title: MicroRNA-24 inhibits growth, induces apoptosis, and reverses radioresistance in laryngeal squamous cell carcinoma by targeting X-linked inhibitor of apoptosis protein.
abstract: BACKGROUND
  Increasing evidence indicates that dysregulation of microRNAs is involved in tumor progression and development. The aim of this study was to investigate the expression of microRNA-24 (miR-24) and its function in laryngeal squamous cell carcinoma (LSCC).
  
  
  METHODS
  Quantitative RT-PCR (qRT-PCR) was used to detect miR-24 expression in LSCC cell lines and tissue samples. MTT, colony formation, and flow cytometry was performed to analyze the effects of miR-24 expression on growth, apoptosis, and radiosensitivity of LSCC cells. Dual-luciferase reporter assays were performed to examine regulation of putative miR-24 targets. Expression of X-linked inhibitor of apoptosis protein (XIAP) mRNA and protein, cleaved or total caspase-3, and cleaved or total PARP protein were detected by qRT-PCR and western blotting assays, respectively.
  
  
  RESULTS
  miR-24 expression levels in LSCC cell lines or tissue were significantly lower than in a normal human keratinocyte cell line or adjacent normal tissues. Functional analyses indicated that re-expression of miR-24 inhibits growth, reduces colony formation, and enhances apoptosis in LSCC cells. In addition, miR-24 upregulation increases LSCC sensitivity to irradiation by enhancing irradiation-induced apoptosis, and luciferase activity indicated that miR-24 binds to the 3'-untranslated region (3'-UTR) of XIAP mRNA. Upregulation of miR-24 inhibits XIAP protein expression in LSCC cells, and silencing of XIAP mimics the effects of miR-24 upregulation on LSCC cells. In addition, XIAP mRNA expression significantly increases in LSCC tissues and is inversely correlated with miR-24 expression.
  
  
  CONCLUSIONS
  Our data suggest that miR-24 inhibits growth, increases apoptosis, and enhances radiosensitivity in LSCC cells by targeting XIAP. Therefore, miR-24 may be a potential molecular target for the treatment of human LSCC.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Tangdu Hospital and Laboratory for Laryngotracheal Reconstruction, Fourth Military Medical University, Xi'an, Shaanxi 710038 PR China.|Department of Otolaryngology-Head and Neck Surgery, Nanjing General Hospital of Nanjing Military Command, Nanjing, Jiangsu 210002 PR China.
authors.forename: Li
authors.initials: L
authors.lastname: Xu
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Lanzhou General Hospital of Lanzhou Military Command, Lanzhou, Gansu 730050 PR China.
authors.forename: Zhifeng
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Nanjing General Hospital of Nanjing Military Command, Nanjing, Jiangsu 210002 PR China.
authors.forename: Fei
authors.initials: F
authors.lastname: Xue
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Nanjing General Hospital of Nanjing Military Command, Nanjing, Jiangsu 210002 PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Tangdu Hospital and Laboratory for Laryngotracheal Reconstruction, Fourth Military Medical University, Xi'an, Shaanxi 710038 PR China.
authors.forename: Ruina
authors.initials: R
authors.lastname: Ma
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Tangdu Hospital and Laboratory for Laryngotracheal Reconstruction, Fourth Military Medical University, Xi'an, Shaanxi 710038 PR China.
authors.forename: Shiyin
authors.initials: S
authors.lastname: Cheng
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Tangdu Hospital and Laboratory for Laryngotracheal Reconstruction, Fourth Military Medical University, Xi'an, Shaanxi 710038 PR China.
authors.forename: Pengcheng
authors.initials: P
authors.lastname: Cui
keywords: Apoptosis; Growth; Laryngeal squamous cell carcinoma; XIAP; miR-24