RET is a heat shock protein 90 (HSP90) client protein and is knocked down upon HSP90 pharmacological block

J Clin Endocrinol Metab. 2010 Jul;95(7):3552-7. doi: 10.1210/jc.2009-2315. Epub 2010 May 5.

Abstract

Context: Mutations of the RET receptor tyrosine kinase are associated to multiple endocrine neoplasia type 2 (MEN2) and sporadic medullary thyroid carcinoma (MTC). The heat shock protein (HSP) 90 chaperone is required for folding and stability of several kinases. HSP90 is specifically inhibited by 17-allyl-amino-17-demethoxygeldanamycin (17-AAG).

Objective: Our aim was to investigate whether RET protein half-life depends on HSP90 and to dissect the molecular pathway responsible for the degradation of RET upon HSP90 inhibition by 17-AAG.

Design: 17-AAG effects were studied in RAT1 fibroblasts exogenously expressing MEN2-associated RET mutants and human MTC-derived cell lines.

Results: 17-AAG induced a 26S proteasome-dependent degradation of wild-type RET and MEN2-associated RET mutants. The compound hampered HSP90/RET interaction and stabilized RET binding to HSP70, leading to the recruitment of the HSP70-associated E3 ligase C-terminus of Hsc70-interacting protein. In turn, C-terminus of Hsc70-interacting protein polyubiquitinated RET, promoting its proteasomal degradation. 17-AAG blocked RET downstream effectors and RET-dependent transcriptional activation of gene promoters. In human MTC cells carrying oncogenic RET mutants, HSP90 inhibition induced receptor degradation and signaling hindrance leading to cell cycle arrest.

Conclusion: RET and MEN2-associated RET mutants rely on HSP90 for protein stability, and HSP90 blockade by 17-AAG promotes RET degradation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Benzoquinones / pharmacology
  • Blotting, Western
  • Cell Line
  • Cells, Cultured
  • Enzyme Inhibitors / pharmacology
  • HSP90 Heat-Shock Proteins / antagonists & inhibitors
  • HSP90 Heat-Shock Proteins / genetics
  • HSP90 Heat-Shock Proteins / metabolism*
  • Humans
  • Lactams, Macrocyclic / pharmacology
  • Macrolides / pharmacology
  • Phosphorylation / genetics
  • Proto-Oncogene Proteins c-ret / genetics
  • Proto-Oncogene Proteins c-ret / metabolism*
  • Signal Transduction / drug effects
  • Transfection

Substances

  • Benzoquinones
  • Enzyme Inhibitors
  • HSP90 Heat-Shock Proteins
  • Lactams, Macrocyclic
  • Macrolides
  • tanespimycin
  • Proto-Oncogene Proteins c-ret
  • RET protein, human
  • monorden