title: Hypoxia-induced apoptosis is blocked by adrenomedullin via upregulation of Bcl-2 in human osteosarcoma cells.
abstract: Adrenomedullin (ADM), a multifunctional regulatory peptide, is potentially induced by hypoxia in physiological and pathological tissues, including many types of malignant tumors. Recent research has demonstrated that ADM expression is highly associated with the prognosis and disease severity of human osteosarcoma. However, the effect of ADM on the apoptosis of osteosarcoma cells and its possible mechanism remain to be elucidated. In the present study, we observed that mRNA and protein levels of ADM were increased in human osteosarcoma SOSP-F5M2 cells under a hypoxic microenvironment induced by cobalt chloride (CoCl2) in a time-dependent manner. Treatment with ADM significantly blunted hypoxic-induced apoptosis, evaluated by Hoechst 33342 staining and Annexin V-FITC/PI labeling. The expression of B-cell lymphoma-2 (Bcl-2) was increased by administration of ADM; meanwhile, this effect was reversed by exogenously adding U0126, a selective inhibitor of MEK or ADM22-52 (ADM-specific receptor antagonist). These results demonstrated that ADM acted as a survival factor to inhibit hypoxic-induced apoptosis via interacting with its receptors CRLR-RAMP (2,3) in osteosarcoma cells. The anti-apoptotic function of ADM was found to be mediated by upregulation of the expression of Bcl-2 partially through activation of the MEK/ERK1/2 signaling pathway. Therefore, targeting of the ADM/ADM acceptors/ERK1/2/Bcl-2 pathway may provide a potential strategy through which to induce the apoptosis of osteosarcoma cells.
authors.affiliation: Department of Orthopaedics, Shaanxi Provincial People's Hospital, Xi'an, Shaanxi 710068, P.R. China.
authors.forename: Xue-Yuan
authors.initials: XY
authors.lastname: Wu
authors.affiliation: Department of Gynaecology, Shaanxi Provincial People's Hospital, Xi'an, Shaanxi 710068, P.R. China.
authors.forename: Cui-Pei
authors.initials: CP
authors.lastname: Hao
authors.affiliation: Department of Orthopaedics, Shaanxi Provincial People's Hospital, Xi'an, Shaanxi 710068, P.R. China.
authors.forename: Ming
authors.initials: M
authors.lastname: Ling
authors.affiliation: Department of Orthopedics, First Affiliated Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China.
authors.forename: Chi-Hua
authors.initials: CH
authors.lastname: Guo
authors.affiliation: Department of Orthopedics, First Affiliated Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Ma
mesh_terms: D053607:Adrenomedullin / Q000096:biosynthesis* / Q000235:genetics; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D001859:Bone Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D015687:Cell Hypoxia / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000235:genetics; D003035:Cobalt / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics; D020935:MAP Kinase Signaling System / Q000235:genetics; D012516:Osteosarcoma / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis* / Q000235:genetics
chemical_list: C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D019253:Proto-Oncogene Proteins c-bcl-2; D053607:Adrenomedullin; D003035:Cobalt; C018021:cobaltous chloride