title: MicroRNA-125b regulates proliferation and radioresistance of oral squamous cell carcinoma.
abstract: BACKGROUND
  MicroRNAs (miRNAs) are involved in essential biological activities, and have been reported to exhibit differential expression profiles in various cancers. Our previous study demonstrated that intercellular adhesion molecule-2 (ICAM2) inhibition induces radiosensitisation in oral squamous cell carcinoma (OSCC) cells. Thus, we hypothesised that certain miRNAs play crucial roles in radioresistance in OSCC by regulating ICAM2 expression.
  
  
  METHODS
  Because predicted target gene analyses revealed that microRNA-125b (miR-125b) potentially regulates ICAM2 mRNA expression, we examined the association between miR-125b and radioresistance. The expression of miR-125b was investigated by real-time quantitative reverse transcriptase-PCR. For a functional analysis, miR-125b was transfected to OSCC-derived cells.
  
  
  RESULTS
  A downregulated expression of miR-125b was found in OSCC-derived cell lines and OSCC samples. The miR-125b-transfected cells showed a decreased proliferation rate, enhanced radiosensitivity to X-ray irradiation and diminished ICAM2 mRNA expression. Moreover, miR-125b expression correlated with OSCC tumour staging and survival.
  
  
  CONCLUSIONS
  These findings suggested that the downregulated miR-125b expression was associated with proliferation and radioresistance mechanisms, probably through ICAM2 signalling. Thus, controlling the expression or activity of miR-125b might contribute to suppressing proliferation and overcoming radioresistance in OSCC.
authors.affiliation: Department of Clinical Molecular Biology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan. m.shiiba@faculty.chiba-u.jp
authors.forename: M
authors.initials: M
authors.lastname: Shiiba
authors.forename: K
authors.initials: K
authors.lastname: Shinozuka
authors.forename: K
authors.initials: K
authors.lastname: Saito
authors.forename: K
authors.initials: K
authors.lastname: Fushimi
authors.forename: A
authors.initials: A
authors.lastname: Kasamatsu
authors.forename: K
authors.initials: K
authors.lastname: Ogawara
authors.forename: K
authors.initials: K
authors.lastname: Uzawa
authors.forename: H
authors.initials: H
authors.lastname: Ito
authors.forename: Y
authors.initials: Y
authors.lastname: Takiguchi
authors.forename: H
authors.initials: H
authors.lastname: Tanzawa
mesh_terms: D015703:Antigens, CD / Q000096:biosynthesis / Q000378:metabolism*; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000532:radiotherapy*; D015815:Cell Adhesion Molecules / Q000096:biosynthesis / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D009062:Mouth Neoplasms / Q000235:genetics / Q000532:radiotherapy*; D011379:Prognosis; D012333:RNA, Messenger / Q000096:biosynthesis; D011836:Radiation Tolerance / Q000235:genetics*; D015398:Signal Transduction; D014162:Transfection; D014965:X-Rays
chemical_list: D015703:Antigens, CD; D015815:Cell Adhesion Molecules; C065289:ICAM2 protein, human; C531888:MIRN125 microRNA, human; D035683:MicroRNAs; D012333:RNA, Messenger