Int J Sports Med 2018; 39(12): 885-892
DOI: 10.1055/a-0660-0198
Physiology & Biochemistry
© Georg Thieme Verlag KG Stuttgart · New York

Exercise Training-induced Modulation in Microenvironment of Rat Mammary Neoplasms

Ana Cristina Corrêa Figueira
1   CIAFEL, Research Center in Physical Activity, Health and Leisure; Faculty of Sport, University of Porto, Porto, Portugal
2   Polytechnic Institute of Setúbal, Setúbal, Portugal, Department of Sciences and Technologies/Sport Sciences, Setúbal, Portugal
,
Mafalda Corrêa Figueira
3   Department of Internal Medicine, Setúbal Hospital Center
,
Carina Silva
1   CIAFEL, Research Center in Physical Activity, Health and Leisure; Faculty of Sport, University of Porto, Porto, Portugal
,
Ana Padrão
1   CIAFEL, Research Center in Physical Activity, Health and Leisure; Faculty of Sport, University of Porto, Porto, Portugal
4   QOPNA, Department of Chemistry, University of Aveiro, Aveiro, Portugal
,
Paula Alexandra Oliveira
5   CITAB, Department of Veterinary Sciences, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal
,
Rita Pinho Ferreira
4   QOPNA, Department of Chemistry, University of Aveiro, Aveiro, Portugal
,
Jose Alberto Duarte
1   CIAFEL, Research Center in Physical Activity, Health and Leisure; Faculty of Sport, University of Porto, Porto, Portugal
› Author Affiliations
Further Information

Publication History



accepted 08 July 2018

Publication Date:
10 August 2018 (online)

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Abstract

Despite the importance attributed to exercise training in the breast cancer (BC) continuum, the underlying mechanisms modulating tumor behavior are unknown. We evaluated the effects of long-term moderate-exercise in the development of mammary tumors, and studied the microenvironment of infiltrative lesions, the amount of connective tissue, and balance between cellular proliferation/death.

Fifty Sprague-Dawley rats, randomly assigned into four groups: two control groups (sedentary and exercised) and two models of BC groups (sedentary and exercised) induced by N-methyl-N-nitrosoureia (MNU), were sacrificed after 35 weeks of moderate-exercise, and all perceptible tumors were removed for histological and immunohistochemistry analysis.

The median number of infiltrative-lesions per animal was lower in the MNU exercised animals (p=0.02). More than one histological pattern was identified, and papillary carcinoma was the most frequent in both groups. Within infiltrative-lesions, the number of immunopositive cells per μm2 of Ki67 was lower in exercised animals (p=0.002). This presents increased cell death per μm2 (p=0.019). Tumors from sedentary animals had a higher expression of collagen deposition (p=0.027).

Long-term moderate-exercise has beneficial effects in tumor development with a diminished prevalence of malignancy. Within infiltrative-lesions, moderate-exercise improves the balance between cell-proliferation and cell-death with decreased connective tissue that suggests lower tumor aggressiveness.