[Multilingualism and Dementia: From the Studies in Brazil and Taiwan].

Our studies in Brazil and Taiwan revealed that the prevalence of dementia was independent of environment, culture, and use of multilingualism. However, language deterioration in dementia was found to be related to its frequency of use and the environment, and both language, and deterioration were asymmetric. Although the cognitive reserve and protective effect of multilingualism on dementia were shown, the decline in language function was found to be related to psychiatric symptoms of dementia, delusions, and depression which were relieved by providing a reliable language environment. It was suggested that language function evaluation should be considered for dementia care.

Citrus compounds inhibit inflammation- and obesity-related colon carcinogenesis in mice.

Dietary polyphenols are important potential chemopreventive natural agents. Other agents, such as citrus compounds, are also candidates for cancer chemopreventives. They act on multiple key elements in signal transduction pathways related to cellular proliferation, differentiation, apoptosis, inflammation, and obesity. This short review article provides our findings of preclinical studies on potential chemopreventive activities of dietary citrus compounds, auraptene, collinin, and citrus unshiu segment membrane (CUSM), using clitis- and obesity-related colon tumorigenesis models. Dietary feeding with auraptene and collinin at dose levels of 0.01% and 0.05% significantly lowered the incidence (50-60% reduction) and multiplicity (67-80% reduction) of colonic adenocarcinomas induced by azoxymetahene [AOM, single intraperitoneal injection of 10 mg/kg body weight (bw)] and dextran sodium sulfate (1% in drinking water). Anti-inflammatory potency of aurapene and collinin may contribute to the effects. Administration with CUSM at 3 doses in diet significantly inhibited development of aberrant crypts foci induced by 5 weekly subcutaneous injections of AOM (15 mg/kg bw) in male db/db mice: 53% inhibition by 0.02% CUSM, 54% inhibition by 0.1% CUSM, and 59% inhibition by 0.5% CUSM. CUSM treatment also decreased serum level of triglycerides. Our findings suggest that certain citrus materials are capable of inhibiting clitis- and obesity-related colon carcinogenesis.

A tobacco-specific carcinogen, NNK, enhances AOM/DSS-induced colon carcinogenesis in male A/J mice.

To determine whether tobacco-derived carcinogens affect colon carcinogenesis, the effects of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) on colon carcinogenesis were examined using an azoxymethane (AOM)/dextran sulfate sodium (DSS) mouse model. NNK (10 micromol) was administered to male A/J mice by a single intraperitoneal (i.p.) injection and then AOM (10 mg/kg body weight, i.p.) was given 1 week after NNK administration. One week later, the mice received 1.5% (w/v) DSS in their drinking water for 7 days. All animals were sacrificed at week 22 to examine the pathological lesions in the colon and lung. The incidence (80%, p < 0.05) and multiplicity (4.0 +/- 3.6, p < 0.05) of colonic tumors of the NNK + AOM + DSS group were significantly higher than that of the AOM + DSS group (incidence, 40%; and multiplicity, 1.2 +/- 1.7). The differences in incidence and multiplicity of lung tumors were insignificant between these two groups. Our findings may suggest that smoking increases the risk of inflammation-related colon cancer development.

A novel prodrug of 4'-geranyloxy-ferulic acid suppresses colitis-related colon carcinogenesis in mice.

