title: Development and characterization of a differentiated thyroid cancer cell line resistant to VEGFR-targeted kinase inhibitors.
abstract: BACKGROUND
  Vascular endothelial growth factor-targeted kinase inhibitors have emerged as highly promising therapies for radioiodine-refractory metastatic differentiated thyroid cancer. Unfortunately, drug resistance uniformly develops, limiting their therapeutic efficacies and thereby constituting a major clinical problem.
  
  
  METHODS
  To study acquired drug resistance and elucidate underlying mechanisms in this setting, BHP2-7 human differentiated thyroid cancer cells were subjected to prolonged continuous in vitro selection with 18 μM pazopanib, a clinically relevant concentration; acquisition of pazopanib resistance was serially assessed, with the resulting resistant cells thereafter subcloned and characterized to assess potential mechanisms of acquired pazopanib resistance.
  
  
  RESULTS
  Stable 2- to 4-fold in vitro pazopanib resistance emerged in response to pazopanib selection associated with similar in vitro growth characteristics but with markedly more aggressive in vivo xenograft growth. Selected cells were cross-resistant to sunitinib and to a lesser extent sorafenib but not to MAPK kinase (MEK1/2) inhibition by GSK1120212. Genotyping demonstrated acquisition of a novel activating KRAS codon 13 GGC to GTT (glycine to valine) mutation, consistent with the observed resistance to upstream vascular endothelial growth factor receptor inhibition yet sensitivity to downstream MAPK kinase (MEK1/2) inhibition.
  
  
  CONCLUSIONS
  Selection of thyroid cancer cells with clinically utilized therapeutics can lead to acquired drug resistance and altered in vivo xenograft behavior that can recapitulate analogous drug resistance observed in patients. This approach has the potential to lead to insights into acquired treatment-related drug resistance in thyroid cancers that can be subjected to subsequent validation in serially collected patient samples and that has the potential to yield preemptive and responsive approaches to dealing with this important clinical problem.
authors.affiliation: Division of Medical Oncology (C.R.I., A.R.B., K.C.B.), Department of Oncology, and Department of Laboratory Medicine and Pathology (B.C.N., D.M., K.W.C., S.K.B.), and the Endocrine Malignancies Disease Oriented Group (C.R.I., A.R.B., S.K.G., K.C.B.), Mayo Clinic, Rochester, Minnesota 55905.
authors.forename: Crescent R
authors.initials: CR
authors.lastname: Isham
authors.forename: Brian C
authors.initials: BC
authors.lastname: Netzel
authors.forename: Ayoko R
authors.initials: AR
authors.lastname: Bossou
authors.forename: Dragana
authors.initials: D
authors.lastname: Milosevic
authors.forename: Kendall W
authors.initials: KW
authors.lastname: Cradic
authors.forename: Stefan K
authors.initials: SK
authors.lastname: Grebe
authors.forename: Keith C
authors.initials: KC
authors.lastname: Bible
mesh_terms: D000818:Animals; D002277:Carcinoma / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology*; D002291:Carcinoma, Papillary; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D004252:DNA Mutational Analysis; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D006801:Humans; D007191:Indazoles; D051379:Mice; D058990:Molecular Targeted Therapy; D009361:Neoplasm Invasiveness; D047428:Protein Kinase Inhibitors / Q000627:therapeutic use*; D011518:Proto-Oncogene Proteins / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras); D011743:Pyrimidines / Q000627:therapeutic use*; D040262:Receptors, Vascular Endothelial Growth Factor / Q000037:antagonists & inhibitors*; D013449:Sulfonamides / Q000627:therapeutic use*; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology*; D023041:Xenograft Model Antitumor Assays; D018631:ras Proteins / Q000235:genetics
chemical_list: D007191:Indazoles; C117307:KRAS protein, human; D047428:Protein Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D011743:Pyrimidines; D013449:Sulfonamides; C516667:pazopanib; D040262:Receptors, Vascular Endothelial Growth Factor; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins