Epigenetic regulator genes direct lineage switching in MLL/AF4 leukaemia

Ricky Tirtakusuma, Conny Bonifer, Anetta Ptasinska, Paulynn Suyin Chin, Pierre Cauchy, Peter Keane, Salam Assi, Sophie Kellaway, Maria Imperato, Peter Cockerill, Olaf Heidenreich*, Simon Bomken*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

Key Points
Myeloid relapse can originate from varying differentiation stages of MLL/AF4-positive ALL.

Dysregulation of epigenetic regulators underpins fundamental lineage reprogramming.

The fusion gene MLL/AF4 defines a high-risk subtype of pro-B acute lymphoblastic leukaemia. Relapse can be associated with a lineage switch from acute lymphoblastic to acute myeloid leukaemia resulting in poor clinical outcomes due to resistance towards chemo- and immuno-therapies. Here we show that the myeloid relapses share oncogene fusion breakpoints with their matched lymphoid presentations and can originate from varying differentiation stages from immature progenitors through to committed B-cell precursors. Lineage switching is linked to substantial changes in chromatin accessibility and rewiring of transcriptional programmes, including alternative splicing. These findings indicate that the execution and maintenance of lymphoid lineage differentiation is impaired. The relapsed myeloid phenotype is recurrently associated with the altered expression, splicing or mutation of chromatin modifiers, including CHD4 coding for the ATPase/helicase of the nucleosome remodelling and deacetylation complex, NuRD. Perturbation of CHD4 alone or in combination with other mutated epigenetic modifiers induces myeloid gene expression in MLL/AF4-positive cell models indicating that lineage switching in MLL/AF4 leukaemia is driven and maintained by disrupted epigenetic regulation.
Original languageEnglish
Article number2021015036
Number of pages40
JournalBlood
Early online date15 Jul 2022
DOIs
Publication statusE-pub ahead of print - 15 Jul 2022

Keywords

  • MLL/AF4
  • KMT2A/AFF1
  • acute lymphoblastic leukaemia
  • nucleosome 53 remodelling and deactylation complex (NuRD)
  • chromatin remodelling

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