Development Of Cancer In Rats Research Articles

Supplementation of Choline-Deficient Diet With Pterostilbene Attenuates Cancer Development and Epigenetic Dysregulation of Gene Expression in Rat Livers

Abstract Objectives Nearly 40% of humans have polymorphisms in genes involved in choline metabolism which makes them prone to developing choline deficiency and increased risk for liver damage and liver cancer. Choline is a source of methyl groups needed for many steps in metabolism and epigenetic regulation of gene expression. Although epigenetic aberrations are known to be induced by choline deficiency, it remains unknown how to reverse the changes and attenuate symptoms. Interestingly, certain dietary compounds such as polyphenols have been demonstrated to reverse aberrant epigenetic patterns and exert anti-cancer action. In the present study, we investigate the effects of pterostilbene (PTS) on liver cancer development in rats fed choline-deficient diet and explore mechanisms underlying these effects. Methods Fischer 344 rats were fed a choline-sufficient (CSAA, healthy control group), a choline-deficient (CDAA, cancer group) L-amino acid-defined diet or a CDAA diet supplemented with PTS (134 mg/kg BW/day) (n = 6 per group). At the end of 52 weeks, analyses of liver nodules and histopathological features were performed followed by genome-wide investigation of gene expression in livers using RNA sequencing. DNA methylation was assessed by pyrosequencing. Results A total of 708 genes were significantly differentially expressed in CDAA + PTS group as compared with CDAA group. Among 351 upregulated genes were Bhmt (4.5-fold), G6pc (3.1-fold), and Aldh1l1 (2.6-fold). These metabolism-related genes were significantly downregulated in CDAA vs. CSAA group and their suppression was associated with liver cancer in previous reports. Among 357 genes found to be significantly downregulated by PTS were strong oncogenes such as Mmp12 (2-fold), Myc (1.9-fold) and Mmp27 (1.8-fold). We found PTS-mediated downregulation of Mmp12, that was a top gene upregulated in CDAA vs. CSAA, coincided with 43% hypermethylation of Mmp12 promoter. Conclusions Our findings demonstrate that PTS-mediated changes in gene expression could correspond to changes in DNA methylation of gene regulatory regions and could at least partially explain the observed attenuation of cancer development due to choline deficiency. Funding Sources UBC VP Academic Award, CFI John. R. Evans Leaders Fund, and BC Knowledge Development Fund granted to BS.

Chemopreventive potential of adrenergic blocker in behavioral stress accelerated prostate cancer development in rats

Chemopreventive potential of adrenergic blocker in behavioral stress accelerated prostate cancer development in rats

Diallyl Trisulfide Inhibits Leptin-induced Oncogenic Signaling in Human Breast Cancer Cells but Fails to Prevent Chemically-induced Luminal-type Cancer in Rats.

Previous studies have demonstrated inhibitory effect of garlic component diallyl trisulfide (DATS) on growth of breast cancer cells in vitro and in vivo. This study investigated the effect of DATS on oncogenic signaling regulated by leptin, which plays an important role in breast carcinogenesis. Leptin-induced phosphorylation and nuclear translocation of STAT3 was inhibited significantly in the presence of DATS in MCF-7 (a luminal-type human breast cancer cell line) and MDA-MB-231 (a basal-like human breast cancer cell line). Leptin-stimulated cell proliferation, clonogenic cell survival, and migration and/or invasion ability in MCF-7 and/or MDA-MB-231 cells were also suppressed by DATS treatment. DATS exposure resulted in inhibition of leptin-stimulated expression of protein and/or mRNA levels of Bcl-2, Bcl-xL, Cyclin D1, vascular endothelial growth factor, and matrix metalloproteinase-2. Western blotting revealed a decrease in protein levels of phosphorylated STAT3 in breast cancer xenografts from DATS-treated mice when compared to controls in vivo. However, the incidence of N-methyl-N-nitrosourea-induced luminal-type breast cancer development in rats was not affected by oral administration of 5 mg/kg or 25 mg/kg DATS. The present study reveals that oncogenic signaling induced by leptin is inhibited in the presence of DATS but higher doses of this phytochemical may be required to achieve chemopreventive activity.

