title: Inhibition of c-myc gene expression in murine lymphoblastoma cells by geldanamycin and herbimycin, antibiotics of benzoquinoid ansamycin group.
abstract: We have shown that geldanamycin (GDM), an antibiotic of benzoquinoid ansamycin group, inhibits DNA replication in cultured mouse lymphoblastoma L5178Y cells. Here we report that GDM selectively inhibited the expression of c-myc gene, proto-oncogene, along with suppression of DNA replication in L5178Y cells, which are consistent with our previous results that c-myc protein promotes cellular DNA replication. The significantly enhanced inhibition by GDM of DNA replication was observed, when the antibiotic was introduced at G1 stage prior to S phase of cell cycle. The results are in favor of the prospects that GDM inhibits DNA replication mainly at time of initiation, and that c-myc protein is essential for the initiation of cellular DNA replication. Furthermore, when c-myc expression was inhibited by GDM, the expression of p53 gene, the product of which may be another DNA replication protein, was stimulated in the tumor cells. Thus, GDM should be useful to investigate the molecular mechanism of DNA replication promoted by c-myc protein and also to distinguish the function of c-myc protein from that of p53 protein in DNA replication.
authors.affiliation: Institute of Applied Microbiology, University of Tokyo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Yamaki
authors.forename: S M
authors.initials: SM
authors.lastname: Iguchi-Ariga
authors.forename: H
authors.initials: H
authors.lastname: Ariga
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D016227:Benzoquinones; D002453:Cell Cycle; D004261:DNA Replication / Q000187:drug effects; D004273:DNA, Neoplasm / Q000096:biosynthesis / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects*; D047029:Lactams, Macrocyclic; D008228:Lymphoma, Non-Hodgkin; D051379:Mice; D015394:Molecular Structure; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D016271:Proto-Oncogene Proteins c-myc; D011519:Proto-Oncogenes; D011809:Quinones / Q000494:pharmacology*; D017828:Rifabutin / Q000031:analogs & derivatives; D014407:Tumor Cells, Cultured
chemical_list: D000900:Anti-Bacterial Agents; D016227:Benzoquinones; D004273:DNA, Neoplasm; D047029:Lactams, Macrocyclic; D011518:Proto-Oncogene Proteins; D016271:Proto-Oncogene Proteins c-myc; D011809:Quinones; D017828:Rifabutin; C020754:herbimycin; C001277:geldanamycin