title: Effect of sunitinib on growth and function of FRTL-5 thyroid cells.
abstract: BACKGROUND
  Sunitinib, a multitargeted vascular endothelial growth factor and receptor tyrosine kinase inhibitor, causes hypothyroidism in patients who take it for treatment of cancer. Although the pathophysiologic mechanism of the hypothyroidism is unclear, it has been claimed that it is due to inhibition of iodide uptake.
  
  
  METHODS
  To evaluate the pathologic mechanism of induction of the hypothyroidism, we studied the effect of sunitinib on FRTL-5 rat thyroid cells. We measured the effect of sunitinib on cell growth, (125)I-iodide uptake and efflux, TSH receptor (TSH-R), and sodium-iodide symporter (NIS) message.
  
  
  RESULTS
  At 48 hours, sunitinib caused a dose-related inhibition of growth with LC(50) of 14.6 muM, but there was no apparent inhibition of growth at 24 hours at concentrations of 0.1-25 microM. Preincubation with sunitinib did not impair the response to TSH, indicating that it did not affect the TSH-R. Incubation with sunitinib for 24 hours caused a dose-related increase of (125)I-iodide uptake and did not reduce iodide efflux or NIS mRNA expression.
  
  
  CONCLUSIONS
  The data indicate that sunitinib is unlikely to cause hypothyroidism by inhibition of iodide uptake.
authors.affiliation: Endocrine Research Laboratory, Endocrinology and Diabetes Division, Veterans Administration Greater Los Angeles Healthcare System, Los Angeles, California 90073, USA.
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Salem
authors.forename: Mike S
authors.initials: MS
authors.lastname: Fenton
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Marion
authors.forename: Jerome M
authors.initials: JM
authors.lastname: Hershman
mesh_terms: D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D007211:Indoles / Q000494:pharmacology*; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics; D011758:Pyrroles / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011989:Receptors, Thyrotropin / Q000187:drug effects / Q000378:metabolism; D000077210:Sunitinib; D027981:Symporters / Q000378:metabolism; D013961:Thyroid Gland / Q000166:cytology / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D013997:Time Factors; D000099209:Sodium-Iodide Symporters
chemical_list: D020533:Angiogenesis Inhibitors; D007211:Indoles; D007457:Iodine Radioisotopes; D011758:Pyrroles; D012333:RNA, Messenger; D011989:Receptors, Thyrotropin; D000077210:Sunitinib; D027981:Symporters; D000099209:Sodium-Iodide Symporters