Voltage-dependent anion channel 1-based peptides interact with hexokinase to prevent its anti-apoptotic activity

Area of Science:

• Mitochondrial biology
• Cancer cell survival mechanisms
• Apoptosis regulation

Background:

• Hexokinase isoforms (HK-I, HK-II) bind to the voltage-dependent anion channel (VDAC) on the outer mitochondrial membrane in brain and tumor cells.
• This interaction is crucial for the anti-apoptotic function of HK-I and HK-II.
• Specific VDAC domains involved in this interaction have been identified.

Purpose of the Study:

• To investigate the potential of VDAC1-based peptides to interfere with the HK-I/HK-II and VDAC interaction.
• To determine if such peptides can disrupt mitochondrial binding of HK and inhibit its anti-apoptotic effects.
• To explore the therapeutic potential of VDAC1-based peptides in cancer treatment.

Main Methods:

• Synthesis of VDAC1 N-terminal region peptides.
• Real-time surface plasmon resonance to assess peptide binding to immobilized HK-I.
• Experiments using isolated brain and tumor mitochondria to evaluate peptide-induced detachment of bound HK.
• Cell-based assays to assess the effect of peptide expression on staurosporine-induced cytochrome c release and cell death.
• Use of cell-penetrating peptides fused to VDAC1 peptides for intracellular delivery.

Main Results:

• Synthetic VDAC1 peptides specifically bound to HK-I in a concentration- and time-dependent manner.
• These peptides successfully detached HK from both brain and tumor-derived mitochondria.
• Expression of VDAC1 peptides in cells prevented HK-mediated protection against apoptosis.
• A cell-penetrating peptide fused to a VDAC1 peptide effectively entered cells and inhibited the anti-apoptotic effects of HK-I and HK-II.
• Both cell-expressed and exogenously added cell-penetrating peptides detached mitochondrial-bound HK-I.

Conclusions:

• HK-I and HK-II promote tumor cell survival by binding to VDAC1, inhibiting cytochrome c release and apoptosis.
• VDAC1-based peptides can effectively disrupt this interaction, detaching HK from mitochondria.
• VDAC1-based peptides hold promise for potentiating the efficacy of conventional chemotherapeutic agents by interfering with HK-mediated anti-apoptotic activity.