Activation of targetable inflammatory immune signaling is seen in myelodysplastic syndromes with SF3B1 mutations

Gaurav S. Choudhary, Andrea Pellagatti, Bogos Agianian, Molly A. Smith, Tushar D. Bhagat, Shanisha Gordon-Mitchell, Srabani Sahu, Sanjay Pandey, Nishi Shah, Srinivas Aluri, Ritesh Aggarwal, Sarah Aminov, Leya Schwartz, Violetta Steeples, Robert N. Booher, Murali Ramachandra, Maria Samson, Milagros Carbajal, Kith Pradhan, Teresa V. BowmanManoj M. Pillai, Britta Will, Amittha Wickrema, Aditi Shastri, Robert K. Bradley, Robert E. Martell, Ulrich G. Steidl, Evripidis Gavathiotis, Jacqueline Boultwood, Daniel T. Starczynowski, Amit Verma

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Background: Mutations in the SF3B1 splicing factor are commonly seen in myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML), yet the specific oncogenic pathways activated by mis-splicing have not been fully elucidated. Inflammatory immune pathways have been shown to play roles in the pathogenesis of MDS, though the exact mechanisms of their activation in splicing mutant cases are not well understood. Methods: RNA-seq data from SF3B1 mutant samples was analyzed and functional roles of interleukin-1 receptor-associated kinase 4 (IRAK4) isoforms were determined. Efficacy of IRAK4 inhibition was evaluated in preclinical models of MDS/AML. Results: RNA-seq splicing analysis of SF3B1 mutant MDS samples revealed retention of full-length exon 6 of IRAK4, a critical downstream mediator that links the Myddosome to inflammatory NF-kB activation. Exon 6 retention leads to a longer isoform, encoding a protein (IRAK4-long) that contains the entire death domain and kinase domain, leading to maximal activation of NF-kB. Cells with wild-type SF3B1 contain smaller IRAK4 isoforms that are targeted for proteasomal degradation. Expression of IRAK4-long in SF3B1 mutant cells induces TRAF6 activation leading to K63-linked ubiquitination of CDK2, associated with a block in hematopoietic differentiation. Inhibition of IRAK4 with CA-4948, leads to reduction in NF-kB activation, inflammatory cytokine production, enhanced myeloid differentiation in vitro and reduced leukemic growth in xenograft models. Conclusions: SF3B1 mutation leads to expression of a therapeutically targetable, longer, oncogenic IRAK4 isoform in AML/MDS models.

Original languageEnglish (US)
Article numbere78136
JournaleLife
Volume11
DOIs
StatePublished - 2022

ASJC Scopus subject areas

  • Neuroscience(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)

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