even in MTX resistant osteosarcoma cells. The down-regulation of Hsp27 played a critical role in bufalin-induced apoptosis in osteosarcoma cells. Bufalin may have merit to be a potential chemotherapeutic agent for osteosarcoma, particularly in MTX-resistant groups.
- Published
- 2012
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