title: Gold nanoparticles and electroporation impose both separate and synergistic radiosensitizing effects in HT-29 tumor cells: an in vitro study.
abstract: OBJECTIVE
  Radiation therapy (RT) is the gold standard treatment for more than half of known tumors. Despite recent improvements in RT efficiency, the side effects of ionizing radiation (IR) in normal tissues are a dose-limiting factor that restricts higher doses in tumor treatment. One approach to enhance the efficiency of RT is the application of radiosensitizers to selectively increase the dose at the tumor site. Gold nanoparticles (GNPs) and electroporation (EP) have shown good potential as radiosensitizers for RT. This study aims to investigate the sensitizing effects of EP, GNPs, and combined GNPs-EP on the dose enhancement factor (DEF) for 6 MV photon energy.
  
  
  METHODS
  Radiosensitizing effects of EP, GNPs, and combinations of GNPs-EP were comparatively investigated in vitro for intestinal colon cancer (HT-29) and Chinese hamster ovary (CHO) cell lines by MTT assay and colony formation assay at 6 MV photon energy in six groups: IR (control group), GNPs+IR, GNPs (24 h)+IR, EP+IR, GNPs+EP+IR, and GNPs (24 h)+EP+IR.
  
  
  RESULTS
  Treatment of both cell lines with EP, GNPs, and combined GNPs-EP significantly enhanced the response of cells to irradiation. However, the HT-29 showed higher DEF values for all groups. In addition, the DEF value for HT-29 cells for GNPs+IR, GNPs (24 h)+IR, EP+IR, GNPs+EP+IR, and GNPs (24 h)+EP+IR was, respectively, 1.17, 1.47, 1.36, 2.61, and 2.89, indicating synergistic radiosensitizing effect for the GNPs (24 h)+EP+IR group. Furthermore, the synergistic effect was observed just for HT-29 tumor cell lines.
  
  
  CONCLUSIONS
  Combined GNPs-EP protocols induced synergistic radiosensitizing effect in HT-29 cells, and the effect is also tumor specific. This combined therapy can be beneficially used for the treatment of intrinsically less radiosensitive tumors.
authors.affiliation: Cellular and Molecular Research Center, Ahvaz Jundishapur University of Medical Sciences, Avhaz, Iran; Department of Medical Physics, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
authors.forename: Zohre
authors.initials: Z
authors.lastname: Rezaee
authors.affiliation: Cellular and Molecular Research Center, Ahvaz Jundishapur University of Medical Sciences, Avhaz, Iran; Department of Medical Physics, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Yadollahpour
authors.affiliation: Cellular and Molecular Research Center, Ahvaz Jundishapur University of Medical Sciences, Avhaz, Iran.
authors.forename: Vahid
authors.initials: V
authors.lastname: Bayati
authors.affiliation: Cellular and Molecular Research Center, Ahvaz Jundishapur University of Medical Sciences, Avhaz, Iran.
authors.forename: Fereshteh
authors.initials: F
authors.lastname: Negad Dehbashi
mesh_terms: D000818:Animals; D016466:CHO Cells; D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D006224:Cricetinae; D003412:Cricetulus; D018274:Electroporation / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D019073:HT29 Cells; D006801:Humans; D053768:Metal Nanoparticles / Q000008:administration & dosage / Q000737:chemistry* / Q000648:ultrastructure; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*
chemical_list: D011838:Radiation-Sensitizing Agents; D006046:Gold
keywords: dose enhancement factor; electroporation; gold nanoparticles; radiosensitizer; synergistic effect