Benzodiazepinedione inhibitors of the Hdm2:p53 complex suppress human tumor cell proliferation in vitro and sensitize tumors to doxorubicin in vivo

Mol Cancer Ther. 2006 Jan;5(1):160-9. doi: 10.1158/1535-7163.MCT-05-0199.


The activity and stability of the p53 tumor suppressor are regulated by the human homologue of the mouse double minute 2 (Hdm2) oncoprotein. It has been hypothesized that small molecules disrupting the Hdm2:p53 complex would allow for the activation of p53 and result in growth suppression. We have identified small-molecule inhibitors of the Hdm2:p53 interaction using our proprietary ThermoFluor microcalorimetry technology. Medicinal chemistry and structure-based drug design led to the development of an optimized series of benzodiazepinediones, including TDP521252 and TDP665759. Activities were dependent on the expression of wild-type (wt) p53 and Hdm2 as determined by lack of potency in mutant or null p53-expressing cell lines or cells engineered to no longer express Hdm2 and wt p53. TDP521252 and TDP665759 inhibited the proliferation of wt p53-expressing cell lines with average IC(50)s of 14 and 0.7 micromol/L, respectively. These results correlated with the direct cellular dissociation of Hdm2 from wt p53 observed within 15 minutes in JAR choriocarcinoma cells. Additional activities of these inhibitors in vitro include stabilization of p53 protein levels, up-regulation of p53 target genes in a DNA damage-independent manner, and induction of apoptosis in HepG2 cells. Administration of TDP665759 to mice led to an increase in p21(waf1/cip1) levels in liver samples. Finally, TDP665759 synergizes with doxorubicin both in culture and in an A375 xenograft model to decrease tumor growth. Taken together, these data support the potential utility of small-molecule inhibitors of the Hdm2:p53 interaction for the treatment of wt p53-expressing tumors.

MeSH terms

  • Animals
  • Antineoplastic Combined Chemotherapy Protocols
  • Apoptosis / drug effects
  • Benzodiazepines / chemistry
  • Benzodiazepines / pharmacology
  • Benzodiazepinones / administration & dosage
  • Benzodiazepinones / pharmacology*
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Doxorubicin / administration & dosage
  • Doxorubicin / pharmacology*
  • Drug Screening Assays, Antitumor
  • Drug Synergism
  • Female
  • Humans
  • Liver Neoplasms, Experimental / drug therapy
  • Liver Neoplasms, Experimental / metabolism
  • Mice
  • Mice, Nude
  • Multiprotein Complexes
  • Mutation
  • Proto-Oncogene Proteins c-mdm2 / drug effects*
  • Proto-Oncogene Proteins c-mdm2 / metabolism
  • Tumor Cells, Cultured
  • Tumor Suppressor Protein p53 / drug effects*
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism
  • Xenograft Model Antitumor Assays


  • Benzodiazepinones
  • Multiprotein Complexes
  • TDP 521252
  • TDP 665759
  • Tumor Suppressor Protein p53
  • Benzodiazepines
  • Doxorubicin
  • MDM2 protein, human
  • Proto-Oncogene Proteins c-mdm2