Cancer-cell-secreted miR-122 suppresses O-GlcNAcylation to promote skeletal muscle proteolysis

Area of Science:

• Molecular Biology
• Cancer Research
• Muscle Physiology

Background:

• Skeletal muscle mass and strength decline in advanced cancers, impacting prognosis.
• Cancer-associated muscle dysregulation is a significant clinical challenge.

Purpose of the Study:

• To elucidate the molecular mechanisms by which cancer suppresses muscle O-linked N-acetylglucosamine (O-GlcNAc) modification.
• To investigate the role of miR-122 and O-GlcNAc transferase (OGT) in cancer-induced muscle wasting.

Main Methods:

• Analysis of O-GlcNAc protein modification in muscle.
• Investigating the role of extracellular vesicles and miR-122.
• Studying OGT targeting and its downstream effects on RYR1 ubiquitination and degradation.
• Examining the influence of hypoxia, lactate, and exercise on O-GlcNAc levels.

Main Results:

• Breast cancer suppresses muscle O-GlcNAc via miR-122 targeting OGT.
• Reduced O-GlcNAc increases RYR1 abundance, leading to elevated cytosolic Ca2+ and calpain activation.
• Cancer-induced muscle O-GlcNAc suppression results in myofibrillar destruction, reduced mass, and impaired contractility in mice.
• Hypoxia and lactate regulate OGT, while exercise elevates O-GlcNAc.

Conclusions:

• O-GlcNAcylation is crucial for maintaining muscle protein homeostasis and contractility.
• Cancer-associated muscle dysregulation involves suppressed O-GlcNAc leading to RYR1-mediated muscle destruction.
• This study reveals a novel mechanism linking cancer, O-GlcNAc metabolism, and muscle wasting.