A Selective Small Molecule DNA2 Inhibitor for Sensitization of Human Cancer Cells to Chemotherapy

Area of Science:

• Molecular Biology
• Cancer Research
• Biochemistry

Background:

• Cancer cells often overexpress DNA2 nuclease/helicase to manage DNA damage and promote survival.
• Inhibiting DNA2 could potentially sensitize cancer cells to genotoxic stresses like radiation and chemotherapy.

Purpose of the Study:

• To investigate the potential of inhibiting the bifunctional DNA2 protein as a strategy to sensitize cancer cells.
• To identify and characterize selective inhibitors of DNA2.

Main Methods:

• Virtual high-throughput screening to identify DNA2 inhibitors.
• Mutagenesis and biochemical analyses to define inhibitor binding and mechanism.
• In vivo studies assessing DNA2 inhibition effects on DNA replication and repair.

Main Results:

• Homozygous deletion of DNA2 sensitizes cells to ionizing radiation and camptothecin (CPT).
• 4-hydroxy-8-nitroquinoline-3-carboxylic acid (C5) identified as a selective DNA2 inhibitor.
• C5 inhibits DNA2's nuclease and helicase activities, affecting DNA repair pathways like resection and recombination.
• C5 potently inhibits restart of stalled replication forks and over-resection, particularly in cells with impaired replication fork protection (e.g., BRCA2-deficient).
• C5 sensitizes cells to CPT and shows synergy with PARP inhibitors.

Conclusions:

• Inhibiting DNA2 is a viable strategy to sensitize cancer cells to DNA-damaging agents.
• C5 is a potent DNA2 inhibitor with potential therapeutic applications in combination cancer therapy.
• C5's efficacy is pronounced in cancer cells with defects in replication fork protection mechanisms.