Evaluation of two models for human topoisomerase I interaction with dsDNA and camptothecin derivatives

Area of Science:

• Biochemistry
• Molecular Biology
• Pharmacology

Background:

• Human topoisomerase I (Top1) is crucial for DNA replication and is a validated anti-cancer target.
• Camptothecin and its derivatives stabilize Top1-DNA covalent complexes, leading to cancer cell death.
• Two distinct models exist for camptothecin binding to Top1/DNA complexes.

Purpose of the Study:

• To calculate and compare interaction energies between camptothecin derivatives and the Top1/DNA complex in two existing binding models.
• To correlate calculated interaction energies with published structure-activity relationships (SAR) for camptothecin derivatives.
• To guide the rational design of novel, more potent camptothecin-based anti-cancer agents.

Main Methods:

• Computational analysis of interaction energies between camptothecin derivatives and Top1/dsDNA covalent complexes.
• Comparison of calculated energies with established SAR data for various camptothecin analogs.
• Evaluation of two proposed binding models (Staker et al. and Laco et al.) for camptothecin interaction.

Main Results:

• Interaction energies in the Laco et al. model showed strong correlation with published SAR for camptothecin and its derivatives.
• The Staker et al. model did not consistently correlate with SAR for several camptothecin derivatives.
• Calculated binding orientations provide insights into Top1-drug interactions.

Conclusions:

• The Laco et al. model provides a more accurate representation of camptothecin derivative binding to Top1/DNA.
• Understanding the precise binding orientation is key to designing improved Top1-targeting anti-cancer drugs.
• This work facilitates the rational development of next-generation camptothecin analogs with enhanced anti-cancer efficacy.