Affiliations: Center for Agricultural Biomaterial, Seoul National
University, San 56-1, Shillim-dong, Kwanak-gu, Seoul 151-742, Korea | Department of Human Nutrition, University of Illinois,
Chicago, IL 61801, USA
Note: [] Address for correspondence: Phyllis E. Bowen, Department of
Human Nutrition, College of Applied Health Sciences, University of Illinois at
Chicago, 1919 W. Taylor, Chicago, IL 60612, USA. Tel.: +1 312 996 0410; Fax: +1
312 413 0319; E-mail: pbowen@uic.edu
Abstract: Animal and epidemiological studies point to a cancer
preventive/therapeutic role for tomato products and its antioxidant, lycopene.
It is hypothesized that lycopene will behave as an antioxidant at low
concentrations and as a prooxidant at high concentrations in LNCaP human
prostate cancer cell culture systems. We characterized the antioxidant, and
prooxidant effects of a hexane extract of tomato paste (TP) and water
solublized lycopene at different concentrations using a prostate cancer cell
line. Placebo (5% triglyceride, Roche Inc.) was used as a control.
After 6, 24 hr and 48 hr incubation, LNCaP cells were harvested and used for
each measurement. Cellular proliferation was determined using the MTT
colorimetric assay. Lycopene and TP hexane extract inhibited cell growth in a
dose-dependent (0.1–50 μM lycopene) manner and growth
inhibition was 55% and 35% at 1 μM lycopene and TP hexane
extract, respectively after 48 hr incubation. The levels of
8-hydroxydeoxyguanosine/deoxyguanosine (an oxidative DNA damage product) was
significantly increased starting at 5 μM lycopene from
both TP hexane extract and pure lycopene after 24 and 48 hr incubation with no
protection at the lower concentrations. Malondialdehyde formation (a lipid
peroxidation product measured by HPLC separation of the MDA-TBA adduct) was
significantly reduced at low concentrations (0.1–1 μM) of
lycopene in all treatments. Clinically relevant concentrations of lycopene and
the tomato fraction containing lycopene significantly reduced LNCaP cancer cell
survival which can only be partially explained by increased DNA damage at high
lycopene concentrations (> 5 μM). Low
concentrations of lycopene acted as a lipid antioxidant but did not protect
DNA.
Keywords: Tomato paste, lycopene, prostate cancer, DNA oxidation, lipid peroxidation
Journal: BioFactors, vol. 23, no. 2, pp. 97-105, 2005
