title: Inhibition of the growth of papillary thyroid carcinoma cells by CI-1040.
abstract: BACKGROUND
  Papillary thyroid carcinoma (PTC), the most common type of thyroid malignancy, usually possesses mutations, either RET/PTC rearrangement or BRAF mutation. Both mutations can activate the mitogen-activated protein kinase kinase/extracellular signal-related kinase signaling transduction pathway, which results in activation of transcription factors that regulate cellular proliferation, differentiation, and apoptosis.
  
  
  OBJECTIVE
  To test the effects of CI-1040 (PD184352), a specific MEK1/2 inhibitor, on PTC cells carrying either an RET/PTC1 rearrangement or a BRAF mutation.
  
  
  METHODS
  The effects of CI-1040 on PTC cells were evaluated in vitro and in vivo.
  
  
  METHODS
  The effects of CI-1040 on PTC cells were evaluated in vitro using a cell proliferation assay, cell cycle analysis, and immunoblotting. The antitumor effects of CI-1040 in vivo were evaluated in an orthotopic mouse model.
  
  
  RESULTS
  The concentrations of CI-1040 needed to inhibit 50% cell growth were 0.052microM for PTC cells with a BRAF mutation and 1.1microM for PTC cells with the RET/PTC1 rearrangement. After 3 weeks of oral administration of CI-1040 (300 mg/kg/d) to mice with orthotopic tumor implants of PTC cells, the mean tumor volume of implants bearing the RET/PTC1 rearrangement (n = 5) was reduced 47.5% compared with untreated mice (from 701.9 to 368.5 mm(3)), and the mean volume of implants with a BRAF mutation (n = 8) was reduced 31.3% (from 297.3 to 204.2 mm(3)).
  
  
  CONCLUSIONS
  CI-1040 inhibits PTC cell growth in vitro and in vivo. Because RET/PTC rearrangements are unique to thyroid carcinomas and a high percentage of PTCs possess either mutation, these findings support the clinical evaluation of CI-1040 for patients with PTC.
authors.affiliation: Department of Head and Neck Surgery, The University of Texas, M.D. Anderson Cancer Center, 1515 Holcombe Blvd, Unit 441, Houston, TX 77030, USA.
authors.forename: Ying C
authors.initials: YC
authors.lastname: Henderson
authors.forename: Soon-Hyun
authors.initials: SH
authors.lastname: Ahn
authors.forename: Gary L
authors.initials: GL
authors.lastname: Clayman
mesh_terms: D000818:Animals; D001549:Benzamides / Q000494:pharmacology*; D002291:Carcinoma, Papillary / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D015321:Gene Rearrangement; D048728:MAP Kinase Kinase Kinase 1 / Q000037:antagonists & inhibitors; D051379:Mice; D008819:Mice, Nude; D009154:Mutation; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics; D051096:Proto-Oncogene Proteins c-ret / Q000235:genetics; D013964:Thyroid Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology
chemical_list: C120227:2-(2-chloro-4-iodophenylamino)-N-cyclopropylmethoxy-3,4-difluorobenzamide; D001549:Benzamides; D004791:Enzyme Inhibitors; D051096:Proto-Oncogene Proteins c-ret; C099282:RET protein, human; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D048728:MAP Kinase Kinase Kinase 1