Epimedin B ameliorates benzo[a]pyrene -induced C2C12 myotube atrophy through p53 signaling pathway

Benzo[a]pyrene (BAP) is an established environmental carcinogen implicated in skeletal muscle atrophy. Epimedin B (Epi B), a major flavonoid component of Epimedium, possesses anti-inflammatory, anti-osteoporotic, and neuroprotective properties. However, the molecular mechanism underlying its protection against BAP-induced myotube atrophy remains largely elusive.

Transcriptomic profiling of BAP-treated C2C12 mouse myoblasts and network pharmacology-based target prediction were integrated to identify the key pathways underlying the ameliorative effect of Epi B against BAP-induced myotube atrophy. An in vitro model of myotube atrophy was established by treating C2C12 mouse myoblasts with 5 μM BAP. Myotube morphology and viability were evaluated using CCK-8 assay, Giemsa staining, and Desmin immunofluorescence. Mechanistic alterations were assessed by qRT-PCR, Western blotting, and flow cytometry. p53 knockdown experiments were performed to verify the role of the p53 pathway.

Integrative analysis of transcriptomics and network pharmacology identified the p53 signaling pathway as a critical mediator of the protective effect of Epi B against BAP-induced myotube atrophy. BAP triggered oxidative stress, mitochondrial dysfunction, and suppression of myotube differentiation, accompanied by p53-mediated upregulation of p21 and BAX/BCL-2 ratio. Administration of 10 μM Epi B reversed these abnormalities by suppressing p53 activation, thereby reducing reactive oxygen species (ROS) production and apoptosis, restoring mitochondrial membrane potential, and ameliorating myotube atrophy. These findings were further corroborated by p53 knockdown experiments, which attenuated the protective effects of Epi B.

These findings suggest that Epi B ameliorates BAP-induced myotube atrophy in C2C12 cells partly through p53 signaling pathway. This study provides novel mechanistic insights into BAP-induced sarcopenia and identifies potential therapeutic targets for intervention by Epi B.