Vitamin K2 supplementation blocks the beneficial effects of IFN-α-2b administered on the early stages of liver cancer development in rats.

Vitamin K2, which is present in dairy products and has been recommended as a micronutrient supplement in humans, contains anticancer properties. Interferon (IFN)-α-2b administered during development of hepatic preneoplasia decreased both number and volume percentage of altered hepatic foci (AHF) by increasing apoptosis in the foci. The aim of this study was to evaluate the effects of IFN-α-2b treatment supplemented with vitamin K2 in the early stages of liver cancer development in rats. Adult male Wistar rats were subjected to a two-phase model of hepatocarcinogenesis (initiated-promoted [IP] group). Animals were divided into four groups: untreated (IP), IP treated with IFN-α-2b (6.5 × 105 U/kg), IP treated with vitamin K2 (10 mg/kg), and IP treated with both compounds. The study results demonstrated that vitamin K2 blocked IFN-α-2b-induced reduction in size and volume of the altered hepatic foci and inhibited IFN-α-2b-induced apoptosis. Its inhibition of IFN-α-2b-induced apoptosis was mediated by increased levels of total hepatic Bcl-2 in rat preneoplastic livers. These findings demonstrate that supportive vitamin supplements or therapies are not always safe because they could put the life of patients treated with IFN-α-2b at risk.

Enhancement of Uterine Cancer Development after Oocyte Depletion by Juvenile Exposure to Gamma Radiation in Rats: - A Comparative Study on Sensitivity of Damage to Female Reproductive Organs by Radiation between Juvenile and Adulthood Using a Rat Model.

To clarify sensitivities of juvenile exposure to radiation on uterine carcinogenesis, female Donryu rats, a high yield strain of uterine corpus cancer, were exposed to 0.2 and 1.0 Gy of gamma radiation at postnatal day 14. Sequential changes in their reproductive organs and hematology, and the effects on uterine tumor development were compared to those in adult rats exposed to the same doses. Half number of the rats in each group was treated with N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) after the radiation to accelerate the development of uterine cancer. Severe apoptosis and depletion of oocytes in the primordial/primary follicles were immediately induced after juvenile exposure at 1.0 Gy only. The ovaries in rats exposed to 1.0 Gy at juvenile showed severe atrophy characterized by the loss of all types of follicles and a lack of corpora lutea by 2 months of age, and all rats elicited an early onset of persistent estrus corresponding to the atrophy. At the termination of 9 months of age, juvenile 1.0 Gy exposure with ENNG treatment increased the incidence of endometrial adenocarcinoma and the multiplicities of combined endometrial adenocarcinomas and their precancerous lesions. Enhancement of uterine cancer development was not apparent at the same exposure without ENNG. In comet assays, neither 0.2 nor 1.0 Gy juvenile exposure induced direct DNA damage to uteri though the damage was found in the ovary at 1.0 Gy. The present results indicated that juvenile exposure to gamma radiation indirectly enhanced uterine cancer development in rats through direct damage to oocytes resulting in serious atrophy of the ovary accompanying early onset of persistent estrus. The damage to ovary was more sensitive at juvenile than adults. The result in comet assay suggested that direct DNA damage to the uterus by radiation was excluded.

Impact of stress and levels of corticosterone on the development of breast cancer in rats.

Stress is experienced during cancer, and impairs the immune system’s ability to protect the body. Our aim was to investigate if isolation stress has an impact on the development of tumors in rats, and to measure the size and number of tumors and the levels of corticosterone. Breast cancer was induced in two groups of female rats (N=20) by administration of a single dose of N-methyl-N-nitrosourea 50 mg/kg. Rats in the control group (cancer induction condition) were allowed to remain together in a large cage, whereas in the second group, rats were also exposed to a stressful condition, that is, isolation (cancer induction and isolation condition, CIIC). The CIIC group displayed anxious behavior after 10 weeks of isolation. In the CIIC group, 16 tumors developed, compared with only eleven tumors in the control cancer induction condition group. In addition, compared with the control group, the volume of tumors in the CIIC group was greater, and more rats had more than one tumor and cells showed greater morphological damage. Levels of corticosterone were also significantly different between the two groups. This study supports the hypothesis that stress can influence the development of cancer, but that stress itself is not a sufficient factor for the development of cancer in rats. The study also provides new information for development of experimental studies and controlled environments.

