Interconnecting molecular pathways in the pathogenesis and drug sensitivity of T-cell acute lymphoblastic leukemia

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• NOTCH1 signaling is crucial in T-cell acute lymphoblastic leukemia (T-ALL) pathogenesis.
• Understanding NOTCH1-mediated dysregulated pathways is vital for developing effective T-ALL therapies.
• Gamma-secretase inhibitors (GSIs) are a therapeutic approach for T-ALL, but resistance can develop.

Purpose of the Study:

• To identify dysregulated pathways in NOTCH1-mediated T-cell leukemogenesis.
• To discover small-molecule inhibitors that can synergize with or replace GSIs in T-ALL treatment.
• To compare gene expression profiles between a mouse model and human T-ALL.

Main Methods:

• Comparative gene expression profiling of a Notch1-induced mouse T-ALL model and human T-ALL.
• Gene set enrichment analysis and connectivity map algorithm for inhibitor prediction.
• In vitro testing of predicted small-molecule inhibitors, including heat-shock protein 90 inhibitors, in T-ALL cell lines.

Main Results:

• NOTCH1-mediated gene expression patterns in human and mouse T-ALL were highly similar.
• Early events involved MYC regulation and activation of NF-kappaB and PI3K/AKT pathways.
• Later events included down-regulation of tumor suppressors and cell cycle regulators.
• Predicted inhibitors, including HSP90, HDAC, PI3K/AKT, and proteasome inhibitors, could reverse NOTCH1-induced gene expression changes.
• HDAC, PI3K, and proteasome inhibitors synergized with GSI in sensitive T-ALL cells.
• Alvespimycin (HSP90 inhibitor) inhibited both GSI-sensitive and -resistant T-ALL cell growth.

Conclusions:

• NOTCH1 signaling drives distinct molecular pathways during leukemogenesis.
• Targeting HSP90 with inhibitors like alvespimycin is a promising strategy for T-ALL, including GSI-resistant cases.
• Combined inhibition of NOTCH1 signaling pathways may overcome therapeutic resistance in T-ALL.