title: Radiation and new molecular agents part I: targeting ATM-ATR checkpoints, DNA repair, and the proteasome.
abstract: In response to DNA breaks, human cells delay their progression through the G1, S, and G2 phases of the cell cycle. This response requires the coordinated effort of the ATM-CHK2-p53 and ATR-CHK1 DNA damage-sensing pathways and DNA repair (eg, DNA-PK and RAD51 complexes). The turnover of many of these DNA damage-associated proteins is controlled by the 26S proteasome. In this article, we review molecular strategies that target each of these pathways using silencing RNA (siRNA), antisense, or small-molecule inhibition. Although these agents can radiosensitize tumor cells, little data are available regarding potential effects on normal tissues to determine the potential therapeutic ratio of these strategies after fractionated radiotherapy. Clinical trials using such agents will require novel correlative science endpoints to track DNA repair and cell-cycle arrest and will need careful assessment of normal tissue toxicity and stability.
authors.affiliation: Department of Radiation Oncology, University of Toronto and Princess Margaret Hospital-University Health Network, Ontario, Canada.
authors.forename: Ananya
authors.initials: A
authors.lastname: Choudhury
authors.forename: Andrew
authors.initials: A
authors.lastname: Cuddihy
authors.forename: Robert G
authors.initials: RG
authors.lastname: Bristow
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D004260:DNA Repair / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018816:Genes, cdc / Q000502:physiology* / Q000528:radiation effects; D006801:Humans; D008967:Molecular Biology / Q000379:methods; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011838:Radiation-Sensitizing Agents / Q000378:metabolism*; D011878:Radiotherapy; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D011838:Radiation-Sensitizing Agents; D025521:Tumor Suppressor Proteins; C576324:ATM protein, human; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; D046988:Proteasome Endopeptidase Complex