P0026 The chemopreventive potential of Curcuma purpurascens rhizome in reducing azoxymethane-induced aberrant crypt foci in rats

Background Curcuma purpurascens rhizome, a member of the Zingiberaceae family, is a popular spice in Indonesia and is traditionally used for assorted remedies. Dichloromethane extract of C. purpurascens rhizome (DECPR) has previously been shown to have apoptosis-inducing effect on colon cancer cells. Methods We examined the potential of DECPR to prevent colon cancer development in rats treated with azoxymethane (AOM, 15 ml/kg) by the incidence of aberrant crypt foci (ACF). Starting from the day immediately after AOM treatment, the rats were orally administered once a day for 2 months with 10% Tween-20 (5 ml/kg, cancer control), DECPR (250 mg/kg, low dose) and DECPR (500 mg/kg, high dose). Meanwhile, the control group was intra-peritoneally injected with fluorouracil (35 mg/kg) for 5 days consecutively. After euthanising the rats, the number of ACF was enumerated in colon tissues. Bax, Bcl-2, and PCNA protein levels were examined using immunohistochemical and western blot analyses. Antioxidant enzymatic activity was measured in colon tissue homogenates and associated with malondialdehyde level. Findings DECPR exposure at both doses significantly decreased AOM-induced ACF formation, which was accompanied with the reduced expression of PCNA. Up-regulation of Bax and down-regulation of Bcl-2 suggested the involvement of apoptosis in the chemopreventive effect of DECPR. In addition, the oxidative stress resulting from AOM treatment was significantly attenuated after administration of DECPR, which was shown by the elevated antioxidant enzymatic activity and reduced malondialdehyde level. Interpretation DECPR significantly inhibits ACF formation in AOM-treated rats and may offer protection against colon cancer development.

The chemopreventive potential of Curcuma purpurascens rhizome in reducing azoxymethane-induced aberrant crypt foci in rats

Curcuma purpurascens BI. rhizome, a member of the Zingiberaceae family, is a popular spice in Indonesia that is traditionally used in assorted remedies. Dichloromethane extract of C. purpurascens BI. rhizome (DECPR) has previously been shown to have an apoptosis-inducing effect on colon cancer cells. In the present study, we examined the potential of DECPR to prevent colon cancer development in rats treated with azoxymethane (AOM) (15 mg/kg) by determining the percentage inhibition in incidence of aberrant crypt foci (ACF). Starting from the day immediately after AOM treatment, three groups of rats were orally administered once a day for 2 months either 10% Tween 20 (5 mL/kg, cancer control), DECPR (250 mg/kg, low dose), or DECPR (500 mg/kg, high dose). Meanwhile, the control group was intraperitoneally injected with 5-fluorouracil (35 mg/kg) for 5 consecutive days. After euthanizing the rats, the number of ACF was enumerated in colon tissues. Bax, Bcl-2, and proliferating cell nuclear antigen (PCNA) protein expressions were examined using immunohistochemical and Western blot analyses. Antioxidant enzymatic activity was measured in colon tissue homogenates and associated with malondialdehyde level. The percentage inhibition of ACF was 56.04% and 68.68% in the low- and high-dose DECPR-treated groups, respectively. The ACF inhibition in the treatment control group was 74.17%. Results revealed that DECPR exposure at both doses significantly decreased AOM-induced ACF formation, which was accompanied by reduced expression of PCNA. Upregulation of Bax and downregulation of Bcl-2 suggested the involvement of apoptosis in the chemopreventive effect of DECPR. In addition, the oxidative stress resulting from AOM treatment was significantly attenuated after administration of DECPR, which was shown by the elevated antioxidant enzymatic activity and reduced malondialdehyde level. Taken together, the present data clearly indicate that DECPR significantly inhibits ACF formation in AOM-treated rats and may offer protection against colon cancer development.

