Moreover, OTK inhibitors or DPC-inducing drug etoposide enhanced the antileukemia effect of POLθ inhibitor in vitro and in vivo. Genetic and pharmacological targeting of POLθ polymerase and helicase activities revealed that both activities are promising targets in leukemia cells. The transforming activities of OTKs and other leukemia-inducing oncogenes, especially of those causing the inhibition of BRCA1/2-mediated homologous recombination with and without concomitant inhibition of DNA-PK–dependent nonhomologous end-joining, was abrogated in Polq−/− murine bone marrow cells. Overexpression of POLθ in OTK-positive cells resulted in the efficient repair of DPC-containing DNA double-strand breaks by POLθ-mediated end-joining.

To counteract this effect, OTKs enhanced the expression of DNA polymerase theta (POLθ) via ERK1/2 serine/threonine kinase-dependent inhibition of c-CBL E3 ligase-mediated ubiquitination of POLθ and its proteasomal degradation. We showed here that formaldehyde generated by serine/1-carbon cycle metabolism contributed to the accumulation of toxic DNA-protein crosslinks (DPCs) in leukemia cells, especially in driver clones harboring oncogenic tyrosine kinases (OTKs: FLT3(internal tandem duplication ), JAK2(V617F), BCR-ABL1). Leukemia cells accumulate DNA damage, but altered DNA repair mechanisms protect them from apoptosis. Gupta, Jean-Yves Masson, Tomasz Skorski DNA polymerase θ protects leukemia cells from metabolically induced DNA damage. Pomerantz, George Morton, Wayne Childers, Huaqing Zhao, Elisabeth M. Sykes, Katarzyna Piwocka, Emir Hadzijusufovic, Peter Valent, Richard T. Chitrala, Jessica Atkins, Malgorzata Drzewiecka, Wanjuan Feng, Joe Chan, Srinivas Chatla, Konstantin Golovine, Jaroslav Jelinek, Tomasz Sliwinski, Jayashri Ghosh, Ksenia Matlawska-Wasowska, Gurushankar Chandramouly, Reza Nejati, Mariusz Wasik, Stephen M.

Umeshkumar Vekariya, Monika Toma, Margaret Nieborowska-Skorska, Bac Viet Le, Marie-Christine Caron, Anna-Mariya Kukuyan, Katherine Sullivan-Reed, Paulina Podszywalow-Bartnicka, Kumaraswamy N.

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