Aerobic Fitness Levels in African American Men, Serum IGF-1, and Growth of Prostate Cancer Cells

Abstract

Prostate cancer affects blacks disproportionately and its evolution may be affected by a sedentary lifestyle. The growth of prostate tumors may be modulated by androgens and insulin-like growth factors. PURPOSE: To test the hypothesis that the serum of males having low aerobic capacity contains concentrations of substances which promote the growth of prostate cancer cells. METHODS: Subjects were healthy young adult African-American males. A sedentary low fitness group (N=8) and active high fitness group (N=9) were identified by a physical activity questionnaire and verified by measurement of peak oxygen uptake (VO2peak, [<38 vs· > 40 ml · kg−1· min−1]). Serum sample from each subject was incubated separately with cultures of androgen dependent LNCaP prostate cancer cells. The serum concentration of testosterone, insulin-like growth factor (IGF-1) and the relative cell growth were measured. REULTS: The significance of intergroup differences was evaluated by a two-tailed t-test at P<0.05. VO2peak was found to be greater and body mass index tended to be lower in the high fitness than in the low fitness group (P<0.05). Intergroup differences in age, height, resting heart rate, blood pressure, body weight and in peak heart rate were not significant (P>0.05). IGF-1 concentration was higher in the serum from low fitness group compared to that from the high fitness group. The relative growth of androgen dependent LNCaP prostate cancer cells was significantly higher when cultured in medium supplemented with serum from individuals in the low fitness group than cultures grown in medium supplemented with serum from individuals in high fitness group. There was no significant intergroup difference in serum testosterone level. CONCLUSION: It is concluded that a lower growth rate of prostate cancer cells may be associated with lower serum concentration of IGF-1 in physically active males with a higher aerobic capacity than in sedentary males with a lower aerobic capacity. These findings suggest that a regimen of physical activity with increases in aerobic capacity inhibits the growth of prostate cancer cells. It is concluded that a sedentary lifestyle may promote the growth of prostate cancer cells.