Cell Reports (Jan 2023)

Oxidized mC modulates synthetic lethality to PARP inhibitors for the treatment of leukemia

  • John P. Brabson,
  • Tiffany Leesang,
  • Yoon Sing Yap,
  • Jingjing Wang,
  • Minh Q. Lam,
  • Byron Fang,
  • Igor Dolgalev,
  • Daniela A. Barbieri,
  • Victoria Strippoli,
  • Carolina P. Bañuelos,
  • Sofia Mohammad,
  • Peter Lyon,
  • Sana Chaudhry,
  • Dane Donich,
  • Anna Swirski,
  • Evan Roberts,
  • Ivelisse Diaz,
  • Daniel Karl,
  • Helena Gomes Dos Santos,
  • Ramin Shiekhattar,
  • Benjamin G. Neel,
  • Stephen D. Nimer,
  • Ramiro E. Verdun,
  • Daniel Bilbao,
  • Maria E. Figueroa,
  • Luisa Cimmino

Journal volume & issue
Vol. 42, no. 1
p. 112027

Abstract

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Summary: TET2 haploinsufficiency is a driving event in myeloid cancers and is associated with a worse prognosis in patients with acute myeloid leukemia (AML). Enhancing residual TET2 activity using vitamin C increases oxidized 5-methylcytosine (mC) formation and promotes active DNA demethylation via base excision repair (BER), which slows leukemia progression. We utilize genetic and compound library screening approaches to identify rational combination treatment strategies to improve use of vitamin C as an adjuvant therapy for AML. In addition to increasing the efficacy of several US Food and Drug Administration (FDA)-approved drugs, vitamin C treatment with poly-ADP-ribosyl polymerase inhibitors (PARPis) elicits a strong synergistic effect to block AML self-renewal in murine and human AML models. Vitamin-C-mediated TET activation combined with PARPis causes enrichment of chromatin-bound PARP1 at oxidized mCs and γH2AX accumulation during mid-S phase, leading to cell cycle stalling and differentiation. Given that most AML subtypes maintain residual TET2 expression, vitamin C could elicit broad efficacy as a PARPi therapeutic adjuvant.

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