Impact of Optimized Ku–DNA Binding Inhibitors on the Cellular and In Vivo DNA Damage Response

Mendoza-Munoz, Pamela L.Deshwar Kushwaha, NarvaChauhan, DineshsinhaGacem, Karim Ben AliGarrett, Joy E.Dynlacht, Joseph R.Charbonnier, Jean-BaptisteGavande, Navnath S.Turchi, John J.2024-11-122024-11-122024-09-26Mendoza-Munoz PL, Kushwaha ND, Chauhan D, et al. Impact of Optimized Ku-DNA Binding Inhibitors on the Cellular and In Vivo DNA Damage Response. Cancers (Basel). 2024;16(19):3286. Published 2024 Sep 26. doi:10.3390/cancers16193286https://hdl.handle.net/1805/44493Background: DNA-dependent protein kinase (DNA-PK) is a validated cancer therapeutic target involved in DNA damage response (DDR) and non-homologous end-joining (NHEJ) repair of DNA double-strand breaks (DSBs). Ku serves as a sensor of DSBs by binding to DNA ends and activating DNA-PK. Inhibition of DNA-PK is a common strategy to block DSB repair and improve efficacy of ionizing radiation (IR) therapy and radiomimetic drug therapies. We have previously developed Ku-DNA binding inhibitors (Ku-DBis) that block in vitro and cellular NHEJ activity, abrogate DNA-PK autophosphorylation, and potentiate cellular sensitivity to IR. Results and Conclusions: Here we report the discovery of oxindole Ku-DBis with improved cellular uptake and retained potent Ku-inhibitory activity. Variable monotherapy activity was observed in a panel of non-small cell lung cancer (NSCLC) cell lines, with ATM-null cells being the most sensitive and showing synergy with IR. BRCA1-deficient cells were resistant to single-agent treatment and antagonistic when combined with DSB-generating therapies. In vivo studies in an NSCLC xenograft model demonstrated that the Ku-DBi treatment blocked IR-dependent DNA-PKcs autophosphorylation, modulated DDR, and reduced tumor cell proliferation. This represents the first in vivo demonstration of a Ku-targeted DNA-binding inhibitor impacting IR response and highlights the potential therapeutic utility of Ku-DBis for cancer treatment.en-USAttribution 4.0 InternationalDNA-PKNon-homologous end joiningDouble-strand break repairKu-DBisSmall-molecule inhibitorsNon-small cell lung cancerImpact of Optimized Ku–DNA Binding Inhibitors on the Cellular and In Vivo DNA Damage ResponseArticle