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Bisintercalating threading diacridines: relationships between DNA binding, cytotoxicity, and cell cycle arrest.
Laurence P G Wakelin1, Xianyong Bu, Alexandra Eleftheriou
1School of Medical Sciences, and the School of Women's and Children's Health, University of New South Wales, Sydney 2052, New South Wales, Australia. l.Wakelin@unsw.edu.au
Journal of Medicinal Chemistry
|December 12, 2003
Summary
New bis(9-aminoacridine-4-carboxamides) DNA bisintercalators show potent cytotoxicity against leukemia cells. Their complex cellular responses depend on side chain and linker structures, impacting transcription and cell cycle progression.
Area of Science:
- Medicinal Chemistry
- Molecular Biology
- Biochemistry
Background:
- Bis(9-aminoacridine-4-carboxamides) were designed as DNA bisintercalators.
- These compounds feature flexible and semirigid linkers and specific side chains to interact with DNA grooves.
- The intended mechanism involves threading into DNA, hydrogen bonding with guanine, and slow dissociation, leading to transcription inhibition.
Purpose of the Study:
- To synthesize and characterize a series of bis(9-aminoacridine-4-carboxamides) with varying linkers and side chains.
- To evaluate their DNA binding properties, including helix unwinding and dissociation rates.
- To assess their cytotoxicity against human leukemic cells and their effects on cell cycle progression.
Main Methods:
- Synthesis of bis(9-aminoacridine-4-carboxamides) with neutral alkyl, charged polyamine, and semirigid piperazine linkers.
- DNA supercoiling assays to determine helix unwinding angles.
- Cytotoxicity assays (IC50 values) on CCRF-CEM cells.
- Cell cycle distribution analysis.
Main Results:
- All synthesized compounds demonstrated bifunctional intercalation into DNA, with helix unwinding angles from 26 to 46 degrees.
- DNA complexes showed significantly slower dissociation rates compared to simple aminoacridines.
- The most potent agents exhibited IC50 values of 35-50 nM against CCRF-CEM cells.
- Dimethylaminoethyl derivatives caused G2/M arrest, suggesting topoisomerase involvement, while morpholino derivatives generally did not affect cell cycle distribution.
Conclusions:
- The synthesized bisintercalating agents are potent cytotoxic agents with slow DNA dissociation kinetics.
- Cellular responses, including cytotoxicity and cell cycle effects, are complex and depend on the specific linker and side chain structures.
- No simple structure-activity relationships were observed, indicating a complex interplay between molecular design and biological outcome.