Tomato lycopene extract supplementation decreases insulin-like growth factor-I levels in colon cancer patients.

Epidemiological studies have shown that high serum levels of insulin-like growth factor-I are associated with an increased risk of colon and other types of cancer. The aim of this study was to determine whether short intervention with dietary tomato lycopene extract will affect serum levels of the insulin-like growth factor system components in colon cancer patients. The study had a double-blind, randomized, placebo-controlled design. Colon cancer patients (n=56), candidates for colectomy, were recruited from the local community a few days to a few weeks before surgery. Personal and medical data were recorded. Plasma concentrations of insulin-like growth factor-I and II and insulin-like growth factor-I-binding protein-3 were assayed by routine laboratory methods. Lycopene was assayed by high-performance liquid chromatography. Plasma lycopene levels increased by twofold after supplementation with tomato lycopene extract. In the placebo-treated group, there was a small nonsignificant increase in lycopene plasma levels. The plasma concentration of insulin-like growth factor-I decreased significantly by about 25% after tomato lycopene extract supplementation as compared with the placebo-treated group (P<0.05). No significant change was observed in insulin-like growth factor-I-binding protein-3 or insulin-like growth factor-II, whereas the insulin-like growth factor-I/insulin-like growth factor-I-binding protein-3 molar ratio decreased significantly (P<0.05). Given that high plasma levels of insulin-like growth factor-I have been suggested as a risk factor for various types of cancer including colon cancer, the results support our suggestion that tomato lycopene extract has a role in the prevention of colon and possibly other types of cancer.

Modulation of transcriptional activity by antioxidant carotenoids.

It is widely accepted that diet changes are a powerful means to prevent cancer. The possible involvement of transcriptional activity in the anticancer activity of carotenoids will be the focus of this review. Carotenoids function as potent antioxidants, and this is clearly a major mechanism of their action. In addition carotenoids action involves interference in several pathways related to cancer cell proliferation and includes changes in the expression of many proteins participating in these processes such as connexins, phase II enzymes, cyclins, cyclin-dependent kinases and their inhibitors. These changes in protein expression suggest that the initial effect involves modulation of transcription by ligand-activated nuclear receptors or by other transcription factors. It is feasible to suggest that carotenoids and their oxidized derivatives interact with a network of transcription systems that are activated by different ligands at low affinity and specificity and that this activation leads to the synergistic inhibition of cell growth.

Lycopene in serum, skin and adipose tissues after tomato-oleoresin supplementation in patients undergoing haemorrhoidectomy or peri-anal fistulotomy.

Lycopene, the main carotenoid found in tomatoes and tomato-based products, has been reported to be protective against several types of cancer. Assessment of changes in plasma concentration of carotenoids following ingestion of lycopene-rich food sources does not necessarily predict changes in lycopene concentration or distribution of its isomers in other body tissues. Our aim was to determine the relationship between concentrations of lycopene and other tomato carotenoids in human serum and body tissues after tomato-oleoresin supplementation. Tomato lycopene oleoresin (30 mg/d) or a placebo was administered for 1 to 7 weeks to seventy-five volunteers undergoing elective haemorrhoidectomy or peri-anal fistulotomy. Carotenoid concentration and isomer distribution in blood and in the surgically removed skin and adipose tissues was measured by HPLC. The serum concentration of lycopene increased after supplementation from 0.26 (SD 0.12) to 0.52 (SD 0.25) micromol/l (n 35; P<0.0001). In the placebo group (n 40), lycopene serum concentration did not change significantly. Serum lycopene concentration after treatment was 2.2-fold greater in the lycopene group than in the placebo group, a slightly higher ratio than that found in skin and adipose tissue (1.6- and 1.4-fold higher than the placebo, respectively). A significant correlation between serum and tissue concentrations was found for both beta-carotene and lycopene in the placebo group, whereas in the lycopene-supplemented group the correlation between serum and tissues remained the same for beta-carotene but for lycopene was weak. Lycopene supplementation did not significantly change the proportion of all-trans v. cis isomers in the serum and tissues, despite the fact that more than 90 % of the supplemented lycopene was in the all-trans form. These results show that tomato-oleoresin supplementation increases lycopene concentrations in serum and in adipose tissue and skin. The ability to increase lycopene levels in tissues is one of the prerequisites for using it as a food supplement with health benefits.