title: MicroRNA-223 enhances radiation sensitivity of U87MG cells in vitro and in vivo by targeting ataxia telangiectasia mutated.
abstract: OBJECTIVE
  Ataxia telangiectasia mutated (ATM) protein is important in the DNA damage response because it repairs radiation-induced damage in cancers. We examined the effect of microRNA-223 (miR-223), a regulator of ATM expression, on radiation sensitivity of cancer cells.
  
  
  METHODS
  Human embryonic kidney 293 T (293T) cells were infected with pLL3.7-miR-223 plasmid to generate the pLL3.7-miR-223 and -empty virus (EV) lentivirus (miR-223 and EV). A dual luciferase assay in which the reporter contained wild-type 3' untranslated region (UTR) of ATM was performed. U87MG cells were infected with miR-223 or EV to establish the overexpressed stable cell lines (U87-223 or U87-EV, respectively). Cells were irradiated in vitro, and dose enhancement ratios at 2 Gy (DER2) were calculated. Hind legs of BALB/c athymic mice were injected with U87-223 or U87-EV cells; after 2 weeks, half of the tumors were irradiated. Tumor volumes were tracked for a total of 5 weeks.
  
  
  RESULTS
  The dual luciferase reporter assay showed a significant reduction in luciferase activity of 293T cells cotransfected with miR-223 and the ATM 3'UTR compared to that in EV control. Overexpression of miR-223 in U87MG cells showed that ATM expression was significantly downregulated in the U87-223 cells compared to that in U87-EV (ATM/β-actin mRNA 1.0 vs 1.5, P<.05). U87-223 cells were hypersensitive to radiation compared to U87-EV cells in vitro (DER2 = 1.32, P<.01). Mice injected with miR-223-expressing tumors had almost the same tumors after 3 weeks (1.5 cm(3) vs 1.7 cm(3)). However, irradiation significantly decreased tumor size in miR-223-expressing tumors compared to those in controls (0.033 cm(3) vs 0.829 cm(3)).
  
  
  CONCLUSIONS
  miR-223 overexpression downregulates ATM expression and sensitizes U87 cells to radiation in vitro and in vivo. MicroRNA-223 may be a novel cancer-targeting therapy, although its cancer- and patient-specific roles are currently undefined.
authors.affiliation: Departments of Radiation Oncology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, PR China.
authors.forename: Liping
authors.initials: L
authors.lastname: Liang
authors.affiliation: Departments of Radiation Oncology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, PR China.
authors.forename: Ji
authors.initials: J
authors.lastname: Zhu
authors.affiliation: Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania.
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: Zaorsky
authors.affiliation: Departments of Radiation Oncology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, PR China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Deng
authors.affiliation: Department of Biochemistry and Molecular Biology, Shanghai Medical College, Fudan University, Shanghai, PR China.
authors.forename: Xingzhong
authors.initials: X
authors.lastname: Wu
authors.affiliation: Departments of Radiation Oncology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, PR China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Colorectal Cancer, Fudan University, Shanghai Cancer Center, Shanghai, PR China.
authors.forename: Fangqi
authors.initials: F
authors.lastname: Liu
authors.affiliation: Department of Colorectal Cancer, Fudan University, Shanghai Cancer Center, Shanghai, PR China.
authors.forename: Guoxiang
authors.initials: G
authors.lastname: Cai
authors.affiliation: Department of Colorectal Cancer, Fudan University, Shanghai Cancer Center, Shanghai, PR China.
authors.forename: Weilie
authors.initials: W
authors.lastname: Gu
authors.affiliation: Departments of Radiation Oncology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, PR China.
authors.forename: Lijun
authors.initials: L
authors.lastname: Shen
authors.affiliation: Departments of Radiation Oncology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, PR China. Electronic address: zhenzhang6@hotmail.com.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhang
mesh_terms: D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D004314:Down Syndrome; D017930:Genes, Reporter; D064593:Heterografts; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D035683:MicroRNAs / Q000502:physiology*; D011836:Radiation Tolerance / Q000502:physiology*
chemical_list: D064007:Ataxia Telangiectasia Mutated Proteins; D008156:Luciferases; D035683:MicroRNAs; C525067:MIR223, human