Age and Sex in the Development of Hepatic Encephalopathy: Role of Alcohol

Hepatic encephalopathy (HE) is a neurological condition linked to liver failure. Acute HE (Type A) occurs with acute liver failure, while chronic HE (Type C) is tied to cirrhosis and portal hypertension. HE treatments lag due to gaps in understanding its development by gender and age. We studied how sex and age impact HE and its severity with combined liver toxins. Our findings indicate that drug-induced (thioacetamide, TAA) brain edema was more severe in aged males than in young males or young/aged female rats. However, adding alcohol (ethanol, EtOH) worsens TAA's brain edema in both young and aged females, with females experiencing a more severe effect than males. These patterns also apply to Type A HE induced by azoxymethane (AZO) in mice. Similarly, TAA-induced behavioral deficits in Type C HE were milder in young and aged females than in males. Conversely, EtOH and TAA in young/aged males led to severe brain edema and fatality without noticeable behavioral changes. TAA metabolism was slower in aged males than in young or middle-aged rats. When TAA-treated aged male rats received EtOH, there was a slow and sustained plasma level of thioacetamide sulfoxide (TASO). This suggests that with EtOH, TAA-induced HE is more severe in aged males. TAA metabolism was similar in young, middle-aged, and aged female rats. However, with EtOH, young and aged females experience more severe drug-induced HE as compared to middle-aged adult rats. These findings strongly suggest that gender and age play a role in the severity of HE development and that the presence of one or more liver toxins may aggravate the severity of the disease progression.

Study on the effect and mechanism of Lacticaseibacillus rhamnosus AFY06 on inflammation-associated colorectal cancer induced by AOM/DSS in mice

Introduction

Lacticaseibacillus rhamnosus AFY06 (LR-AFY06) is a microorganism isolated from naturally fermented yogurt in Xinjiang, China.

Methods

In this study, we investigated the effects and mechanisms of LR-AFY06 in a mouse model of inflammation-associated colon cancer. The mouse model was established by azoxymethane/dextran sulfate sodium (AOM/DSS) induction. The tumor number in intestinal tissues was counted, and the histopathological analysis was performed on colon tissues. Enzyme-linked immunosorbent assay and real-time quantitative polymerase chain reaction were performed to measure relevant protein levels in colon tissues.

Results

LR-AFY06 treatment alleviated weight loss, increased organ index, reduced intestinal tumor incidence, improved histopathological damage, decreased the levels of inflammatory cytokines such as interleukin-6 (IL-6), interleukin-1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), nuclear factor κB (NF-κB), and inducible nitric oxide synthase (iNOS) in the serum and colon tissue, downregulated the mRNA expression of inhibitor of NF-κB beta (IκBβ), p65, p50, p52, B-cell lymphoma-2 (Bcl-2), and B-cell lymphoma-extra large (Bcl-xL) in colon tissues, and increased the mRNA expression of Bid and caspase-8. The high concentration of LR-AFY06 exerted a better effect than the low concentration; however, the effect was slightly inferior to that of aspirin. Moreover, LR-AFY06 mitigated the intestinal inflammatory process and inhibited intestinal tumor development by regulating the NF-κB and apoptosis pathways.

Discussion

The present study indicates the regulatory potential of LR-AFY06 in inflammation-associated colorectal cancer in mice, providing a valuable basis for further research.

Mitotic Spindle Positioning (MISP) Facilitates Colorectal Cancer Progression by Forming a Complex with Opa Interacting Protein 5 (OIP5) and Activating the JAK2-STAT3 Signaling Pathway

Patients with inflammatory bowel disease (IBD) who experience long-term chronic inflammation of the colon are at an increased risk of developing colorectal cancer (CRC). Mitotic spindle positioning (MISP), an actin-binding protein, plays a role in mitosis and spindle positioning. MISP is found on the apical membrane of the intestinal mucosa and helps stabilize and elongate microvilli, offering protection against colitis. This study explored the role of MISP in colorectal tumorigenesis using a database, human CRC cells, and a mouse model for colitis-induced colorectal tumors triggered by azoxymethane (AOM)/dextran sodium sulfate (DSS) treatment. We found that MISP was highly expressed in colon cancer patient tissues and that reduced MISP expression inhibited cell proliferation. Notably, MISP-deficient mice showed reduced colon tumor formation in the AOM/DSS-induced colitis model. Furthermore, MISP was found to form a complex with Opa interacting protein 5 (OIP5) in the cytoplasm, influencing the expression of OIP5 in a unidirectional manner. We also observed that MISP increased the levels of phosphorylated STAT3 in the JAK2-STAT3 signaling pathway, which is linked to tumorigenesis. These findings indicate that MISP could be a risk factor for CRC, and targeting MISP might provide insights into the mechanisms of colitis-induced colorectal tumorigenesis.

Genetic and microbial determinants of azoxymethane-induced colorectal tumor susceptibility in Collaborative Cross mice and their implication in human cancer

The insights into interactions between host genetics and gut microbiome (GM) in colorectal tumor susceptibility (CTS) remains lacking. We used Collaborative Cross mouse population model to identify genetic and microbial determinants of Azoxymethane-induced CTS. We identified 4417 CTS-associated single nucleotide polymorphisms (SNPs) containing 334 genes that were transcriptionally altered in human colorectal cancers (CRCs) and consistently clustered independent human CRC cohorts into two subgroups with different prognosis. We discovered a set of genera in early-life associated with CTS and defined a 16-genus signature that accurately predicted CTS, the majority of which were correlated with human CRCs. We identified 547 SNPs associated with abundances of these genera. Mediation analysis revealed GM as mediators partially exerting the effect of SNP UNC3869242 within Duox2 on CTS. Intestine cell-specific depletion of Duox2 altered GM composition and contribution of Duox2 depletion to CTS was significantly influenced by GM. Our findings provide potential novel targets for personalized CRC prevention and treatment.

Fecal microbiota transplanted from old mice promotes more colonic inflammation, proliferation, and tumor formation in azoxymethane-treated A/J mice than microbiota originating from young mice

Aging is a strong risk factor for colorectal cancer (CRC). It is well established that gut microbial dysbiosis can play a role in the etiology of CRC. Although the composition of the gut microbial community changes with age and is reported to become more pro-inflammatory, it is unclear whether such changes are also pro-tumorigenic for the colon. To address this gap, we conducted fecal microbiota transplants (FMT) from young (DY, ~6 wk) and old (DO, ~72 wk) donor mice into young (8 wk) recipient mice that were pre-treated with antibiotics. After initiating tumorigenesis with azoxymethane, recipients were maintained for 19 wk during which time they received monthly FMT boosters. Compared to recipients of young donors (RY), recipients of old donors (RO) had an approximately 3-fold higher prevalence of histologically confirmed colon tumors (15.8 vs 50%, Chi2 P = .03), approximately 2-fold higher proliferating colonocytes as well as significantly elevated colonic IL-6, IL-1β and Tnf-α. Transcriptomics analysis of the colonic mucosa revealed a striking upregulation of mitochondria-related genes in the RO mice, a finding corroborated by increased mitochondrial abundance. Amongst the differences in fecal microbiome observed between DY and DO mice, the genera Ruminoclostridium, Lachnoclostridium and Marvinbryantia were more abundant in DY mice while the genera Bacteroides and Akkermansia were more abundant in DO mice. Amongst recipients, Ruminoclostridium and Lachnoclostridium were higher in RY mice while Bacteroides was higher in RO mice. Differences in fecal microbiota were observed between young and old mice, some of which persisted upon transplant into recipient mice. Recipients of old donors displayed significantly higher colonic proliferation, inflammation and tumor abundance compared to recipients of young donors. These findings support an etiological role for altered gut microbial communities in the increased risk for CRC with increasing age and establishes that such risk can be transmitted between individuals.

