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BRCA1 or CDK12 loss sensitizes cells to CHK1 inhibitors
Hana Paculová1, Juraj Kramara2, Šárka Šimečková3,4
11 Department of Chemistry and Toxicology, Veterinary Research Institute, Brno, Czech Republic.
Abstract:
A broad spectrum of tumors develop resistance to classic chemotherapy, necessitating the discovery of new therapies. One successful strategy exploits the synthetic lethality between poly(ADP-ribose) polymerase 1/2 proteins and DNA damage response genes, including BRCA1, a factor involved in homologous recombination-mediated DNA repair, and CDK12, a transcriptional kinase known to regulate the expression of DDR genes. CHK1 inhibitors have been shown to enhance the anti-cancer effect of DNA-damaging compounds. Since loss of BRCA1 increases replication stress and leads to DNA damage, we tested a hypothesis that CDK12- or BRCA1-depleted cells rely extensively on S-phase-related CHK1 functions for survival. The silencing of BRCA1 or CDK12 sensitized tumor cells to CHK1 inhibitors in vitro and in vivo. BRCA1 downregulation combined with CHK1 inhibition induced excessive amounts of DNA damage, resulting in an inability to complete the S-phase. Therefore, we suggest CHK1 inhibition as a strategy for targeting BRCA1- or CDK12-deficient tumors.
Insights
Tumor cells lacking BRCA1 or CDK12 are sensitive to CHK1 inhibitors. Combining CHK1 inhibition with BRCA1 loss causes DNA damage, preventing S-phase completion and offering a new cancer therapy strategy.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Tumor resistance to chemotherapy necessitates novel therapeutic strategies.
- Synthetic lethality approaches exploit vulnerabilities in cancer cells, such as those involving DNA damage response (DDR) genes like BRCA1 and CDK12.
- CHK1 inhibitors show promise in enhancing the efficacy of DNA-damaging agents.
Purpose of the Study:
- To investigate the hypothesis that tumor cells with deficiencies in BRCA1 or CDK12 are dependent on CHK1 for survival.
- To evaluate CHK1 inhibition as a potential therapeutic strategy for BRCA1- or CDK12-deficient cancers.
Main Methods:
- Utilized cell depletion techniques (e.g., silencing) to reduce BRCA1 or CDK12 expression in tumor cells.
- Assessed the sensitivity of these depleted cells to CHK1 inhibitors in both in vitro and in vivo models.
- Quantified DNA damage and S-phase progression following combined BRCA1 downregulation and CHK1 inhibition.
Main Results:
- BRCA1 or CDK12 depletion significantly sensitized tumor cells to CHK1 inhibitors.
- The combination of BRCA1 downregulation and CHK1 inhibition led to excessive DNA damage.
- This excessive DNA damage resulted in an inability of tumor cells to complete the S-phase of the cell cycle.
Conclusions:
- CHK1 inhibition is a viable therapeutic strategy for targeting tumors with BRCA1 or CDK12 deficiencies.
- Exploiting synthetic lethality between DDR gene defects and CHK1 inhibition offers a promising avenue for cancer treatment.