title: Parthenolide promotes the ubiquitination of MDM2 and activates p53 cellular functions.
abstract: MDM2 belongs to a class of ring-finger domain-containing ubiquitin ligases that mediate the proteasomal degradation of numerous proteins, including themselves. Arguably, the most important substrate of MDM2 is p53, which controls cell cycle progression and apoptosis. MDM2 and p53 are parts of a feedback regulatory loop whose perturbations are often present in cancer and are targets for anticancer drug development. We found that the natural product, small-molecule anti-inflammatory agent parthenolide (PN), which is actively being investigated as a potential therapeutic for many human cancers, induces ubiquitination of MDM2 in treated cells, resulting in the activation of p53 and other MDM2-regulated tumor-suppressor proteins. Using cells with functional gene deletions and small interfering RNA knockdown studies, we found that these effects required the DNA damage transducer ataxia telangiectasia mutated. The effects of PN on tumor suppressor activation were comparable with that of nutlin-3a, a recently developed small molecule that was designed to interfere with the interaction between MDM2 and p53 but does not promote MDM2 ubiquitination. Our study illustrates an alternative approach for controlling MDM2 and p53 activities and identifies an additional critically important cancer pathway affected by PN.
authors.affiliation: Department of Molecular and Cellular Oncology, The University of Texas M. D. Anderson Cancer Center, Unit 079, 1515 Holcombe Boulevard, Houston, TX 77030-4009, USA.
authors.forename: Y N Vashisht
authors.initials: YN
authors.lastname: Gopal
authors.forename: Ekkawit
authors.initials: E
authors.lastname: Chanchorn
authors.forename: Michael W
authors.initials: MW
authors.lastname: Van Dyke
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D045325:HCT116 Cells; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases / Q000378:metabolism; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D008954:Models, Biological; D010879:Piperazines / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D051736:Proto-Oncogene Proteins c-mdm2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012717:Sesquiterpenes / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism / Q000502:physiology*; D054875:Ubiquitination / Q000187:drug effects*; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D000970:Antineoplastic Agents; D007093:Imidazoles; D010879:Piperazines; D012717:Sesquiterpenes; D016159:Tumor Suppressor Protein p53; C002669:parthenolide; C482205:nutlin 3; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; C110550:HDAC1 protein, human; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases