Beef meat promotion of dimethylhydrazine-induced colorectal carcinogenesis biomarkers is suppressed by dietary calcium

Red meat consumption is associated with increased risk of colorectal cancer. We have previously shown that haemin, Hb and red meat promote carcinogen-induced preneoplastic lesions: aberrant crypt foci (ACF) and mucin-depleted foci (MDF) in rats. We have also shown that dietary calcium, antioxidant mix and olive oil inhibit haemin-induced ACF promotion, and normalize faecal lipoperoxides and cytotoxicity. Here we tested if these strategies are effective also against red meat promotion in dimethylhydrazine-induced rats. Three diets with 60% beef meat were supplemented with calcium phosphate (33 g/kg), antioxidant agents (rutin and butylated hydroxyanisole, 0•05% each) and olive oil (5 %). ACF, MDF, faecal water cytotoxicity, thiobarbituric acid reactive substances (TBARS) and urinary 1,4-dihydroxynonane mercapturic acid (DHN-MA) were measured. Beef meat diet increased the number of ACF (þ30 %) and MDF (þ100 %) (P,0•001), which confirms our previous findings. Promotion was associated with increased faecal water TBARs ( £ 4) and cytotoxicity ( £ 2), and urinary DHN-MA excretion ( £ 15). Calcium fully inhibited beef meat-induced ACF and MDF promotion, and normalized faecal TBARS and cytotoxicity, but did not reduce urinary DHN-MA. Unexpectedly, high-calcium control diet-fed rats had more MDF and ACF in the colon than low-calcium control diet-fed rats. Antioxidant mix and olive oil did not normalize beef meat promotion nor biochemical factors. The results confirm that haem causes promotion of colon carcinogenesis by red meat. They suggest that calcium can reduce colorectal cancer risk in meat-eaters. The results support the concept that toxicity associated with the excess of a useful nutrient may be prevented by another nutrient

Apc mutation induces resistance of colonic cells to lipoperoxide-triggered apoptosis induced by faecal water from haem-fed rats

Recent epidemiological studies suggest that high meat intake is associated with promotion of colon cancer linked to haem-iron intake. We previously reported that dietary haem, in the form of either haemoglobin or meat, promotes precancerous lesions in the colon of rats given a low-calcium diet. The mechanism of promotion by haem is not known, but is associated with increased lipid peroxidation in faecal water and strong cytotoxic activity of faecal water on a cancerous mouse colonic epithelial cell line. To better understand the involvement of faecal water components of haem-fed rats in colon cancer promotion, we explored the effect of faecal water on normal (Apc +/+) or premalignant cells (Apc Min/+). Further, we tested if this effect was correlated to lipoperoxidation and 4-hydroxynonenal (HNE). We show here for the first time that heterozygote Apc mutation represents a strong selective advantage, via resistance to apoptosis induction (caspase 3 pathway), for colonic cells exposed to a haem-iron induced lipoperoxidation. The fact that HNE treatment of the cells provoked the same effects as the faecal water of rats fed the haem-rich diet suggests that this compound triggers apoptosis in those cells. We propose that this mechanism could be involved in the promotion of colon carcinogenesis by haem in vivo

New Marker of Colon Cancer Risk Associated with Heme Intake: 1,4-Dihydroxynonane Mercapturic Acid

Background: Red meat consumption is associated with an increased risk of colon cancer. Animal studies show that heme, found in red meat, promotes preneoplastic lesions in the colon, probably due to the oxidative properties of this compound. End products of lipid peroxidation, such as 4-hydroxynonenal metabolites or 8-iso-prostaglandin-F2 (8-iso-PGF2), could reflect this oxidative process and could be used as biomarkers of colon cancer risk associated with heme intake. Methods: We measured urinary excretion of 8-iso-PGF2 and 1,4-dihydroxynonane mercapturic acid (DHN-MA), the major urinary metabolite of 4-hydroxynonenal, in three studies. In a short-term and a carcinogenesis long-term animal study, we fed rats four different diets (control, chicken, beef, and blood sausage as a high heme diet). In a randomized crossover human study, four different diets were fed (a 60 g/d red meat baseline diet, 120 g/d red meat, baseline diet supplemented with heme iron, and baseline diet supplemented with non-heme iron). Results: DHN-MA excretion increased dramatically in rats fed high heme diets, and the excretion paralleled the number of preneoplastic lesions in azoxymethane initiated rats (P < 0.0001). In the human study, the heme supplemented diet resulted in a 2-fold increase in DHN-MA (P < 0.001). Urinary 8-iso-PGF2 increased moderately in rats fed a high heme diet (P < 0.0001), but not in humans. Conclusion: Urinary DHN-MA is a useful noninvasive biomarker for determining the risk of preneoplastic lesions associated with heme iron consumption and should be further investigated as a potential biomarker of colon cancer risk. (Cancer Epidemiol Biomarkers Prev 2006;15(11):2274–9

Meat processing and colon carcinogenesis: Cooked, nitrite-treated and oxidized high-heme cured meat promotes mucin depleted foci in rats

Processed meat intake is associated with colorectal cancer risk, but no experimental study supports the epidemiologic evidence. To study the effect of meat processing on carcinogenesis promotion, we first did a 14-day study with 16 models of cured meat. Studied factors, in a 2 × 2 × 2 × 2 design, were muscle color (a proxy for heme level), processing temperature, added nitrite, and packaging. Fischer 344 rats were fed these 16 diets, and we evaluated fecal and urinary fat oxidation and cytotoxicity, three biomarkers of heme-induced carcinogenesis promotion. A principal component analysis allowed for selection of four cured meats for inclusion into a promotion study. These selected diets were given for 100 days to rats pretreated with 1,2-dimethylhydrazine. Colons were scored for preneoplastic lesions: aberrant crypt foci (ACF) and mucin-depleted foci (MDF). Cured meat diets significantly increased the number of ACF/colon compared with a no-meat control diet (P = 0.002). Only the cooked nitrite-treated and oxidized high heme meat significantly increased the fecal level of apparent total N-nitroso compounds (ATNC) and the number of MDF per colon compared with the no-meat control diet (P < 0.05). This nitrite-treated and oxidized cured meat specifically increased the MDF number compared with similar non nitrite-treated meat (P = 0.03) and with similar non oxidized meat (P = 0.004). Thus, a model cured meat, similar to ham stored aerobically, increased the number of preneoplastic lesions, which suggests colon carcinogenesis promotion. Nitrite treatment and oxidation increased this promoting effect, which was linked with increased fecal ATNC level. This study could lead to process modifications to make non promoting processed meat

Red wine and pomegranate extracts suppress cured meat promotion of colonic mucin-depleted foci in carcinogen-induced rats

Processed meat intake is carcinogenic to humans. We have shown that intake of a workshop-made cured meat with erythorbate promotes colon carcinogenesis in rats. We speculated that polyphenols could inhibit this effect by limitation of endogenous lipid peroxidation and nitrosation. Polyphenol-rich plant extracts were added to the workshop-made cured meat and given for 14 days to rats and 100 days to azoxymethane-induced rats to evaluate the inhibition of preneoplastic lesions. Colons of 100-d study were scored for precancerous lesions (mucin-depleted foci, MDF), and biochemical end points of peroxidation and nitrosation were measured in urinary and fecal samples. In comparison with cured meat-fed rats, dried red wine, pomegranate extract, α-tocopherol added at one dose to cured meat and withdrawal of erythorbate significantly decreased the number of MDF per colon (but white grape and rosemary extracts did not). This protection was associated with the full suppression of fecal excretion of nitrosyl iron, suggesting that this nitroso compound might be a promoter of carcinogenesis. At optimized concentrations, the incorporation of these plant extracts in cured meat might reduce the risk of colorectal cancer associated with processed meat consumption

Freeze-Dried Ham Promotes Azoxymethane-Induced Mucin-Depleted Foci and Aberrant Crypt Foci in Rat Colon

Processed and red meat consumption is associated with the risk of colorectal cancer. Meta-analyses have suggested that the risk associated with processed meat is higher. Most processed meats are cured and cooked, which leads to formation of free nitrosyl heme. We speculated that free nitrosyl heme is more toxic than native myoglobin. The promoting effect of a freeze-dried, cooked, cured ham diet was looked for in a 100-day study. Colon carcinogenesis endpoints were aberrant crypt foci and mucin depleted foci (MDF). A second study (14 days) was designed 1) to compare the effect of ham, hemoglobin, and hemin; and 2) to test the effect of sodium chloride, nitrite, and phosphate in diet on early biomarkers associated with heme-induced promotion. In the 100-day study, control and ham-fed rats had 3.5 and 8.5 MDF/colon, respectively (P < 0.0001). Promotion was associated with cytotoxicity and lipid peroxidation. In the short-term study, cytotoxicity and lipid peroxidation of fecal water, and the urinary marker of lipid peroxidation, increased dramatically in ham- and hemin-fed rat. In contrast, the hemoglobin diet, sodium chloride, nitrite, phosphate diet had no effect. Freeze-dried cooked ham can promote colon carcinogenesis in a rodent model. Hemin, but not hemoglobin, mimicked ham effect on early biochemical markers associated with carcinogenesis

Effects of sodium nitrite reduction, removal or replacement on cured and cooked meat for microbiological growth, food safety, colon ecosystem, and colorectal carcinogenesis in Fischer 344 rats

Epidemiological and experimental evidence indicated that processed meat consumption is associated with colorectal cancer risks. Several studies suggest the involvement of nitrite or nitrate additives via N-nitroso-compound formation (NOCs). Compared to the reference level (120 mg/kg of ham), sodium nitrite removal and reduction (90 mg/kg) similarly decreased preneoplastic lesions in F344 rats, but only reduction had an inhibitory effect on Listeria monocytogenes growth comparable to that obtained using the reference nitrite level and an effective lipid peroxidation control. Among the three nitrite salt alternatives tested, none of them led to a significant gain when compared to the reference level: vegetable stock, due to nitrate presence, was very similar to this reference nitrite level, yeast extract induced a strong luminal peroxidation and no decrease in preneoplastic lesions in rats despite the absence of NOCs, and polyphenol rich extract induced the clearest downward trend on preneoplastic lesions in rats but the concomitant presence of nitrosyl iron in feces. Except the vegetable stock, other alternatives were less efficient than sodium nitrite in reducing L. monocytogenes growth