MT1-MMP and TIMP-2 are first expressed in the colon glands after a single dose of azoxymethane (AOM)

Tissue inhibitor of metalloproteinase-2 (TIMP-2) and membrane-type 1-matrix metalloproteinase (MT1-MMP) are always expressed during the cancer process. The aim was to identify which regions of the colon mucosa MT1-MMP and TIMP-2 begin to express themselves, as well as to establish their expression in relation to cell proliferation and mucin production. After intraperitoneal injection of 15 mg/kg of azoxymethane (AOM) at 4, 12, and 20 weeks, histological sections of the middle segment of the rat colon mucosa were evaluated by immunohistochemistry for cell proliferation and expression of MT1-MMP and TIMP-2 and histochemistry for mucin. As a result, a single dose of AOM initially increased the intensity of MT1-MMP and TIMP-2 expression in the conjunctive cells and glands, concurrently with alterations in the distribution of the mucin produced in the gland of the large intestine mucosa and cell proliferation. As a result, at 4 and 12 weeks, a single dose of AOM initially stimulated the expression of MT1-MMP and TIMP-2 in the conjunctive cells and glands with greater intensity. Changes in the cell proliferation and distribution of the mucin produced in the large intestine mucosa gland were observed. We conclude that MT1-MMP and TIMP-2 were first and strongly expressed in all cells of the colon glands, concurrently with an increase in cell proliferation and a diffuse dispersion of mucin, indicating the onset of the dysplasia process following a single dosage of AOM.

The effect of aerobic and resistance exercise on the progression of colorectal cancer in an animal model

PURPOSE

The aim of this study was to assess the effects of resistance and aerobic exercise on colorectal cancer (CRC) development in mice induced by azoxymethane (AOM) coupled with colitis.

METHODS

Forty animals induced with CRC were used, divided into five groups of eight animals each: sedentary; continuous aerobics; continuous anaerobic; aerobic PI; and anaerobic PI. AOM was administered to the animals in two doses of 10 mg/kg each over the course of two weeks, the first dose administered in the third week and the second administered in the fourth. For the colitis, three cycles of dextran sodium sulfate were administered for five days, separated by two weeks of water. The 14th week of the experiment saw the euthanasia, the removal of their colons, and the creation of microscopy slides for histological analysis.

RESULTS

Preneoplastic lesions developed in all five groups; there were no significant differences between them. However, in terms of inflammatory symptoms, mucosal ulceration was much more frequently in the exercise groups than in the sedentary group (p = 0.016). The number of polyps overall (p = 0.002), the distal region's polyp development (p = 0.003), and the proximal region's polyp development (p = 0.04) were all statistically different than sedentary group.

CONCLUSIONS

The study discovered no significant difference in disease activity index scores between groups, but there was a significant difference in the number of polyps and the presence of mucosal ulceration in the colon.

A Novel Mouse Model of Intrahepatic Cholangiocarcinoma Induced by Azoxymethane

Cholangiocarcinoma is the second most common primary cancer of the liver and has a poor prognosis. Various animal models, including carcinogen-induced and genetically engineered rodent models, have been established to clarify the mechanisms underlying cholangiocarcinoma development. In the present study, we developed a novel mouse model of malignant lesions in the biliary ducts induced by the administration of the carcinogen azoxymethane to obese C57BLKS/J-db/db mice. A histopathological analysis revealed that the biliary tract lesions in the liver appeared to be an intrahepatic cholangiocarcinoma with higher tumor incidence, shorter experimental duration, and a markedly increased incidence in obese mice. Molecular markers analyzed using a microarray and a qPCR indicated that the cancerous lesions originated from the cholangiocytes and developed in the inflamed livers. These findings indicated that this is a novel mouse model of intrahepatic cholangiocarcinoma in the context of steatohepatitis. This model can be used to provide a better understanding of the pathogenic mechanisms of cholangiocarcinoma and to develop novel therapeutic strategies for this malignancy.

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.

Investigation into the Potential Role of Propionibacterium freudenreichii in Prevention of Colorectal Cancer and Its Effects on the Diversity of Gut Microbiota in Rats

Colorectal cancer (CRC) accounts for 10% of all cancer diagnoses and cancer-related deaths worldwide. Over the past two decades, several studies have demonstrated the clinical benefits of probiotic supplementation and some studies have shown that certain probiotics can modulate immunity and strengthen gut microbiota diversity. This study aims to assess the impact of the Propionibacterium freudenreichii (PF) probiotic against CRC induced by azoxymethane (AOM), and to investigate its effects on gut microbiota diversity in rats, as well as to evaluate the anti-proliferative activities of PF in HCT116 CRC cells. This experiment was performed using four groups of SD rats: normal control, AOM group, PF group (1 × 10⁹ CFU/mL), and standard drug control (5-fluorouracil, 35 mg/kg). Methylene blue staining of colon tissues showed that the administration of PF significantly reduced the formation of colonic aberrant crypt foci (ACF) compared to the AOM control group. In addition, treated rats had lower levels of malondialdehyde in their colon tissue homogenates, indicating that lipid peroxidation was suppressed by PF supplementation. Furthermore, 16S rRNA gene analysis revealed that probiotic treatment enhanced the diversity of gut microbiota in rats. In vitro study showed that the viability of HCT116 cells was inhibited by the probiotic cell-free supernatant with an IC₅₀ value of 13.3 ± 0.133. In conclusion, these results reveal that consuming PF as probiotic supplements modulates gut microbiota, inhibits the carcinogenic effects of AOM, and exerts anti-proliferative activity against CRC cells. Further studies are required to elucidate the role of PF on the immune response during the development and growth of CRC.

Development and Characterization of Novel Chronic Eosinophilic Inflammation- Mediated Murine Model of Malignant Pancreatitis

AIMS

Develop a novel murine models of malignant pancreatitis.

BACKGROUND

Although patients with chronic pancreatitis are at a greater risk of developing pancreatic cancer, there is no definitive mouse model that currently develops chronic pancreatitis-induced pancreatic cancer.

OBJECTIVE

Characterization of eosinophilic inflammation-mediated malignant pancreatitis in novel murine model.

METHODS

We developed a murine model of chronic eosinophilic inflammation associated with pancreatitis that also shows characteristic features of pancreatic malignancy. The mouse received cerulein and azoxymethane via intraperitoneal administration developed pathological malignant phenotype, as well as concomitant lung inflammation.

RESULTS

We discovered pathological alterations in the pancreas that were associated with chronic pancreatitis, including a buildup of eosinophilic inflammation. Eosinophil degranulation was reported nearby in the pancreas tissue sections that show acinar-to-ductal metaplasia and acinar cell atrophy, both of which are characteristic of pancreatic malignancies. Additionally, we also observed the formation of PanIN lesions after three initial doses of AOM and eight weeks of cerulein with the AOM treatment regimen. We discovered that persistent pancreatic eosinophilic inflammation linked with a pancreatic malignant phenotype contributes to pulmonary damage. The RNA seq analysis also confirmed the induction of fibro-inflammatory and oncogenic proteins in pancreas and lung tissues. Further, in the current manuscript, we now report the stepwise kinetically time-dependent cellular inflammation, genes and proteins involved in the development of pancreatitis malignancy and associated acute lung injury by analyzing the mice of 3 AOM with 3, 8, and 12 weeks of the cerulein challenged protocol regime.

CONCLUSION

We first show that sustained long-term eosinophilic inflammation induces time-dependent proinflammatory, profibrotic and malignancy-associated genes that promote pancreatic malignancy and acute lung injury in mice.

