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Adenine nucleotide translocator mediates the mitochondrial membrane permeabilization induced by lonidamine, arsenite
A S Belzacq1, C El Hamel, H L Vieira
1CNRS-UMR6022, Université de Technologie de Compiègne, BP 20529, F-60205 Compiègne, France.
Abstract:
An increasing number of experimental chemotherapeutic agents induce apoptosis by directly triggering mitochondrial membrane permeabilization (MMP). Here we examined MMP induced by lonidamine, arsenite, and the retinoid derivative CD437. Cells overexpressing the cytomegalovirus-encoded protein vMIA, a protein which interacts with the adenine nucleotide translocator, were strongly protected against the MMP-inducing and apoptogenic effects of lonidamine, arsenite, and CD437. In a cell-free system, lonidamine, arsenite, and CD437 induced the permeabilization of ANT proteoliposomes, yet had no effect on protein-free liposomes. The ANT-dependent membrane permeabilization was inhibited by the two ANT ligands ATP and ADP, as well as by recombinant Bcl-2 protein. Lonidamine, arsenite, and CD437, added to synthetic planar lipid bilayers containing ANT, elicited ANT channel activities with clearly distinct conductance levels of 20+/-7, 100+/-30, and 47+/-7 pS, respectively. Altering the ATP/ADP gradient built up on the inner mitochondrial membrane by inhibition of glycolysis and/or oxidative phosphorylation differentially modulated the cytocidal potential of lonidamine, arsenite, and CD437. Inhibition of F(0)F(1)ATPase without glycolysis inhibition sensitized to lonidamine-induced cell death. In contrast, only the combined inhibition of glycolysis plus F(0)F(1)ATPase sensitized to arsenite-induced cell death. No sensitization to cell death induction by CD437 was achieved by glucose depletion and/or oligomycin addition. These results indicate that ANT is a target of lonidamine, arsenite, and CD437 and unravel an unexpected heterogeneity in the mode of action of these three compounds.
Insights
Three chemotherapy agents trigger apoptosis by inducing mitochondrial membrane permeabilization (MMP). The adenine nucleotide translocator (ANT) is a key target, with distinct interactions for lonidamine, arsenite, and CD437, revealing varied mechanisms of cell death.
Area of Science:
- Biochemistry
- Cell Biology
- Pharmacology
Background:
- Many experimental chemotherapeutics induce apoptosis via mitochondrial membrane permeabilization (MMP).
- Understanding the precise molecular targets and mechanisms of these agents is crucial for developing effective cancer therapies.
Purpose of the Study:
- To investigate the role of the adenine nucleotide translocator (ANT) in MMP induced by lonidamine, arsenite, and CD437.
- To elucidate the distinct mechanisms by which these agents trigger apoptosis and identify potential therapeutic vulnerabilities.
Main Methods:
- Utilized cells overexpressing vMIA (an ANT-interacting protein) to assess protection against MMP.
- Performed cell-free assays using ANT proteoliposomes and synthetic lipid bilayers to study direct interactions.
- Manipulated mitochondrial bioenergetics by inhibiting glycolysis and F(0)F(1)ATPase to modulate drug sensitivity.
Main Results:
- vMIA overexpression conferred significant protection against lonidamine, arsenite, and CD437-induced apoptosis.
- Lonidamine, arsenite, and CD437 directly permeabilized ANT proteoliposomes in a ligand-dependent manner (ATP/ADP inhibition).
- These agents formed distinct ANT channels with varying conductance levels, and their cytotoxic effects were differentially modulated by bioenergetic status.
Conclusions:
- The adenine nucleotide translocator (ANT) is a direct molecular target for lonidamine, arsenite, and CD437.
- These compounds exhibit a heterogeneous mode of action, impacting ANT function and cellular apoptosis through distinct pathways.
- Targeting ANT and understanding cellular bioenergetics offers novel strategies for cancer chemotherapy.