RAD51 is a druggable target that sustains replication fork progression upon DNA replication stress

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Replication fork progression is vital for preventing genomic instability.
• RAD51, a homologous recombination protein, plays a significant role in S phase DNA replication.
• RAD51 is implicated in protecting nascent DNA and restarting stalled replication forks.

Purpose of the Study:

• To investigate the specific role of RAD51 during S phase using pharmacological inhibition.
• To compare the effects of RAD51 inhibition on replication fork progression in non-transformed versus cancer cells.

Main Methods:

• Pharmacological inhibition of RAD51 in various cellular models.
• Assessment of replication fork progression under normal and replication stress conditions.
• Analysis of DNA polymerase α association with chromatin and γH2Ax foci.

Main Results:

• RAD51 inhibition did not affect replication fork progression in non-transformed cells without stress.
• RAD51 became essential for replication fork progression in non-transformed cells under replication stress.
• RAD51 inhibition compromised fork progression during reinitiation and reduced replication fork speed in colorectal cancer cells.
• RAD51 inhibition led to reduced DNA polymerase α association with chromatin and increased γH2Ax foci in cancer cells.

Conclusions:

• RAD51 is critical for maintaining replication fork integrity and progression, particularly under replication stress.
• Colorectal cancer cells exhibit a higher dependence on RAD51 activity under basal conditions compared to non-transformed cells.
• Differential dependence on RAD51 offers a potential strategy for developing targeted cancer therapies.