Chemoproteomics-based kinome profiling and target deconvolution of clinical multi-kinase inhibitors in primary...

Area of Science:

• Oncology
• Molecular Biology
• Pharmacology

Background:

• Pharmacological induction of apoptosis is a key strategy for treating chronic lymphocytic leukemia (CLL).
• Identifying effective therapeutic agents targeting neoplastic B cells in CLL is crucial.

Purpose of the Study:

• To profile clinical multi-kinase inhibitors for their apoptosis-inducing efficacy in primary CLL cells.
• To identify the specific molecular targets of effective inhibitors within CLL cells.

Main Methods:

• Profiling of clinical multi-kinase inhibitors on primary CLL cells.
• Quantitative monitoring of kinase expression and inhibitor binding profiles using kinobeads proteomics.
• Analysis of drug effects on specific protein complexes, including the positive transcriptional elongation factor (p-TEFb).

Main Results:

• CDK inhibitors BMS-387032 and flavopiridol demonstrated significant apoptosis induction in CLL cells, unlike other kinase inhibitors.
• These CDK inhibitors primarily targeted CDK9, cyclin T1, AFF3/4, and MLLT1, components of the p-TEFb complex.
• Both drugs also bound to the basal transcription factor BTF2/TFIIH containing CDK7, albeit with lower potency.

Conclusions:

• Inhibitors targeting the p-TEFb complex show significant potential for treating chronic lymphocytic leukemia (CLL).
• The findings support the clinical development of p-TEFb inhibitors for CLL therapy.
• The mechanism of action differs from staurosporine and geldanamycin, highlighting specificity.