Elimusertib, a Novel ATR Inhibitor, Induces Anti-Tumor Effects through Replication Catastrophe in Breast Cancers
Purpose
Sustained proliferation and accelerated cell cycle progression in cancer cells inherently elevate levels of DNA damage, disrupting normal replication and transcription processes. Ataxia telangiectasia and Rad3-related (ATR) kinase plays a critical role in initiating the DNA damage response. Inhibition of ATR by agents such as elimusertib increases replication stress and induces DNA damage. This study aimed to investigate the anti-tumor effects of elimusertib and explore its mechanism of action, particularly in relation to replication stress in breast cancer cells.
Materials and Methods
The anti-tumor effects of elimusertib were evaluated in vitro using MTT assays and colony formation assays across various breast cancer cell lines. In vivo studies were conducted using breast cancer xenograft models and patient-derived xenograft models. Cell cycle progression was analyzed by flow cytometry, and the BrdU assay was utilized to identify actively replicating cells and assess progression through the S-phase. DNA damage, including single-stranded and double-stranded breaks, was quantified using alkaline and neutral comet assays, respectively.
Results
Elimusertib treatment delayed S-phase progression in MDA-MB-453 and MDA-MB-231 breast cancer cell lines and triggered caspase-7-dependent apoptosis. An increase in the sub-G1 population detected through flow cytometry, along with Annexin V staining, further confirmed the induction of apoptotic cell death. BrdU assays demonstrated elevated levels of single-stranded DNA in sensitive cells, indicating that aberrant replication in S-phase led to DNA damage and ultimately caused replication catastrophe. The anti-tumor effects observed in vitro were consistent with results obtained from in vivo xenograft and patient-derived xenograft models, supporting the efficacy of elimusertib.
Conclusion
Elimusertib (BAY-1895344) exerts anti-tumor effects in breast cancer cells characterized by high replication rates by inducing replication catastrophe. The drug is particularly effective against cells experiencing elevated replication stress. These findings support further investigation and development of elimusertib as a therapeutic strategy for cancers with high rates of DNA replication and associated stress.