eng Oriental Scientific Publishing Company Biomedical and Pharmacology Journal 0974-6242 2015-12-28 8 2 785 792 10.13005/bpj/827 1826 article Anoosheh Leila 1 Kordi Mohammad Reza 2 Gaeini Abbasali 2 Mahdian Reza 3 Mirakhori Zahra 1 Exercise Physiology Ph.D., Faculty of Physical Education and Sports Sciences, University of Tehran, Tehran, Iran Faculty of Physical Education and Sports Sciences, University of Tehran, Tehran, Iran Department, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran The purpose of the present research was to determine the effects of aerobic exercise on NF-kB, Lin28B, let-7a microRNA and IL-6 of tumor tissue in mice with breast cancer. 20 female BALB/c mice were injected with MC4-L2 estrogen-receptor-positive breast-cancer cells,  then divided into two groups of 10 mice each: tumor-exercise (TE) and tumor-control (TC). The TE group performed aerobic exercise five days per week for six weeks. Widths and lengths of the tumors were measured weekly using digital calipers. The mice were sacrificed 48 hours after the last exercise session. Expression of NF-kB, Lin28B and miRNA let-7a genes were quantified with Real time-PCR and IL-6 was measured by the ELISA test. Tumor volume, expression of NF-kB and Lin28B genes and IL-6 levels diminished significantly in the TE group compared with the TC group, but let-7a microRNA expression showed a significant increase in the TE group compared with the TC group (P<0.05). The results demonstrate that aerobic exercise can have an effective role in the diminution of IL-6, Lin28B and NF-kB, and the increase of microRNA let-7a and it seems that regular aerobic training may at least have a therapeutic role in estrogen-receptor-dependent breast cancers. However, more studies are needed. https://biomedpharmajournal.org/vol8no2/effects-of-exercise-training-on-development-of-breast-cancer-in-mice/ Estrogen-receptor-dependent breast cancer Aerobic training NF-kB  Lin28B  microRNA let-7a