High-throughput screening in niche-based assay identifies compounds to target preleukemic stem cells

Area of Science:

• Oncology
• Hematology
• Stem Cell Biology

Background:

• Current T cell acute lymphoblastic leukemia (T-ALL) therapies reduce tumor burden but relapse is common due to persistent preleukemic stem cells (pre-LSCs).
• Pre-LSCs exhibit lower proliferation than leukemic blasts, contributing to their resistance to conventional chemotherapy.
• Targeting pre-LSCs, which are dependent on their microenvironment, is crucial for improving T-ALL treatment outcomes.

Purpose of the Study:

• To develop a high-throughput screening method for identifying compounds that specifically target pre-LSCs.
• To investigate the efficacy of identified compounds against pre-LSCs maintained in a supportive niche environment.
• To understand the mechanisms by which effective compounds disrupt pre-LSC survival and self-renewal.

Main Methods:

• Engineered stromal cells to create a niche-like environment with optimal NOTCH1 activation for maintaining primary pre-LSCs.
• Developed a multiparametric readout assay to monitor pre-LSCs induced by SCL/TAL1 and LMO1 oncogenes.
• Screened a targeted compound library, including the estrogen derivative 2-methoxyestradiol (2-ME2).

Main Results:

• 2-methoxyestradiol (2-ME2) demonstrated efficacy in disrupting both cell-autonomous and non-cell-autonomous pathways crucial for pre-LSC survival.
• 2-ME2 abrogated pre-LSC viability and self-renewal in vivo by inhibiting MYC translation (a NOTCH1 effector) and SCL/TAL1 activity.
• Normal hematopoietic stem/progenitor cells remained functional, indicating specificity of 2-ME2's action.

Conclusions:

• Recapitulating tissue-like properties in high-throughput screening is a promising approach for discovering novel cancer therapeutics.
• 2-ME2 represents a potential therapeutic agent for T-ALL by targeting resistant pre-LSCs.
• This study highlights the importance of targeting the pre-LSC population for achieving durable remission in T-ALL.