The inhibitory effects of a novel prodrug, 3-(4'-geranyloxy-3'-methoxyphenyl)-2-trans-propenoyl-L-alanyl-L-proline (GAP), of the secondary metabolite 4'-geranyloxy-3'-methoxyphenyl)-2-trans-propenoic acid (4'-geranyloxy-ferulic acid), on colon carcinogenesis was investigated using an azoxymetahen (AOM)/dextran sodium sulfate (DSS) model. GAP was synthetically derived from ferulic acid. Male CD-1 (ICR) mice initiated with a single intraperitoneal injection of azoxymethane (10 mg/kg body weight) were promoted by 1% (wt/vol) DSS in drinking water for 7 days. They were then given modified AIN-76A diet containing 0.01% or 0.05% GAP for 17 wk. At Week 20, the development of colonic adenocarcinoma was significantly inhibited by GAP feeding at dose levels of 0.01% [60% incidence (P = 0.0158) with a multiplicity of and 1.13 +/- 1.13 (P < 0.05)] and 0.05% [53% incidence (P = 0.0057) with a multiplicity of 0.08 +/- 1.08 (P < 0.01)], when compared to the AOM/DSS group (95% incidence with a multiplicity of 3.10 +/- 3.06). Dietary GAP modulated the mitotic and apoptotic indexes in the crypt cells and lowered 8-hydroxy-2'-deoxyguanosine (8-OHdG)-positive cells in the colonic mucosa. Urinary level of 8-OHdG was lowered by GAP feeding. Additionally, dietary GAP elevated the immunoreactivity of an inducible form of heme oxygenase 1 in the colonic mucosa. Our results indicate that GAP is able to inhibit colitis-related colon carcinogenesis by modulating proliferation and oxidative stress in mice.

A novel rasH2 mouse carcinogenesis model that is highly susceptible to 4-NQO-induced tongue and esophageal carcinogenesis is useful for preclinical chemoprevention studies.

We investigated the susceptibility of 4-nitroquinoline 1-oxide (4-NQO)-induced tongue carcinogenesis in male CB6F1-Tg-rasH2 @Jcl mice (Tg mice). The Tg mice were administered 4-NQO (20 p.p.m. in drinking water) for 2, 4, 6 or 8 weeks, and thereafter they were untreated up to week 24. At week 24, a higher incidence (80%) of tongue neoplasm with dysplasia was noted in the mice that received 4-NQO for 8 weeks in comparison with the other groups (20% incidence for each) treated with 4-NQO for 2, 4 and 6 weeks. Esophageal tumors also developed in the Tg mice were 4-NQO. Immunohistochemical observation revealed that the EP receptors, especially EP(1) and EP(2), expressed in the tongue and esophageal lesions induced by 4-NQO, thus suggesting the involvement of prostaglandin (PG) E(2) and EP(1,2) receptors in the tongue and esophageal carcinogenesis. Using this animal model, we investigated the potential chemopreventive ability of pitavastatin (1, 5 and 10 p.p.m. in diet for 15 weeks), starting 1 week after the cessation of 4-NQO-exposure (20 p.p.m. in drinking water for 8 weeks). Dietary pitavastatin at 10 p.p.m. significantly reduced the incidence and multiplicity of the tongue, but not esophageal neoplasms by the modulation of prostaglandin E2 biosynthesis, EP(1) and EP(2) expression and proliferation. Our results thus suggest that a rasH2 mouse model of 4-NQO-induced tongue and esophageal carcinogenesis can be utilized for investigating the pathogenesis of cancer development in these tissues and may well prove to be useful for identifying candidate cancer chemopreventive agents for the upper digestive organs.

9trans,11trans conjugated linoleic acid inhibits the development of azoxymethane-induced colonic aberrant crypt foci in rats.

We investigated the effects of 9trans,11trans (9t,11t)-conjugated linoleic acid (CLA) isomer on azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF) in rats. Male F344 rats were given 2 weekly subcutaneous injections of AOM (20 mg/kg bw) to induce colonic ACF. They also were fed a diet containing either 0.01%, 0.1%, or 1% 9t,11t-CLA for 4 wk starting 1 wk before the first dosing of AOM. The group that received a diet supplemented with 9t,11t-CLA had a significantly lower number of ACF/colon in comparison to the AOM alone group in a dose-dependent manner up to 0.1%. Furthermore, treatment with 9t,11t-CLA induced apoptosis and suppressed cell proliferation activity in the non-lesional crypts. The downregulation of cyclooxygenase-2 and cyclin D1 and the activation of peroxisome proliferators activated receptor gamma were observed in the colonic mucosa of rats fed a diet supplemented with 9t,11t-CLA. Our findings thus provide some novel insight into the chemopreventive effect of 9t,11t-CLA against preinitiation as well as postinitiation stages of colorectal carcinogenesis.

