Targeted Vpr-derived peptides reach mitochondria to induce apoptosis of alphaVbeta3-expressing endothelial cells

Area of Science:

• Biochemistry
• Molecular Biology
• Oncology

Background:

• The HIV-1 Vpr protein induces apoptosis by permeabilizing mitochondrial membranes.
• This process involves interactions with VDAC and ANT proteins.

Purpose of the Study:

• To design and evaluate a novel peptide, TEAM-VP, for targeted cancer therapy.
• To investigate TEAM-VP's mechanism of action in inducing mitochondrial membrane permeabilization (MMP) and apoptosis in tumor endothelial cells.

Main Methods:

• Design of a chimeric peptide (TEAM-VP) combining a tumor-homing motif with a Vpr-derived MMP-inducing sequence.
• In vitro studies using isolated mitochondria to assess TEAM-VP's interaction with VDAC and ANT, and its effect on oxygen consumption and Bcl-2 resistance.
• Cell-based assays to evaluate TEAM-VP's cellular uptake, intracellular localization, and mitochondrial targeting in angiogenic endothelial cells.
• Analysis of mitochondrial function, including membrane potential dissipation, cytochrome c release, and induction of apoptosis.

Main Results:

• TEAM-VP effectively interacts with VDAC and ANT, reducing mitochondrial oxygen consumption and inducing MMP.
• The peptide selectively targets alpha(V)beta(3) integrins on angiogenic endothelial cells, internalizes, and localizes to mitochondria without lysosomal damage.
• TEAM-VP induces mitochondrial fission, dissipates the mitochondrial transmembrane potential (DeltaPsi(m)), triggers cytochrome c release, and promotes apoptosis in tumor endothelial cells.

Conclusions:

• TEAM-VP is the first virus-derived mitochondriotoxic peptide designed for selective tumor endothelial cell killing.
• This chimeric peptide demonstrates potential as a therapeutic agent targeting tumor neovasculature.