The Effect of 8 Weeks of Interval Aerobic Exercise before and after Induction of Breast Cancer on Serum Level of Irisin and Tumor Growth in Balb/c mice

Irisin is a myokine, can be used as a new indicator of relationship between exercise and reduction of incidence and progression of cancer. The aim of this study was to investigate the effect of 8 weeks of interval aerobic exercise before and after induction of breast cancer on serum level of irisin and tumor growth in Balb/c mice.
In this quasi-experimental study, 40 adult female Balb/c mice were randomly divided into four groups of control, tumor, exercise, and exercise with tumor. The main training with 70% and 50% of the maximum rate of oxygen consumption (VO2max) intensity was performed 4 weeks before and 4 weeks after tumor induction. Tumor and exercise with tumor groups were cancerous with murine breast tumors of adenocarcinoma through subcutaneous surgery. Tumor growth was measured weekly, and at the end of the study, tumors were surgically removed. Serum irisin was measured using enzyme-linked immuonosorbent assay (ELISA) method. Real-time polymerase chain reaction (Real-time PCR) was used to investigate the expression of vascular endothelial growth factor (VEGF) gene. Data were analyzed using Student’s t and Pearson correlation tests at the significance level of P Findings: There was a significant decrease in tumor growth rate in exercise group with tumor compared to tumor group. Serum levels of irisin increased significantly in exercise and exercise with tumor groups compared to control and tumor groups, respectively. The expression of vascular endothelial growth factor in exercise with tumor group showed a significant decrease compared to tumor group (P = 0.003). There was a significant correlation between irisin levels and tumor growth ratio in exercise with tumor group (P It seems that positive regular aerobic exercises can reduce the growth of breast cancer cells in Balb/c mice by increasing the irisin level and decreasing expression of vascular endothelial growth factor.