Effect of diet and exercise on serum insulin, IGF-I, and IGFBP-1 levels and growth of LNCaP cells in vitro (United States).
OBJECTIVE
Accumulating evidence indicates that prostate cancer is associated with high levels of serum IGF-I. This study was conducted to determine whether a low-fat diet and exercise (DE) intervention may modulate the IGF axis and reduce prostate cancer cell growth in vitro.


METHODS
Fasting serum was obtained from 14 men (age 60 +/- 3 years) participating in an 11-day DE program and from eight similarly aged men who had followed the DE program for 14.2 +/- 1.7 years (long-term). Insulin, IGF-I, IGFBP-1, and IGFBP-3 were measured by ELISA, and serum was used to stimulate LNCaP cell growth in vitro.


RESULTS
Serum IGF-I levels decreased by 20% while IGFBP-1 increased by 53% after 11-day DE. In the long-term group, IGF-I was 55% lower, while IGFBP-1 was 150% higher relative to baseline. Serum insulin decreased by 25% after 11-day DE and was 68% lower in the long-term group, relative to baseline. No changes in serum IGFBP-3 were observed. Serum-stimulated LNCaP cell growth was reduced by 30% in post-11-day serum and by 44% in long-term serum relative to baseline. LNCaP cells incubated with post-DE serum showed increased apoptosis/ necrosis, compared to baseline.


CONCLUSIONS
A low-fat diet and exercise intervention induces in-vivo changes in the circulating IGF axis and is associated with reduced growth and enhanced apoptosis/necrosis of LNCaP tumor cells in vitro.
Ngo
Tung H
TH
Department of Physiological Science, University of California, Los Angeles, CA 90095, USA.
Barnard
R James
RJ
Tymchuk
Christopher N
CN
Cohen
Pinchas
P
Aronson
William J
WJ
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D017209:Apoptosis; D018752:Diet, Fat-Restricted; D004797:Enzyme-Linked Immunosorbent Assay; D015444:Exercise; D006801:Humans; D066298:In Vitro Techniques; D007328:Insulin / Q000097:blood*; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000473:pathology* / Q000517:prevention & control*; D014407:Tumor Cells, Cultured
D007328:Insulin; D018970:Insulin-Like Growth Factor Binding Protein 1; D007334:Insulin-Like Growth Factor I