Therapeutic Potential of 6-Gingerol in Prevention of Colon Cancer Induced by Azoxymethane through the Modulation of Antioxidant Potential and Inflammation

A polyphenolic component of ginger, 6-gingerol, is widely reported to possess antioxidant, anti-inflammatory and anticancer activities. In the current study, it was aimed to investigate the anticancer effects of 6-gingerol (6-Gin) on azoxymethane (AOM)-induced colon cancer in rats. The results reveal that 6-Gin treatment significantly improves the antioxidant status disturbed by AOM intoxication. The 6-Gin treatment animal group showed enhanced activity of catalase (CAT) (46.6 ± 6.4 vs. 23.3 ± 4.3 U/mg protein), superoxide dismutase (SOD) (81.3 ± 7.6 vs. 60.4 ± 3.5 U/mg protein) and glutathione-S-transferase (GST) (90.3 ± 9.4 vs. 53.8 ± 10 mU/mg protein) (p < 0.05) as compared to the disease control group. Furthermore, the results reveal that AOM significantly enhances the inflammatory response and 6-gingerol potentially attenuates this response, estimated by markers, such as tumor necrosis factor-α (TNF-α) (1346 ± 67 vs. 1023 ± 58 pg/g), C-reactive protein (CRP) (1.12 ± 0.08 vs. 0.92 ± 0.7 ng/mL) and interleukin-6 (IL-6) (945 ± 67 vs. 653 ± 33 pg/g). In addition, the lipid peroxidation estimated in terms of malondialdehyde (MDA) provoked by AOM exposure is significantly reduced by 6-gingerol treatment (167 ± 7.5 vs. 128.3 nmol/g). Furthermore, 6-gingerol significantly maintains the colon tissue architecture disturbed by the AOM treatment. Loss of tumor suppressor protein, phosphatase and tensin homolog (PTEN) expression was noticed in the AOM treated group, whereas in the animals treated with 6-gingerol, the positivity of PTEN expression was high. In conclusion, the current findings advocate the health-promoting effects of 6-gingerol on colon cancer, which might be due to its antioxidant and anti-inflammatory potential.

Gender-based effect of absence of gut microbiota on the protective efficacy of Bifidobacterium longum-fermented rice bran diet against inflammation-associated colon tumorigenesis

Dietary rice bran (RB) has shown capacity to influence metabolism by modulation of gut microbiota in individuals at risk for colorectal cancer (CRC), which warranted attention for delineating mechanisms for bidirectional influences and cross-feeding between the host and RB-modified gut microbiota to reduce CRC. Accordingly, in the present study, fermented rice bran (FRB, fermented with a RB responsive microbe Bifidobacterium longum), and non-fermented RB were fed as 10% w/w (diet) to gut microbiota-intactspf or germ-free micegf to investigate comparative efficacy against inflammation-associated azoxymethane/dextran sodium sulfate (AOM/DSS)-induced CRC. Results indicated both microbiota-dependent and independent mechanisms for RB meditated protective efficacy against CRC that was associated with reduced neoplastic lesion size and local-mucosal/systemic inflammation, and restoration of colonic epithelial integrity. Enrichment of beneficial commensals (such as, Clostridiales, Blautia, Roseburia), phenolic metabolites (benzoate and catechol metabolism), and dietary components (ferulic acid-4 sulfate, trigonelline, and salicylate) were correlated with anti-CRC efficacy. Germ-free studies revealed gender-specific physiological variables could differentially impact CRC growth and progression. In the germ-free females, the RB dietary treatment showed a ∼72% reduction in the incidence of colonic epithelial erosion when compared to the ∼40% reduction in FRB-fed micegf . Ex vivo fermentation of RB did not parallel the localized-protective benefits of gut microbial metabolism by RB in damaged colonic tissues. Findings from this study suggest potential needs for safety considerations of fermented fiber rich foods as dietary strategies against severe inflammation-associated colon tumorigenesis (particularly with severe damage to the colonic epithelium).

Protective role of a melon superoxide dismutase combined with gliadin (GliSODin) on the status of lipid peroxidation and antioxidant defense against azoxymethane-induced experimental colon carcinogenesis

Background

Azoxymethane (AOM) is a potent carcinogenic agent commonly used to induce colon cancer in rats and mice, with the cytotoxicity of AOM mediated by oxidative stress.

Aim of Study

This study investigated the protective effect of a natural antioxidant (GliSODin) against AOM-induced oxidative stress and carcinogenesis in rat colon.

Methods

Twenty male Wistar rats were randomly divided into four groups (five rats/group). The control group was fed a basal diet. AOM-treated group (AOM) was fed a basal diet and received intraperitoneal injections of AOM for 2 weeks at a dose of 15 mg/kg. The GliSODin treatment group (superoxide dismutase [SOD]) received oral supplementation of GliSODin (300 mg/kg) for 3 months, and the fourth combined group received AOM and GliSODin (AOM + SOD). All animals were continuously fed ad libitum until the age of 16 weeks when all rats were sacrificed. The colon tissues were examined microscopically for pathological changes and aberrant crypt foci (ACF) development, oxidant status (lipid peroxidation-LPO), and enzyme antioxidant system (glutathione [GSH], GSH-S-transferase, catalase, and SOD).

Results

Our results showed that AOM induced ACF development and oxidative stress (GSH depletion and lipid peroxidation) in rat colonic cells. The concomitant treatment of AOM with GliSODin significantly ameliorated the cytotoxic effects of AOM.

Conclusion

The results of this study provide in vivo evidence that GliSODin reduced the AOM-induced colon cancer in rats, through their potent antioxidant activities.

Mice carrying an epithelial deletion of the glucocorticoid receptor NR3C1 develop a higher tumor load in experimental colitis-associated cancer

The glucocorticoid receptor NR3C1 is expressed in multiple cell types in the gut and elsewhere. Intestinal epithelial cells both produce and respond to glucocorticoids in different physiological and pathological contexts. In experimental colitis, glucocorticoids have been shown to exert a dual role, dampening inflammation while producing a deterioration in animal status, including death. Mice with tamoxifen-inducible, intestinal epithelial-specific deletion of NR3C1 (NR3C1^ΔIEC mice) are protected against experimental colitis, suggesting glucocorticoid epithelial actions are deleterious. Since glucocorticoids modulate epithelial proliferation, it follows that they may affect the development of colon cancer. In this study, we set out to test this hypothesis using the dextran sulfate sodium-azoxymethane model of colitis-associated cancer. Knockout (KO) mice were found to exhibit a twofold higher tumor load but similar incidence and tumor size. Tumors had a higher trend to extend close to the submucosal layer (36% vs. 0%) in NR3C1^ΔIEC mice, and overexpressed Lgr5, Egfr, and Myc, consistent with distinct expression of proliferative/stemness markers. Snai1 and Snai2 were upregulated specifically in tumors of NR3C1^ΔIEC mice, suggesting enhanced epithelial to mesenchymal transition in the absence of the intestinal epithelial glucocorticoid (GC) receptor. We conclude that endogenous GC epithelial signaling is involved in colitis-associated cancer.NEW & NOTEWORTHY Mice carrying a tamoxifen-inducible deletion of the glucocorticoid receptor in intestinal epithelial cells (NR3C1^ΔIEC mice) and their corresponding controls were subjected to the azoxymethane-dextran sulfate sodium model of colitis-associated cancer. KO mice exhibit a twofold higher tumor load, with a higher trend to extend close to the submucosal layer (36% vs. 0%), but with similar incidence and tumor size. Colonic tumors in NR3C1^ΔIEC mice showed signs of increased neoplastic transformation and tumor-associated inflammation.

