PIG7 promotes leukemia cell chemosensitivity via lysosomal membrane permeabilization

Area of Science:

• Cell Biology
• Molecular Oncology
• Biochemistry

Background:

• PIG7 (p53-inducible gene 7) is implicated in cellular stress responses.
• Previous studies showed PIG7 sensitizes leukemia cells to chemotherapy without inducing apoptosis or differentiation.
• The precise mechanism of PIG7-mediated sensitization remains unclear.

Purpose of the Study:

• To elucidate the molecular mechanisms by which PIG7 enhances chemotherapy sensitivity in acute leukemia.
• To investigate the role of lysosomal stability and cell death pathways in PIG7-induced sensitization.

Main Methods:

• Overexpression of PIG7 in leukemia cell lines.
• Assessment of lysosomal membrane permeabilization (LMP) and protease release.
• Measurement of reactive oxygen species (ROS) and mitochondrial membrane potential (ΔΨm).
• Analysis of autophagy and necroptosis markers.
• Evaluation of the role of intrinsic antagonism (protease inhibitors).

Main Results:

• Exogenous PIG7 expression decreased lysosomal stability, inducing LMP and release of cathepsins B, D, and L.
• PIG7 overexpression increased ROS and decreased mitochondrial membrane potential (ΔΨm).
• Autophagy and necroptosis markers were stimulated, but cell death was initially inhibited by protease inhibitors.
• Combined chemotherapy and PIG7 treatment overcame intrinsic antagonism, inducing cell death via both caspase-dependent and independent pathways.

Conclusions:

• PIG7 sensitizes leukemia cells to chemotherapy by compromising lysosomal integrity, leading to protease release and subsequent cell death.
• The PIG7-induced cell death pathway is complex, involving ROS, mitochondrial dysfunction, and interplay with autophagy and necroptosis.
• PIG7's effectiveness is greater in drug-resistant leukemia with low endogenous PIG7 expression, suggesting therapeutic potential.