title: Investigation of the interaction between the MIR-503 and CD40 genes in irradiated U937 cells.
abstract: BACKGROUND
  MicroRNAs (miRNAs) are a group of small noncoding RNAs that take part in diverse biological processes by suppressing target gene expression. Relatively few miRNAs have been studied in detail, especially miR-503, and hence the biological relevance of majority remains to be uncovered. Whether altered expression of miRNA-503 affects the immunity response to radiotherapy has yet to be addressed.
  
  
  RESULTS
  In the present study, we applied ionizing radiation with a dose of either 0.1 Gy or 5 Gy to irradiate U937 cells to confirm CD40 as a miR-503 target, which was identified using a bioimformatics tool. In high dose (5 Gy) ionizing-irradiated U937 cells, expression of miR-503 was up regulated while the expression of CD40 gene was down regulated. Using the transfection of the miR-503 gene into U937 cells and Luciferase assay, we confirmed that miR-503 suppressed the expression of CD40, and was a negtive regulator of CD40.
  
  
  CONCLUSIONS
  To our knowledge, we are the first to describe involvement of miR-503 in radiobiological effect at a molecular level. This initial finding suggested the evidence that ionizing radiation could alter the expression of miR-503 and its target gene CD40, and may be very important to shed light on a possible mechanism regarding regulation of immune responses to irradiation.
authors.affiliation: Department of Radiation Oncology, China-Japan Union Hospital of Jilin University, Changchun 130033, China.
authors.forename: Guanghui
authors.initials: G
authors.lastname: Cheng
authors.forename: Shilong
authors.initials: S
authors.lastname: Sun
authors.forename: Zhanfeng
authors.initials: Z
authors.lastname: Wang
authors.forename: Shunzi
authors.initials: S
authors.lastname: Jin
mesh_terms: D019013:CD40 Antigens / Q000235:genetics* / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000528:radiation effects*; D006801:Humans; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D011839:Radiation, Ionizing; D020298:U937 Cells
chemical_list: D019013:CD40 Antigens; C545473:MIRN503 microRNA, human; D035683:MicroRNAs