Adiponectin deficiency enhances colorectal carcinogenesis and liver tumor formation induced by azoxymethane in mice

AIM:To investigate the causal relationship between hypoadiponectinemia and colorectal carcinogenesis in in vivo experimental model,and to determine the con-tribution of adiponectin defi ciency to colorectal cancer development and proliferation.METHODS:We examined the influence of adiponectin defi ciency on colorectal carcinogenesis induced by the administration of azoxymethane(AOM)(7.5 mg/kg,in-traperitoneal injection once a week for 8 wk),by using adiponectin-knockout(KO) mice.RESULTS:At 53 wk after the fi rst AOM treatment,KOmice developed larger and histologically more progres-sive colorectal tumors with greater frequency com-pared with wild-type(WT) mice,although the tumor incidence was not different between WT and KO mice.KO mice showed increased cell proliferation of colorec-tal tumor cells,which correlated with the expression levels of cyclooxygenase-2(COX-2) in the colorectal tumors.In addition,KO mice showed higher incidence and frequency of liver tumors after AOM treatment.Thirteen percent of WT mice developed liver tumors,and these WT mice had only a single tumor.In contrast,50% of KO mice developed liver tumors,and 58% of these KO mice had multiple tumors.CONCLUSION:Adiponectin deficiency enhances colorectal carcinogenesis and liver tumor formation induced by AOM in mice.This study strongly suggests that hypoadiponectinemia could be involved in the pathogenesis for colorectal cancer and liver tumor in human subjects.

Azoxymethane-induced rat aberrant crypt foci:Relevance in studying chemoprevention of colon cancer

The pathogenesis of colon cancer involves sequential and multistep progression of epithelial cells initiated to a cancerous state with defined precancerous intermediaries. Aberrant crypt foci （ACF） represent the earliest identifiable intermediate precancerous lesions during colon carcinogenesis in both laboratory animals and humans. ACF are easily induced by colon-specific carcinogens in rodents and can be used to learn more about the process of colon carcinogenesis. For over two decades, since its first discovery, azoxymethane （AOM）-induced rodent ACF have served as surrogate biomarkers in the screening of various anticarcinogens and carcinogens. Several dietary constituents and phytochemicals have been tested for their colon cancer chemopreventive efficacy using the ACF system. There has been substantial effort in defining and refining ACF in terms of understanding their molecular make-up, and extensive research in this field is currently in progress. In chemoprevention studies, AOM-induced rat ACF have been very successful as biomarkers, and have provided several standardized analyses of data. There have been several studies that have reported that ACF data do not correlate to actual colon tumor outcome, however, and hence there has been an ambiguity about their role as biomarkers. The scope of this mini-review is to provide valuable insights and limitations of AOM-induced rat ACF as biomarkers in colon cancer chemoprevention studies. The role of the dynamics and biological heterogeneity of ACF is critical in understanding them as biomarkers in chemoprevention studies.

Chemopreventive Potential of Select Herbal Teas and Spices on Azoxymethane-Induced Aberrant Crypt Foci in Fisher 344 Male Rats

Colon cancer is the third leading cause of death in the US. Selected herbal teas and spices may reduce incidence of chronic diseases, including cancer. The objective of this study was to identify the effect of strawberry leaf, raspberry leaf, hibiscus teas and cinnamon on azoxymethane (AOM)-induced aberrant crypt foci (ACF) in Fisher 344 male rats. After acclimatization period (1 wk), 49 male weanling rats were divided into 16 groups. Control (CON) group fed AIN-93G diet;15 treatment groups were administered control diet + strawberry leaf tea (STW), raspberry leaf tea (RAS), hibiscus tea (HIB), cinnamon (CIN), strawberry leaf tea + cinnamon (STW + CIN), raspberry leaf tea + cinnamon, (RAS + CIN), hibiscus tea + cinnamon (HIB + CIN), and strawberry leaf tea + raspberry leaf tea + hibiscus tea + cinnamon in combination (COM) at 2 levels each (teas added at 1% and 2%;CIN added at 2.5% and 5%). Rats received 24 mg/kg body weight AOM in saline s/c at 7 and 8 weeks of age. Animals received experimental diets until sacrificed by CO2 asphyxiation (17 weeks of age). ACF were enumerated in colons. Hepatic antioxidant enzymes were determined;superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), and glutathione (GH). Treatment groups had reduction in ACF compared to CON (154). Lowest ACF observed in HIB 2% + CIN 5% (13.16) with 91.45% reduction compared to CON. ACF observed in treatment groups administered teas and cinnamon combinations were lower than those administered teas singly. SOD and CAT activities in rats administered treatment diets were higher than CON (13.63 U/mL, 0.95 umol·min-l·ml-1). Rats administered COM (20.65 U/mL) had highest SOD activity. CAT activity was 51.27% higher in rats administered HIB 2% (1.96 umol·min-l·ml-1). GPX activity ranged from 7.26 (STW 1% + CIN 2.5%) to 9.59 (STW 2%) umol·min-l·ml-1. Results suggest that herbal teas and spices may reduce the risk of colon cancer and improve antioxidant status;regular consumption may provide beneficial health effects.