A lipophilic statin, pitavastatin, suppresses inflammation-associated mouse colon carcinogenesis.

3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors are known to modulate carcinogenesis. In this study, we investigated whether a lipophilic HMG-CoA reductase inhibitor pitavastatin suppresses inflammation-related mouse colon carcinogenesis. Male CD-1 (ICR) mice were initiated with a single intraperitoneal injection of azoxymethane (AOM, 10 mg/kg body weight) and promoted by 2% (w/v) dextran sodium sulfate (DSS) in drinking water for 7 days. The experimental diets containing pitavastatin at 2 dose levels (1 and 10 ppm) were fed to male CD-1 (ICR) mice for 17 weeks, staring 1 week after the cessation of DSS exposure. The effects of dietary pitavastatin on colonic tumor development were assessed at Weeks 5, 10 and 20. Feeding with pitavastatin at both doses significantly inhibited the multiplicity of colonic adenocarcinoma at Week 20. Furthermore, the treatment significantly lowered the positive rates of proliferating cell nuclear antigen and increased the apoptotic index in the colonic epithelial malignancies. The treatment also reduced nitrotyrosine-positivity in the colonic mucosa. Our findings thus show that pitavastatin is effective in inhibiting colitis-related colon carcinogenesis through modulation of mucosal inflammation, oxidative/nitrosative stress, and cell proliferation.

Citrus auraptene suppresses azoxymethane-induced colonic preneoplastic lesions in C57BL/KsJ-db/db mice.

The current study was designed to investigate whether dietary citrus auraptene (AUR) suppresses the development of azoxymethane (AOM)-induced colorectal preneoplastic lesions in C57BL/KsJ-db/db (db/db) mice with obese and diabetic phenotypes. Female db/db and wild (+/+) mice were divided into the AOM + AUR, AOM alone, AUR alone, and the untreated groups in each phenotype. AOM was given 3 weekly intraperitoneal injections (10 mg/kg bw). AUR (250 ppm) was given in diet during the study (for 10 wk). Dietary AUR significantly reduced the number of aberrant crypt foci (ACF) and Beta -catenin-accumulated crypt (BCAC) in both phenotypes. The treatment also lowered cell proliferation activity and increased apoptotic cells in both lesions. Our findings indicate that dietary AUR is able to suppress the early phase of colon carcinogenesis in both phenotypes, suggesting possible application of AUR as a chemopreventive agent in both the high-risk and general populations for colorectal cancer.

Tumor-initiating potency of a novel heterocyclic amine, aminophenylnorharman in mouse colonic carcinogenesis model.

A novel heterocyclic amine, 9-(4'-aminophenyl)-9H-pyrido[3,4-b]indole (aminophenylnorharman, APNH), which is formed from nonmutagenic 9H-pyrido[3,4-b]indole (norharman) and aniline, is mutagenic to bacteria and mammalian cells and potently carcinogenic in rats. APNH is detected in human urine samples, suggesting that humans are continuously exposed to APNH. In the present study, (32)P-postlabelin analysis revealed that the levels of APNH-DNA adduct 24 hr after the treatment with APNH (1, 5 and 20 mg/kg body weight) in male ICR mice were increased in a dose-dependent manner in the colon and liver. Based on these findings, we determined the tumor-initiating potency of APNH in an inflammation-related and two-stage mouse colon carcinogenesis model. Male Crj: CD-1 (ICR) mice were given a single intragastric administration (1, 2, 5 or 10 mg/kg body weight) of APNH and subsequent 1-week oral exposure to dextran sodium sulfate (DSS, 2% in drinking water). Treatment with APNH and DSS resulted in numerous colon tumor development: the incidence and multiplicity of the tumors were the highest in the mice received 10 mg/kg body weight of APNH and followed by DSS. Development of colon tumors was dose-dependent of APNH. Seven of 9 (77.8%) colonic adenocarcinomas developed in mice treated with APNH (10 mg/kg body weight) and DSS had beta-catenin gene mutations at codons 32 and 37, being predominantly transversion. These findings indicate that APNH has an initiating activity in inflamed mouse colon and the APNH-DNA adduct formation correlates with its tumorigenic potential.

