T-ALL leukemia stem cell 'stemness' is epigenetically controlled by the master regulator SPI1

Area of Science:

• Hematology
• Molecular Biology
• Cancer Research

Background:

• Leukemia stem cells (LSCs) drive leukemia but their key determinants remain poorly understood.
• Identifying LSC-specific regulators is crucial for developing targeted therapies.

Purpose of the Study:

• To identify the key molecular determinants of LSC stemness in a T-ALL model.
• To elucidate the regulatory mechanisms maintaining LSC properties.

Main Methods:

• Single-cell RNA-seq analysis was employed to identify key regulators in LSCs.
• Genetic and pharmacological perturbations were used to assess the role of identified regulators.

Main Results:

• SPI1 was identified as a master regulator of LSC-specific gene expression and activity.
• A β-catenin-SPI1-HAVCR2 regulatory circuit maintains LSC stemness, independent of the initial driver mutation.
• Disrupting this circuit prevented LSC formation and eliminated existing LSCs.
• SPI1 silencing via DNA methylation reduces LSC stemness, but can be reversed by 5-AZ treatment.

Conclusions:

• SPI1 is a critical determinant of LSC stemness in T-ALL.
• The identified regulatory circuit presents a potential therapeutic target for leukemia.
• Similar mechanisms may be relevant in human T-ALL, suggesting broad applicability.