Feeding Walnuts and Peanuts Reduced Development of Azoxymethane-Induced Precancerous Lesions

Walnuts and peanuts contain phytochemicals that exhibit properties that may prevent colon cancer development. The objective was to determine the potential of walnuts and peanuts on Azoxymethane (AOM) induced Aberrant Crypt Foci (ACF) and the activity of detoxification enzymes: Glutathione S-Transferase (GST), Catalase (CAT), and Superoxide Dismutase (SOD) in Fisher 344 male rats. After 1 week acclimatization period, 20 rats were randomly divided into 5 groups. One was fed AIN93G Control (C) diet, 4 groups were fed walnuts (W) and peanuts (P) at 5% and 10%. At 7 - 8 weeks, rats received AOM injections at 16 mg/kg body weight (subcutaneously). Rats were killed by CO2 asphyxiation at 17 weeks. Enzyme activities GST, CAT and SOD were determined. ACF incidence in rats fed W (5% and 10%) was 131 and 95, and in those fed P (5% and 10%) was 110 and 56. Rats fed W and P had a significant (p < 0.05) percent reduction (17.92% - 65.09%) in total ACF compared to C (159). Liver GST activity (μmol/mg) in rats fed W (5% and 10%) was 3.64 and 3.98, and in those fed P (5% and 10%) was 3.84 and 3.30, compared to rats fed C (0.26). CAT activity (μmol/mg) in rats fed W (5% and 10%) was 0.57 and 0.65 and in those fed P (5% and 10%), was 0.76 and 1.26, compared to rats fed C (0.14). SOD activity (U/mg) in rats fed W (5% and 10%) was 529.38 and 576.57 and in those fed P (5% and 10%), was 293.50 and 466.95, compared to rats fed C (82.42). Feeding walnuts and peanuts, especially at 10%, significantly (p < 0.05) reduced the incidence of AOM induced ACF, likely due to the phytochemicals present in nuts.

Fulminant liver failure models with subsequent encephalopathy in the mouse

BACKGROUND:A reliable model of fulminant liver failure (FLF) is urgently required in this research field.This study aimed to develop a murine FLF model.METHODS:We used three groups of male C57BL/6 mice:control,with azoxymethane treatment (AOM group),and with galactosamine and tumor necrosis factor-alpha treatment (Gal+TNF-α group).The effects of body temperature (BT) control on survival in all three groups were investigated Using BT control,we compared the survival,histopathological findings and biochemical/coagulation profiles between the two experimental groups.The effects of hydration on international normalized ratios of prothrombin time (PT INRs) were also checked.Dose-dependent survival curves were constructed for both experimental groups.Neurological behavior was assessed using a coma scale.RESULTS:No unexpected BT effects were seen in the control group.The AOM group,but not the Gal+TNF-α group showed a significant difference in survival curves between those with and without BT care.Histopathological assessment showed consistent FLF findings in both experimental groups with BT care.There were significant differences between the experimental groups in aspartate aminotransferase levels and PT-INRs,and significant differences in PT-INRs between the sufficiently and insufficiently hydrated groups.There were significant differences between FLF models in the duration of each coma stage,with significant differences in stages 1 and 3 as percentages of the disease state (stages 1-4).The two FLF models with BT care showed different survival curves in the dose-dependent survival study.CONCLUSIONS:AOM provides a good FLF model,but requires a specialized environment and careful BT control.Other FLF models may also be useful,depending on the research purpose.Thoughtful attention to caregiving and close observation are indispensable for successful FLF models.

TNFR1 Deficiency Protects Mice from Colitis-Associated Colorectal Cancer Coupled with a Decreased Level of Oxidative Damage in the Colon: Implications for Anti-TNF Therapy of Unremitting Colitis

It has long been appreciated that there is a direct relationship between the intensity and duration of inflammatory bowel diseases (IBD) and increasing intestinal cancer risk but which elements of the inflammatory response are responsible have not been identified. Anti-TNF drugs have been successful at treating IBD but considering the presumed anti-tumor activity of TNF, it is important to understand whether the treatment impacts on the patients’ intestinal cancer risk. We modeled this relationship by “treating mice lacking TNF receptors with a colon cancer causing combination of azoxymethane followed by repeated dextran sulphate sodium exposures (AOM + DSS regime). TNF receptor type1 gene deficient (TNFR1-/-) and TNFR2-/- mice experienced similar clinical illnesses and colonic inflammation as C57BL/6 wildtype controls during the AOM + DSS regime. Despite the inflammation, TNFR1-/- mice developed significantly fewer colon tumors than the other strains. The reduced tumor incidence was a product of the combined lack of receptor expression on hematopoietic and nonhematopoietic cells, shown using bone marrow cell chimeras of wildtype and TNFR1-/- mice. As oxidative damage is a potent contributing factor to tumorigenesis and inflammatory leukocytes make copious amounts of reactive oxygen radicals, we measured oxidative damage in the animals’ colons. TNFR1-/- mice showed less damage compared to the other strains. We subsequently examined mice deficient in their leukocyte NADPH oxidative pathway (Nox2-/-) for their cancer incidence using the AOM + DSS regime. Nox2-/- mice became inflamed but had fewer tumors than wildtype mice. We conclude that TNF promotes colon cancer including through promoting oxidative processes utilizing TNFR1 in leukocytes. Moreover, the C57BL/6 strain can be used to dissociate mechanisms of colon inflammation from tumorigenic processes. We interpret our results to mean that IBD patients on TNF antagonist therapies will potentially benefit with reduced colon cancer risk even if they do not respond with reduced inflammation.

