TR-57 Treatment of SUM159 Cells Induces Mitochondrial Dysfunction without Affecting Membrane Potential

Area of Science:

• Biochemistry
• Cell Biology
• Cancer Research

Background:

• Imipridones are a novel class of antitumor agents targeting ClpXP, a mitochondrial protease.
• Understanding the precise mechanism of imipridone action is crucial for developing effective cancer therapies.

Purpose of the Study:

• To investigate the molecular mechanisms underlying the action of imipridone derivative TR-57 in SUM159 human breast cancer cells.
• To elucidate the effects of TR-57 on mitochondrial function, oxidative phosphorylation, and ATP hydrolysis.

Main Methods:

• Treatment of SUM159 cells with TR-57.
• Analysis of mitochondrial morphology, mtDNA content, and protein expression of respiratory chain complexes and F_OF₁-ATPase.
• Assessment of mitochondrial membrane potential and ATP transfer proteins.

Main Results:

• TR-57 induced mitochondrial fragmentation, mtDNA degradation, and significant inhibition of Complexes I-IV, leading to complete oxidative phosphorylation blockade.
• F_OF₁-ATPase subunit content decreased, accompanied by the disappearance of its inhibitor ATPIF1.
• Despite respiratory chain inhibition, TR-57-treated cells maintained mitochondrial polarization, supported by F_OF₁-ATPase-mediated cytoplasmic ATP hydrolysis.

Conclusions:

• TR-57 effectively disrupts mitochondrial respiratory function in breast cancer cells.
• The F_OF₁-ATPase plays a critical role in maintaining mitochondrial integrity under TR-57 treatment through ATP hydrolysis.