An Autophagy-Disrupting Small Molecule Promotes Cancer Cell Death via Caspase Activation

Area of Science:

• Cell Biology
• Molecular Biology
• Pharmacology

Background:

• Autophagy is a cellular process crucial for maintaining homeostasis, but its dysregulation is implicated in cancer.
• Targeting autophagy is a promising strategy for cancer therapy.
• Developing novel autophagy inhibitors is essential for cancer research.

Purpose of the Study:

• To identify and characterize a novel autophagy inhibitor.
• To elucidate the mechanism of action of the identified compound.
• To explore its potential in cancer cell death induction.

Main Methods:

• High-content screening of an imidazole library.
• Cell-based assays to assess autophagy inhibition and cell death.
• Analysis of lysosomal membrane permeabilization (LMP) and apoptosis induction.
• Western blotting to detect protein cleavage and activation (Bid, Bax, caspases).

Main Results:

• Autophazole (Atz) was identified as a novel autophagy inhibitor.
• Atz induced lysosomal membrane permeabilization (LMP), leading to nonfunctional autolysosomes.
• Atz promoted apoptosis through LMP-mediated release of cathepsins, Bid cleavage, Bax activation, and caspase cascade.
• Atz effectively induced cancer cell death.

Conclusions:

• Autophazole (Atz) is a potent inducer of cancer cell death via lysosomal membrane permeabilization and apoptosis.
• The mechanism involves cathepsin release, Bid cleavage, Bax activation, and caspase-dependent cell death.
• Atz serves as a valuable chemical probe for investigating autophagy and developing new cancer therapies.