Early effects of protein kinase modulators on DNA synthesis in rat cerebral cortex.
By using tissue miniunits, protein kinase modulators, and topoisomerase inhibitors in short-term incubation (0-90 min) we studied (1) the role of protein phosphorylation in the immediate control of DNA replication in the developing rat cerebral cortex and (2) the mechanism of action for genistein-mediated DNA synthesis inhibition. Genistein decreased the DNA synthesis within less than 30 min. None of the other protein kinase inhibitors examined (herbimycin A, staurosporine, calphostin-C) or the protein phosphatase inhibitor sodium orthovanadate inhibited DNA synthesis and they did not affect the genistein-mediated inhibition. The selective topoisomerase inhibitors camptothecin and etoposide decreased the DNA synthesis to an extent similar to that of genistein and within less than 30 min. In addition, the effects of these substances on topoisomerase I and II were studied. Etoposide and genistein but not herbimycin A, staurosporine, or calphostin-C strongly inhibited the activity of topoisomerase II. Our results (1) strongly suggest that the net rate of DNA replication during the S phase of the cell cycle is independent of protein phosphorylation and (2) indicate that the early inhibitory effect of genistein on DNA synthesis is mediated by topoisomerase II inhibition rather than protein tyrosine kinase inhibition.
Yakisich
J S
JS
Applied Biochemistry, Clinical Research Center, Karolinska Institute, Novum, Huddinge University Hospital, Huddinge, S-141 86, Sweden.
Sidén
A
A
Vargas
V I
VI
Eneroth
P
P
Cruz
M
M
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D016227:Benzoquinones; D002166:Camptothecin / Q000494:pharmacology; D002540:Cerebral Cortex / Q000187:drug effects* / Q000201:enzymology*; D004261:DNA Replication / Q000187:drug effects*; D004264:DNA Topoisomerases, Type I / Q000378:metabolism; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D004278:DNA, Superhelical / Q000187:drug effects; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005047:Etoposide / Q000494:pharmacology; D019833:Genistein / Q000494:pharmacology*; D047029:Lactams, Macrocyclic; D009281:Naphthalenes / Q000494:pharmacology; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000037:antagonists & inhibitors / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011809:Quinones / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017828:Rifabutin / Q000031:analogs & derivatives; D019311:Staurosporine / Q000494:pharmacology; D013256:Steroids; D014638:Vanadates / Q000494:pharmacology
D000893:Anti-Inflammatory Agents; D016227:Benzoquinones; D004278:DNA, Superhelical; D004791:Enzyme Inhibitors; D047029:Lactams, Macrocyclic; D009281:Naphthalenes; D019384:Nucleic Acid Synthesis Inhibitors; D011809:Quinones; D013256:Steroids; D017828:Rifabutin; D019000:Phosphotyrosine; D014638:Vanadates; D005047:Etoposide; C020754:herbimycin; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D004264:DNA Topoisomerases, Type I; D004250:DNA Topoisomerases, Type II; D019311:Staurosporine; C058819:calphostin C; D002166:Camptothecin; D004121:Dimethyl Sulfoxide