Inulin Diet Intervention on Chemopreventive and Inflammatory Markers in Tumorigenesis of Colorectal Cancer

Abstract The aim of this experiment was to investigate the infl uence of inulin administration on chemopreventive and inflammatory markers in dimethylhydrazine induced colorectal cancer development in rats. A group of 30 Sprague-Dawley rats was divided into a control group (CG), a group with dimethylhydrazine (DMH), and a group given dimethylhydrazine combined with the prebiotic (DMH+PRE). Dimethylhydrazine injection significantly (p<0.001) elevated the immunoreactivity chemopreventive markers COX-2, NFκB, iNOS, elevated serum and jejunal mucosa levels of proinfl ammatory cytokine IL-2, and decreased serum and jejunal mucosa levels of regulatory cytokine IL-10. Inulin diet intervention significantly suppressed immunoreactivity of COX- 2, NFκB, iNOS positive cells in the tunica mucosae and tela submucosae of rat colon tissue, increased levels of IL-2 and decreased levels of IL-10. By determining the chemopreventive markers COX-2, iNOS and NFkB, which can be characterized as inflammatory markers, we confirmed the presence of inflammation in the colon as the number of COX-2, NFkB and iNOS immunoreactive cells was significantly higher after DMH application than in the control group. These findings indicate that dietary intake of inulin suppressed the expression of the observed markers, which play an important role in carcinogenesis and inflammation, which predispose the use of inulin in the prevention or treatment of human chronic diseases and its use as a nutritional supplement in veterinary medicine.

An expression analysis of miR-200a in serum and liver tissue during the process of liver cancer development in rats

To explore whether microRNA-200a (miR-200a) could be used as a novel biomarker of liver cancer using a rat model system. Diethylnitrosamine abdominal injection was applied to induce liver cancer in the F344 rat strain (n =40); ten unmodeled rats served as controls. In addition, human subjects with normal healthy liver (n =10), liver cirrhosis (n =10), and liver cancer (n =10) were enrolled in the study. Blood samples from both rats and patients and rats' livers were collected for analysis. Real-time quantitative PCR and enzyme-linked immunosorbent assay were used respectively to measure the expressions of serum miR-200a and alpha-fetoprotein (AFP) for all rat and human subjects. In situ hybridization was used to detect the miR-200a expression in the rats' livers. Comparison of normal rats and the liver cancer modeled rats showed that the latter had significantly lower expression of miR-200a (P less than 0.05), with decreasing expression following the progression of liver injury to cancer (liver cirrhosis rats less than early liver cancer rats less than advanced liver cancer rats); in contrast, the AFP levels were significantly higher in the liver cancer modeled rats only at the early and advanced stages of the liver cancer (P less than 0.05). These suggested that miR-200a expression decreases during the developmental process of liver cancer, while AFP expression increases distinctly at the stage of tumor formation. Analysis of the human subjects' clinical samples showed that miR-200a expression was decreased in both liver cirrhosis patients and liver cancer patients (vs. normal liver subjects, P less than 0.05), while AFP showed abnormal expression only in the patients with liver cancer. Comparison of the normal rats and modeled rats using in situ hybridization showed the positive rates for miR-200a expression were 1.00% +/- 0.01% in rats with normal liver, 0.37% +/- 0.03% in rats with fibrotic liver, 0.14% +/- 0.01% in rats with cirrhotic liver, 0.05% +/- 0.00% in rats with early stage liver cancer, and 0.01% +/- 0.00% in rats with advanced stage liver cancer. MiR-200a may play an important role in liver cancer development and may have diagnostic value for indicating early liver cancer.

