depudecin and Cell-Transformation--Neoplastic

Depudecin is a fungal metabolite that reverts the rounded phenotype of NIH 3T3 fibroblasts transformed with v-ras and v-src oncogenes to the flattened phenotype of the nontransformed parental cells. The mechanism of detransformation induced by this agent had not been determined. Here, we demonstrate that depudecin inhibits histone deacetylase (HDAC) activity effectively both in vivo and in vitro. Depudecin induces similar morphological reversion in v-ras transformed NIH 3T3 cells as do other naturally occurring HDAC inhibitors such as trichostatin A or trapoxin. It competitively inhibits the binding of [3H]trapoxin in vitro and the nuclear binding of a trapoxin-coumarin fluorophore in vivo, suggesting that depudecin shares a nuclear binding protein and site on that protein with trapoxin. Furthermore, depudecin induces hyperacetylation of histones in a dose-dependent manner and at concentrations comparable with that required for detransformation. An in vitro histone deacetylase assay, using purified recombinant HDAC1, reveals that depudecin inhibits 50% of the enzyme activity at a concentration of 4.7 microM. These results demonstrate that depudecin is a novel HDAC inhibitor and suggest that its ability to induce morphological reversion of transformed cells is the result of its HDAC inhibitory activity.

Topics: 3T3 Cells; Alkadienes; Animals; Cell Transformation, Neoplastic; Epoxy Compounds; Fatty Alcohols; Fibroblasts; Histone Deacetylase Inhibitors; Mice

(-)-Depudecin is a fungal metabolite that reverts the rounded phenotype of NIH3T3 fibroblasts transformed with v-ras and v-src oncogenes to the flat phenotype of the nontransformed parental cells. The mechanism of action of this detransformation agent is unknown. Although depudecin appears to be an excellent molecule for probing signaling pathways that regulate changes in the cytoskeletal architecture, reagents based on depudecin are not available as it has not yet been successfully synthesized. We therefore set out to synthesize (-)-depudecin.. An asymmetric synthesis of (-)-depudecin has been developed. A cell staining assay has been used to reveal the ability of synthetic depudecin, but not several structural variants, to induce a flattened morphology in v-Ha-ras-transformed NIH3T3 cells. This assay also shows that depudecin induces an intricate network of actin stress fibers in these cells and in MG63 osteosarcoma cells and reveals the essential role of the epoxide and hydroxyl moieties in depudecin. Cycloheximide and actinomycin D inhibited the ability of depudecin to induce a morphological change, suggesting that both mRNA synthesis and de novo protein synthesis are required for depudecin-mediated suppression of the transformed phenotypes in ras-transformed cells.. The synthetic procedure provides access to (-)-depudecin and could be readily modified to produce depudecin-related reagents for the identification of depudecin's cellular target(s). This target appears to be involved in the regulation of the assembly of the actin microfilament component of the cytoskeleton in mammalian cells.

Topics: 3T3 Cells; Actins; Alkadienes; Animals; Bone Neoplasms; Cell Nucleus; Cell Transformation, Neoplastic; Cycloheximide; Cytoskeleton; Dactinomycin; Epoxy Compounds; Fatty Alcohols; Genes, ras; Magnetic Resonance Spectroscopy; Mice; Osteosarcoma; Protein Synthesis Inhibitors; Signal Transduction; Spectrophotometry, Infrared; Stereoisomerism; Tumor Cells, Cultured

A novel compound depudecin inducing the flat phenotype of ras- and src- transformed NIH3T3 cells at a concentration of 1 microgram/ml was isolated from the culture broth of Alternaria brassicicola. Based on its spectroscopic characteristics and X-ray crystallographic analysis of its bis-(1S)-(-)-camphanate, the structure of depudecin was determined to be (2R,3S,4S,5E,7S,8S,9R)-2,9- dihydroxy-3,4;7,8-diepoxy-undeca-5,10-diene.

Topics: 3T3 Cells; Alkadienes; Alternaria; Animals; Cell Transformation, Neoplastic; Epoxy Compounds; Fatty Alcohols; Fermentation; Genes, ras; Genes, src; Mice; Phenotype

A novel compound, depudecin, induced production of the flat phenotype of Ki-ras-transformed NIH3T3 cells at the low concentration of 1 microgram/ml. This effect was reversible. Actin stress fiber was detected in these cells after depudecin treatment. Almost complete reversion to the flat phenotype was observed at 6 h after depudecin addition. The synthesis of ras-mRNA did not decrease enough with depudecin treatment at the concentration of 10 micrograms/ml to reverse the transformed morphology.

Topics: 3T3 Cells; Actins; Alkadienes; Animals; Antifungal Agents; Cell Division; Cell Line, Transformed; Cell Transformation, Neoplastic; Epoxy Compounds; Fatty Alcohols; Gene Expression; Genes, ras; Hydroxamic Acids; Kinetics; Mice; Phenotype; RNA, Messenger