Geldanamycin-stimulated destabilization of mutated p53 is mediated by the proteasome in vivo

Luke Whitesell, Patrick Sutphin, Wen G. An, Theodor Schulte, Mikhail V. Blagosklonny, Len Neckers

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Abstract

Mutation of the tumor suppressor gene p53 is the most common genetic abnormality detected in human cancers. Wild type p53 is a short-lived protein with very low basal intracellular levels. Most mutated forms of the protein, however, display markedly increased intracellular levels as an essential feature of their positive transforming activity. In this report, we have used selective inhibitors of the 20S proteasome to demonstrate that processing of p53 by ubiquitination and proteasome-mediated degradation is impaired by commonly occuring mutations of the protein. We found that this impairment of p53 turnover can be reversed by treatment of tumor cells with the benzoquinone ansamycin, geldanamycin, leading to a marked reduction in intracellular p53 levels. Finally, using cells which over-express a mutant p53 protein, we were able to demonstrate that restoration of proteasome-mediated degradation by geldanamycin is accompanied by p53 polyubiquitination. Although much remains to be learned about the mechanisms involved, our data demonstrate that selective de-stabilization of mutant transforming proteins such as p53 can be achieved pharmacologically with agents such as geldanamycin which modify the function of molecular chaperone proteins within tumor cells.

Original languageEnglish (US)
Pages (from-to)2809-2816
Number of pages8
JournalOncogene
Volume14
Issue number23
DOIs
Publication statusPublished - 1997

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Keywords

  • Benzoquinone ansamycins
  • Lactacystin
  • Proteasome
  • Ubiquitin

ASJC Scopus subject areas

  • Molecular Biology
  • Cancer Research
  • Genetics

Cite this

Whitesell, L., Sutphin, P., An, W. G., Schulte, T., Blagosklonny, M. V., & Neckers, L. (1997). Geldanamycin-stimulated destabilization of mutated p53 is mediated by the proteasome in vivo. Oncogene, 14(23), 2809-2816. https://doi.org/10.1038/sj.onc.1201120