Étude de l'influence de l'hormone de croissance sur les activités hépatiques de glucuronoconjugaison chez le rat

L'influence de l'hormone de croissance (gh) sur les activites de glucuronidation hepatiques est etudiee chez des rats males, hypophysectomises ou non, et traites ou non avec du cortisol et de la thyroxine de facon a compenser l'absence d'hormones thyroidiennes et de glucocorticoides chez les animaux hypophysectomises. Deux doses de gh ont ete utilisees, la plus faible permettant de mimer un rythme de secretion de gh de type male, la plus forte permettant de mimer un rythme de secretion de type femelle. La gh agit de facon variable sur l'expression des enzymes de glucuronidation du paranitrophenol, de l'androsterone, de la testosterone, de la bilirubine et de l'oestrone, selon l'activite consideree. La gh diminue particulierement l'activite de glucuronidation de la bilirubine, vraisemblablement a un niveau transcriptionnel ou post-transcriptionnel. Cette influence ne s'apparente pas a un processus de feminisation par une exposition continue a l'hormone comme c'est le cas pour d'autres enzymes de metabolisation hepatiques, particulierement certaines monooxygenases a cytochrome p-450 ou certaines glutathion s-transferases (gsts), qui ont ete etudiees en parallele. Cette etude en parallele a par ailleurs montre l'existence d'une forte similitude de comportement de l'activite de glucuronidation de la bilirubine et de l'expression de la sous-unite 6 des gsts en fonction de l'hypophysectomie et des traitements utilises. La signification et les bases moleculaires de cette relation restent a etablir. La gh modifie egalement l'etat fonctionnel des enzymes de glucuronidation qui depend de l'environnement membranaire de ces enzymes, en interaction avec le traitement par le cortisol et la thyroxine. Cet effet est en relation avec une augmentation des lysophospholipides dans la membrane microsomale. En revanche, la faible influence de la gh sur differents parametres de fluidite membranaire, qui sont dependants de la composition en acides gras des microsomes elle-meme modifiee par la gh et l'hypophysectomie, ne semble pas etre en relation avec l'effet de cette hormone sur l'etat fonctionnel des enzymes de glucuronidation. La gh influence donc l'expression des enzymes de glucuronidation mais aussi leur etat fonctionnel, via la composition lipidique de la membrane microsomale. Les consequences sur le fonctionnement d'autres proteines membranaire reste a determinerL'influence de l'hormone de croissance (gh) sur les activites de glucuronidation hepatiques est etudiee chez des rats males, hypophysectomises ou non, et traites ou non avec du cortisol et de la thyroxine de facon a compenser l'absence d'hormones thyroidiennes et de glucocorticoides chez les animaux hypophysectomises. Deux doses de gh ont ete utilisees, la plus faible permettant de mimer un rythme de secretion de gh de type male, la plus forte permettant de mimer un rythme de secretion de type femelle. La gh agit de facon variable sur l'expression des enzymes de glucuronidation du paranitrophenol, de l'androsterone, de la testosterone, de la bilirubine et de l'oestrone, selon l'activite consideree. La gh diminue particulierement l'activite de glucuronidation de la bilirubine, vraisemblablement a un niveau transcriptionnel ou post-transcriptionnel. Cette influence ne s'apparente pas a un processus de feminisation par une exposition continue a l'hormone comme c'est le cas pour d'autres enzymes de metabolisation hepatiques, particulierement certaines monooxygenases a cytochrome p-450 ou certaines glutathion s-transferases (gsts), qui ont ete etudiees en parallele. Cette etude en parallele a par ailleurs montre l'existence d'une forte similitude de comportement de l'activite de glucuronidation de la bilirubine et de l'expression de la sous-unite 6 des gsts en fonction de l'hypophysectomie et des traitements utilises. La signification et les bases moleculaires de cette relation restent a etablir. La gh modifie egalement l'etat fonctionnel des enzymes de glucuronidation qui depend de l'environnement membranaire de ces enzymes, en interaction avec le traitement par le cortisol et la thyroxine. Cet effet est en relation avec une augmentation des lysophospholipides dans la membrane microsomale. En revanche, la faible influence de la gh sur differents parametres de fluidite membranaire, qui sont dependants de la composition en acides gras des microsomes elle-meme modifiee par la gh et l'hypophysectomie, ne semble pas etre en relation avec l'effet de cette hormone sur l'etat fonctionnel des enzymes de glucuronidation. La gh influence donc l'expression des enzymes de glucuronidation mais aussi leur etat fonctionnel, via la composition lipidique de la membrane microsomale. Les consequences sur le fonctionnement d'autres proteines membranaires reste a determine