Malate-aspartate shuttle promotes l-lactate oxidation in mitochondria

Area of Science:

• Biochemistry
• Cancer Biology
• Cell Metabolism

Background:

• Cancer cells exhibit altered metabolism, including aerobic glycolysis (Warburg effect), to meet high energy demands for proliferation.
• Despite high glycolysis, cancer cell mitochondria often remain oxidative, suggesting a coordinated metabolic strategy.
• The Warburg effect's inefficiency for energy production implies alternative mechanisms are employed by cancer cells.

Purpose of the Study:

• To investigate the coordination between glycolysis and oxidative phosphorylation in colon cancer.
• To explore the role of mitochondria-associated malate-aspartate and lactate shuttles in coupling these metabolic pathways.
• To understand how cancer cells maintain redox homeostasis under high glycolytic conditions.

Main Methods:

• Investigated colon cancer cells.
• Focused on mitochondria-associated malate-aspartate and lactate shuttles.
• Analyzed the control of NAD+/NADH homeostasis and l-lactate oxidation.

Main Results:

• The malate-aspartate shuttle was shown to regulate NAD+/NADH balance.
• This regulation supports the activity of mitochondrial lactate dehydrogenase.
• Aerobic oxidation of glycolytic l-lactate within mitochondria was enabled.

Conclusions:

• The malate-aspartate shuttle is a key regulator coupling aerobic glycolysis and oxidative phosphorylation in colon cancer.
• Maintaining NAD+/NADH homeostasis is crucial for mitochondrial lactate oxidation.
• Accelerated oxidative phosphorylation, facilitated by glycolysis, supports cancer cell proliferation.