title: Novel HSP90 inhibitors effectively target functions of thyroid cancer stem cell preventing migration and invasion.
abstract: BACKGROUND
  Thyroid cancer stem cells (CSCs) with ALDH and CD44 markers contribute to tumor growth and aggressiveness. We hypothesized that novel HSP90 inhibitors (KU711, WGA-TA) and 17-AAG can effectively target the function of thyroid CSCs in vitro and prevent migration and invasion.
  
  
  METHODS
  Validated papillary (TPC1), follicular (FTC238,WRO), and anaplastic (ACT1) human thyroid cancer cell lines were treated with 3 HSP90 inhibitors. CSCs were quantified for aldehyde dehydrogenase by flow cytometry, CD44 expression by Western blot, and thyrosphere formation assay. Cellular pathway proteins were analyzed by Western blot and migration/invasion by Boyden-chambers.
  
  
  RESULTS
  WGA-TA and 17-AAG induced HSP70 compensation (not observed with KU711) on Western blot in all cell lines (>1,000 fold vs controls). Only WGA-TA degraded HSP90-Cdc37 complexing by 60-70% versus controls. Expression of HSP90 clients β-catenin, BRAF, Akt, and phospho-Akt were significantly inhibited by WGA-TA treatment (50-80%, 50-90%, >80%, and >90%) compared with controls, KU711, and 17-AAG treatment. KU711 and WGA-TA decreased CD44 expression in all cell lines (25-60% vs controls/17-AAG), decreased ALDEFLOR activity by 69-98% (P < .005), and decreased sphere formation by 64-99% (P < .05 each). Finally, cell migration was decreased by 31-98%, 100%, and 30-38%, and invasion by 75-100%, 100%, and 47% by KU711,WGA-TA, and 17-AAG treatment (P < .05) each, respectively.
  
  
  CONCLUSIONS
  KU711 and WGA-TA are novel HSP90 inhibitors targeting CSC function and inhibiting cell migration/invasion in differentiated and anaplastic thyroid cancers, warranting further translational evaluation in vivo.
authors.affiliation: Department of Surgery, University of Michigan, Ann Arbor, MI.
authors.forename: Peter T
authors.initials: PT
authors.lastname: White
authors.affiliation: Department of Surgery, University of Michigan, Ann Arbor, MI.
authors.forename: Chitra
authors.initials: C
authors.lastname: Subramanian
authors.affiliation: Department of Surgery, University of Michigan, Ann Arbor, MI.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhu
authors.affiliation: Department of Medicinal Chemistry, The University of Kansas, Lawrence, KS.
authors.forename: Huaping
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Medicinal Chemistry, The University of Kansas, Lawrence, KS.
authors.forename: Huiping
authors.initials: H
authors.lastname: Zhao
authors.affiliation: Department of Medicinal Chemistry, The University of Kansas, Lawrence, KS.
authors.forename: Robert
authors.initials: R
authors.lastname: Gallagher
authors.affiliation: Department of Medicinal Chemistry, The University of Kansas, Lawrence, KS.
authors.forename: Barbara N
authors.initials: BN
authors.lastname: Timmermann
authors.affiliation: Department of Medicinal Chemistry, The University of Kansas, Lawrence, KS.
authors.forename: Brian S J
authors.initials: BS
authors.lastname: Blagg
authors.affiliation: Department of Surgery, University of Michigan, Ann Arbor, MI. Electronic address: cohenmar@med.umich.edu.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Cohen
mesh_terms: D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors*; D006801:Humans; D009361:Neoplasm Invasiveness / Q000517:prevention & control; D014411:Neoplastic Stem Cells / Q000187:drug effects*; D013961:Thyroid Gland / Q000187:drug effects* / Q000473:pathology*; D013964:Thyroid Neoplasms / Q000188:drug therapy / Q000473:pathology*
chemical_list: D016588:Anticarcinogenic Agents; D018841:HSP90 Heat-Shock Proteins