Global gene expression analysis of the mouse colonic mucosa treated with azoxymethane and dextran sodium sulfate.

BACKGROUND: Chronic inflammation is well known to be a risk factor for colon cancer. Previously we established a novel mouse model of inflammation-related colon carcinogenesis, which is useful to examine the involvement of inflammation in colon carcinogenesis. To shed light on the alterations in global gene expression in the background of inflammation-related colon cancer and gain further insights into the molecular mechanisms underlying inflammation-related colon carcinogenesis, we conducted a comprehensive DNA microarray analysis using our model. METHODS: Male ICR mice were given a single ip injection of azoxymethane (AOM, 10 mg/kg body weight), followed by the addition of 2% (w/v) dextran sodium sulfate (DSS) to their drinking water for 7 days, starting 1 week after the AOM injection. We performed DNA microarray analysis (Affymetrix GeneChip) on non-tumorous mucosa obtained from mice that received AOM/DSS, AOM alone, and DSS alone, and untreated mice at wks 5 and 10. RESULTS: Markedly up-regulated genes in the colonic mucosa given AOM/DSS at wk 5 or 10 included Wnt inhibitory factor 1 (Wif1, 48.5-fold increase at wk 5 and 5.7-fold increase at wk 10) and plasminogen activator, tissue (Plat, 48.5-fold increase at wk 5), myelocytomatosis oncogene (Myc, 3.0-fold increase at wk 5), and phospholipase A2, group IIA (platelets, synovial fluid) (Plscr2, 8.0-fold increase at wk 10). The notable down-regulated genes in the colonic mucosa of mice treated with AOM/DSS were the peroxisome proliferator activated receptor binding protein (Pparbp, 0.06-fold decrease at wk 10) and the transforming growth factor, beta 3 (Tgfb3, 0.14-fold decrease at wk 10). The inflammation-related gene, peroxisome proliferator activated receptor gamma (Ppargamma 0.38-fold decrease at wk 5), was also down-regulated in the colonic mucosa of mice that received AOM/DSS. CONCLUSION: This is the first report describing global gene expression analysis of an AOM/DSS-induced mouse colon carcinogenesis model, and our findings provide new insights into the mechanisms of inflammation-related colon carcinogenesis and the establishment of novel therapies and preventative strategies against carcinogenesis.

Ursodeoxycholic acid versus sulfasalazine in colitis-related colon carcinogenesis in mice.

