Document Type

Article

Publication Date

3-17-2026

Comments

This article is the author's final published version in Cell Reports Medicine, Volume 7, Issue 3, March 2026, Article Number 102687.

The published version is available at https://doi.org/10.1016/j.xcrm.2026.102687. Copyright © 2026 The Author(s).

Abstract

Myeloid malignancies carrying somatic DNMT3A mutations (DNMT3Amut) are refractory to standard therapy. DNMT3Amut leukemia cells accumulate toxic DNA double-strand breaks (DSBs) and stalled replication forks, rendering them dependent on DNA damage response (DDR). We report here that DNA polymerase theta (Polθ), a key element in DSB repair by end-joining (Polθ-mediated end-joining [TMEJ]) and in fork restarting, promotes survival and proliferation of DNMT3Amut leukemia cells. Polθ is overexpressed in DNMT3Amut leukemia cells due to abrogation of PARP1 PARylation-dependent UBE2O E3 ligase-mediated ubiquitination and proteasomal degradation of Polθ. In addition, PARP1-mediated recruitment of the SMARCAD1-MSH2/MSH3 repressive complex to DSBs is diminished in DNMT3Amut leukemia cells, which facilitates association of Polθ with DNA damage. Polθ inhibitors enhance the anti-leukemic effects of standard drugs such as FLT3 kinase inhibitor quizartinib, cytarabine ± doxorubicin, and etoposide in vitro and in mice with DNMT3Amut leukemia. Altogether, Polθ is an attractive target in DNMT3Amut hematological malignancies.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

PubMed ID

41850232

Language

English

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