Diagnostic and Therapeutic Value of the Exercise-Induced Myokine Irisin in Cancer Biology: A Comprehensive Review.

Objectives: Cancer is a multifactorial disease determined by several factors. Metabolic disorders such as obesity and diabetes significantly contribute to cancer risk by promoting chronic inflammation, insulin resistance, and hormonal dysregulation. Obesity and hyperglycaemia elevate insulin-like growth factor-1 (IGF-1) levels, driving oncogenic pathways such as PI3K/Akt/mTOR, which promote tumour proliferation and survival. Furthermore, cancer cells undergo metabolic reprogramming, characterised by increased reliance on glycolysis (Warburg effect), facilitating tumour growth and therapy resistance. Hence, body weight reduction and glycaemic control may represent potential strategies for cancer prevention and treatment. Irisin, a myokine secreted by skeletal muscle, plays a critical role in cellular metabolism and energy homeostasis. Emerging evidence suggests that irisin may exert tumour-suppressive effects by modulating key metabolic and oncogenic pathways. Methods: A systematic literature search identified studies investigating irisin's effects in various cancer models. Results: In vitro, irisin exerts dose- and time-dependent anti-proliferative effects in a variety of cancer cell lines, primarily via PI3K/Akt/mTOR inhibition and AMPK activation, leading to cell cycle arrest and apoptosis. Additionally, irisin inhibits epithelial-mesenchymal transition, which suppresses cancer cell migration and invasion. However, conflicting findings, particularly in hepatocellular carcinoma, suggest tissue-specific responses. Similarly, clinical data regarding systemic and tumoural irisin levels remain inconsistent and appear to vary based on cancer type and stage. Conclusions: Irisin represents a promising therapeutic target due to its ability to modulate metabolic and oncogenic pathways. However, further research is needed to elucidate its clinical relevance and optimise its application as an adjunct to existing cancer therapies.