Genetic mapping of Mom5, a novel modifier of Apc(Min)-induced intestinal tumorigenesis.

The initial purpose of this study was to assess the role of estrogen receptor beta (ERbeta) in intestinal tumorigenesis by examining the effects of an ERbeta knockout (ERbeta(-/-)) on Apc(Min) mice. In order to accomplish this goal on a uniform genetic background, we were required to backcross the ERbeta knockout from the 129P2 genetic background to the B6 genetic background for 10 generations. Midway through this process, we performed a test cross in which mice from the N(5) backcross generation of the ERbeta knockout strain were intercrossed with Apc(Min/+) mice to obtain Apc(Min/+) ERbeta(+/+), Apc(Min/+) ERbeta(+/-) and Apc(Min/+) ERbeta(-/-) mice. Intestinal tumorigenesis in the N(5)F(2) mice was evaluated at 14 weeks of age. The analysis of the impact of ERbeta in the N(5) cross was complicated by segregating 129P2-derived alleles that affected tumor number and were unlinked to ERbeta. Genetic linkage analysis of this cross permitted the localization of a single genetic modifier of tumor number in Apc(Min/+) mice. This locus, Modifier of Min 5 (Mom5), maps to proximal mouse chromosome 5; the 129P2 allele of this locus is associated with a 50% reduction in mean intestinal tumor number. Through in silico analysis and confirmatory sequencing, we have identified the Rad50-interacting protein-1 gene as a strong candidate for Mom5.

Disruption of estrogen receptor signaling enhances intestinal neoplasia in Apc(Min/+) mice.

Estrogen receptors (ERs) [ERalpha (Esr1) and ERbeta (Esr2)] are expressed in the human colon, but during the multistep process of colorectal carcinogenesis, expression of both ERalpha and ERbeta is lost, suggesting that loss of ER function might promote colorectal carcinogenesis. Through crosses between an ERalpha knockout and Apc(Min) mouse strains, we demonstrate that ERalpha deficiency is associated with a significant increase in intestinal tumor multiplicity, size and burden in Apc(Min/+) mice. Within the normal intestinal epithelium of Apc(Min/+) mice, ERalpha deficiency is associated with an accumulation of nuclear beta-catenin, an indicator of activation of the Wnt-beta-catenin-signaling pathway, which is known to play a critical role in intestinal cancers. Consistent with the hypothesis that ERalpha deficiency is associated with activation of Wnt-beta-catenin signaling, ERalpha deficiency in the intestinal epithelium of Apc(Min/+) mice also correlated with increased expression of Wnt-beta-catenin target genes. Through crosses between an ERbeta knockout and Apc(Min) mouse strains, we observed some evidence that ERbeta deficiency is associated with an increased incidence of colon tumors in Apc(Min/+) mice. This effect of ERbeta deficiency does not involve modulation of Wnt-beta-catenin signaling. Our studies suggest that ERalpha and ERbeta signaling modulate colorectal carcinogenesis, and ERalpha does so, at least in part, by regulating the activity of the Wnt-beta-catenin pathway.

The plant lignans matairesinol and secoisolariciresinol administered to Min mice do not protect against intestinal tumor formation.

The lignans matairesinol (MAT) and secoisolariciresinol (SECO) were fed to Min mice at 0.02% (w/w) in diet to study their effects on intestinal tumor development. The mean number (67 vs. 51, P=0.052) and size (1.4 vs. 1.2 mm, P=0.011) of tumors in the MAT group was elevated when compared with the control group. Tumor formation of the SECO group did not differ from the control group. Intake of MAT increased the level of both MAT and enterolactone in the plasma while SECO feeding increased SECO, enterodiol, and enterolactone (P=0.001). These results showed that MAT or SECO do not prevent intestinal carcinogenesis in Min mice and that MAT may have adverse effects.

Morphometric analysis of the small intestine in wild type mice C57BL/6L -- a developmental study.

