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Updated: Jul 25, 2025

Dual CRISPR-Interference Strategy for Targeting Synthetic Lethal Interactions Between Non-Coding RNAs in Cancer Cells
Published on: May 30, 2025
Simultaneous Targeting of DNA Polymerase Theta and PARP1 or RAD52 Triggers Dual Synthetic Lethality in Homologous
Katherine Sullivan-Reed1, Monika M Toma1, Malgorzata Drzewiecka1,2
1Fels Cancer Institute for Personalized Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania.
Abstract:
DNA polymerase theta (Polθ, encoded by POLQ gene) plays an essential role in Polθ-mediated end-joining (TMEJ) of DNA double-strand breaks (DSB). Inhibition of Polθ is synthetic lethal in homologous recombination (HR)-deficient tumor cells. However, DSBs can be also repaired by PARP1 and RAD52-mediated mechanisms. Because leukemia cells accumulate spontaneous DSBs, we tested if simultaneous targeting of Polθ and PARP1 or RAD52 enhance the synthetic lethal effect in HR-deficient leukemia cells. Transformation potential of the oncogenes inducing BRCA1/2-deficiency (BCR-ABL1 and AML1-ETO) was severely limited in Polq-/-;Parp1-/- and Polq-/-;Rad52-/- cells when compared with single knockouts, which was associated with accumulation of DSBs. Small-molecule inhibitor of Polθ (Polθi) when combined with PARP or RAD52 inhibitors (PARPi, RAD52i) caused accumulation of DSBs and exerted increased effect against HR-deficient leukemia and myeloproliferative neoplasm cells.
Implications:
In conclusion, we show that PARPi or RAD52i might improve therapeutic effect of Polθi against HR-deficient leukemias.
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