SAHA shows preferential cytotoxicity in mutant p53 cancer cells by destabilizing mutant p53 through inhibition of the HDAC6-Hsp90 chaperone axis

Cell Death Differ. 2011 Dec;18(12):1904-13. doi: 10.1038/cdd.2011.71. Epub 2011 Jun 3.


Mutant p53 (mutp53) cancers are surprisingly dependent on their hyperstable mutp53 protein for survival, identifying mutp53 as a potentially significant clinical target. However, exploration of effective small molecule therapies targeting mutp53 has barely begun. Mutp53 hyperstabilization, a hallmark of p53 mutation, is cancer cell-specific and due to massive upregulation of the HSP90 chaperone machinery during malignant transformation. We recently showed that stable complex formation between HSP90 and its mutp53 client inhibits E3 ligases MDM2 and CHIP, causing mutp53 stabilization. Histone deacetylase (HDAC) inhibitors (HDACi) are a new class of promising anti-cancer drugs, hyperacetylating histone and non-histone targets. Currently, suberoylanilide hydroxamic acid (SAHA) is the only FDA-approved HDACi. We show that SAHA exhibits preferential cytotoxicity for mutant, rather than wild-type and null p53 human cancer cells. Loss/gain-of-function experiments revealed that although able to exert multiple cellular effects, SAHA's cytotoxicity is caused to a significant degree by its ability to strongly destabilize mutp53 at the level of protein degradation. The underlying mechanism is SAHA's inhibition of HDAC6, an essential positive regulator of HSP90. This releases mutp53 and enables its MDM2- and CHIP-mediated degradation. SAHA also strongly chemosensitizes mutp53 cancer cells for chemotherapy due to its ability to degrade mutp53. This identifies a novel action of SAHA with the prospect of SAHA becoming a centerpiece in mutp53-specific anticancer strategies.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology*
  • Cell Line, Tumor
  • Cell Movement / drug effects
  • Cell Survival / drug effects
  • Clinical Trials as Topic
  • Down-Regulation
  • Enzyme Activation
  • HSP90 Heat-Shock Proteins / metabolism*
  • Histone Deacetylase 6
  • Histone Deacetylase Inhibitors / pharmacology*
  • Histone Deacetylases / metabolism*
  • Humans
  • Hydroxamic Acids / pharmacology*
  • Inhibitory Concentration 50
  • Leupeptins / pharmacology
  • Molecular Targeted Therapy
  • Mutant Proteins / genetics
  • Mutant Proteins / metabolism*
  • Proteasome Endopeptidase Complex / metabolism
  • Proteasome Inhibitors
  • Protein Stability / drug effects
  • Proteolysis
  • Proto-Oncogene Proteins c-mdm2 / metabolism
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism*
  • Ubiquitin-Protein Ligases / metabolism
  • Vorinostat


  • Antineoplastic Agents
  • HSP90 Heat-Shock Proteins
  • Histone Deacetylase Inhibitors
  • Hydroxamic Acids
  • Leupeptins
  • Mutant Proteins
  • Proteasome Inhibitors
  • TP53 protein, human
  • Tumor Suppressor Protein p53
  • Vorinostat
  • MDM2 protein, human
  • Proto-Oncogene Proteins c-mdm2
  • STUB1 protein, human
  • Ubiquitin-Protein Ligases
  • Proteasome Endopeptidase Complex
  • HDAC6 protein, human
  • Histone Deacetylase 6
  • Histone Deacetylases
  • benzyloxycarbonylleucyl-leucyl-leucine aldehyde