Exercise modality-specific acute myokine response and anti-cancer potential in breast cancer cell lines in vitro

Abstract Exercise-induced myokines mediate the systemic communication between muscle and tumor cells. However, how exercise-conditioned serum (ECS) affects different breast cancer (BC) subtypes remains largely unknown. This study investigated the intensity-dependent effects of an acute session of aerobic exercise on the myokine profile and the subsequent anti-cancer effect (ACE) of ECS on BC cell lines in vitro. In a crossover design, 18 premenopausal women completed three visits: a baseline measurement session followed by two 45-min continuous exercise treadmill protocols at 75% (CE75) and 45% (CE45) of VO 2 peak. Blood samples were collected 5 min before exercise, during exercise at 15, 30, and 45 (last minute of exercise) minutes. Six myokines (OSM, SPARC, IL-6, BDNF, FGF-21, decorin) were quantified using Miliplex Human Cytokine/Chemokine/Growth Factor Panel A, HCYTA-60K-06, and Decorin Duo Set ELISA kit. Several BC cell lines, including HER2-positive (SK-BR-3) and triple-negative (MDA-MB-231, HCC1937, HCC1143), were treated with 25% ECS for 72 h to assess cell viability using ATP-based luminescence assay CellTiter-Glo 2.0 (Promega) after CE75 and CE45. CE75 elicited a significantly greater increase in decorin ( p < 0.01) and SPARC ( p = 0.03) systemic levels, while OSM peaked at 30 min ( p = 0.042). The SK-BR-3 cell line reduced ATP-based viability after exposure to ECS at both intensities (CE45: p = 0.005; CE75: p = 0.002). In contrast, the aggressive MDA-MB-231 phenotype showed intensity-dependent inhibition, with a statistically significant difference between CE75 and CE45 at 45 min ( p = 0.043). Furthermore, strong positive correlations were found between IL-6, FGF-21, and OSM during both protocols. Notably, the strongest association was found between ΔOSM and ΔFGF-21 (CE75: p < 0.01, ρ = 0.80; CE45: p < 0.001, ρ = 0.92.). Moreover, ΔMDA-MB-231 ATP levels correlated with ΔFGF-21 ( p < 0.05, ρ = 0.67) at CE75. The effect of ECS depends on BC cell line subtype and exercise intensity, with SK-BR-3 being most susceptible and higher intensity being more effective. These preliminary in vitro findings indicate that both BC subtype and exercise intensity are relevant considerations for future work toward precision exercise prescription and require validation in BC patient cohorts.