Splicing factor deficits render hematopoietic stem and progenitor cells sensitive to STAT3 inhibition

Area of Science:

• Hematology
• Molecular Biology
• Cancer Research

Background:

• Hematopoietic stem and progenitor cells (HSPCs) are crucial for lifelong blood cell production.
• Mutations in splicing factors, particularly SF3B1, are early events in hematologic malignancies linked to HSPC dysfunction.
• The precise mechanisms by which splicing factor deficits impair HSPCs are not fully understood.

Purpose of the Study:

• To investigate the role of STAT3 activation in HSPC formation in the context of splicing factor mutations.
• To determine if STAT3 inhibition represents a therapeutic vulnerability in SF3B1-mutant HSPCs.
• To explore the mechanistic link between splicing defects and STAT3 signaling.

Main Methods:

• Utilized zebrafish models to study HSPC formation in sf3b1 homozygous mutants.
• Investigated the sensitivity of SF3B1 heterozygous HSPCs to STAT3 inhibition in zebrafish, mouse, and human cell lines.
• Analyzed the impact of STAT3 inhibition on splicing fidelity in SF3B1 mutant cells.
• Examined HSPCs with mutations in other splicing factors and those treated with splicing modulators.

Main Results:

• HSPC formation in sf3b1 homozygous mutant zebrafish depends on STAT3 activation.
• SF3B1 heterozygosity confers increased sensitivity to STAT3 inhibition across species (zebrafish, mouse, human HSPCs).
• HSPCs with mutations in other splicing factors or treated with splicing modulators also exhibit heightened sensitivity to STAT3 inhibition.
• STAT3 inhibition was shown to worsen aberrant splicing in SF3B1 mutant cells.

Conclusions:

• Splicing factor mutant HSPCs exhibit a conserved vulnerability to STAT3 inhibition.
• Targeting STAT3 may offer a selective therapeutic strategy for hematologic malignancies with splicing factor mutations.
• This study elucidates a critical link between splicing machinery defects and STAT3 signaling in HSPC biology and disease.