ω-3-Polyunsaturated Fatty Acids and Colon Cancer

C olorectal cancer is the third most common cancer in USA. American Cancer Society has estimated about 103,170 cases of colon and 40,290 cases of rectal cancer in 2012. Colorectal cancer deaths account for 9% of all cancer deaths; 51,690 deaths from colorectal cancer are estimated in 2012 [1]. Fatty acid composition of dietary fat is one of detrimental factors in colon cancer development. Studies have indicated that diets containing high level of ω-6-polyunsaturated fatty acids such as linoleic acid enhance whereas diets containing ω-3- polyunsaturated fatty acids such as eicosapentaenoic acid reduce chemically-induced colon cancer development in rodents [2,3]. Diets containing fish oil (source of ω-3-polyunsaturated fatty acid) decrease colon carcinogenesis [4]. The effects of dietary fish oil on eicosanoid metabolism have been implicated as a potential mechanism of colon cancer prevention. ω-3-Fattyacids present in fish oil inhibit oxidative metabolism of arachidonic acid by the cyclooxygenase (COX) pathway responsible for prostaglandin synthesis which act as a tumor promoter [5]. Dietary mustard oil, a rich source of α-linolenic acid, an ω-3fatty acid prevented colon cancer development in rats [6]. Dietary flaxseed oil, another very rich source of α-linolenic acid was effective in preventing colon cancer development in rats. Dietary flaxseed oil decreased the ratio of ω-6 to ω-3-fatty acids to optimal levels [7]. Dietary flaxseed meal, a rich source of α-linolenic acid, an ω-3-fatty acid and lignans also prevented colon cancer development in rats by increasing ω-3-fatty acids in serum and tissues, and decreasing expressions of COX-1 and COX-2 levels in tissues [8]. α-Linolenic acid and lignans (enterodiol and enterolactone derived from flaxseed) caused a decrease in cell proliferation and an increase in apoptosis in Caco-2, human colon cancer cells [9]. Dietary flaxseed also prevented intestinal tumor development in APC M in mice (a transgenic mice with mutation in APC gene causing development of spontaneous intestinal tumors) by increasing ω-3-fatty acids and lignans, and decreasing expressions of COX-1 and COX-2 levels [10]. Dietary canola oil, another source of α-linolenic acid was effective in preventing colon cancer development in rats by increasing ω-3-fatty acids in serum and tissues and decreasing the expression of COX-1 and COX-2 in tissues [11]. These studies have provided evidence indicating consumption of ω-3-fatty acids provides protection against colon cancer development in animal models and cell culture. Thus, dietary consumption of ω-3 fatty acid (fish, mustard, flax, canola) may provide protection in humans too. However, further studies in human volunteers are needed to establish the efficacy of ω-3-fatty acids for preventing colon cancer.

Abstract 5543: Partial inhibition of estrogen-induced breast cancer by tamoxifen in female ACI rats: Implications of oxidant stress