Recently the increasing prevalence of gastrointestinal diseases, including neoplasm, has resulted in the necessity of characterising not only the tumours, but also healthy mucosa. Research into the morphological changes of healthy mucosa under different experimental conditions, including drugs, special diets and the use of probiotic bacteria, is greatly facilitated by the availability of animal models. In spite of the widespread use of mice in gastrointestinal research, there is a lack of information on the qualitative and quantitative histological characteristics of the intestinal mucosa of the mouse. The aim of this study was to assess the morphological characteristics and the postnatal development of the small intestine of wild type mice -- C57BL/6J. The mice were aged either 5 weeks or 12 weeks. The 12-week-old mice had been weaned at the age of 5 weeks. After dissection the small intestine was divided into 5 equal portions and randomly chosen microscopical sections from each were stained with haematoxylin and eosin. The parameters describing the morphology of the small intestine (villus height, depth of the crypt, villus width near the crypt, width of the villus connective tissue near the crypt, thickness of the muscular layer and the height of the enterocytes and their nuclei) were evaluated under a light microscope. In both age groups the height and width of the villi decreased, while the thickness of the muscular layer increased in the distal direction. The height of the enterocytes decreased and the height of the enterocyte nucleus increased towards the colon in both age groups. The depth of the crypts was greater in the younger animals than in the older ones. Our data provides the baseline morphological description of the small intestinal mucosa in wild type mice, strain C57BL/6J, which can be used as a reference for testing the influence of drugs, toxins, nutrients and inborn mutations on the mouse intestine.

Berries as chemopreventive dietary constituents--a mechanistic approach with the ApcMin/+ mouse.

Berries contain a number of compounds that are proposed to have anticarcinogenic properties. We wanted to see if pure ellagic acid, natural ellagitannins and three wild berries have any effect on the adenoma formation in Apc- mutated Min/+ mice. Min/+ mice were fed high-fat AIN93-G diets containing 10% (w/w) freeze-dried bilberry (Vaccinium myrtillus), lingonberry (Vaccinium vitis-idaea), cloudberry (Rubus chamaemorus), cloudberry seeds or cloudberry pulp or pure ellagic acid at 1564 mg/kg for 10 weeks. beta-Catenin and cyclin D1 protein levels in the adenomas and in the normal-appearing mucosa were determined by Western blotting and immunohistochemistry. Early changes in gene expression in the normal-appearing mucosa were analyzed by Affymetrix microarrays. Three wild berries significantly reduced tumour number (15-30%, p < 0.05), and cloudberry and lingonberry also reduced tumour size by over 60% (p < 0.01). Cloudberry resulted in decreased levels of nuclear beta-catenin and cyclin D1 and lingonberry in the level of cyclin D1 in the large adenomas (p < 0.05). Affymetrix microarrays revealed changes in genes implicated in colon carcinogenesis, including the decreased expression of the adenosine deaminase, ecto-5f-nucleotidase and PGE2 receptor subtype EP4. Ellagic acid had no effect on the number or size of adenomas in the distal or total small intestine but it increased adenoma size in the duodenum when compared with the control diet (p < 0.05). Neither cloudberry seed nor pulp had any effect on the adenoma formation. Berries seem to have great potential as a source of chemopreventive components.

Three Nordic berries inhibit intestinal tumorigenesis in multiple intestinal neoplasia/+ mice by modulating beta-catenin signaling in the tumor and transcription in the mucosa.

Berries contain a number of compounds that are proposed to have anticarcinogenic properties. We studied the effects and molecular mechanisms of wild berries with different phenolic profiles on intestinal tumorigenesis in multiple intestinal neoplasia/+ mice. The mice were fed a high-fat AIN93-G diet (Con) or AIN93-G diets containing 10% (w:w) freeze-dried bilberry, lingonberry (LB), or cloudberry (CB) for 10 wk. All 3 berries significantly inhibited the formation of intestinal adenomas as indicated by a 15-30% reduction in tumor number (P < 0.05). CB and LB also reduced tumor burden by over 60% (P < 0.05). Compared to Con, CB and LB resulted in a larger (P < 0.05) proportion of small adenomas (43, 69, and 64%, respectively) and a smaller proportion of large adenomas (56, 29, and 33%, respectively). Beta-catenin and cyclin D1 in the small and large adenomas and in the normal-appearing mucosa were measured by Western blotting and immunohistochemistry. CB resulted in decreased levels of nuclear beta-catenin and cyclin D1 and LB in the level of cyclin D1 in the large adenomas (P < 0.05). Early changes in gene expression in the normal-appearing mucosa were analyzed by Affymetrix microarrays, which revealed changes in genes implicated in colon carcinogenesis, including the decreased expression of the adenosine deaminase, ecto-5'-nucleotidase, and prostaglandin E2 receptor subtype EP4. Our results indicate that berries are potentially a rich source of chemopreventive components.

