Nonsense-Mediated RNA Decay Is a Targetable Vulnerability in Splicing Factor Mutant Myeloid Neoplasms by Enhancing...

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Mutant spliceosome proteins in myeloid neoplasms cause aberrant RNA splicing, producing nonsense transcripts.
• The nonsense-mediated RNA decay (NMD) pathway degrades these nonsense transcripts.
• In vitro studies show NMD inhibition preferentially kills cells with spliceosome mutations.

Purpose of the Study:

• To provide in vivo evidence that NMD is a therapeutic vulnerability in splicing factor mutant myeloid neoplasms.
• To investigate the effects of SMG1 kinase inhibition (SMG1i) on these cells in vivo.

Main Methods:

• Utilized a SMG1 kinase inhibitor (SMG1i) in mouse acute myeloid leukemia and human K562 cell line models.
• Assessed cellular sensitivity to SMG1i in wild-type versus spliceosome mutant cells.
• Measured R-loop levels, DNA damage, and NMD transcript isoforms following SMG1i treatment.
• Investigated the role of R-loops and DNA repair genes (ATR, RAD51) in treatment response.

Main Results:

• Spliceosome mutant cells showed increased sensitivity to in vivo SMG1i compared to wild-type cells.
• SMG1i disrupted NMD, increasing R-loop accumulation and DNA damage, particularly in mutant cells.
• Degrading R-loops rescued mutant cells from SMG1i-induced death.
• SMG1i increased NMD transcript isoforms enriched for DNA repair genes; co-inhibition of ATR or RAD51 enhanced cell death.

Conclusions:

• In vivo inhibition of NMD via SMG1 kinase is a viable therapeutic strategy for myeloid neoplasms with aberrant splicing.
• R-loop accumulation and DNA damage are key mechanisms mediating the anti-leukemia effects of NMD inhibition.
• Combined targeting of NMD and DNA repair pathways presents a promising approach for treating these malignancies.