title: A mechanistic study of gold nanoparticle radiosensitisation using targeted microbeam irradiation.
abstract: Gold nanoparticles (GNPs) have been demonstrated as effective radiosensitizing agents in a range of preclinical models using broad field sources of various energies. This study aimed to distinguish between these mechanisms by applying subcellular targeting using a soft X-ray microbeam in combination with GNPs. DNA damage and repair kinetics were determined following nuclear and cytoplasmic irradiation using a soft X-ray (carbon K-shell, 278 eV) microbeam in MDA-MB-231 breast cancer and AG01522 fibroblast cells with and without GNPs. To investigate the mechanism of the GNP induced radiosensitization, GNP-induced mitochondrial depolarisation was quantified by TMRE staining, and levels of DNA damage were compared in cells with depolarised and functional mitochondria. Differential effects were observed following radiation exposure between the two cell lines. These findings were validated 24 hours after removal of GNPs by flow cytometry analysis of mitochondrial depolarisation. This study provides further evidence that GNP radiosensitisation is mediated by mitochondrial function and it is the first report applying a soft X-ray microbeam to study the radiobiological effects of GNPs to enable the separation of physical and biological effects.
authors.affiliation: Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, BT7 9AE, Belfast, UK.
authors.forename: Mihaela
authors.initials: M
authors.lastname: Ghita
authors.affiliation: Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, BT7 9AE, Belfast, UK.|Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: McMahon
authors.affiliation: Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, BT7 9AE, Belfast, UK.
authors.forename: Laura E
authors.initials: LE
authors.lastname: Taggart
authors.affiliation: Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, BT7 9AE, Belfast, UK.
authors.forename: Karl T
authors.initials: KT
authors.lastname: Butterworth
authors.affiliation: National Physics Laboratory, Teddington, TW11 0LW, London, UK.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Schettino
authors.affiliation: Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, BT7 9AE, Belfast, UK.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Prise
mesh_terms: D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism / Q000528:radiation effects; D004249:DNA Damage; D006046:Gold / Q000737:chemistry*; D006801:Humans; D007700:Kinetics; D053768:Metal Nanoparticles / Q000737:chemistry*; D008928:Mitochondria / Q000378:metabolism / Q000528:radiation effects; D011838:Radiation-Sensitizing Agents / Q000737:chemistry*; D013347:Subcellular Fractions / Q000378:metabolism / Q000528:radiation effects; D000071857:Tumor Suppressor p53-Binding Protein 1 / Q000378:metabolism; D014965:X-Rays
chemical_list: D011838:Radiation-Sensitizing Agents; C498301:TP53BP1 protein, human; D000071857:Tumor Suppressor p53-Binding Protein 1; D006046:Gold