title: CdTe quantum dots as fluorescent probes to study transferrin receptors in glioblastoma cells.
abstract: BACKGROUND
  Overexpression of transferrin receptors (TfRs), which are responsible for the intracellular uptake of ferric transferrin (Tf), has been described in various cancers. Although molecular biology methods allow the identification of different types of receptors in cancer cells, they do not provide features about TfRs internalization, quantification and distribution on cell surface. This information can, however, be accessed by fluorescence techniques. In this work, the quantum dots (QDs)' unique properties were explored to strengthen our understanding of TfRs in cancer cells.
  
  
  METHODS
  QDs were conjugated to Tf by covalent coupling and QDs-(Tf) bioconjugates were applied to quantify and evaluate the distribution of TfRs in two human glioblastoma cells lines, U87 and DBTRG-05MG, and also in HeLa cells by using flow cytometry and confocal microscopy.
  
  
  RESULTS
  HeLa and DBTRG-05MG cells showed practically the same TfR labeling profile by QDs-(Tf), while U87 cells were less labeled by bioconjugates. Furthermore, inhibition studies demonstrated that QDs-(Tf) were able to label cells with high specificity.
  
  
  CONCLUSIONS
  HeLa and DBTRG-05MG cells presented a similar and a higher amount of TfR than U87 cells. Moreover, DBTRG-05MG cells are more efficient in recycling the TfR than the other two cells types.
  
  
  CONCLUSIONS
  This is the first study about TfRs in human glioblastoma cells using QDs. This new fluorescent tool can contribute to our understanding of the cancer cell biology and can help in the development of new therapies targeting these receptors.
authors.affiliation: Biophysics and Radiobiology Department, Federal University of Pernambuco, Recife, PE, Brazil.
authors.forename: Paulo E
authors.initials: PE
authors.lastname: Cabral Filho
authors.affiliation: CNC- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.
authors.forename: Ana L C
authors.initials: AL
authors.lastname: Cardoso
authors.affiliation: Biophysics and Radiobiology Department, Federal University of Pernambuco, Recife, PE, Brazil.
authors.forename: Maria I A
authors.initials: MI
authors.lastname: Pereira
authors.affiliation: Biophysics and Radiobiology Department, Federal University of Pernambuco, Recife, PE, Brazil.
authors.forename: Ana P M
authors.initials: AP
authors.lastname: Ramos
authors.affiliation: Department of Fundamental Chemistry, Federal University of Pernambuco, Recife, PE, Brazil.
authors.forename: Fernando
authors.initials: F
authors.lastname: Hallwass
authors.affiliation: Department of Life Sciences, Faculty of Science and Technology, University of Coimbra, Coimbra, Portugal; Coimbra Chemistry Center, University of Coimbra, Coimbra, Portugal.
authors.forename: M Margarida C A
authors.initials: MM
authors.lastname: Castro
authors.affiliation: Department of Life Sciences, Faculty of Science and Technology, University of Coimbra, Coimbra, Portugal; Coimbra Chemistry Center, University of Coimbra, Coimbra, Portugal.
authors.forename: Carlos F G C
authors.initials: CF
authors.lastname: Geraldes
authors.affiliation: Department of Pharmaceutical Sciences, Federal University of Pernambuco, Recife, PE, Brazil.
authors.forename: Beate S
authors.initials: BS
authors.lastname: Santos
authors.affiliation: CNC- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Pedroso de Lima
authors.affiliation: Department of Fundamental Chemistry, Federal University of Pernambuco, Recife, PE, Brazil.
authors.forename: Giovannia A L
authors.initials: GA
authors.lastname: Pereira
authors.affiliation: Biophysics and Radiobiology Department, Federal University of Pernambuco, Recife, PE, Brazil. Electronic address: adriana.fontes.biofisica@gmail.com.
authors.forename: Adriana
authors.initials: A
authors.lastname: Fontes
mesh_terms: D001932:Brain Neoplasms / Q000737:chemistry*; D005456:Fluorescent Dyes; D005909:Glioblastoma / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D018613:Microscopy, Confocal; D045663:Quantum Dots; D011990:Receptors, Transferrin / Q000032:analysis*
chemical_list: D005456:Fluorescent Dyes; D011990:Receptors, Transferrin
keywords: Bioconjugation; Cancer cells; Covalent binding; Nanoparticles; Receptors; Transferrin