Discovery and development of novel DNA-PK inhibitors by targeting the unique Ku-DNA interaction
Navnath S Gavande1,2, Pamela S VanderVere-Carozza1, Katherine S Pawelczak3
1Department of Medicine, Indiana University School of Medicine, Indianapolis IN 46202, USA.
Abstract:
DNA-dependent protein kinase (DNA-PK) plays a critical role in the non-homologous end joining (NHEJ) repair pathway and the DNA damage response (DDR). DNA-PK has therefore been pursued for the development of anti-cancer therapeutics in combination with ionizing radiation (IR). We report the discovery of a new class of DNA-PK inhibitors that act via a novel mechanism of action, inhibition of the Ku-DNA interaction. We have developed a series of highly potent and specific Ku-DNA binding inhibitors (Ku-DBi's) that block the Ku-DNA interaction and inhibit DNA-PK kinase activity. Ku-DBi's directly interact with the Ku and inhibit in vitro NHEJ, cellular NHEJ, and potentiate the cellular activity of radiomimetic agents and IR. Analysis of Ku-null cells demonstrates that Ku-DBi's cellular activity is a direct result of Ku inhibition, as Ku-null cells are insensitive to Ku-DBi's. The utility of Ku-DBi's was also revealed in a CRISPR gene-editing model where we demonstrate that the efficiency of gene insertion events was increased in cells pre-treated with Ku-DBi's, consistent with inhibition of NHEJ and activation of homologous recombination to facilitate gene insertion. These data demonstrate the discovery and application of new series of compounds that modulate DNA repair pathways via a unique mechanism of action.
Insights
Researchers discovered new DNA-PK inhibitors that block Ku-DNA interactions, offering a novel approach to cancer therapy. These compounds enhance radiation and radiomimetic drug effectiveness by modulating DNA repair pathways.
Area of Science:
- Molecular Biology
- Cancer Therapeutics
- DNA Repair Mechanisms
Background:
- DNA-dependent protein kinase (DNA-PK) is crucial for non-homologous end joining (NHEJ) and DNA damage response (DDR).
- DNA-PK inhibitors are explored as anti-cancer agents, often combined with ionizing radiation (IR).
- Targeting the Ku-DNA interaction represents a novel strategy for modulating DNA-PK activity.
Purpose of the Study:
- To discover and characterize a new class of DNA-PK inhibitors.
- To investigate a novel mechanism of action involving the inhibition of Ku-DNA interaction.
- To evaluate the therapeutic potential of these inhibitors in cancer treatment and gene editing.
Main Methods:
- Development of potent and specific Ku-DNA binding inhibitors (Ku-DBi's).
- In vitro and cellular assays to assess NHEJ inhibition and DNA-PK kinase activity.
- Studies using Ku-null cells and CRISPR gene-editing models to validate mechanism and utility.
Main Results:
- Ku-DBi's effectively block Ku-DNA interaction, inhibiting DNA-PK kinase activity.
- These inhibitors reduce both in vitro and cellular NHEJ, potentiating IR and radiomimetic agent effects.
- Ku-DBi's enhance gene insertion efficiency in CRISPR models by promoting homologous recombination.
Conclusions:
- A new class of Ku-DNA binding inhibitors (Ku-DBi's) has been discovered.
- These compounds represent a novel therapeutic strategy by targeting the Ku-DNA interaction to modulate DNA repair.
- Ku-DBi's show promise for enhancing cancer therapy and improving CRISPR gene-editing efficiency.
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