PURPOSE: Inflammation influences carcinogenesis. In the current study, we investigated whether ursodeoxycholic acid (UDCA) can inhibit colitis-related mouse colon carcinogenesis and compared it with the effects of sulfasalazine. EXPERIMENTAL DESIGN: Male CD-1 mice were given a single i.p. injection of azoxymethane followed by 1-week oral exposure of 1% dextran sodium sulfate in drinking water. They are then maintained on a basal diet mixed with UDCA (0.016%, 0.08%, or 0.4%) or sulfasalazine (0.05%) for 17 weeks. At week 20, the tumor-inhibitory effects of both chemicals were assessed by counting the incidence and multiplicity of colonic neoplasms. The immunohistochemical expression of the proliferating cell nuclear antigen labeling index in colonic epithelial malignancies was also assessed. Finally, at week 5, the mRNA expressions for cyclooxygenase-2, inducible nitric oxide synthase, peroxisome proliferator-activated receptor-gamma, and tumor necrosis factor-alpha were measured in nontumorous mucosa. RESULTS: Feeding the mice with UDCA at all doses significantly inhibited the multiplicity of colonic adenocarcinoma. The treatment also significantly lowered the proliferating cell nuclear antigen labeling index in the colonic malignancies. UDCA feeding reduced the expression of inducible nitric oxide synthase and tumor necrosis factor-alpha mRNA in the colonic mucosa, while not significantly affecting the expression of cyclooxygenase-2 mRNA and peroxisome proliferator-activated receptor-gamma mRNA. Sulfasalazine caused a nonsignificant reduction in the incidence and multiplicity of colonic neoplasia and did not affect these mRNA expression. CONCLUSIONS: Our findings suggest that UDCA rather than sulfasalazine could serve as an effective suppressing agent in colitis-related colon cancer development in mice.

A specific inducible nitric oxide synthase inhibitor, ONO-1714 attenuates inflammation-related large bowel carcinogenesis in male Apc(Min/+) mice.

It is generally assumed that inflammation influences carcinogenesis. We previously reported that dextran sodium sulfate (DSS) strongly enhances colon carcinogenesis in the Apc(Min/+) mice and the over-expression of inducible nitric oxide synthase (iNOS) contributes to this enhancement. In the current study, we investigated the effect of a selective iNOS inhibitor, ONO-1714 on colitis-related colon carcinogenesis in the Apc(Min/+) mouse treated with DSS. Male C57BL/6J Apc(Min/+) and Apc(+/+) mice were exposed to 1% DSS in their drinking water for 7 days. ONO-1714 was given to the mice at a dose level of 50 or 100 ppm in diet for 5 weeks (during the administration of DSS). The tumor inhibitory effects by ONO-1714 were assessed at week 5 by counting the incidence and multiplicity of colonic neoplasms. Additionally, we assessed serum lipid levels and colonic mRNA expression for cyclooxygenase (COX)-2, iNOS, tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta. Feeding with ONO-1714 significantly inhibited the occurrence of colonic adenocarcinoma in a dose-dependent manner in the Apc(Min/+) mice. In addition, the treatment with ONO-1714 significantly lowered the serum triglyceride levels and mRNA expression levels of COX-2, TNFalpha and IL-1beta of colonic mucosa in the DSS-treated Apc(Min/+) mice. Neither ONO-1714 nor DSS affected the colonic pathology in the Apc(+/+) mice. Our findings may suggest that ONO-1714 could therefore serve as an effective agent for suppression of colitis-related colon cancer development in the Apc(Min/+) mice.

Dietary beta-cryptoxanthin inhibits N-butyl-N-(4-hydroxybutyl)nitrosamine-induced urinary bladder carcinogenesis in male ICR mice.

Recent epidemiological studies have indicated that high dietary consumption of fruit and vegetables results in lower risk of bladder cancer. To confirm these findings, we investigated in the current study the effects of dietary administration with beta-cryptoxanthin extracted from Citras unshiu oranges on N-butyl-N-(4-hydroxybutyl)nitrosamine (OH-BBN)-induced urinary bladder carcinogenesis in mice. Male ICR mice were divided into 6 experimental and control groups. Groups 1 through 4 were given OH-BBN (500 ppm) in drinking water for 6 weeks to induced urinary bladder neoplasms. Mice in groups 2, 3 and 4 were fed the diets mixed with 1, 5 and 25 ppm of beta-cryptoxanthin, respectively, starting 1 week after the cessation of OH-BBN exposure, and kept on these diets for 24 weeks until the termination of the study. Group 5 was treated with the diet containing the test compound (25 ppm) alone, and group 6 served as an untreated control. All animals were sacrificed at week 32 for histopathology and immunohistochemistry (cyclin D1). Feeding with beta-cryptoxanthin decreased the incidence and multiplicity of preneoplastic and neoplastic lesions of urinary bladder. Notably, the highest dose (25 ppm) of the test chemical significantly lowered the occurrence of bladder carcinoma, in conjunction with reducing the cyclin D1-positive cell ratio. These findings suggest that beta-cryptoxanthin is able to prevent OH-BBN-induced bladder carcinogenesis in mice.

