Effect Of Exercise On Anti-tumor Efficacy Of Nanoparticles Delivery System For Breast Cancer

Prevention and treatment of malignant breast cancer, which is prevalent among younger women, have become an issue of growing concern in both research and clinical practice. With more understanding in pathologic features and biological characteristics of breast cancer and advances in the state-of-art techniques for early diagnoses and adjuvant therapy, new solutions for breast cancer focus more on multidisciplinary approach and combined therapy. During recent years, researchers at home and abroad have been investigating the effects of exercise on breast cancer patients undergoing operative, radio/chemo, and endocrine therapy. Encouraging evidence showed that aerobic exercise can strengthen both physical and psychological functions, fight fatigue, and improve overall quality of life for breast cancer patients. In this article, experimental evidences and reviews of exercise and breast cancer were gathered, and on that basis, all the benefits of aerobic exercise on breast cancer were summarized and possible mechanisms were analyzed. To investigate and prove the benefits and mechanism of exercise on breast cancer, an animal model with human breast cancer cell was set up, and treatment for the animal model included both tumor-targeting nanoparticles and exercise. The experimental results suggested a positive effect of exercise as an adjunctive therapy and partly proved some mechanisms.Methods: In the experimental part, the animal model of nude mice implanted with Bcap-37 human breast cells was established. Combined therapy included administration of tumor-targeting nanoparticles and 30min wheel running of low intensity. Targeting nanoparticles were prepared with mitoxantone encapsulated in a macromolecular polymer PLA-PLL-RGD. Tumor growth and progression were observed and the effect of 30min wheel running on anti-tumor efficacy of mitoxantone-loaded PLL-PLA-RGD nanoparticles was analyzed with gathered statistics and blood routine results. Results: Compared with the control group, average tumor volume of the combined therapy group was remarkably smaller (p=0.007), the administration-only group reached significance (p=0.048) and the exercise-only group didn't reach significance (p=0.369) statistically. The experimental results showed that the combined therapy of administration of tumor-targeting nanoparticles and 30min wheel running remarkably inhibits the growth of breast malignant tumor. The blood routine test showed significant decrease in different parameters of the administration-only group, such as RBC and HGB, while no significance occurred in the combined group, indicating the effect of exercise as an adjunctive therapy on inhibiting side-effects of the tumor-targeting nanoparticles.Conclusion: Our conclusion is that 30min wheel running can enhance the anti-tumor efficacy of mitoxantone-loaded PLA-PLL-RGD nanoparticles and is a positive contributor to rehabilitation of breast cancer.With multidisciplinary knowledge and approach, we investigated the effect of low-intensive aerobic exercise as an adjunctive therapy for breast cancer patients. On the basis of reviews and clinical results of the benefits of exercise in improving quality of life and promoting breast cancer rehabilitation, we explained some mechanisms through animal models of breast cancer, in the hope of promoting further research in the field of exercise and breast cancer rehabilitation.