title: The novel chemical entity YTR107 inhibits recruitment of nucleophosmin to sites of DNA damage, suppressing repair of DNA double-strand breaks and enhancing radiosensitization.
abstract: OBJECTIVE
  Radiation therapy continues to be an important therapeutic strategy for providing definitive local/regional control of human cancer. However, oncogenes that harbor driver mutations and/or amplifications can compromise therapeutic efficacy. Thus, there is a need for novel approaches that enhance the DNA damage produced by ionizing radiation.
  
  
  METHODS
  A forward chemical genetic approach coupled with cell-based phenotypic screening of several tumor cell lines was used to identify a novel chemical entity (NCE) that functioned as a radiation sensitizer. Proteomics, comet assays, confocal microscopy, and immunoblotting were used to identify the biological target.
  
  
  RESULTS
  The screening process identified a 5-((N-benzyl-1H-indol-3-yl)-methylene)pyrimidine-2,4,6(1H,3H,5H)trione as an NCE that radiosensitized cancer cells expressing amplified and/or mutated RAS, ErbB, PIK3CA, and/or BRAF oncogenes. Affinity-based solid-phase resin capture followed by liquid chromatography/tandem mass spectrometry identified the chaperone nucleophosmin (NPM) as the NCE target. SiRNA suppression of NPM abrogated radiosensitization by the NCE. Confocal microscopy showed that the NCE inhibited NPM shuttling to radiation-induced DNA damage repair foci, and the analysis of comet assays indicated a diminished rate of DNA double-strand break repair.
  
  
  CONCLUSIONS
  These data support the hypothesis that inhibition of DNA repair due to inhibition of NPM shuttling increases the efficacy of DNA-damaging therapeutic strategies.
authors: Department of Radiation Oncology, Division of Animal Care, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
authors: Konjeti R
authors: KR
authors: Sekhar
authors: Yerramreddy Thirupathi
authors: YT
authors: Reddy
authors: Penthala Narsimha
authors: PN
authors: Reddy
authors: Peter A
authors: PA
authors: Crooks
authors: Amudhan
authors: A
authors: Venkateswaran
authors: William Hayes
authors: WH
authors: McDonald
authors: Ling
authors: L
authors: Geng
authors: Soumya
authors: S
authors: Sasi
authors: Robert P
authors: RP
authors: Van Der Waal
authors: Joseph L Roti
authors: JL
authors: Roti
authors: Kenneth J
authors: KJ
authors: Salleng
authors: Girish
authors: G
authors: Rachakonda
authors: Michael L
authors: ML
authors: Freeman
mesh_terms: D000818:Animals; D001463:Barbiturates / Q000494:pharmacology; D045744:Cell Line, Tumor; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects*; D004249:DNA Damage / Q000187:drug effects; D004260:DNA Repair / Q000187:drug effects*; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D051379:Mice; D008819:Mice, Nude; D018832:Molecular Chaperones / Q000378:metabolism; D058990:Molecular Targeted Therapy; D009369:Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D000090243:Nucleophosmin; D011836:Radiation Tolerance / Q000187:drug effects; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D011897:Random Allocation
chemical_list: C569647:5-((N-benzyl-1H-indol-3-yl)methylene)pyrimidine-2,4,6(1H,3H,5H)trione; D001463:Barbiturates; D007211:Indoles; D018832:Molecular Chaperones; C000716967:NPM1 protein, human; D009687:Nuclear Proteins; D011838:Radiation-Sensitizing Agents; D000090243:Nucleophosmin