title: Alpha particles induce pan-nuclear phosphorylation of H2AX in primary human lymphocytes mediated through ATM.
abstract: The use of high linear energy transfer radiations in the form of carbon ions in heavy ion beam lines or alpha particles in new radionuclide treatments has increased substantially over the past decade and will continue to do so due to the favourable dose distributions they can offer versus conventional therapies. Previously it has been shown that exposure to heavy ions induces pan-nuclear phosphorylation of several DNA repair proteins such as H2AX and ATM in vitro. Here we describe similar effects of alpha particles on ex vivo irradiated primary human peripheral blood lymphocytes. Following alpha particle irradiation pan-nuclear phosphorylation of H2AX and ATM, but not DNA-PK and 53BP1, was observed throughout the nucleus. Inhibition of ATM, but not DNA-PK, resulted in the loss of pan-nuclear phosphorylation of H2AX in alpha particle irradiated lymphocytes. Pan-nuclear gamma-H2AX signal was rapidly lost over 24h at a much greater rate than foci loss. Surprisingly, pan-nuclear gamma-H2AX intensity was not dependent on the number of alpha particle induced double strand breaks, rather the number of alpha particles which had traversed the cell nucleus. This distinct fluence dependent damage signature of particle radiation is important in both the fields of radioprotection and clinical oncology in determining radionuclide biological dosimetry and may be indicative of patient response to new radionuclide cancer therapies.
authors.affiliation: Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast 7AE BT9, United Kingdom. Electronic address: sjh.horn@gmail.com.
authors.forename: Simon
authors.initials: S
authors.lastname: Horn
authors.affiliation: Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast 7AE BT9, United Kingdom; Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Belfast 7AE BT9, United Kingdom.
authors.forename: Darren
authors.initials: D
authors.lastname: Brady
authors.affiliation: Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast 7AE BT9, United Kingdom.
authors.forename: Kevin
authors.initials: K
authors.lastname: Prise
mesh_terms: D000328:Adult; D000512:Alpha Particles; D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D053903:DNA Breaks, Double-Stranded; D051747:DNA-Activated Protein Kinase / Q000378:metabolism; D006657:Histones / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D010766:Phosphorylation / Q000528:radiation effects; D000071857:Tumor Suppressor p53-Binding Protein 1
chemical_list: C468783:H2AX protein, human; D006657:Histones; D047908:Intracellular Signaling Peptides and Proteins; C498301:TP53BP1 protein, human; D000071857:Tumor Suppressor p53-Binding Protein 1; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D051747:DNA-Activated Protein Kinase
keywords: Alpha particles; Complex damage; DNA double strand break; Pan-nuclear intensity