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The interaction of DNA-targeted platinum phenanthridinium complexes with DNA in human cells
J Whittaker1, W D McFadyen, B C Baguley
1School of Biochemistry and Molecular Genetics, University of New South Wales, Sydney, NSW, Australia.
Abstract:
DNA-targeted platinum phenanthridinium complexes were investigated in intact human cells and in tumour-bearing mice. The DNA sequence specificity of platinum phenanthridinium complexes was examined in intact human cells using a Taq DNA polymerase stop assay. It was found that the platinum phenanthridinium complexes had a similar sequence specificity to that of cisplatin. However, the rate at which DNA was damaged in intact human cells was 6-fold greater for the platinum phenanthridinium chloride complexes compared with cisplatin. These results are consistent with a DNA-targeting hypothesis where the attachment of an intercalating group to cisplatin places the platinum in close proximity to DNA and increases the rate of DNA platination. Platinum phenanthridinium iodide complexes were also tested, but damaged DNA at a rate similar to cisplatin. The platinum phenanthridinium complexes with shorter linker chain lengths damaged DNA more efficiently than the longer linker chain length complexes. The platinum phenanthridinium chloride complexes also showed significant anti-tumour activity in tumour-bearing (P388) mice.
Insights
New platinum phenanthridinium complexes show enhanced DNA damage and anti-tumor activity. These DNA-targeting agents offer a promising strategy for cancer therapy, demonstrating improved efficacy over cisplatin.
Area of Science:
- Medicinal Chemistry
- Molecular Biology
- Cancer Research
Background:
- Platinum-based drugs like cisplatin are crucial in cancer chemotherapy.
- Understanding DNA-drug interactions is key to developing more effective anti-cancer agents.
- Phenanthridinium compounds are known DNA intercalators.
Purpose of the Study:
- To investigate the DNA-damaging potential and anti-tumor activity of novel platinum phenanthridinium complexes.
- To compare the efficacy of these complexes with cisplatin.
- To explore the relationship between complex structure and DNA interaction.
Main Methods:
- Taq DNA polymerase stop assay in intact human cells to determine DNA sequence specificity.
- In vivo studies using tumor-bearing mice (P388) to assess anti-tumor activity.
- Evaluation of complexes with varying linker chain lengths.
Main Results:
- Platinum phenanthridinium complexes exhibited similar DNA sequence specificity to cisplatin.
- Platinum phenanthridinium chloride complexes demonstrated a 6-fold higher rate of DNA damage in human cells compared to cisplatin.
- Complexes with shorter linker chains were more efficient at damaging DNA.
- Platinum phenanthridinium chloride complexes showed significant anti-tumor activity in P388 tumor-bearing mice.
Conclusions:
- Attachment of an intercalating phenanthridinium group to cisplatin enhances DNA platination rates.
- Platinum phenanthridinium complexes represent a promising class of DNA-targeting anti-cancer agents.
- Structural modifications, such as linker length, influence the efficiency of these complexes.