title: DNA aptamers that target human glioblastoma multiforme cells overexpressing epidermal growth factor receptor variant III in vitro.
abstract: OBJECTIVE
  Aptamers are oligonucleic acid or peptide molecules that bind to a specific target molecule in cells, thus may act as effective vehicles for drug or siRNA delivery. In this study we investigated the DNA aptamers that target human glioblastoma multiforme (GBM) cells overexpressing epidermal growth factor receptor variant III (EGFRvIII), which was linked to radiation and chemotherapeutic resistance of this most aggressive brain tumor.
  
  
  METHODS
  A 73-mer ssDNA library containing molecules with 30 nt of random sequence flanked by two primer hybridization sites was chosen as the initial library. Cell systematic evolution of ligands by exponential enrichment (Cell-SELEX) method was used to select the DNA aptamers that target EGFRvIII. The binding affinity of the aptamers was measured using a cell-based biotin-avidin ELISA.
  
  
  RESULTS
  After 14 rounds of selection, four DNA aptamers (32, 41, 43, and 47) that specifically bound to the EGFRvIII-overexpressing human glioma U87Δ cells with Kd values of less than 100 nmol/L were discovered. These aptamers were able to distinguish the U87Δ cells from the negative control human glioma U87MG cells and HEK293 cells. Aptamer 32 specifically bound to the EGFRvIII protein with an affinity similar to the EGFR antibody (Kd values of aptamer 32 and the EGFR antibody were 0.62±0.04 and 0.32±0.01 nmol/L, respectively), and this aptamer was localized in the cell nucleus.
  
  
  CONCLUSIONS
  The DNA aptamers are promising molecular probes for the diagnosis and treatment of GBM.
authors.affiliation: Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Tan
authors.forename: Yu-sheng
authors.initials: YS
authors.lastname: Shi
authors.forename: Xi-dong
authors.initials: XD
authors.lastname: Wu
authors.forename: Hui-yu
authors.initials: HY
authors.lastname: Liang
authors.forename: Yu-bo
authors.initials: YB
authors.lastname: Gao
authors.forename: Shu-ji
authors.initials: SJ
authors.lastname: Li
authors.forename: Xing-mei
authors.initials: XM
authors.lastname: Zhang
authors.forename: Fang
authors.initials: F
authors.lastname: Wang
authors.forename: Tian-ming
authors.initials: TM
authors.lastname: Gao
mesh_terms: D052157:Aptamers, Nucleotide / Q000494:pharmacology*; D001483:Base Sequence; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D017931:DNA Primers; D066246:ErbB Receptors / Q000378:metabolism*; D005434:Flow Cytometry; D005909:Glioblastoma / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D015335:Molecular Probes; D052156:SELEX Aptamer Technique
chemical_list: D052157:Aptamers, Nucleotide; D017931:DNA Primers; D015335:Molecular Probes; D066246:ErbB Receptors