Abstract Epidemiological and experimental evidence strongly supports the role of estrogens in the etiology of breast cancer. Both estrogen receptor [ER]-dependent and ER-independent mechanisms are implicated in estrogen-induced breast carcinogenesis. Tamoxifen, a selective ER modulator is widely used as chemoprotectant in human breast cancer. It binds to ERs and interferes with normal binding of estrogen to ER and the resultant ER-dependent processes. Tamoxifen treatment for six months has previously been reported to result in complete abrogation of 17β-estradiol (E2)-induced breast cancer in female ACI rats. We investigated the effect of tamoxifen on breast tumor incidence in female ACI rats after treatment with tamoxifen for 8 months. Female ACI rats were treated with E2 (3 mg pellet, s.c.), tamoxifen (40 mg pellet, s.c.) or with a combination of E2 and tamoxifen. At the time of surgery, breast tumors were detected in the 44% of rats co-treated with tamoxifen + E2 compared to 82% in rats treated with E2 alone. The tumors were confirmed as breast adenocarcinomas by histopathological examination of paraffin-embedded tissues. Immunohistochemical and real time-PCR analysis indicated increased expression of ER-α and progesterone receptor in E2-treated mammary tissue compared to age-matched controls and inhibition of these receptors in the mammary tissue of tamoxifen-treated groups. Cytochrome P450 3A4 (CYP 3A4), and CYP 2D6, the main enzymes involved in tamoxifen metabolism were unchanged in the mammary tissue of all the treatment groups compared to controls. Tissue levels of oxidative stress markers were quantified in the mammary tissues of rats. Superoxide dismutase 2, catalase and glutathione peroxidase expressions were differentially altered in E2, tamoxifen and tamoxifen + E2 co-treated groups compared to age-matched controls. Co-treatment with tamoxifen did not decrease E2-mediated increases in 8-iso-prostane F2α levels, a marker of lipid peroxidation/oxidative stress. Oxidative stress-mediated DNA damage marker, 8-hydroxydeoxyguanosine, was quantified in the mammary tissues of all the treatment groups. Co-treatment of tamoxifen with E2 did not inhibit E2-mediated increase in 8-hydroxydeoxyguanosine levels in mammary tissue. In summary, our studies suggest that inhibition of ER-mediated processes by tamoxifen does not completely abrogate estrogen-dependent breast tumor development in a rat model of estrogen-induced breast cancer. Our results further demonstrate that tamoxifen does not decrease E2-mediated oxidant stress and DNA damage. Thus, chronic exposure to estrogen-mediated oxidative stress may contribute to the development of breast cancer in rats co-treated with E2 and tamoxifen. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5543. doi:10.1158/1538-7445.AM2011-5543

In vitro profiling of epigenetic modifications underlying heavy metal toxicity of tungsten-alloy and its components

Tungsten-alloy has carcinogenic potential as demonstrated by cancer development in rats with intramuscular implanted tungsten-alloy pellets. This suggests a potential involvement of epigenetic events previously implicated as environmental triggers of cancer. Here, we tested metal induced cytotoxicity and epigenetic modifications including H3 acetylation, H3-Ser10 phosphorylation and H3-K4 trimethylation. We exposed human embryonic kidney (HEK293), human neuroepithelioma (SKNMC), and mouse myoblast (C2C12) cultures for 1-day and hippocampal primary neuronal cultures for 1-week to 50–200μg/ml of tungsten-alloy (91% tungsten/6% nickel/3% cobalt), tungsten, nickel, and cobalt. We also examined the potential role of intracellular calcium in metal mediated histone modifications by addition of calcium channel blockers/chelators to the metal solutions. Tungsten and its alloy showed cytotoxicity at concentrations >50μg/ml, while we found significant toxicity with cobalt and nickel for most tested concentrations. Diverse cell-specific toxic effects were observed, with C2C12 being relatively resistant to tungsten-alloy mediated toxic impact. Tungsten-alloy, but not tungsten, caused almost complete dephosphorylation of H3-Ser10 in C2C12 and hippocampal primary neuronal cultures with H3-hypoacetylation in C2C12. Dramatic H3-Ser10 dephosphorylation was found in all cobalt treated cultures with a decrease in H3 pan-acetylation in C2C12, SKNMC and HEK293. Trimethylation of H3-K4 was not affected. Both tungsten-alloy and cobalt mediated H3-Ser10 dephosphorylation were reversed with BAPTA-AM, highlighting the role of intracellular calcium, confirmed with 2-photon calcium imaging. In summary, our results for the first time reveal epigenetic modifications triggered by tungsten-alloy exposure in C2C12 and hippocampal primary neuronal cultures suggesting the underlying synergistic effects of tungsten, nickel and cobalt mediated by changes in intracellular calcium homeostasis and buffering.

