title: Critical role of heat shock protein 27 in bufalin-induced apoptosis in human osteosarcomas: a proteomic-based research.
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.
authors.affiliation: Bone and Soft Tissue Tumor Center, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China.
authors.forename: Xian-biao
authors.initials: XB
authors.lastname: Xie
authors.forename: Jun-qiang
authors.initials: JQ
authors.lastname: Yin
authors.forename: Li-li
authors.initials: LL
authors.lastname: Wen
authors.forename: Zhen-hua
authors.initials: ZH
authors.lastname: Gao
authors.forename: Chang-ye
authors.initials: CY
authors.lastname: Zou
authors.forename: Jin
authors.initials: J
authors.lastname: Wang
authors.forename: Gang
authors.initials: G
authors.lastname: Huang
authors.forename: Qing-lian
authors.initials: QL
authors.lastname: Tang
authors.forename: Chiara
authors.initials: C
authors.lastname: Colombo
authors.forename: Wei-ling
authors.initials: WL
authors.lastname: He
authors.forename: Qiang
authors.initials: Q
authors.lastname: Jia
authors.forename: Jing-nan
authors.initials: JN
authors.lastname: Shen
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D001859:Bone Neoplasms / Q000235:genetics / Q000378:metabolism*; D002018:Bufanolides / Q000494:pharmacology*; D045744:Cell Line, Tumor; D045304:Cytochromes c / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D055551:HSP27 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D012516:Osteosarcoma / Q000235:genetics / Q000378:metabolism*; D020543:Proteome; D040901:Proteomics; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051996:Transcription Factor RelA / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D002018:Bufanolides; D055551:HSP27 Heat-Shock Proteins; D020543:Proteome; D051996:Transcription Factor RelA; C095591:chan su; D045304:Cytochromes c; D051057:Proto-Oncogene Proteins c-akt; C022777:bufalin