Inhibition of Chemically-Induced Colon Cancer by Dietary Treatment of <i>Hibiscus sabdariffa</i>L. Dried Calyx in Rats

This study examined the chemopreventive effect of feeding sorrel calyx as meal and juice against azoxymethane (AOM) induced colon cancer in Fisher 344 male rats. Rats were randomly assigned to five different groups and administered either sorrel meal (5% & 10%) or juice (2.5% & 5%) and control diet. Tumors were induced in rats with two subcutaneous injections (16 mg/kg body weight) of AOM at 6 & 7 weeks of age. Rats were killed at 45 weeks of age and samples (colon, liver) were collected. Tumor incidence, size and numbers were analyzed macroscopically. Activity of drug metabolizing (Cytochrome P2E1 (CYP2E1) & Glutathione S-Transferase (GST)) and antioxidative enzymes (Catalase and Superoxide dismutase) were determined in liver. Dietary feeding of sorrel calyx decreased (P < 0.05) tumor incidence and multiplicity in rats. Tumor size was reduced (P < 0.05) by 78% in rats fed with sorrel calyx meal at 10% compared to control. Rats administered with AOM alone increased liver CYP2E1 activity. Supplementation of sorrel increased (P < 0.05) activities of antioxidative enzymes. Highest reduction in GST activity was observed in rats that were treated with sorrel juice at 5%. Results of this study indicated the chemopreventive potential of sorrel meal and calyx agent chemically induced colon cancer in rats. This study also provided scientific evidence for using sorrel as a functional food in chemoprevention.

Endothelin-2 Differential Expression in Normal and Early-Stages of Colon Cancer Development

The endothelin family has been related with several pathological diseases including cardiovascular disorders, hypertension and cancer. However, little is known about endothelin system in early stages of colorectal cancer and there are no studies evaluating differences in proximal and distal colon segments. To deepen in this issue, we have studied the endothelin’s family gene and protein expression in normal mice and early stage of a mice model of Azoxymethane (AOM) and Dextran Sodium Sulphate (DSS) induced colorectal cancer in proximal and distal segments. Additionally, using nonlinear microscopy (NLM) techniques, we have characterized collagen changes in early stages of cancer disease development. In the present study, we have found significant differential gene expression and protein localization between these colon regions, which allow us to hypothesize a new role for the ET-2 as an early marker of colon cancer development.

UPLC-Q-TOF/MS-Based Serum Metabolomics Reveals Potential Anti-tumor Mechanism of Banxia Xiexin Decoction in Colorectal Cancer Mice

Objective To clarify the potential mechanism of Banxia Xiexin Decoction(BXD)on colorectal cancer(CRC)from the perspective of metabolomics.Methods Forty male C57BL/6 mice were randomly divided into normal control(NC),azoxymethane/dextran sulfate sodium(AOM/DSS)model,low-dose BXD(L-BXD),high-dose BXD(H-BXD)and mesalamine(MS)groups according to a random number table,8 mice in each group.Colorectal cancer model was induced by AOM/DSS.BXD was administered daily at doses of 3.915(L-BXD)and 15.66 g/kg(H-BXD)by gavage for consecutive 21 days,and 100 mg/kg MS was used as positive control.Following the entire modeling cycle,colon length of mice was measured and quantity of colorectal tumors were counted.The spleen and thymus index were determined by calculating the spleen/thymus weight to body weight.Inflammatory cytokine and changes of serum metabolites were analyzed by enzyme-linked immunosorbent assay kits and ultra performance liquid chromatography-quadrupole/time-of-flight mass spectrometry(UPLC-Q/TOF-MS),respectively.Results Notably,BXD supplementation protected against weight loss,mitigated tumor formation,and diminished histologic damage in mice treated with AOM/DSS(P<0.05 or P<0.01).Moreover,BXD suppressed expression of serum inflammatory enzymes,and improved the spleen and thymus index(P<0.05).Compared with the normal group,102 kinds of differential metabolites were screened in the AOM/DSS group,including 48 potential biomarkers,involving 18 main metabolic pathways.Totally 18 potential biomarkers related to CRC were identified,and the anti-CRC mechanism of BXD was closely related to D-glutamine and D-glutamate metabolism,phenylalanine,tyrosine and tryptophan biosynthesis,arginine biosynthesis,nitrogen metabolism and so on.Conclusion BXD exerts partial protective effects on AOM/DSS-induced CRC by reducing inflammation,protecting organism immunity ability,and regulating amino acid metabolism.