title: Inhibition of oleandrin on the proliferation show and invasion of osteosarcoma cells in vitro by suppressing Wnt/β-catenin signaling pathway.
abstract: BACKGROUND
  Osteosarcoma (OS) is a high-grade bone sarcoma with early metastasis potential, and the clinical chemotherapy drugs that are currently used for its treatment have some limitations. Recently, several studies have reported the selective antitumor effect of oleandrin on various tumor cells. In this study, we aimed to evaluate the effects and underlying mechanisms of oleandrin on OS cells.
  
  
  METHODS
  The effect of oleandrin on the proliferation, morphology, and apoptosis of U2OS and SaOS-2 cells were analyzed in vitro. The activity of the Wnt/β-catenin signaling pathway was determined using a dual luciferase assay. Semi-quantitative RT-PCR and western blot assays were performed to evaluate the mRNA and total protein expression of the downstream target genes. Changes of β-catenin in intracellular localization were also explored using a western blot after separating the nucleus and cytoplasm proteins. The MMP-2 and MMP-9 enzymatic activities were determined using gelatin zymography.
  
  
  RESULTS
  Oleandrin significantly inhibited the proliferation and invasion of OS cells in vitro, and induced their apoptosis. After treatment with oleandrin, the TOP/FOP flash ratio in OS cells was noticeably decreased, which indicated that the Wnt/β-catenin signaling pathway was repressed. The expression of related Wnt target genes and total β-catenin was downregulated, and a reduced nuclear β-catenin level by oleandrin was observed as well. In addition, oleandrin suppressed the activities of MMP-2 and MMP-9.
  
  
  CONCLUSIONS
  Oleandrin, in vitro, exerted a strong antitumor effect on human OS cells by suppressing the Wnt/β-catenin signaling pathway, which interfered with the proliferation and invasion of OS cells, as well as induced cells apoptosis. Moreover, the expression and activities of MMP-2 and MMP-9 were downregulated by oleandrin, which contributed to the cells' lower invasiveness.
authors.affiliation: Department of Orthopaedics, Peking University Third Hospital, North Garden Street No. 49, Haidian District, Beijing, 100191, People's Republic of China. mayl_pth2012@163.com.
authors.forename: Yunlong
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Department of Orthopaedics, Peking University Third Hospital, North Garden Street No. 49, Haidian District, Beijing, 100191, People's Republic of China. zhubin_ortho@163.com.
authors.forename: Bin
authors.initials: B
authors.lastname: Zhu
authors.affiliation: Department of Orthopaedics, Peking University Third Hospital, North Garden Street No. 49, Haidian District, Beijing, 100191, People's Republic of China. xgliudoctor@163.com.
authors.forename: Xiaoguang
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Orthopaedics, Peking University Third Hospital, North Garden Street No. 49, Haidian District, Beijing, 100191, People's Republic of China. yuhuileiah@126.com.
authors.forename: Huilei
authors.initials: H
authors.lastname: Yu
authors.affiliation: Department of Orthopaedics, Peking University Third Hospital, North Garden Street No. 49, Haidian District, Beijing, 100191, People's Republic of China. eathonecho@163.com.
authors.forename: Lei
authors.initials: L
authors.lastname: Yong
authors.affiliation: Department of Orthopaedics, Peking University Third Hospital, North Garden Street No. 49, Haidian District, Beijing, 100191, People's Republic of China. lx86831@163.com.
authors.forename: Xiao
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Orthopaedics, Peking University Third Hospital, North Garden Street No. 49, Haidian District, Beijing, 100191, People's Republic of China. shaojia2001@163.com.
authors.forename: Jia
authors.initials: J
authors.lastname: Shao
authors.affiliation: Department of Orthopaedics, Peking University Third Hospital, North Garden Street No. 49, Haidian District, Beijing, 100191, People's Republic of China. zhongjunliu1@163.com.
authors.forename: Zhongjun
authors.initials: Z
authors.lastname: Liu
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001859:Bone Neoplasms / Q000188:drug therapy* / Q000473:pathology; D002298:Cardenolides / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis; D009361:Neoplasm Invasiveness / Q000473:pathology*; D012516:Osteosarcoma / Q000188:drug therapy* / Q000473:pathology; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051153:Wnt Proteins / Q000037:antagonists & inhibitors; D060449:Wnt Signaling Pathway / Q000187:drug effects*; D051176:beta Catenin / Q000037:antagonists & inhibitors
chemical_list: D000970:Antineoplastic Agents; D002298:Cardenolides; D012333:RNA, Messenger; D051153:Wnt Proteins; D051176:beta Catenin; C522361:MMP2 protein, human; D020778:Matrix Metalloproteinase 2; C579270:MMP9 protein, human; D020780:Matrix Metalloproteinase 9; C021065:oleandrin