A prostaglandin E2 receptor subtype EP1-selective antagonist, ONO-8711, suppresses 4-nitroquinoline 1-oxide-induced rat tongue carcinogenesis.

We previously reported that certain cyclooxygenase (COX) inhibitors could inhibit chemically induced tongue carcinogenesis. In the present study, we investigated the effects of prostaglandin E(2) (PGE(2)) receptor EP(1)-selective antagonist ONO-8711 on 4-nitroquinoline 1-oxide (4-NQO)-induced oral carcinogenesis to know whether an EP(1) receptor involves in oral carcinogenesis. Male Fischer 344 rats were given drinking water containing 4-NQO for 8 weeks (20 p.p.m. for the initial 2 weeks, 25 p.p.m. for 2 weeks, and then 30 p.p.m. for 4 weeks). After 4-NQO treatment, animals were given 400 or 800 p.p.m. ONO-8711 containing diets for 23 weeks. The incidence of tongue squamous cell carcinomas (SCC) in the 4-NQO-treated rats was 64%, while that in the rats given ONO-8711 after 4-NQO exposure was 29 (P<0.05) and 29% (P<0.05) in the 400 and 800 p.p.m. of ONO-8711, respectively. The multiplicity of tongue cancer was also smaller in the 4-NQO + ONO-8711 (400 p.p.m. ONO-8711, 0.35 +/- 0.61; and 800 p.p.m. ONO-8711, 0.29 +/- 0.47; P<0.05), when compared with the 4-NQO alone group (0.88 +/- 0.88). Feeding with ONO-8711 significantly reduced PGE(2) level and cell proliferation activity in the non-tumorous epithelium of the tongue. Also, treatment with ONO-8711 resulted in the decrease in EP(1) immunohistochemical expression in the tongue lesions induced by 4-NQO. The results suggest that EP(1) receptor involves in oral carcinogenesis, and that an EP1-selective antagonist ONO-8711 exerts the cancer chemopreventive effects through the suppression of EP(1) expression, PGE(2) biosynthesis and cell proliferation.

Diet supplemented with citrus unshiu segment membrane suppresses chemically induced colonic preneoplastic lesions and fatty liver in male db/db mice.

The modulatory effects of dietary citrus unshiu segment membrane (CUSM) on the occurrence of aberrant crypt foci (ACF) and beta-catenin accumulated crypts (BCACs) were determined in male C57BL/KsJ-db/db (db/db) mice initiated with azoxymethane (AOM). Male db/db, db/+ and +/+ mice were given 5 weekly subcutaneous injections of AOM (15 mg/kg body weight), and then they were fed the diet containing 0.02%, 0.1% or 0.5% CUSM for 7 weeks. At Week 12, a significant increase in the numbers of ACF and BCAC was noted in the db/db mice in comparison with the db/+ and +/+ mice. Feeding with CUSM caused reduction in the frequency of ACF in all genotypes of mice and the potency was high in order of the db/db mice, db/+ mice and +/+ mice. The number of BCACs was also reduced by feeding with CUSM, thus resulting in a 28-61% reduction in the db/db mice, possibly due to suppression of cell proliferation activity in the lesions by feeding with CUSM-containing diet. Clinical chemistry revealed a low serum level of triglyceride in mice fed CUSM. In addition, CUSM feeding inhibited fatty metamorphosis and fibrosis in the liver of db/db mice. Our findings show that CUSM in the diet has a chemopreventive ability against the early phase of AOM-induced colon carcinogenesis in the db/db as well as db/+ and +/+ mice, indicating potential use of CUSM in cancer chemoprevention in obese people.

