Relationship between aerobic capacity of African American males, serum concentration of insulin-like growth factor-1 and growth of prostate cancer cells

A85

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. This study tested the hypothesis that the serum of males having low aerobic capacity contains concentrations of substances which promote the growth of prostate cancer cells. Subjects were healthy young adult African-American males. A sedentary low fitness group (N=8) and an active high fitness group (N=9) were identified by questionnaire and verified by measurement of peak oxygen consumption (< 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 concentrations of testosterone, insulin-like growth factor-1 (IGF-1) and the relative cell growth were measured. The significance of intergroup differences was evaluated by a two-tailed t-test at p< 0.05. Peak oxygen consumption and power output were found to be greater and body mass index 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 and respiratory exchange ratio were not significant (p > 0.1). 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. It is concluded that a lower growth rate of prostate cancer cells may be associated with a lower serum concentration of IGF-1 in active males with a higher aerobic capacity than in sedentary males with a lower aerobic capacity. These findings suggest that a regimen of physical exercise which increases aerobic capacity inhibits the growth of prostate cancer cells. It is concluded that a sedentary lifestyle may promote the growth of prostate cancers.
 (Supported in part by grant 2 G12 RR003048 from the RCMI program, Division of Research Infrastructure, National Center for Research Resources, NIH and USMRMC grant DAMD17-03-1-0123)