Molecular pathways: exploiting tumor-specific molecular defects in DNA repair pathways for precision cancer therapy

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Cancer cells often possess disabling mutations in genome maintenance and DNA repair pathways.
• These DNA repair defects, absent in healthy tissues, create a mutator phenotype, accelerating cancer progression.
• Defects in homologous recombination-mediated DNA double-strand break (DSB) repair are common in cancer.

Purpose of the Study:

• To explore targeted therapeutic strategies for cancer cells with homologous recombination deficiencies.
• To understand the mechanisms by which inhibiting DNA repair pathways selectively targets cancer cells.

Main Methods:

• Focus on pharmacologically repressing Poly (ADP-ribose) polymerase 1 (PARP1) activity.
• Inhibition of DNA-dependent protein kinase, catalytic subunit (DNA-PKcs), a nonhomologous end joining kinase.
• Leveraging the differential DNA repair capacities between cancer cells and normal tissues.

Main Results:

• Homologous recombination-defective tumors are selectively targeted by PARP1 or DNA-PKcs inhibitors.
• Normal tissues can repair drug-induced genotoxic lesions via homologous recombination.
• Cancer cells with homologous recombination defects cannot repair these lesions, leading to apoptosis.

Conclusions:

• Targeting DNA repair pathways, specifically PARP1 and DNA-PKcs, offers a promising strategy for cancer therapy.
• Exploiting cancer-specific DNA repair deficiencies can lead to selective cancer cell eradication.
• This approach offers a therapeutic window by sparing normal tissues with intact repair mechanisms.