Can cancer risks be altered by changing nutritional traditions?

Nongenotoxic effects and a reduction of the DXR-induced genotoxic effects of Helianthus annuus Linné (sunflower) seeds revealed by micronucleus assays in mouse bone marrow

Background

This research evaluated the genotoxicity of oil and tincture of H. annuus L. seeds using the micronucleus assay in bone marrow of mice. The interaction between these preparations and the genotoxic effects of doxorubicin (DXR) was also analysed (antigenotoxicity test).

Methods

Experimental groups were evaluated at 24-48 h post treatment with N-Nitroso-N-ethylurea (positive control – NEU), DXR (chemotherapeutic), NaCl (negative control), a sunflower tincture (THALS) and two sources of sunflower oils (POHALS and FOHALS). Antigenotoxic assays were carried out using the sunflower tincture and oils separately and in combination with NUE or DXR.

Results

For THALS, analysis of the MNPCEs showed no significant differences between treatment doses (250–2,000 mg.Kg^-1) and NaCl. A significant reduction in MNPCE was observed when THALS (2,000 mg.Kg^-1) was administered in combination with DXR (5 mg.Kg^-1). For POHALS or FOHALS, analysis of the MNPCEs also showed no significant differences between treatment doses (250–2,000 mg.Kg^-1) and NaCl. However, the combination DXR + POHALS (2,000 mg.Kg^-1) or DXR + FOHALS (2,000 mg.Kg^-1) not contributed to the MNPCEs reduction.

Conclusions

This research suggests absence of genotoxicity of THALS, dose-, time- and sex-independent, and its combination with DXR can reduce the genotoxic effects of DXR. POHALS and FOHALS also showed absence of genotoxicity, but their association with DXR showed no antigenotoxic effects.

Involvement of reactive oxygen species in the immunosuppressive effect of 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1), a food-born carcinogenic heterocyclic amine

A heterocyclic amine, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) is one of the potent food-borne dietary carcinogens derived mainly from burnt meat products. In the present study, we investigated the immunosuppressive effect of Trp-P-1 on the blastogenesis of lymphocytes prepared from spleen and thymus of Balb/c mice. Trp-P-1 inhibited, in a dose-dependent manner, proliferation of splenocytes in response to a B-cell mitogen, lipopolysaccharide and of both splenocytes and thymocytes in response to T-cell mitogens, concanavalin A and phytohemagglutinin, or non-receptor-mediated stimuli, phobol 12-myristate 13-acetate/ionomycin. Interestingly, Trp-P-1-inhibited proliferation in the splenocytes was restored almost completely by N-acetyl-l-cysteine (NAC) and partially by glutathione (GSH), whereas no effect was found when superoxide dismutase and catalase were used. Moreover, Trp-P-1 enhanced the mitogen-induced NF-kappaB binding activity to its cognate binding sequences, which is known to be mediated by intracellular reactive oxygen species (ROS) generation. Collectively, these results suggest that the immunosuppressive effect of Trp-P-1 is mediated by suppressing blastogenesis of lymphocytes via intracellular generation of ROS sensitive to NAC and/or GSH.

Extensive intestinal metaplasia in gastric carcinoma and in other lesions requiring surgery: a study of 3,421 gastrectomy specimens from dwellers of the Atlantic and Pacific basins

BACKGROUND

Extensive intestinal metaplasia (EIM) has been reported in gastrectomies from patients dwelling in the Pacific and Atlantic basins.

AIMS

To compare all the results in an attempt to explain the findings.

METHOD

All sections from 3,421 gastrectomies were reviewed at various hospitals: 1946 in the Atlantic and 1475 in the Pacific basin. Sections with EIM showed IM encompassing one or more entire low power field (>or=5 mm in length/section) in one or more section.

RESULTS

In the Atlantic basin, EIM was present in 18.8% (153 of 814) of specimens with intestinal carcinoma (IC) and in 10.3% (65 of 630) of those with diffuse carcinoma (DC). In the Pacific basin, EIM was found in 62.9% (412 of 655) of gastrectomies with IC and in 33.3% (160 of 481) of those with DC. The numbers of specimens with EIM were significantly higher in the Pacific than in the Atlantic basin for both carcinoma phenotypes, particularly among elderly patients (>or=60 years).

CONCLUSIONS

The proportion of gastrectomies with EIM was higher among populations at a higher gastric cancer risk than in those with a lower cancer risk. EIM was mostly associated with IC rather than DC or with miscellaneous gastric diseases (841 control gastrectomies) in both basins. The proportion of gastrectomies with EIM was significantly higher in Vancouver than in New York and in Santiago de Chile than in Buenos Aires, even though these populations reside at approximately the same geographical latitude, but in different basins. Environmental factors seem to accelerate the evolution of EIM.

Colonic screening and surveillance

Screening for colorectal cancer has not obtained worldwide acceptance in spite of its proven survival benefit for average-risk persons and some high-risk groups. The incidence of and mortality from colorectal cancer are worrying in Europe as well as in the USA, Australia and Japan. The best evidence-based studies are those published on screening using faecal occult blood tests, endoscopic methods and different tumour markers having been evaluated to a lesser degree. Feasibility studies are necessary before massive screening can be undertaken because the results obtained from randomized studies may not be reproduced to a satisfactory degree in average- as well as high-risk populations. Primary prevention by dietary intervention and drugs has been studied in great detail, so far without any major breakthrough. This chapter will address different screening methods in populations with a varying risk of colorectal cancer, together with providing a short review of prevention and intervention strategies.

Carcinogenicity and mutagenicity testing, then and now

Cancer is a dread disease worldwide. Mortality of individuals suffering from cancer is high, despite the current improved methods of precocious detection, surgery and therapy. Prevention of cancer is the recognized goal of many activities in cancer research. This aim was recognized early to involve the bioassay of environmental chemicals or mixtures. The first such study involved application of coal tar to the ear of rabbits, and later on to the skin of mice. Subsequently, laboratory rats were introduced, and hamsters were utilized as a substitute for the unwieldy tests in rabbits. Investigators also became concerned with the mechanisms of carcinogenesis, and more definitive approaches to carcinogen bioassay in laboratory animals, as possible indicators of cancer risk in humans. These tests were expensive and lengthy, and did not serve the important purpose of accurately measuring risk of cancer to humans. Once it was realized that DNA and the genetic apparatus might be a key target, rapid bioassays in bacterial and mammalian cell systems were introduced successfully. Thus, batteries of tests are now available to detect effectively human cancer risks, and provide novel approaches to determine the underlying mechanisms, as a sound basis for cancer prevention.