Upregulation of polycistronic microRNA-143 and microRNA-145 in colonocytes suppresses colitis and inflammation-associated colon cancer

Because ADAM17 promotes colonic tumorigenesis, we investigated potential miRNAs regulating ADAM17; and examined effects of diet and tumorigenesis on these miRNAs. We also examined pre-miRNA processing and tumour suppressor roles of several of these miRNAs in experimental colon cancer. Using TargetScan, miR-145, miR-148a, and miR-152 were predicted to regulate ADAM17. miR-143 was also investigated as miR-143 and miR-145 are co-transcribed and associated with decreased tumour growth. HCT116 colon cancer cells (CCC) were co-transfected with predicted ADAM17-regulating miRNAs and luciferase reporters controlled by ADAM17-3'UTR. Separately, pre-miR-143 processing by colonic cells was measured. miRNAs were quantified by RT-PCR. Tumours were induced with AOM/DSS in WT and transgenic mice (Tg) expressing pre-miR-143/miR-145 under villin promoter. HCT116 transfection with miR-145, -148a or -152, but not scrambled miRNA inhibited ADAM17 expression and luciferase activity. The latter was suppressed by mutations in ADAM17-3'UTR. Lysates from colonocytes, but not CCC, processed pre-miR-143 and mixing experiments suggested CCC lacked a competency factor. Colonic miR-143, miR-145, miR-148a, and miR-152 were downregulated in tumours and more moderately by feeding mice a Western diet. Tg mice were resistant to DSS colitis and had significantly lower cancer incidence and tumour multiplicity. Tg expression blocked up-regulation of putative targets of miR-143 and miR-145, including ADAM17, K-Ras, XPO5, and SET. miR-145, miR-148a, and miR-152 directly suppress colonocyte ADAM17 and are down-regulated in colon cancer. This is the first direct demonstration of tumour suppressor roles for miR-143 and miR-145 in an in vivo model of colonic tumorigenesis.

Blockade of Glycosphingolipid Synthesis Inhibits Cell Cycle and Spheroid Growth of Colon Cancer Cells In Vitro and Experimental Colon Cancer Incidence In Vivo

Colorectal cancer (CRC) is one of the most frequently diagnosed cancers in humans. At early stages CRC is treated by surgery and at advanced stages combined with chemotherapy. We examined here the potential effect of glucosylceramide synthase (GCS)-inhibition on CRC biology. GCS is the rate-limiting enzyme in the glycosphingolipid (GSL)-biosynthesis pathway and overexpressed in many human tumors. We suppressed GSL-biosynthesis using the GCS inhibitor Genz-123346 (Genz), NB-DNJ (Miglustat) or by genetic targeting of the GCS-encoding gene UDP-glucose-ceramide-glucosyltransferase- (UGCG). GCS-inhibition or GSL-depletion led to a marked arrest of the cell cycle in Lovo cells. UGCG silencing strongly also inhibited tumor spheroid growth in Lovo cells and moderately in HCT116 cells. MS/MS analysis demonstrated markedly elevated levels of sphingomyelin (SM) and phosphatidylcholine (PC) that occurred in a Genz-concentration dependent manner. Ultrastructural analysis of Genz-treated cells indicated multi-lamellar lipid storage in vesicular compartments. In mice, Genz lowered the incidence of experimentally induced colorectal tumors and in particular the growth of colorectal adenomas. These results highlight the potential for GCS-based inhibition in the treatment of CRC.

Azoxymethane Alters the Plasma Metabolome to a Greater Extent in Mice Fed a High-Fat Diet Compared to an AIN-93 Diet

Consumption of a high-fat diet (HFD) links obesity to colon cancer in humans. Our data show that a HFD (45% energy fat versus 16% energy fat in an AIN-93 diet (AIN)) promotes azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF) formation in a mouse cancer model. However, the underlying metabolic basis remains to be determined. In the present study, we hypothesize that AOM treatment results in different plasma metabolomic responses in diet-induced obese mice. An untargeted metabolomic analysis was performed on the plasma samples by gas chromatography time-of-flight mass spectrometry (GC-TOF-MS). We found that 53 of 144 identified metabolites were different between the 4 groups of mice (AIN, AIN + AOM, HFD, HFD + AOM), and sparse partial least-squares discriminant analysis showed a separation between the HFD and HFD + AOM groups but not the AIN and AIN + AOM groups. Moreover, the concentrations of dihydrocholesterol and cholesterol were inversely associated with AOM-induced colonic ACF formation. Functional pathway analyses indicated that diets and AOM-induced colonic ACF modulated five metabolic pathways. Collectively, in addition to differential plasma metabolomic responses, AOM treatment decreases dihydrocholesterol and cholesterol levels and alters the composition of plasma metabolome to a greater extent in mice fed a HFD compared to the AIN.

Synbiotic sheep milk ice cream reduces chemically induced mouse colon carcinogenesis

Sheep dairy products containing prebiotic and probiotic ingredients may have health-promoting properties. Thus, this study evaluated the effects of sheep milk ice cream [conventional full-fat (CONV), full-fat enriched with probiotic (PROB, 100 mg % wt/wt of Lacticaseibacillus casei 01), or nonfat synbiotic (SYNB, Lacticaseibacillus casei 01 and inulin, 10% wt/wt)] on carcinogen-induced colonic crypt cytotoxicity and premalignant lesion development. Male Swiss mice received 2 doses of colon carcinogen azoxymethane (AOM, 15 mg/kg of body weight) at wk 3 and 4. Two weeks before and during AOM administrations (4 wk) mice were treated with CONV, PROB, or SYNB by gavage (10 mL/kg). Mice were euthanized at wk 4 or 25 (n = 5 or 10 mice/group, respectively). At wk 4, a significant reduction in micronucleated colonocytes was observed in PROB and SYNB groups, and a significant decrease in both p53 expression and apoptosis indexes in colonic crypts was observed in SYNB group. At wk 25, both PROB and SYNB interventions reduced the mean number of colonic premalignant lesions. However, only SYNB group showed lower incidence and number of high-grade premalignant lesions in the colonic mucosa. These findings indicate that PROB or SYNB sheep milk ice cream, especially SYNB intervention, can reduce chemically induced mouse colon carcinogenesis.

Promising Chemoprevention of Colonic Aberrant Crypt Foci by Portunus segnis Muscle and Shell Extracts in Azoxymethane-Induced Colorectal Cancer in Rats

BACKGROUND AND PURPOSE

This study subjected a rat model to the extracts of muscle and shell tissues from Portunus segnis to assess their therapeutic effects on the HT-29 colon cancer cells as well as on colonic Aberrant Crypt Foci (ACF) induced by Azoxymethane (AOM).

METHODS

The cell line was exposed to the extracts to compare the cytotoxicity of hexane, butanol, ethyl acetate, and water extract of muscle and ethanolic extract of the shell. Male rats (n=40) were assigned into control, positive, negative, and treatment groups. The animals were injected with AOM, except the control group, and then exposed to 250 and 500mg/kg of the crude extracts. Immunohistochemical localization of Bax and Bcl-2, as well as ACF and antioxidant enzymes, were evaluated in the rat colon.

RESULTS

The butanolic muscle extract and ethanolic shell one demonstrated an IC50 of 9.02±0.19μg/ml and 20.23±0.27μg/ml towards the cell line, respectively. Dietary exposure inhibited the ACF formation and crypt multiplicity in the colon compared to the cancer control group. The activity of SOD and CAT increased, while that of MDA decreased. The expression of Bax and Bcl-2 increased and decreased, respectively.

CONCLUSION

Taken together, the results show that both extractions were suggested to be suppressive to AOMinduced colon cancer.

