title: Diaryl Disulfides as Novel Stabilizers of Tumor Suppressor Pdcd4.
abstract: The translation inhibitor and tumor suppressor Pdcd4 was reported to be lost in various tumors and put forward as prognostic marker in tumorigenesis. Decreased Pdcd4 protein stability due to PI3K-mTOR-p70S6K1 dependent phosphorylation of Pdcd4 followed by β-TrCP1-mediated ubiquitination, and proteasomal destruction of the protein was characterized as a major mechanism contributing to the loss of Pdcd4 expression in tumors. In an attempt to identify stabilizers of Pdcd4, we used a luciferase-based high-throughput compatible cellular assay to monitor phosphorylation-dependent proteasomal degradation of Pdcd4 in response to mitogen stimulation. Following a screen of approximately 2000 compounds, we identified 1,2-bis(4-chlorophenyl)disulfide as a novel Pdcd4 stabilizer. To determine an initial structure-activity relationship, we used 3 additional compounds, synthesized according to previous reports, and 2 commercially available compounds for further testing, in which either the linker between the aryls was modified (compounds 2-4) or the chlorine residues were replaced by groups with different electronic properties (compounds 5 and 6). We observed that those compounds with alterations in the sulfide linker completely lost the Pdcd4 stabilizing potential. In contrast, modifications in the chlorine residues showed only minor effects on the Pdcd4 stabilizing activity. A reporter with a mutated phospho-degron verified the specificity of the compounds for stabilizing the Pdcd4 reporter. Interestingly, the active diaryl disulfides inhibited proliferation and viability at concentrations where they stabilized Pdcd4, suggesting that Pdcd4 stabilization might contribute to the anti-proliferative properties. Finally, computational modelling indicated that the flexibility of the disulfide linker might be necessary to exert the biological functions of the compounds, as the inactive compound appeared to be energetically more restricted.
authors.affiliation: Institute of Biochemistry I, Faculty of Medicine, Goethe-University Frankfurt, 60590, Frankfurt, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Schmid
authors.affiliation: Institute of Biochemistry I, Faculty of Medicine, Goethe-University Frankfurt, 60590, Frankfurt, Germany.
authors.forename: Johanna S
authors.initials: JS
authors.lastname: Blees
authors.affiliation: Institute of Biochemistry I, Faculty of Medicine, Goethe-University Frankfurt, 60590, Frankfurt, Germany.
authors.forename: Magdalena M
authors.initials: MM
authors.lastname: Bajer
authors.affiliation: Institute of Biochemistry I, Faculty of Medicine, Goethe-University Frankfurt, 60590, Frankfurt, Germany.
authors.forename: Janine
authors.initials: J
authors.lastname: Wild
authors.affiliation: Dipartimento di Chimica e Tecnologie del Farmaco, Istituto Pasteur - Fondazione Cenci Bolognetti, "Sapienza" University of Rome, 00185, Rome, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Pescatori
authors.affiliation: Dipartimento di Chimica e Tecnologie del Farmaco, Istituto Pasteur - Fondazione Cenci Bolognetti, "Sapienza" University of Rome, 00185, Rome, Italy.
authors.forename: Giuliana
authors.initials: G
authors.lastname: Cuzzucoli Crucitti
authors.affiliation: Dipartimento di Chimica e Tecnologie del Farmaco, Istituto Pasteur - Fondazione Cenci Bolognetti, "Sapienza" University of Rome, 00185, Rome, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Scipione
authors.affiliation: Dipartimento di Chimica e Tecnologie del Farmaco, Istituto Pasteur - Fondazione Cenci Bolognetti, "Sapienza" University of Rome, 00185, Rome, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Costi
authors.affiliation: Molecular Targets Laboratory, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, MD, 21702, United States of America.|Basic Science Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, 21702, United States of America.
authors.forename: Curtis J
authors.initials: CJ
authors.lastname: Henrich
authors.affiliation: Institute of Biochemistry I, Faculty of Medicine, Goethe-University Frankfurt, 60590, Frankfurt, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Brüne
authors.affiliation: Laboratory of Cancer Prevention, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, MD, 21702, United States of America.
authors.forename: Nancy H
authors.initials: NH
authors.lastname: Colburn
authors.affiliation: Dipartimento di Chimica e Tecnologie del Farmaco, Istituto Pasteur - Fondazione Cenci Bolognetti, "Sapienza" University of Rome, 00185, Rome, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Di Santo
mesh_terms: D051017:Apoptosis Regulatory Proteins / Q000187:drug effects* / Q000378:metabolism; D002453:Cell Cycle; D049109:Cell Proliferation; D057809:HEK293 Cells; D006801:Humans; D016601:RNA-Binding Proteins / Q000187:drug effects* / Q000378:metabolism; D013329:Structure-Activity Relationship; D013440:Sulfides / Q000737:chemistry / Q000494:pharmacology*; D025521:Tumor Suppressor Proteins / Q000187:drug effects* / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; C114487:PDCD4 protein, human; D016601:RNA-Binding Proteins; D013440:Sulfides; D025521:Tumor Suppressor Proteins