Suitability of a batch in vitro fermentation model using human faecal microbiota for prediction of conversion of flaxseed lignans to enterolactone with reference to an in vivo rat model.

BACKGROUND: In vitro fermentation models have been used widely for studies of shortchain fatty acid (SCFA) formation from carbohydrates, whereas the suitability of these methods for enterolactone (ENL) formation has received less attention. AIM: The aim was to study the suitability of an in vitro fermentation model for prediction of bioconversion of lignans to ENL, to compare the approach with that of an in vivo rat model and to study the SCFA formation in both models. METHODS: Predigested samples of rye bran (R), flaxseed meal (F) alone, or in combination with rye bran (R&F) and a faecal control were incubated in an in vitro fermentation model using human faecal microbiota. In the in vivo experiment rats consumed a non-fibre control diet (C) or diets supplemented either with rye bran (R), flaxseed meal (F) alone, or with their combination (R&F) for four weeks. Enterodiol (END), ENL and SCFA concentrations were measured from in vitro faecal fermentation samples and from the intestinal contents of rats. Plasma ENL concentrations from rats were also measured. RESULTS: The highest ENL production was found in vitro with the F supplement (areas under curve: 740 +/- 4, 7,500 +/- 400, 2,600 +/- 500 and 1,520 +/- 70 nmol x h for the R, F, R&F supplements and faecal control, respectively). In vivo, the concentration of ENL in caecal digesta from flaxseed meal was significantly (P < 0.05) enhanced by the presence of rye bran (medians 261, 407 and 24 nmol/g in the F, R&F and C groups, respectively). No correlation was found between the models regarding ENL production, possibly due to different responses to the presence of rye bran matrix, differences in microbiota or application of a batch in the in vitro fermentation model. Rye bran supplementation enhanced butyrate production both in vitro and in vivo. CONCLUSION: In vitro fermentation and the in vivo rat models responded differently to the presence of rye bran and no correlation with regard to the ENL formation from flaxseed lignans was observed.

Effects of a flaxseed mixture and plant oils rich in alpha-linolenic acid on the adenoma formation in multiple intestinal neoplasia (Min) mice.

Flaxseed is a dietary source of possible chemopreventive compounds such as lignans and alpha-linolenic acid (ALA). To study the effects of a flaxseed mixture on adenoma formation in multiple intestinal neoplasia mice, the mice were fed a diet containing 2.7 % flaxseed, 4.5 % fibre and 3.7 % ALA. To elucidate the effect of oils of the mixture we also composed a diet without flaxseed but with the same oil composition. The median number of adenomas in the small intestine was fifty-four for the control group, and thirty-seven (P=0.023) and forty-two (P=0.095) for flaxseed and oil groups, respectively. Compared with controls (1.2 mm), the adenoma size was smaller in the flaxseed (0.9 mm; P=0.002) and oil (1.0 mm; P=0.012) groups. Both diets changed the proportions of n-3 and n-6 fatty acids in the colonic mucosa. Membrane beta-catenin and protein kinase C (PKC)-zeta levels were reduced in the adenoma v. mucosa (P<0.05), and an inverse association was found between the membrane PKC-zeta in the mucosa and the adenoma number (r -0.460, P=0.008, n 32). Only the flaxseed diet increased lignan levels in the caecum (P=0.002) and in plasma (P=0.002) but they were not associated with tumour formation. The results suggest that the preventive effect of flaxseed on colon carcinogenesis may be due to the oil part of flaxseed, and the loss of beta-catenin and PKC-zeta from the membranes of the mucosal tissue may play a permissive role in intestinal tumour development.