Cardamonin Attenuates Experimental Colitis and Associated Colorectal Cancer

Cardamonin is a naturally occurring chalcone, majorly from the Zingiberaceae family, which includes a wide range of spices from India. Herein, we investigated the anti-inflammatory property of cardamonin using different in vitro and in vivo systems. In RAW 264.7 cells, treatment with cardamonin showed a reduced nitrous oxide production without affecting the cell viability and decreased the expression of iNOS, TNF-α, and IL-6, and inhibited NF-kB signaling which emphasizes the role of cardamonin as an anti-inflammatory molecule. In a mouse model of dextran sodium sulfate (DSS)-induced colitis, cardamonin treatment protected the mice from colitis. Subsequently, we evaluated the therapeutic potential of this chalcone in a colitis-associated colon cancer model. We performed microRNA profiling in the different groups and observed that cardamonin modulates miRNA expression, thereby inhibiting tumor formation. Together, our findings indicate that cardamonin has the potential to be considered for future therapy against colorectal cancer.

Corticotropin-Releasing Hormone Receptor Alters the Tumor Development and Growth in Apcmin/+ Mice and in a Chemically-Induced Model of Colon Cancer

The neuroendocrine circuit of the corticotropin-releasing hormone (CRH) family peptides, via their cognate receptors CRHR1 and CRHR2, copes with psychological stress. However, peripheral effects of the CRH system in colon cancer remains elusive. Thus, we investigate the role of CRHR1 and CRHR2 in colon cancer. Human colon cancer biopsies were used to measure the mRNA levels of the CRH family by quantitative real-time PCR. Two animal models of colon cancer were used: Apcmin/+ mice and azoxymethane (AOM)/dextran sulfate sodium (DSS)-treated mice. The mRNA levels of CRHR2 and UCN III are reduced in human colon cancer tissues compared to those of normal tissues. Crhr1 deletion suppresses the tumor development and growth in Apcmin/+ mice, while Crhr2 deficiency exacerbates the tumorigenicity. Crhr1 deficiency not only inhibits the expression of tumor-promoting cyclooxygenase 2, but also upregulates tumor-suppressing phospholipase A2 in Apcmin/+ mice; however, Crhr2 deficiency does not change these expressions. In the AOM/DSS model, Crhr2 deficiency worsens the tumorigenesis. In conclusion, Crhr1 deficiency confers tumor-suppressing effects in Apcmin/+ mice, but Crhr2 deficiency worsens the tumorigenicity in both Apcmin/+ and AOM/DSS-treated mice. Therefore, pharmacological inhibitors of CRHR1 or activators of CRHR2 could be of significance as anti-colon cancer drugs.

Alterations in the Gut Microbiome and Suppression of Histone Deacetylases by Resveratrol Are Associated with Attenuation of Colonic Inflammation and Protection Against Colorectal Cancer

Inflammatory bowel disease (IBD) is known to significantly increase the risk for development of colorectal cancer (CRC), suggesting inflammation and cancer development are closely intertwined. Thus, agents that suppress inflammation may prevent the onset of cancer. In the current study, we used resveratrol, an anti-inflammatory stilbenoid, to study the role of microbiota in preventing inflammation-driven CRC. Resveratrol treatment in the azoxymethane (AOM) and dextran sodium sulphate (DSS) CRC murine model caused an increase in anti-inflammatory CD4 + FOXP3 + (Tregs) and CD4 + IL10 + cells, a decrease in proinflammatory Th1 and Th17 cells, and attenuated CRC development. Gut microbial profile studies demonstrated that resveratrol altered the gut microbiome and short chain fatty acid (SCFA), with modest increases in n-butyric acid and a potential butyrate precursor isobutyric acid. Fecal transfer from resveratrol-treated CRC mice and butyrate supplementation resulted in attenuation of disease and suppression of the inflammatory T cell response. Data also revealed both resveratrol and sodium butyrate (BUT) were capable of inhibiting histone deacetylases (HDACs), correlating with Treg induction. Analysis of The Cancer Genome Atlas (TCGA) datasets revealed increased expression of Treg-specific transcription factor FoxP3 or anti-inflammatory IL-10 resulted in an increase in 5-year survival of patients with CRC. These data suggest that alterations in the gut microbiome lead to an anti-inflammatory T cell response, leading to attenuation of inflammation-driven CRC.

Lactobacillus fermentum V3 ameliorates colitis-associated tumorigenesis by modulating the gut microbiome

Lactobacillus spp., a common probiotic used as a dietary supplement, is good for the digestive system. However, its anti-cancer activity still remains unclear. In this study, we aim to examine the effect of Lactobacillus fermentum, Lactobacillus acidophilus and Lactobacillus rhamnosus on azoxymethane/dextran sulfate sodium (AOM/DSS)-induced colitis-associated cancer. Male ICR mice were injected with 10 mg/kg AOM and 2.5% DSS via drinking water, and then fed with different Lactobacillus (1 × 10⁸ CFU/day) for 14 weeks. The colonic tissues were collected for biomedical analysis, and gut microbiota profiling was detected by next generation high-throughput sequencing comparing to the 16S rRNA gene. We found that pretreatment with Lactobacillus fermentum (Lac.ferm) significantly inhibits colonic tumor formation (P < 0.05) and markedly decreases pro-inflammatory cytokines in AOM/DSS-induced mice. Furthermore, 16S rRNA sequencing data showed that Lac.ferm altered the composition of gut microbiota by reducing the percentage of Bacteroides. Moreover, linear discriminant analysis scores revealed that Lactobacillus fermentum within phylum Firmicutes was the prominent species existing in the Lac.ferm-treated group. Overall, the above findings suggest that dietary Lac.ferm could modulate the gut microbial community, which might be beneficial to alleviating colon cancer progression.

Diffuse reflectance spectroscopy to monitor murine colorectal tumor progression and therapeutic response

SIGNIFICANCE

Many studies in colorectal cancer (CRC) use murine ectopic tumor models to determine response to treatment. However, these models do not replicate the tumor microenvironment of CRC. Physiological information of treatment response derived via diffuse reflectance spectroscopy (DRS) from murine primary CRC tumors provide a better understanding for the development of new drugs and dosing strategies in CRC.

AIM

Tumor response to chemotherapy in a primary CRC model was quantified via DRS to extract total hemoglobin content (tHb), oxygen saturation (StO2), oxyhemoglobin, and deoxyhemoglobin in tissue.

APPROACH

A multimodal DRS and imaging probe (0.78 mm outside diameter) was designed and validated to acquire diffuse spectra longitudinally-via endoscopic guidance-in developing colon tumors under 5-fluoruracil (5-FU) maximum-tolerated (MTD) and metronomic regimens. A filtering algorithm was developed to compensate for positional uncertainty in DRS measurements Results: A maximum increase in StO2 was observed in both MTD and metronomic chemotherapy-treated murine primary CRC tumors at week 4 of neoadjuvant chemotherapy, with 21  ±  6  %   and 17  ±  6  %   fold changes, respectively. No significant changes were observed in tHb.

CONCLUSION

Our study demonstrates the feasibility of DRS to quantify response to treatment in primary CRC models.

Enterotoxigenic Bacteroides fragilis infection exacerbates tumorigenesis in AOM/DSS mouse model

The azoxymethane (AOM)/dextran sulfate sodium (DSS) murine model is commonly used to study colitis-associated cancer. The human commensal bacterium, enterotoxigenic Bacteroides fragilis (ETBF) secretes the Bacteroides fragilis toxin (BFT) which is necessary and sufficient to cause colitis. We report that BALB/c mice infected with WT-ETBF and administered three cycles of AOM/DSS developed numerous, large-sized polyps predominantly in the colorectal region. In addition, AOM/DSS-treated BALB/c mice orally inoculated with wild-type nontoxigenic Bacteroides fragilis (WT-NTBF) overexpressing bft (rETBF) developed numerous polyps whereas mice infected with WT-NTBF overexpressing a biologically inactive bft (rNTBF) did not promote polyp formation. Unexpectedly, the combination of AOM+ETBF did not induce polyp formation whereas ETBF+DSS did induce polyp development in a subset of BALB/c mice. In conclusion, WT-ETBF promoted polyp development in AOM/DSS murine model with increased colitis in BALB/c mice. The model described herein provides an experimental platform for understanding ETBF-induced colonic tumorigenesis and studying colorectal cancer in wild-type mice.

