Targeting the PI5P4K Lipid Kinase Family in Cancer Using Covalent Inhibitors

Area of Science:

• Biochemistry
• Molecular Biology
• Cancer Research

Background:

• Phosphoinositide 5-phosphate 4-kinases (PI5P4Ks) are implicated in cancer cell proliferation.
• Targeting PI5P4Ks for cancer therapy is hindered by a lack of potent and specific small molecule inhibitors.
• Understanding PI5P4K's role in disease pathogenesis is crucial for developing new treatments.

Purpose of the Study:

• To discover and characterize a novel, potent, and specific inhibitor of PI5P4Ks.
• To investigate the therapeutic potential of PI5P4K inhibition in cancer, particularly leukemia.
• To elucidate the mechanism by which PI5P4K inhibition affects cellular processes like autophagy.

Main Methods:

• Discovery and chemical synthesis of THZ-P1-2, a pan-PI5P4K inhibitor.
• Biochemical assays to confirm target engagement and specificity across the kinome.
• Cell-based assays using AML/ALL cell lines to assess sensitivity and cellular effects.
• Analysis of autophagy markers, including TFEB nuclear localization and autophagosome clearance.

Main Results:

• THZ-P1-2 was identified as a covalent inhibitor targeting PI5P4Kα/β/γ.
• The inhibitor demonstrated potent on-target engagement with minimal off-target effects.
• AML/ALL cell lines exhibited sensitivity to THZ-P1-2, correlating with PI5P4K's role in leukemogenesis.
• THZ-P1-2 induced defects in autophagosome clearance and altered TFEB activity, mimicking genetic PI5P4K deletion.

Conclusions:

• PI5P4Ks are validated as tractable therapeutic targets for cancer and other diseases.
• THZ-P1-2 serves as a valuable chemical probe for further research into PI5P4K function.
• This study provides a foundation for drug discovery efforts targeting PI5P4Ks in cancer metabolism and autophagy-dependent disorders.