Catalpa seed oil rich in 9t,11t,13c-conjugated linolenic acid suppresses the development of colonic aberrant crypt foci induced by azoxymethane in rats.

Catalpa (Catalpa ovata) seed oil (CPO) is a unique oil that contains a high amount of 9trans,11trans,13cis-conjugated linolenic acid. In the present study, we investigated whether dietary administration with CPO affects the development of azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF) in male F344 rats to elucidate its possible cancer chemopreventive efficiency. Also, the effect of CPO on the fatty acid composition of liver tissue and colonic mucosa, the serum levels of total cholesterol and triglyceride, and the mRNA expression of cyclooxygenase (COX)-2 in the colonic mucosa were measured. In addition, the cell proliferation activity and apoptotic index in the colonic mucosa were estimated immunohistochemically. Animals were given two weekly subcutaneous injections of AOM (20 mg/kg body weight). They also received the experimental diet containing 0.01%, 0.1% or 1% CPO for 4 weeks, starting one week before the first dosing of AOM. AOM exposure produced a substantial number of ACF (99+/-28) at the end of the study (week 4). Dietary administration of CPO reduced the number of ACF (AOM + 0.01% CPO, 32+/-11, P<0.001; AOM + 0.1% CPO, 35+/-18, P<0.001; AOM + 1% CPO, 18+/-10, P<0.001). 9t,11t-conjugated linoleic acid was detected in the liver tissue and colonic mucosa of rats fed the CPO-containing diet. Additionally, dietary administration with CPO decreased the serum triglyceride level and the expression of COX-2 mRNA in the colonic mucosa. The indices of cell proliferation and apoptosis in the colonic mucosa of rats treated with AOM and 1% CPO have significant differences when compared with the AOM alone group. These findings suggest the possible chemopreventive activity of CPO in the early phase of colon carcinogenesis.

Preventive effects of chrysin on the development of azoxymethane-induced colonic aberrant crypt foci in rats.

The modifying effects of dietary feeding with chrysin (5,7-dihydroxyflavone) on the development of azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF) were investigated in male F344 rats. We also assessed the effect of chrysin on mitosis and apoptosis in 'normal appearing' crypts. To induce ACF, rats were given two weekly subcutaneous injections of AOM (20 mg/kg body weight). They also received an experimental diet containing chrysin (0.001 or 0.01%) for 4 weeks, starting 1 week before the first dose of AOM. AOM exposure produced a substantial number of ACF (73+/-13/rat) at the end of the study (week 4). Dietary administration of chrysin caused significant reduction in the frequency of ACF: 0.001% chrysin, 37+/-17/rat (49% reduction, P<0.001); and 0.01% chrysin, 40+/-10/rat (45% reduction, P<0.001). In addition, chrysin administration significantly reduced the mitotic index and significantly increased the apoptotic index in 'normal appearing' crypts. These findings might suggest a possible chemopreventive activity of chrysin in the early step of colon tumorigenesis through modulation of cryptal cell proliferation activity and apoptosis.

Dietary administration with prenyloxycoumarins, auraptene and collinin, inhibits colitis-related colon carcinogenesis in mice.

