Intratumoral Effects of Continuous Endurance Training and High Intensity Interval Training on Genes Expression of miR-21 and bcl-2 in Breast Cancer Bearing Female mice

Apoptosis and tumor growth are inhibited by intratumoral miR-21 via upregulation of bcl-2. Hence, the aim of the present study was determine the effects of continuous endurance training (ET) and high intensity interval training (HIIT) on intratumoral miR-21 and bcl-2 of breast cancer bearing female mice.
Eighteen female BALB/c mice after inducing breast cancer through MC4-L2 cell lines injection were randomly divided into three groups (n=6) including control, continuous endurance training (ET) and high intensity interval training (HIIT). Then, both experimental groups including ET (75 min/day, constant running speed corresponding to 60–65%) and HIIT (six intervals for 3 min and 20 seconds, 85-90% V̇O2 peak, 90 second of active rest at 30-35% V̇O2 peak separating intervals) performed exercise protocols at 15% inclination, five days a week for ten weeks. Tumor volume was measured and recorded by caliper every week. miR-21 and bcl-2 gene expression were determined by qReal-time PCR. Statistic data values also were measured by One-way ANOVA.
The results of the present study showed that miR-21 gene expression was significantly reduced in both experimental groups compared to control group (p≤0.001). While, bcl-2 gene expression had no significant change in comparison with control group (p≥0.05). There was also observed a significant reduction in tumor volume of two experimental groups in comparison with control group. It should be noted that tumor volume reduction in HIIT was larger than ET.
HIIT is possibly more effective than ET in attenuating cancer cells progression via its intratumoral effects.