Regular Voluntary Running Inhibits Androgen-Independent Prostate Cancer Growth in Mice

Abstract

Benefits of regular physical exercise were demonstrated as preventive and coadjuvant nonpharmacological anticancer therapy. However, the role of exercise in modulating prostate cancer behavior has yet to be established. Prostate tumors were induced in C57BL/6 male mice (n = 28) by subcutaneous inoculation of a suspension of murine androgen-independent RM1 cells (1.5 × 105 cells/500 μL phosphate-buffered saline) in the dorsal region. Mice were randomly allocated into 2 study groups: sedentary tumor-induced (n = 14) and exercised tumor-induced (n = 14). Exercise consisted of voluntary running in wheeled cages. Mice (n = 7 per group) were sacrificed either 14 or 28days after cell inoculation to evaluate tumor weight and percentage of area occupied by immunohistochemistry stained cells for Ki-67 and TdT-mediated dUTP-biotin nick end labeling, used as surrogate markers of cell proliferation and apoptosis, respectively. Compared with sedentary tumor-induced mice, the tumors developed by exercised tumor-induced mice were significantly smaller at 14days (0.17 [0.12]g vs 0.48 [0.24]g, P < .05) and at 28days (0.92 [0.73]g vs 2.09 [1.31]g, P < .05), with smaller Ki-67 and greater TdT-mediated dUTP-biotin nick end-labeling stained areas (P < .05). These results suggest that regular voluntary running inhibits prostate cancer cell growth by reducing cell proliferation and enhancing apoptosis.