Cells

Skeletal muscle is increasingly recognized as a dynamic endocrine and paracrine organ that communicates with distal tissues through a diverse secretome of peptides, proteins, metabolites, and extracellular vesicles (EVs), collectively referred to as myokines and exerkines. Beyond cataloging individual factors, emerging evidence suggests that muscle-derived signals can convey information through an integrated, context-dependent “endocrine code”—a pattern defined by secretion kinetics, co-released signal combinations, delivery modalities, and target-tissue receptor landscapes. This review synthesizes current evidence on (i) conceptual and experimental criteria for defining bona fide myokines, (ii) mechanisms governing myokine expression, processing, and release across exercise modes and physiological states, and (iii) major muscle–organ axes that connect physical activity to systemic metabolic homeostasis, immune remodeling, tissue regeneration, and neurocognitive adaptation. We further discuss non-protein mediators such as lactate, succinate, and β-aminoisobutyric acid, and highlight EVs as a multiplexed delivery modality whose interpretation requires stringent isolation, contamination controls, and functional validation. Finally, we evaluate translational opportunities—including biomarker panels, therapeutic targeting of the myostatin/activin, fibroblast growth factor 21 (FGF21), and growth differentiation factor 15 (GDF15) pathways, and precision exercise prescriptions informed by multi-omics and artificial intelligence—while emphasizing analytical standardization, causal validation, and transparent reporting as prerequisites for clinical impact.

Metabolic stress caused by lipid overload is a key driver of cellular dysfunction in aging and disease. Excess saturated fatty acids such as palmitate impair fatty acid oxidation (FAO), promote lipid accumulation, and increase reactive oxygen species (ROS), ultimately triggering premature senescence-like states. Senescence further amplifies vulnerability by worsening mitochondrial dysfunction, enhancing lipid imbalance, and sustaining pro-inflammatory signaling. Here, we investigated the role of the neuron-enriched RNA-binding protein HuD (ELAVL4) in protecting cells against lipotoxic stress. Using Neuro2a neuroblastoma cells, we found that HuD knockdown suppressed FAO, leading to increased lipid accumulation and elevated ROS following palmitate exposure. HuD-deficient cells also exhibited cytosolic mitochondrial DNA release, IRF phosphorylation, and upregulation of senescence markers. Mechanistically, RNA immunoprecipitation revealed that HuD binds directly to PPARα mRNA, sustaining its expression by competing with the PPARα-targeting microRNAs miR-9-5p and miR-22-3p. Loss of HuD reduced PPARα levels, thereby weakening the FAO capacity and sensitizing cells to palmitate-induced lipotoxic stress. These findings identify a previously unrecognized HuD–PPARα–FAO axis that restrains metabolic stress and senescence. By linking post-transcriptional regulation to lipid metabolism and inflammatory signaling, this work highlights stress-induced premature senescence as both an outcome and a propagator of metabolic dysfunction, providing insight into mechanisms of aging-related vulnerability.

Pancreatic cancer is a highly intractable malignancy that necessitates personalized treatment strategies. Conventional patient-derived models, such as three-dimensional organoids, are often limited by intellectual property constraints and high costs. In this study, we developed an affordable adherent culture system for patient-derived pancreatic cancer cells using a proprietary medium and laminin-coated dishes. Primary cultures were successfully established from 28 patients with pancreatic ductal adenocarcinoma, exceeding a 90% success rate. Validation of eight samples confirmed maintenance of epithelial cell adhesion molecule expression and preservation of oncogenic KRAS mutations. Transcriptomic profiling revealed consistent upregulation of a six-gene signature (FAP, IGFBP5, PRRX1, SPARC, WNT5A, and ADAMTS12), which is associated with malignancy. In vitro drug sensitivity assays revealed interpatient heterogeneity with preliminary clinical associations. In conclusion, this simplified platform provides high-purity cancer cells and serves as a functional precision medicine tool. Beyond conventional chemotherapy, this platform has the potential to support applications ranging from biomarker validation and exploratory preclinical testing of novel therapeutics, including immune checkpoint inhibitors and antibody–drug conjugates. This optimization can lead to personalized therapeutic strategies for pancreatic cancer.