Synergistic Induction of the Senescence-Associated Genes by 5-Bromodeoxyuridine and AT-Binding Ligands in HeLa Cells

• Published in: Experimental cell research 2002-06, Vol.276 (2), p.174-184
• Main Authors: Suzuki, Toshikazu, Michishita, Eriko, Ogino, Hideki, Fujii, Michihiko, Ayusawa, Dai
• Format: Article
• Language: English
• Subjects: 5-bromodeoxyuridine; Antiviral Agents - pharmacology; AT Rich Sequence - drug effects; AT Rich Sequence - genetics; AT-binding ligands; Bisbenzimidazole - pharmacology; Bromodeoxyuridine - pharmacology; Bromouracil - pharmacology; Cell Division - drug effects; Cell Division - genetics; Cellular Senescence - drug effects; Cellular Senescence - genetics; Chromosome Mapping; Distamycins - pharmacology; DNA - drug effects; DNA - genetics; Dose-Response Relationship, Drug; Eukaryotic Cells - cytology; Eukaryotic Cells - drug effects; Eukaryotic Cells - metabolism; Fluorescent Dyes - pharmacology; Gene Expression Regulation - drug effects; Gene Expression Regulation - genetics; Genes - drug effects; Genes - genetics; HeLa Cells; Humans; Netropsin - pharmacology; nuclear matrix; Nuclear Matrix - drug effects; Nuclear Matrix - metabolism; Nuclear Proteins - drug effects; Nuclear Proteins - genetics; Nuclear Proteins - metabolism; Protein Binding - drug effects; Protein Binding - genetics; RNA, Messenger - drug effects; RNA, Messenger - genetics; scaffold/nuclear matrix attachment region; senescence-associated genes
• ISSN: 0014-4827; 1090-2422
• DOI: 10.1006/excr.2002.5524

5-Bromodeoxyuridine induces a senescence-like phenomenon in mammalian cells. This effect was dramatically potentiated by AT-binding ligands such as distamycin A, netropsin, and Hoechst 33258. The genes most remarkably affected by these ligands include the widely used senescence-associated genes and were located on or nearby Giemsa-dark bands of human chromosomes. We hypothesize that AT-rich scaffold/nuclear matrix attachment region sequences are involved in this phenomenon. In fact, upon substitution of thymine with 5-bromouracil, a rat S/MAR sequence reduced its degree of bending and became insensitive to cancellation of the bending by distamycin A. The S/MAR sequence containing 5-bromouracil also bound more tightly to nuclear scaffold proteins in vitro and this binding was not inhibited by distamycin A. Under the same conditions, the S/MAR sequence containing thymine easily dissociated from the nuclear scaffold proteins. Taken together, the synergistic induction of the genes may be explained not only by opening of condensed chromatin by distamycin A but also by increase in the binding of 5-bromouracil-containing S/MAR sequences to the nuclear scaffolds.