We previously reported the chemopreventive ability of a prenyloxycoumarin auraptene in chemically induced carcinogenesis in digestive tract, liver and urinary bladder of rodents. The current study was designed to determine whether dietary feeding of auraptene and its related prenyloxycoumarin collinin can inhibit colitis-related mouse colon carcinogenesis. The experimental diets, containing the compounds at 2 dose levels (0.01 and 0.05%), were fed for 17 weeks to male CD-1 (ICR) mice that were initiated with a single intraperitoneal injection of azoxymethane (AOM, 10 mg/kg body weight) and promoted by 1% (w/v) DSS in drinking water for 7 days. Their tumor inhibitory effects were assessed at week 20 by counting the incidence and multiplicity of colonic neoplasms and the immunohistochemical expression of proliferating cell nuclear antigen (PCNA)-labeling index, apoptotic index, cyclooxygenase (COX)-2, inducible nitric oxide (iNOS) and nitrotyrosine in colonic epithelial malignancy. Feeding with auraptene or collinin, at both doses, significantly inhibited the occurrence of colonic adenocarcinoma. In addition, feeding with auraptene or collinin significantly lowered the positive rates of PCNA, COX-2, iNOS and nitrotyrosine in adenocarcinomas, while the treatment increased the apoptotic index in colonic malignancies. Our findings may suggest that certain prenyloxycoumarins, such as auraptene and collinin, could serve as an effective agent against colitis-related colon cancer development in rodents.

beta-Catenin-accumulated crypts in the colonic mucosa of juvenile ApcMin/+ mice.

Although Apc(Min/+) mice are widely used for an animal model of human familial adenomatous polyposis (FAP), a majority of intestinal polyps locate in the small intestine. We recently reported that numerous beta-catenin-accumulated crypts (BCAC), which are reliable precursor lesions for colonic adenocarcinoma, develop in the large bowel of aged Apc(Min/+) mice. In this study, we determined the presence and location of BCAC in the large intestine of juvenile Apc(Min/+) mice (3 and 5 weeks of age). Surprisingly, BCAC were noted in the colon of even Apc(Min/+) mice of both ages, and mainly located in the distal and middle segments of the colon. Also, a few microadenomas were detected in Apc(Min/+) mice of 5-week old. Our results may indicate need of further investigation of the colorectal mucosa of Apc(Min/+) mice for examining colorectal carcinogenesis using Apc(Min/+) mice.

An animal model for the rapid induction of tongue neoplasms in human c-Ha-ras proto-oncogene transgenic rats by 4-nitroquinoline 1-oxide: its potential use for preclinical chemoprevention studies.

Oral squamous cell carcinoma is one of the most common human neoplasms, and prevention of this malignancy requires a better understanding of its carcinogenesis process. To this end, we tried to establish an animal model using the human c-Ha-ras proto-oncogene-carrying transgenic (Tg) rats and the carcinogen 4-nitroquinoline 1-oxide (4-NQO). 4-NQO (20 p.p.m.) was administered to Tg and non-Tg rats for 8 weeks in their drinking water, and then the occurrence of tongue carcinogenesis was compared during the experimental period of 22 weeks. In addition, we determined the DNA ploidy in tongue lesions and examined the immunohistochemical expression of five biomarkers such as cyclin D1, glutathione S-transferase placental form, cyclooxygenase (COX)-2, inducible nitric oxide synthase (iNOS) and beta-catenin. Next, the cancer chemopreventive effects of nimesulide, pioglitazone and a synthetic geranylated derivative, which have been reported to be inhibitors of tongue carcinogenesis, were examined in Tg rats treated with 4-NQO. Either during or after treatment with 4-NQO in the drinking water, tongue dysplasia and tumors were observed on the tongues of both Tg and non-Tg rats, with a greater incidence and multiplicity in Tg rats. Histopathologically, squamous cell dysplasia, papilloma and carcinoma with or without invasion were present in the tongue. Immunohistochemistry revealed that expression levels against five biomarkers increase with disease progression, and the changes correlated with those of the DNA ploidy pattern. Interestingly, a strong expression of COX-2, iNOS and beta-catenin was observed on the invasive front of squamous cell carcinomas. A subsequent chemoprevention study using Tg rats showed that the chemicals tested suppressed the occurrence of tongue carcinomas when they were administered after 4-NQO-exposure. These results may thus indicate that our 4-NQO-induced Tg rat tongue carcinogenesis model simulates many aspects of human oral carcinogenesis and it can be applied for an analysis of oral cancer development while also helping to identify potentially effective cancer chemopreventive agents against oral cancer.