title: Checkpoint kinase 1 protein expression indicates sensitization to therapy by checkpoint kinase 1 inhibition in non-small cell lung cancer.
abstract: BACKGROUND
  When presenting with advanced stage disease, lung cancer patients have <5% 5-y survival. The overexpression of checkpoint kinase 1 (CHK1) is associated with poorer outcomes and may contribute to therapy resistance. Targeting CHK1 with small-molecule inhibitors in p53 mutant tumors might improve the effectiveness of chemotherapy and radiotherapy in non-small cell lung cancer (NSCLC).
  
  
  METHODS
  We evaluated CHK1 messenger RNA and protein levels in multiple NSCLC cell lines. We assessed cell line sensitization to gemcitabine, pemetrexed, and radiotherapy by CHK1 inhibition with the small molecule AZD7762 using proliferation and clonogenic cell survival assays. We analyzed CHK1 signaling by Western blotting to confirm that AZD7762 inhibits CHK1.
  
  
  RESULTS
  We selected two p53 mutant NSCLC cell lines with either high (H1299) or low (H1993) CHK1 levels for further analysis. We found that AZD7762 sensitized both cell lines to gemcitabine, pemetrexed, and radiotherapy. Chemosensitization levels were greater, however, for the higher CHK1 protein expressing cell line, H1299, when compared with H1993. Furthermore, analysis of the CHK1 signaling pathway showed that H1299 cells have an increased dependence on the CHK1 pathway in response to chemotherapy. There was no increased sensitization to radiation in H1299 versus H1993.
  
  
  CONCLUSIONS
  CHK1 inhibition by AZD7762 preferentially sensitizes high CHK1 expressing cells, H1299, to anti-metabolite chemotherapy as compared with low CHK1 expressing H1993 cells. Thus, CHK1 inhibitors may improve the efficacy of standard lung cancer therapies, especially for those subgroups of tumors harboring higher expression levels of CHK1 protein.
authors.affiliation: Section of Thoracic Surgery, Department of Surgery, University of Michigan Medical School, Ann Arbor, Michigan.
authors.forename: Svetlana
authors.initials: S
authors.lastname: Grabauskiene
authors.affiliation: Section of Thoracic Surgery, Department of Surgery, University of Michigan Medical School, Ann Arbor, Michigan.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Bergeron
authors.affiliation: Section of Thoracic Surgery, Department of Surgery, University of Michigan Medical School, Ann Arbor, Michigan.
authors.forename: Guoan
authors.initials: G
authors.lastname: Chen
authors.affiliation: Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan; University of Michigan Comprehensive Cancer Center, Ann Arbor, Michigan.
authors.forename: Dafydd G
authors.initials: DG
authors.lastname: Thomas
authors.affiliation: Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan; University of Michigan Comprehensive Cancer Center, Ann Arbor, Michigan.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Giordano
authors.affiliation: Section of Thoracic Surgery, Department of Surgery, University of Michigan Medical School, Ann Arbor, Michigan; University of Michigan Comprehensive Cancer Center, Ann Arbor, Michigan.
authors.forename: David G
authors.initials: DG
authors.lastname: Beer
authors.affiliation: Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, Michigan; University of Michigan Comprehensive Cancer Center, Ann Arbor, Michigan.
authors.forename: Meredith A
authors.initials: MA
authors.lastname: Morgan
authors.affiliation: Section of Thoracic Surgery, Department of Surgery, University of Michigan Medical School, Ann Arbor, Michigan; University of Michigan Comprehensive Cancer Center, Ann Arbor, Michigan. Electronic address: reddyrm@med.umich.edu.
authors.forename: Rishindra M
authors.initials: RM
authors.lastname: Reddy
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism; D000964:Antimetabolites, Antineoplastic / Q000627:therapeutic use; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D018287:Carcinoma, Large Cell / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D000071877:Checkpoint Kinase 1; D003841:Deoxycytidine / Q000031:analogs & derivatives / Q000627:therapeutic use; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D005971:Glutamates / Q000627:therapeutic use; D006147:Guanine / Q000031:analogs & derivatives / Q000627:therapeutic use; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000378:metabolism; D000068437:Pemetrexed; D047428:Protein Kinase Inhibitors / Q000627:therapeutic use; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D013876:Thiophenes / Q000627:therapeutic use; D014508:Urea / Q000031:analogs & derivatives / Q000627:therapeutic use; D000093542:Gemcitabine
chemical_list: C532363:3-(carbamoylamino)-5-(3-fluorophenyl)-N-(3-piperidyl)thiophene-2-carboxamide; D000964:Antimetabolites, Antineoplastic; D005971:Glutamates; D047428:Protein Kinase Inhibitors; D013876:Thiophenes; D000068437:Pemetrexed; D003841:Deoxycytidine; D006147:Guanine; D014508:Urea; D011494:Protein Kinases; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; D000093542:Gemcitabine
keywords: AZD7762; CHK1; Chemosensitivity; Combination therapies; NSCLC cell lines; Radiosensitivity