title: Topoisomerase II poisoning and antineoplastic action by DNA-nonbinding diacetyl and dicarboxaldoxime derivatives of ferrocene.
abstract: Topoisomerase II is a major molecular target for a number of DNA-binding anticancer drugs. In the present study, we report topoisomerase II inhibition and anticancer activity by four substituted ferrocene derivatives which do not bind to DNA. The first derivative, acetyl-substituted ferrocene (monoacetylferrocene), showed a minor inhibition of topoisomerase II activity along with a consequent inhibition of cancer cell proliferation. The second derivative (diacetylferrocene) showed a higher potency of action compared to the monosubstituted derivative. The third and fourth derivatives, with mono- and disubstituted carboxaldoxime groups (ferrocenecarboxaldoxime and ferrocenedicarboxaldoxime), showed a higher anticancer action and stronger topoisomerase II inhibition. To understand their molecular mechanism of action, cleavage assays were carried out to monitor the drug-induced, topoisomerase II mediated DNA cleavage. The results show that diacetylferrocene and ferrocenedicarboxaldoxime could form an enzyme-drug-DNA ternary complex, called a "cleavage complex," resulting in DNA cleavage. These results along with those of an immunoprecipitation assay indicate that the two compounds interact with topoisomerase II alone and poison its activity by trapping the enzyme and enzyme-cleaved DNA in the covalently closed cleavage complex. The formation of such a complex has numerous genetic implications, which ultimately results in neoplastic cell death.
authors.affiliation: Department of Biochemistry, University of Hyderabad, Hyderabad, 500 046, India.
authors.forename: Y N
authors.initials: YN
authors.lastname: Vashisht Gopal
authors.forename: D
authors.initials: D
authors.lastname: Jayaraju
authors.forename: A K
authors.initials: AK
authors.lastname: Kondapi
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001665:Binding Sites; D002417:Cattle; D002455:Cell Division / Q000187:drug effects; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005296:Ferrous Compounds / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D000075163:Metallocenes; D013816:Thermodynamics; D059005:Topoisomerase II Inhibitors; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D005296:Ferrous Compounds; D000075163:Metallocenes; D059005:Topoisomerase II Inhibitors; C053522:1-acetylferrocene; D004247:DNA; D004250:DNA Topoisomerases, Type II; C004998:ferrocene