title: Metformin inhibits the proliferation, metastasis, and cancer stem-like sphere formation in osteosarcoma MG63 cells in vitro.
abstract: Metformin is an oral drug that has been widely used to treat type 2 diabetes mellitus. Interestingly, accumulated evidence indicate that metformin may reduce the risk of cancer in patients with type 2 diabetes and inhibit tumor cell growth and survival in numerous malignancies, including osteosarcoma (OS) cells. In the present study, we aimed to investigate the effects of metformin on the proliferation, migration, invasion, and sphere formation in OS MG63 cells in vitro. Metformin suppressed OS MG63 cell proliferation in a dose- and time-dependent manner and markedly blocked anti-metastatic potentials, migration, and invasion, by downregulating matrix metalloproteinase 2 (MMP2) and MMP9. Besides, we established OS cancer stem-like cell (CSC) model with sarcosphere formation assay and demonstrated that metformin posed damage on CSCs in OS by inhibiting sphere formation and by inducing their stemness loss. The stemness of CSCs in OS such as self-renewal and differentiation potentials was both impaired with a significant decrease of Oct-4 and Nanog activation. Consistent with this, the positive rates of CD90, CD133, and stage-specific embryonic antigen-4 (SSEA-4) were all observed with reductions in response to metformin exposure. In addition, Western blot showed that metformin activated AMPKα at Tyr172, followed by a downregulated phosphorylation of mammalian target of rapamycin (mTOR)/S6 and feedback activation of p-AKT Ser(473) in both OS MG63 cells and CSCs. This indicates that AMPK/mTOR/S6 signaling pathway might be involved in the growth inhibition of both OS MG63 cells and CSCs. These results suggest that metformin, a potential anti-neoplastic agent, might make it a novel therapeutic choice for the treatment of OS in the future.
authors.affiliation: Shanghai Key Laboratory for Prevention and Treatment of Bone and joint Diseases with Integrated Chinese-Western Medicine, Shanghai Institute of Orthopedics and Traumatology, Shanghai, 20025, People's Republic of China.|Department of Orthopaedics, Ruijin Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, 20025, People's Republic of China.|Wuxi Xinrui Hospital, Department of Orthopaedics, Wuxi Branch, Ruijin Hospital, School of Medicine, Shanghai Jiaotong University, Wuxi, 214028, People's Republic of China.
authors.forename: Xu
authors.initials: X
authors.lastname: Chen
authors.affiliation: Shanghai Key Laboratory for Prevention and Treatment of Bone and joint Diseases with Integrated Chinese-Western Medicine, Shanghai Institute of Orthopedics and Traumatology, Shanghai, 20025, People's Republic of China.|Department of Orthopaedics, Ruijin Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, 20025, People's Republic of China.
authors.forename: Chuanzhen
authors.initials: C
authors.lastname: Hu
authors.affiliation: Shanghai Key Laboratory for Prevention and Treatment of Bone and joint Diseases with Integrated Chinese-Western Medicine, Shanghai Institute of Orthopedics and Traumatology, Shanghai, 20025, People's Republic of China. weibinzhang6462@163.com.|Department of Orthopaedics, Ruijin Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, 20025, People's Republic of China. weibinzhang6462@163.com.
authors.forename: Weibin
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Shanghai Key Laboratory for Prevention and Treatment of Bone and joint Diseases with Integrated Chinese-Western Medicine, Shanghai Institute of Orthopedics and Traumatology, Shanghai, 20025, People's Republic of China. yuhuiss@163.com.|Department of Orthopaedics, Ruijin Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, 20025, People's Republic of China. yuhuiss@163.com.
authors.forename: Yuhui
authors.initials: Y
authors.lastname: Shen
authors.affiliation: Shanghai Key Laboratory for Prevention and Treatment of Bone and joint Diseases with Integrated Chinese-Western Medicine, Shanghai Institute of Orthopedics and Traumatology, Shanghai, 20025, People's Republic of China.
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.affiliation: Shanghai Key Laboratory for Prevention and Treatment of Bone and joint Diseases with Integrated Chinese-Western Medicine, Shanghai Institute of Orthopedics and Traumatology, Shanghai, 20025, People's Republic of China.
authors.forename: Fangqiong
authors.initials: F
authors.lastname: Hu
authors.affiliation: Department of Orthopaedics, Ruijin Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, 20025, People's Republic of China.
authors.forename: Pei
authors.initials: P
authors.lastname: Yu
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy / Q000473:pathology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D018398:Homeodomain Proteins / Q000235:genetics; D006801:Humans; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis* / Q000235:genetics; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis* / Q000235:genetics; D008687:Metformin / Q000008:administration & dosage*; D000071317:Nanog Homeobox Protein; D009361:Neoplasm Invasiveness / Q000235:genetics / Q000473:pathology; D009362:Neoplasm Metastasis; D014411:Neoplastic Stem Cells / Q000187:drug effects; D050814:Octamer Transcription Factor-3 / Q000235:genetics; D012516:Osteosarcoma / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology
chemical_list: D018398:Homeodomain Proteins; C486780:NANOG protein, human; D000071317:Nanog Homeobox Protein; D050814:Octamer Transcription Factor-3; D008687:Metformin; D055372:AMP-Activated Protein Kinases; C526180:PRKAA1 protein, human; C522361:MMP2 protein, human; D020778:Matrix Metalloproteinase 2; C579270:MMP9 protein, human; D020780:Matrix Metalloproteinase 9
keywords: AMPK/mTOR/S6 signaling pathway; Cancer stem-like cells; Metastasis; Metformin; Osteosarcoma