Role of Lymphatic Deficiency in the Pathogenesis and Progression of Inflammatory Bowel Disease to Colorectal Cancer in an Experimental Mouse Model

BACKGROUND

Inflammatory bowel disease (IBD) is characterized by chronic inflammation, which can progress to colorectal cancer, with duration of disease being the most important risk factor. Although many factors are involved, the pathogenic link between inflammation and cancer and the role played by the lymphatic system have not been fully investigated. This project uses lymphatic-deficient mice (Angiopoietin-2 [Ang2] knockout) to examine the lymphatic system in the progression of IBD to colorectal cancer.

METHODS

Angiopoietin-2 wild-type, heterozygote, and knockout mice received a single injection of the procarcinogen azoxymethane and had an IBD-promoting chemical irritant (dextran sodium sulfate) added to their drinking water over a 7-week period. We measured disease activity (weight loss, stool consistency, fecal occult blood) during the study and at sacrifice, collected blood for cytokine/biomarker (Ang2, interleukin [IL] 1-β, IL-6, tumor necrosis factor α [TNFα], and VEGF-C) enzyme-linked immunosorbent assay analysis, measured colon length, and assessed tumor burden.

RESULTS

Ang2 knockout (KO) mice exhibited reduced (55%) survival vs wild-type (100%) and heterozygotes (91%; P < 0.01 and P < 0.0001, respectively). Most (>89%) mice developed tumors, and the incidence of colorectal cancer did not differ among the genotypes (P = 0.32). The tumor area was significantly increased in KO mice (P = 0.004). Of the biomarkers measured in the serum, Ang2 and TNF-α concentrations were significantly different among the genotypes (P = 3.35e-08 and P = 0.003 respectively). Disease activity was significantly increased in KO mice compared with wild-type and heterozygote mice (P = 0.033).

CONCLUSIONS

Lymphatic deficiency, defective lymphangiogenesis, and impaired lymphatic-generated inflammation did not protect against clinical IBD or progression to colorectal cancer in this experimental model.

Increased Incidence of Colon Tumors in AOM-Treated Apc 1638N/+ Mice Reveals Higher Frequency of Tumor Associated Neutrophils in Colon Than Small Intestine

Colorectal cancer (CRC) is one of the most common cancers and a major cause of mortality. Mice with truncating Apc germline mutations have been used as a standard model of CRC, but most of the Apc-mutated lines develop multiple tumors in the proximal small intestine and rarely in the colon precluding detailed analysis of colon tumor microenvironment. Our aim was to develop a model with higher resemblance to human CRC and to characterize tumor infiltrating immune cells in spontaneously developing colon tumors compared to small intestinal tumors. Therefore, the Apc^1638N/+ line was treated repeatedly with azoxymethane (AOM) and 90% colon tumor incidence and 4 to 5 colon tumors per mouse were achieved. Of note, AOM treatment specifically increased the tumor burden in the colon, but not in the small intestine. Histological grading and WNT-signaling activity did not differ significantly between small intestinal and colon tumors with some lesions progressing to invasive adenocarcinoma in both locations. However, characterization of the intratumoral myeloid cell compartment revealed a massive infiltration of colon tumors with neutrophils − 6-fold higher than in small intestinal tumors. Moreover, CCL17-expressing macrophages and dendritic cells accumulated in the tumors indicating the establishment of a tumor-promoting immunosuppressive environment. Thus, Apc^1638N/+ mice treated with AOM are a suitable and straightforward model to study the influence of immune cells and chemokines on colon carcinogenesis.

Liver Pathology in Rats Treated with Newcastle Disease Virus Strains AF2240 and V4-UPM

BACKGROUND

Treatment of cancer with chemo-radiotherapy causes severe side effects due to cytotoxic effects towards normal tissues which often results in morbidity. Therefore, developing anticancer agents which can selectively target the cancer cells and cause less side effects are the main objectives of the new therapeutic strategies for treatment advanced or metastatic cancers. Newcastle disease virus strains AF2240 and V4-UPM were shown to be cytolytic against various cancer cells in-vitro and very effective as antileukemicagents.

METHODS

45 rats at 6 weeks of age, were randomly assigned to nine groups with 5 rats in each group, both azoxymethane (AOM) and 5-Fluorouracil (5-FU) were given to rats according to the body weight. NDV virus strains (AF2240 and V4-UPM) doses were determined to rats according to CD50 resulted from MTT assay. After 8 doses of NDV strians and 5-FU, tissue sections preparations and histopathological study of rats' organs were done.

RESULTS

In this article morphological changes of rats' organs, especially in livers, after treatment with a colon carcinogen (azoxymethane) and Newcastle disease virus strains have been recorded. We observed liver damage caused by AOM evidenced by morphological changes and enzymatic elevation were protected by the oncolytic viruses sections. Also we found that combination treatment NDV with 5-FU had greater antitumor efficacy than treatment with NDV or 5-FU alone.

CONCLUSION

We noted morphological changes in liver and other rats' organs due to a chemical carcinogen and their protection by NDV AF2240 and NDV V4-UPM seems to be most protective.

Determination of the Potential Tumor-Suppressive Effects of Gsdme in a Chemically Induced and in a Genetically Modified Intestinal Cancer Mouse Model

Gasdermin E (GSDME), also known as deafness autosomal dominant 5 (DFNA5) and previously identified to be an inducer of regulated cell death, is frequently epigenetically inactivated in different cancer types, suggesting that GSDME is a tumor suppressor gene. In this study, we aimed to evaluate the tumor-suppressive effects of GSDME in two intestinal cancer mouse models. To mimic the silencing of GSDME by methylation as observed in human cancers, a Gsdme knockout (KO) mouse was developed. The effect of GSDME on tumorigenesis was studied both in a chemically induced and in a genetic intestinal cancer mouse model, as strong evidence shows that GSDME plays a role in human colorectal cancer and representative mouse models for intestinal cancer are available. Azoxymethane (AOM) was used to induce colorectal tumors in the chemically induced intestinal cancer model (n = 100). For the genetic intestinal cancer model, Apc^1638N/+ mice were used (n = 37). In both experiments, the number of mice bearing microscopic proliferative lesions, the number and type of lesions per mouse and the histopathological features of the adenocarcinomas were compared between Gsdme KO and wild type (WT) mice. Unfortunately, we found no major differences between Gsdme KO and WT mice, neither for the number of affected mice nor for the multiplicity of proliferative lesions in the mice. However, recent breakthroughs on gasdermin function indicate that GSDME is an executioner of necrotic cell death. Therefore, it is possible that GSDME may be important for creating an inflammatory microenvironment around the tumor. This is in line with the trend towards more severe inflammation in WT compared to Gsdme KO mice, that we observed in our study. We conclude that the effect of GSDME in tumor biology is probably more subtle than previously thought.

In vitro and histological investigation of antitumor effect of some triazole compounds in colon cancer cell line

1,2,4-Triazoles are used as antifungal, antibacterial, antimicrobial, and antioxidant against some oxidative radical species. Recently, many 1,2,4-triazoles continue to be synthesized. In this study, the effect of the 1,2,4-triazole derivatives on human colon cancer (HT29) was investigated in vitro and in vivo in rats. MTT test was applied to in in vitro experiments. For in vivo study, rats were divided into seven groups as follows: Control group (negative control), azoxymethane (AOM), AOM + cisplatin 15, AOM + L1, AOM + L2, AOM + L3, and AOM + L4. To create colon cancer, the AOM injection was injected subcutaneously at a dose of 15 mg/kg, three times (once weekly). The in vivo studies were completed at 28 weeks. It was found that the 1,2,4-triazole derivatives reduced the cell viability (P < 0.05). In all animals in the experimental groups, mild dysplasia was detected in 100% of the colon mucosal epithelium. Severe dysplasia and adenocarcinoma were observed in L1 groups. As a result, this study determined that the 1,2,4-triazole derivatives exhibit antitumor activity.

