Molecular mechanism for the selective impairment of cancer mitochondrial function by a mitochondrially targeted...

Area of Science:

• Biochemistry
• Cell Biology
• Mitochondrial Medicine

Background:

• Mitochondria are crucial for cellular energy production.
• Vitamin E derivatives are being investigated for therapeutic potential.
• Targeting tumor mitochondria offers a novel therapeutic strategy.

Purpose of the Study:

• To investigate the effects of vitamin E derivatives, specifically α-tocopheryl succinate (α-TOS), α-tocopheryl acetyl ether (α-TEA), and mitochondrially targeted vitamin E succinate (MitoVES), on mitochondrial energy functions.
• To compare the efficacy of these compounds in isolated mitochondria, sub-mitochondrial particles, and various cancer cell lines versus normal hepatocytes.

Main Methods:

• Isolated mitochondria, sub-mitochondrial particles (SMPs), and cell lines (AS-30D hepatoma, rodent and human carcinoma, rat hepatocytes) were used.
• Mitochondrial respiration, ATP hydrolysis, Ca(2+) uptake, and membrane potential (∆ψ(m)) were measured.
• The effects of α-TOS, α-TEA, and MitoVES at varying concentrations were analyzed.

Main Results:

• MitoVES at low doses (1-10μM) stimulated basal respiration and ATP hydrolysis but inhibited state 3 respiration and Ca(2+) uptake in isolated mitochondria by collapsing membrane potential.
• All three compounds inhibited uncoupled respiration and SMP basal respiration at higher concentrations, with efficacy MitoVES > α-TEA > α-TOS.
• At high doses (>10μM), respiratory complex II was identified as a sensitive target of MitoVES.
• MitoVES acted as an uncoupler at low doses, potently inducing O(2) uptake, ∆ψ(m) collapse, oxidative phosphorylation inhibition, and ATP depletion in cancer cells compared to normal hepatocytes.

Conclusions:

• MitoVES exhibits potent anti-cancer activity by targeting mitochondrial energy metabolism.
• Cancer cell mitochondria are preferential targets of MitoVES compared to normal rat hepatocytes.
• The findings highlight the potential clinical relevance of MitoVES in cancer therapy due to its selective action on tumor mitochondria.