NGO, T.H.*; BARNARD, R.J.; TYMCHUK, C.N.; COHEN, P.; ARONSON, W.J.: Low-fat Diet and Exercise Induced Apoptosis of LNCaP Cells via Modulation of the IGF Axis

To determine whether a low-fat, high-fiber diet and aerobic exercise (DE) intervention may prevent prostate cancer cell growth in vitro via its effects on the circulating IGF axis, fasting serum was obtained from 14 men before and after an 11-day DE program and from 8 men who had followed the DE program for a mean of 14.2 years. Serum IGF-I decreased by 60ng/mL while IGFBP-1 increased by 20ng/mL after 11 days of DE. In the 14.2-year DE group, IGF-I was 170ng/mL lower, while IGFBP-1 was 50ng/mL higher relative to pre-DE serum. Insulin decreased by 4.3 microU/mL after 11 days of DE and was 11.6 microU/mL lower in the 14.2 DE group, relative to pre-DE. LNCaP cell growth was reduced by 30% when incubated with media containing post 11-day serum and by 44% with media containing 14.2-year serum (relative to pre-DE serum). To assess the role of IGFBP-1, we added IGFBP-1 to pre-DE serum and demonstrated reduced LNCaP cell growth in a dose-dependent manner. Post-DE serum and pre-DE serum + IGFBP-1 showed increased apoptosis of LNCaP cells. These results demonstrate that DE induces changes in the circulating IGF axis in vivo that lead to reduced growth and apoptosis of LNCaP tumor cells in vitro.