Administration of High-Dose Vitamin C and Irinotecan Ameliorates Colorectal Cancer Induced by Azoxymethane and Dextran Sodium Sulfate in Mice

High-dose vitamin C administration has been reported to exhibit antitumor effect in various mouse models of cancer. However, the underlying mechanism of antitumor effect against colorectal cancer remains to be elucidated. In this study, we investigated the antitumor effect of high-dose vitamin C in a mouse model of chronic inflammation-associated colorectal cancer induced by azoxymethane (AOM) and dextran sodium sulfate (DSS). After cancer induction, the mice were administered vitamin C and/or irinotecan. Because irinotecan is a key drug in colorectal cancer treatment, it was used for comparison in this study. We examined reactive oxygen species (ROS) and interleukin-6 (IL-6) levels in the plasma of mice, as well as collagen type I and caspase-1 expression and neutrophil and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL)-positive cell counts in the colon tissue. Vitamin C and/or irinotecan administration decreased the plasma level of ROS and IL-6 and increased the expression of collagen type I and caspase-1. Furthermore, it increased neutrophil and TUNEL-positive cell counts. The most significant changes in the parameters analyzed were observed when both vitamin C and irinotecan were administered.

Intermittent hypoxia promotes carcinogenesis in azoxymethane and dextran sodium sulfate-induced colon cancer model

Intermittent hypoxia (IH), a characteristic of obstructive sleep apnea, is known to promote cancer progression and aggressiveness in mouse models. However, little is known regarding the effect of IH on cancer initiation. Here, the effect of IH on carcinogenesis was explored in azoxymethane (AOM) and dextran sodium sulfate (DSS)-induced colon cancer models with three different protocols. In the first protocol, two other application time points (early or late initiation of IH) were applied. In the second protocol, mice were divided into only two groups, and then exposed to either N or IH conditions for 14 days. In the third protocol, a pharmacological inhibition study for anti-inflammation (5-aminosalicylate) or anti-oxidative stress (N-acetylcysteine [NAC]) was performed. The number of tumors was significantly higher in the IH-1 than in the N or IH-2 groups. 8-oxo-2'-deoxyguanosine (8-OHdG) levels were higher in tumors of the IH-1 group than in that of the N and IH-2 groups. Gene expression related to reactive oxygen species production was higher in the IH-1 group than in the N and IH-2 groups, and it showed a positive correlation with 8-OHdG levels. Prior to cancer development 8-OHdG levels were already elevated in colonic epithelial regions in the IH group, possibly due to an imbalance between oxidative stress and antioxidant systems. NAC treatment resulted in a significant reduction in the number of tumors in mice exposed to IH. In conclusion, IH promotes carcinogenesis in a chemically-induced colon cancer model where elevated 8-OHdG may contribute to the increased tumor induction.

Effects of Dietary Fibre from the Traditional Indonesian Food, Green Cincau (Premna oblongifolia Merr.) on Preneoplastic Lesions and Short Chain Fatty Acid Production in an Azoxymethane Rat Model of Colon Cancer

Green cincau (Premna oblongifolia Merr.) is a traditional food of Indonesia and provides a natural source of dietary fibre and antioxidants. This study evaluated the ability of green cincau, and other dietary fibres with or without the addition of anti-oxidant, epigallocatechin-3-gallate (EGCG), to prevent colorectal cancer in a 12 week azoxymethane (AOM) rat model. While all dietary treatments stimulated short chain fatty acid production (SCFA) in the digesta and faeces, no one treatment was able to significantly protect against aberrant crypt formation (ACF), when compared to the control diet. However, feeding green cincau leaves or extracts did not result in an increase in ACF compared to the control diet. Unexpectedly, when the dietary fibre source was pectin, 0.1% EGCG increased proliferative activity and liver lipid peroxidation when compared to the control diet containing cellulose. Examination of faecal microbial communities identified the presence of short chain acid producing bacteria, but a distinct community profile was not observed from any individual diet group. Overall, this research implies that combining dietary fibre with an antioxidant does not automatically equate to a beneficial response. Further work is required to investigate the health-promoting properties of green cincau.

A role for the vitamin D pathway in non-intestinal lesions in genetic and carcinogen models of colorectal cancer and in familial adenomatous polyposis

Vitamin D is implicated in the etiology of cancers of the gastrointestinal tract, usually characterized by alteration in the APC/β-catenin/TCF tumor suppressor pathway. The vitamin D receptor (VDR) is also implicated in cardiovascular and skin diseases as well as in immunity. Activated VDR can indirectly alter β-catenin nuclear localization and directly suppress β-catenin/TCF mediated transcriptional activity. We treated VDR null mice with the carcinogen azoxymethane (AOM) and generated mice bearing a mutated APC (hypomorph) on a VDR null background (Apc^1638N/+Vdr^−/−). VDR null mice do not develop GI or extra-colonic tumors but loss of VDR decreased intestinal tumor latency and increased progression to adenocarcinoma in both models. AOM treatment of VDR null mice also caused squamous cell carcinoma of the anus. Although levels and distribution of total or activated β-catenin in the epithelial component of tumors were unaffected by loss of VDR, β-catenin dependent cyclin D1 expression was affected suggesting a direct VDR effect on β-catenin co-activator activity. Extra-colonic mucosa manifestations in Apc^1638N/+Vdr^−/− animals included increased nuclear β-catenin in submucosal stromal cells, spleno- and cardiomegaly and large epidermoid cysts characteristic of the FAP variant, Gardner's syndrome. Consistent with this, SNPs in the VDR, vitamin D binding protein and CYP24 as well as mutations in APC distal to codon 850 were strongly associated with Gardners syndrome in a cohort of 457 FAP patients, This work suggests that alterations in the vitamin D/VDR axis are important in Gardner's syndrome, as well as in the etiology of anal cancer.

Macrophage depletion using clodronate liposomes decreases tumorigenesis and alters gut microbiota in the AOM/DSS mouse model of colon cancer

We examined the role of macrophages in inflammation associated with colorectal cancer (CRC). Given the emerging evidence on immune-microbiota interactions in CRC, we also sought to examine the interaction between macrophages and gut microbiota. To induce CRC, male C57BL/6 mice ( n = 32) received a single injection of azoxymethane (AOM), followed by three cycles of dextran sodium sulfate (DSS)-supplemented water in weeks 1, 4, and 7. Prior to the final DSS cycle ( week 7) and twice weekly until euthanasia, mice ( n = 16/group) received either 200 μl ip of clodronate-filled liposomes (CLD) or phosphate-buffered saline (PBS) encapsulated liposomes to deplete macrophages. Colon tissue was analyzed for polyp burden, macrophage markers, transcription factors, and inflammatory mediators. Stool samples were collected, and DNA was isolated and subsequently sequenced for 16S rRNA. Clodronate liposomes decreased tumor number by ∼36% and specifically large (≥1 mm) tumors by ∼36% ( P < 0.05). This was consistent with a decrease in gene expression of EMR1 in the colon tissue and polyp tissue as well as expression of select markers associated with M1 (IL-6) and M2 macrophages (IL-13, IL-10, TGFβ, CCL17) in the colon tissue ( P < 0.05). Similarly, there was a decrease in STAT3 and p38 MAPK and ERK signaling in colon tissue. Clodronate liposomes increased the relative abundance of the Firmicutes phylum ( P < 0.05) and specifically Lactobacillaceae and Clostridiaceae families, which have been associated with reduced CRC risk. Overall, these data support the development of therapeutic strategies to target macrophages in CRC and provide support for further evaluation of immune-microbiota interactions in CRC. NEW & NOTEWORTHY We found that macrophage depletion during late-stage tumorigenesis is effective at reducing tumor growth. This was associated with a decrease in macrophage markers and chemokines in the colon tissue and a decrease in transcription factors that are linked to colorectal cancer. The macrophage-depleted group was found to have an increased abundance of Firmicutes, a phylum with documented anti-tumorigenic effects. Overall, these data support the development of therapeutic strategies to target macrophages in colorectal cancer.

