title: Pirarubicin inhibits multidrug-resistant osteosarcoma cell proliferation through induction of G2/M phase cell cycle arrest.
abstract: OBJECTIVE
  Pirarubicin (THP) is recently found to be effective in treating patients with advanced, relapsed or recurrent high-grade osteosarcoma. In this study, the effects of THP on the multidrug-resistant (MDR) osteosarcoma cells were assessed, and the underlying mechanisms for the disruption of cell cycle kinetics by THP were explored.
  
  
  METHODS
  Human osteosarcoma cell line MG63 and human MDR osteosarcoma cell line MG63/DOX were tested. The cytotoxicity of drugs was examined using a cell proliferation assay with the Cell Counting Kit-8 (CCK-8). The distribution of cells across the cell cycle was determined with flow cytometry. The expression of cell cycle-regulated genes cyclin B1 and Cdc2 (CDK1), and the phosphorylated Cdc2 and Cdc25C was examined using Western blot analyses.
  
  
  RESULTS
  MG63/DOX cells were highly resistant to doxorubicin (ADM) and gemcitabine (GEM), but were sensitive or lowly resistant to THP, methotrexate (MTX) and cisplatin (DDP). Treatment of MG63/DOX cells with THP (200-1000 ng/mL) inhibited the cell proliferation in time- and concentration-dependent manners. THP (50-500 ng/mL) induced MG63/DOX cell cycle arrest at the G(2)/M phase in time- and concentration-dependent manners. Furthermore, the treatment of MG63/DOX cells with THP (200-1000 ng/mL) downregulated cyclin B1 expression, and decreased the phosphorylated Cdc2 at Thr(161). Conversely, the treatment increased the phosphorylated Cdc2 at Thr(14)/Tyr(15) and Cdc25C at Ser(216), which led to a decrease in Cdc2-cyclin B1 activity.
  
  
  CONCLUSIONS
  The cytotoxicity of THP to MG63/DOX cells may be in part due to its ability to arrest cell cycle progression at the G(2)/M phase, which supports the use of THP for managing patients with MDR osteosarcoma.
authors.affiliation: Department of Oncology, Affiliated People's 6th Hospital, Shanghai Jiao Tong University, China.
authors.forename: Shui-er
authors.initials: SE
authors.lastname: Zheng
authors.forename: Sang
authors.initials: S
authors.lastname: Xiong
authors.forename: Feng
authors.initials: F
authors.lastname: Lin
authors.forename: Guang-lei
authors.initials: GL
authors.lastname: Qiao
authors.forename: Tao
authors.initials: T
authors.lastname: Feng
authors.forename: Zan
authors.initials: Z
authors.lastname: Shen
authors.forename: Da-liu
authors.initials: DL
authors.lastname: Min
authors.forename: Chun-ling
authors.initials: CL
authors.lastname: Zhang
authors.forename: Yang
authors.initials: Y
authors.lastname: Yao
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D016203:CDC2 Protein Kinase / Q000235:genetics; D059447:Cell Cycle Checkpoints / Q000187:drug effects*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D056744:Cyclin B1 / Q000235:genetics; D004317:Doxorubicin / Q000031:analogs & derivatives* / Q000494:pharmacology; D016195:G2 Phase / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D012516:Osteosarcoma / Q000188:drug therapy* / Q000235:genetics; D020687:cdc25 Phosphatases / Q000235:genetics
chemical_list: D000970:Antineoplastic Agents; D056744:Cyclin B1; D004317:Doxorubicin; C027260:pirarubicin; D016203:CDC2 Protein Kinase; C517009:CDC25C protein, human; D020687:cdc25 Phosphatases