Non-oxidized and oxidized flaxseed orbitides differently induce HepG2 cell apoptosis: involvement of cellular uptake...

Area of Science:

• Biochemistry
• Molecular Biology
• Cancer Research

Background:

• Flaxseed orbitides possess anti-cancer properties.
• Oxidation of methionine-containing flaxseed orbitides (e.g., [1-9-NαC]-linusorb B2) yields less effective sulfoxide and sulfone forms.
• The reduced efficacy of oxidized flaxseed orbitides remains unexplained.

Purpose of the Study:

• To investigate the reasons behind the differential anti-cancer efficacy of oxidized versus non-oxidized flaxseed orbitides.
• To elucidate the molecular mechanisms underlying the anti-cancer activity of flaxseed orbitides.

Main Methods:

• Comparative analysis of non-oxidized ([1-9-NαC]-linusorb B3 (CLA), [1-9-NαC]-linusorb B2 (CLB)) and oxidized (CLC, CLK) flaxseed orbitides.
• Assessment of pro-apoptotic protein levels (Bax/Bcl-2, CytoC, caspase-3, caspase-8).
• Measurement of cellular orbitide absorption and DR4 protein interaction using fluorescence quenching and molecular docking.

Main Results:

• Both oxidized and non-oxidized flaxseed orbitides upregulated pro-apoptotic proteins in a dose-dependent manner.
• Non-oxidized flaxseed orbitides demonstrated significantly higher anti-cancer efficacy than oxidized forms.
• Higher cellular uptake and enhanced binding to the DR4 death receptor were observed for non-oxidized orbitides.
• DR4 activation was crucial for non-oxidized orbitides' ability to induce caspase-3 expression.

Conclusions:

• Non-oxidized flaxseed orbitides are more potent anti-cancer agents than their oxidized counterparts.
• Enhanced cellular uptake and superior activation of the DR4-mediated death receptor pathway explain the increased efficacy of non-oxidized flaxseed orbitides.
• These findings highlight the importance of the oxidation state of flaxseed orbitides for their anti-cancer activity.