Allyl isothiocyanate-rich mustard seed powder inhibits bladder cancer growth and muscle invasion

Allyl isothiocyanate (AITC), which occurs in many common cruciferous vegetables, was recently shown to be selectively delivered to bladder cancer tissues through urinary excretion and to inhibit bladder cancer development in rats. The present investigation was designed to test the hypothesis that AITC-containing cruciferous vegetables also inhibit bladder cancer development. We focused on an AITC-rich mustard seed powder (MSP-1). AITC was stably stored as its glucosinolate precursor (sinigrin) in MSP-1. Upon addition of water, however, sinigrin was readily hydrolyzed by the accompanying endogenous myrosinase. This myrosinase was also required for full conversion of sinigrin to AITC in vivo, but the matrix of MSP-1 had no effect on AITC bioavailability. Sinigrin itself was not bioactive, whereas hydrated MSP-1 caused apoptosis and G(2)/M phase arrest in bladder cancer cell lines in vitro. Comparison between hydrated MSP-1 and pure sinigrin with added myrosinase suggested that the anticancer effect of MSP-1 was derived principally, if not entirely, from the AITC generated from sinigrin. In an orthotopic rat bladder cancer model, oral MSP-1 at 71.5 mg/kg (sinigrin dose of 9 μmol/kg) inhibited bladder cancer growth by 34.5% (P < 0.05) and blocked muscle invasion by 100%. Moreover, the anticancer activity was associated with significant modulation of key cancer therapeutic targets, including vascular endothelial growth factor, cyclin B1 and caspase 3. On an equimolar basis, the anticancer activity of AITC delivered as MSP-1 appears to be more robust than that of pure AITC. MSP-1 is thus an attractive delivery vehicle for AITC and it strongly inhibits bladder cancer development and progression.

Synbiotic intervention of Bifidobacterium lactis and resistant starch protects against colorectal cancer development in rats

This study evaluated the effect of a probiotic bacteria 'Bifidobacterium lactis', the carbohydrate 'resistant starch' (RS) and their combination (synbiotic), on their ability to protect against colorectal cancer (CRC). Bifidobacterium lactis has been shown previously to utilize RS as a substrate and up-regulate the acute apoptotic response to a carcinogen in the colon [Le Leu et al. (2005) J. Nutr., 135, 996-1001]. Sprague-Dawley rats were divided into six equal groups and fed semi-purified diets for 30 weeks. Colonic neoplasms were induced by 2 weekly injections of azoxymethane (15 mg/kg body wt). The experimental groups were as follows: control-no added dietary fibre or RS; RS in two forms-Hi-maize 958 or Hi-maize 260; B.lactis (lyophilized)-added to control and RS diets (six treatment groups in all). Rats fed RS in combination with B.lactis showed significantly lowered incidence and multiplicity of colonic neoplasms (P < 0.01) by >50% compared with the control group. There was a trend for protection by RS alone (P = 0.07), whereas no protection against cancer was seen in the group supplemented with only B.lactis. Fermentation events [short-chain fatty acid (SCFA), pH] were altered by the inclusion of RS into the diet, whereas the inclusion of B.lactis into the diet had no significant effect on the fermentation parameters. The synbiotic combination of RS and B.lactis significantly protects against the development of CRC in the rat-azoxymethane model. Synbiotic combination of prebiotic and probiotic seems likely to be a superior preventive strategy to prebiotic alone.

Effect of processing on folic acid fortified Baladi bread and its possible effect on the prevention of colon cancer

This paper studied the possible effect of folic acid in fortified Baladi bread on the prevention of colon cancer development in rats. Wheat flour samples (82% extraction rate) and soy bean flour were analyzed to determine their folic acid contents using the High Performance Liquid Chromatography (HPLC). Unfortified and folic acid fortified Baladi breads were prepared. Samples from each step of bread preparation were analyzed for folic acid concentration. Protein, fat, ash, fibers and carbohydrates percentages were also determined. Rats were divided into five groups, four of them were injected subcutaneously with dimethylhydrazine (DMH). After 15 weeks, the rats were sacrificed for pathological examination. Results showed that the folic acid content in wheat flour (82% extraction rate) was found to be highly significantly lower than that in soybean flour. After baking, folic acid content in all breads was found to decrease significantly. The highest protein and fat contents were found in soybean flour fortified Baladi bread. The colons of rats of groups 3 (fed 5% soy flour fortified Baladi bread) and 5 (fed Baladi bread fortified with 5% soy flour + 8 mg folic acid/kg wheat flour) were the mostly affected by DMH injection as premalignant changes were observed.

