title: Radiation modulation of microRNA in prostate cancer cell lines.
abstract: BACKGROUND
  MicroRNAs (miRNA) are gene regulators and play an important role in response to cellular stress.
  
  
  METHODS
  Using multiplexed quantitative real-time PCR we performed global miRNA screening of prostate cancer cells in response to radiation treatment.
  
  
  RESULTS
  Several miRNA were significantly altered in response to radiation treatment. Significant changes were observed in miR-521 and miR-34c. To determine the role of miR-521 in radiation response we transiently overexpressed miR-521 using miR-521 mimic. The miR-521 mimic significantly sensitized prostate cancer cells to radiation treatment. Conversely, ectopic inhibition of miR-521 resulted in radiation resistance of prostate cancer cells. To determine the mechanism by which miR-521 modulates radiation sensitivity we measured the expression levels of one of its predicted target protein, Cockayne syndrome protein A (CSA). CSA is a DNA repair protein, and its levels correlated inversely with the levels of miR-521. Radiation treatment downregulated the levels of miR-521 and upregulated CSA protein. Similarly, ectopic inhibition of miR-521 resulted in increased CSA protein levels. Therefore by altering the levels of CSA protein, miR-521 sensitized prostate cancer cells to radiation treatment.
  
  
  CONCLUSIONS
  miR-521 modulates the expression levels of DNA repair protein, CSA and plays an important role, in the radio-sensitivity of prostate cancer cell lines. Thus miR-521 can be a potential target for enhancing the effect of radiation treatment on prostate cancer cells.
authors.affiliation: Radiation Oncology, Winship Cancer Institute, Emory University, Atlanta, Georgia 30322, USA. sjosson@emory.edu
authors.forename: Sajni
authors.initials: S
authors.lastname: Josson
authors.forename: Shian-Ying
authors.initials: SY
authors.lastname: Sung
authors.forename: Kaiqin
authors.initials: K
authors.lastname: Lao
authors.forename: Leland W K
authors.initials: LW
authors.lastname: Chung
authors.forename: Peter A S
authors.initials: PA
authors.lastname: Johnstone
mesh_terms: D045744:Cell Line, Tumor / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D045643:DNA Repair Enzymes / Q000378:metabolism; D015536:Down-Regulation; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000378:metabolism* / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000473:pathology*; D011836:Radiation Tolerance; D013482:Superoxide Dismutase / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D015854:Up-Regulation
chemical_list: C095472:ERCC8 protein, human; C532480:MIRN521 microRNA, human; D035683:MicroRNAs; D014157:Transcription Factors; D013482:Superoxide Dismutase; D045643:DNA Repair Enzymes