Effects of resveratrol, an important component of red wine, on intestinal cancer development

Effects of resveratrol, an important component of red wine, on intestinal cancer development Xiaoying Zhang1, Jan Anderson1, Radhey S Kaushik2,3, Chandradhar Dwivedi11Department of Pharmaceutical Sciences; 2Department of Veterinary Sciences; 3Department of Biology/Microbiology, South Dakota State University, Brookings, SD, USAAbstract: Resveratrol, a natural product derived from grapes and an important component of red wine, has been shown to inhibit cyclooxygenase and prevent various cancers. The purpose of this study is to investigate the effects of dietary grape extract, a source of resveratrol on intestinal cancer development in rats and to determine effects of resveratrol on cell growth in human colonic adenocarcinoma (Caco-2) cells, thus elucidating possible mechanisms of action of resveratrol. Results showed that dietary grape extract (5%, about 7 μg resveratrol consumed daily) significantly decreased the incidence and multiplicity of tumors in small intestine in rats and resveratrol significantly inhibited cell viability and cell proliferation in Caco-2 cells.Keywords: resveratrol, grapes, colonic adenocarcinoma, Caco-2 cells

OL-025 Influence of pregnancy on the development of liver cancer in rats

OL-025 Influence of pregnancy on the development of liver cancer in rats

Suppression of azoxymethane-induced colon cancer development in rats by dietary resistant starch

Resistant starch is a complex carbohydrate that reaches the colon where it can be fermented by the colonic microflora resulting in production of short chain fatty acids (SCFA), in particular butyrate. RS effects on colorectal tumourigenesis are contrasting and protection remains controversial. Butyrate has an important role as the preferred metabolic fuel and regulator of colonocyte proliferation, differentiation and apoptosis and may play a role in cancer prevention. Thus variation in butyrate production from different substrates might explain the variation in effect of RS. This study evaluated the hypothesis that feeding dietary resistant starch (as high amylose maize starch) would protect against azoxymethane (AOM)-colon carcinogenesis and favourably influence the colonic luminal environment. Male Sprague-Dawley rats (n = 90 were provided one of three diets: Control (without added dietary fibre or RS), 10% HAS (contained 100 g/kg raw high amylose maize starch) or 20% HAS (contained 200 g/kg high amylose maize starch). Rats were fed their experimental diets for 4 weeks after which they were injected with AOM (15 mg/kg) during the fifth and six week. Colons were resected (25 weeks post second injection) for evaluation of tumour formation, apoptosis, proliferating cell nuclear antigen (PCNA) labelling index and short chain fatty acid levels. Feeding resistant starch significantly reduced the incidence (P

Biphasic Effect of Falcarinol on CaCo-2 Cell Proliferation, DNA Damage, and Apoptosis

The polyacetylene falcarinol, isolated from carrots, has been shown to be protective against chemically induced colon cancer development in rats, but the mechanisms are not fully understood. In this study CaCo-2 cells were exposed to falcarinol (0.5-100 microM) and the effects on proliferation, DNA damage, and apoptosis investigated. Low-dose falcarinol exposure (0.5-10 microM) decreased expression of the apoptosis indicator caspase-3 concomitantly with decreased basal DNA strand breakage. Cell proliferation was increased (1-10 microM), whereas cellular attachment was unaffected by <10 microM falcarinol. At concentrations above 20 microM falcarinol, proliferation of CaCo-2 cells decreased and the number of cells expressing active caspase-3 increased simultaneously with increased cell detachment. Furthermore, DNA single-strand breakage was significantly increased at concentrations above 10 microM falcarinol. Thus, the effects of falcarinol on CaCo-2 cells appear to be biphasic, inducing pro-proliferative and apoptotic characteristics at low and high concentrations of falcarinol, respectively.