3'-Hydroxypterostilbene Suppresses Colitis-Associated Tumorigenesis by Inhibition of IL-6/STAT3 Signaling in Mice

3'-Hydroxypterostilbene (trans-3,5-dimethoxy-3',4'-hydroxystilbene) presents in Sphaerophysa salsula, Pterocarpus marsupium, and honey bee propolis and has been reported to exhibit several biological activities. Herein, we aimed to explore the chemopreventive effects of dietary 3'-hydroxypterostilbene and underlying molecular mechanisms on colitis-associated cancer using the azoxymethane (AOM)/dextran sodium sulfate (DSS) model. 3'-Hydroxypterostilbene administration effectively ameliorated the colon shortening and number of tumors in AOM/DSS-treated mice (3.2 ± 1.2 of the high-dose treatment versus 13.8 ± 5.3 of the AOM/DSS group, p < 0.05). Molecular analysis exhibited the anti-inflammatory activity of 3'-hydroxypterostilbene by a significant decrease in the levels of inducible nitric oxide synthase, cyclooxygenase-2, and interleukin-6 (IL-6) (p < 0.05). Moreover, dietary 3'-hydroxypterostilbene also significantly diminished IL-6/signal transducer and activator of transcription signaling and restored colonic suppressor of cytokine signaling 3 levels in the colonic tissue of mice (p < 0.05). Collectively, these results demonstrated for the first time the in vivo chemopreventive efficacy and molecular mechanisms of dietary 3'-hydroxypterostilbene against colitis-associated colonic tumorigenesis.

ST-Producing E. coli Oppose Carcinogen-Induced Colorectal Tumorigenesis in Mice

There is a geographic inequality in the incidence of colorectal cancer, lowest in developing countries, and greatest in developed countries. This disparity suggests an environmental contribution to cancer resistance in endemic populations. Enterotoxigenic bacteria associated with diarrheal disease are prevalent in developing countries, including enterotoxigenic E. coli (ETEC) producing heat-stable enterotoxins (STs). STs are peptides that are structurally homologous to paracrine hormones that regulate the intestinal guanylyl cyclase C (GUCY2C) receptor. Beyond secretion, GUCY2C is a tumor suppressor universally silenced by loss of expression of its paracrine hormone during carcinogenesis. Thus, the geographic imbalance in colorectal cancer, in part, may reflect chronic exposure to ST-producing organisms that restore GUCY2C signaling silenced by hormone loss during transformation. Here, mice colonized for 18 weeks with control E. coli or those engineered to secrete ST exhibited normal growth, with comparable weight gain and normal stool water content, without evidence of secretory diarrhea. Enterotoxin-producing, but not control, E. coli, generated ST that activated colonic GUCY2C signaling, cyclic guanosine monophosphate (cGMP) production, and cGMP-dependent protein phosphorylation in colonized mice. Moreover, mice colonized with ST-producing E. coli exhibited a 50% reduction in carcinogen-induced colorectal tumor burden. Thus, chronic colonization with ETEC producing ST could contribute to endemic cancer resistance in developing countries, reinforcing a novel paradigm of colorectal cancer chemoprevention with oral GUCY2C-targeted agents.

Black Raspberries Enhance Natural Killer Cell Infiltration into the Colon and Suppress the Progression of Colorectal Cancer

Natural killer (NK) cells are an essential component of innate immunity against cancer development. Many studies have been conducted to evaluate immune-modulating effects using dietary compounds. Our laboratory has been investigating the chemopreventive potential of black raspberries (BRBs) and previously demonstrated their beneficial modulation of genetic and epigenetic biomarkers in patients with colorectal cancer (CRC). The current study investigated their potential on modulating NK cells. To avoid the excessive inflammation caused by the dextran sulfate sodium (DSS) treatment that leads to colitis, we treated the mice with overnight DSS so that it would slightly irritate the colon but still promote colon carcinogenesis with 100% incidence in both the Apc^Min/+ mice and azoxymethane (AOM)-treated mice. A significant decrease of tissue-infiltrating NK cells along the progression of microadenoma-to-adenoma and adenoma-to-adenocarcinoma was observed in the Apc^Min/+ /DSS and AOM/DSS mice, respectively. Depletion of NK cells significantly promoted the development of CRC, suggesting a critical role of NK cells in combating CRC progression. BRBs significantly suppressed the CRC progression and increased the number of tissue-infiltrating NK cells in both mouse models. Moreover, we further determined BRBs' effects on NK cells in the human biopsy specimens collected from our previously completed clinical trial, in which CRC patients consumed BRBs for an average of 4 weeks during a presurgical window. We observed an increased number and an enhanced cytotoxicity of NK cells by BRB intervention. The current study provides evidence that BRBs have the potential to enhance the tumor immunesurveillance of NK cells that can be beneficial in the setting of CRC prevention and treatment.

Korean Solar Salt Ameliorates Colon Carcinogenesis in an AOM/DSS-Induced C57BL/6 Mouse Model

The effects of Korean solar salt on an azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced colon cancer C57BL/6 mouse model were studied. Korean solar salt samples (SS-S, solar salt from S salt field; SS-Yb, solar salt from Yb salt field), nine-time-baked bamboo salt (BS-9x, made from SS-Yb), purified salt (PS), and SS-G (solar salt from Guérande, France) were orally administered at a concentration of 1% during AOM/DSS colon cancer induction, and compared for their protective effects during colon carcinogenesis in C57BL/6 mice. SS-S and SS-Yb suppressed colon length shortening and tumor counts in mouse colons. Histological evaluation by hematoxylin and eosin staining also revealed suppression of tumorigenesis by SS-S. Conversely, PS and SS-G did not show a similar suppressive efficacy as Korean solar salt. SS-S and SS-Yb promoted colon mRNA expression of an apoptosis-related factor and cell-cycle-related gene and suppressed pro-inflammatory factor. SS-Yb baked into BS-9x further promoted these anti-carcinogenic efficacies. Taken together, the results indicate that Korean solar salt, especially SS-S and SS-Yb, exhibited anti-cancer activity by modulating apoptosis- and inflammation-related gene expression during colon carcinogenesis in mice, and bamboo salt baked from SS-Yb showed enhanced anti-cancer functionality.

Bamboo Salt Suppresses Colon Carcinogenesis in C57BL/6 Mice with Chemically Induced Colitis

The aim of our experiment was to evaluate the anticancer effect of bamboo salt (BS) on C57BL/6 mice in an azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced colon cancer model. BS, solar salt, and purified salt were evaluated for their protective effects during AOM/DSS-induced colon carcinogenesis in C57BL/6 mice. BS, especially after baking for nine separate intervals (BS9x), suppressed colon carcinogenesis in the mice. BS9x decreased colon length shortening, weight-to-length ratios, and tumor counts. Pathological evidence from histological evaluation by hematoxylin and eosin staining also revealed suppression of tumorigenesis. BS9x lowered serum levels of proinflammatory cytokines (TNF-α, IL-6, and IL-1β) to close to those of the Normal group. Additionally, BS9x suppressed colon mRNA expression of proinflammatory factors and significantly regulated mRNA levels of the apoptosis-related factors, Bax and Bcl-2, and the cell cycle-related genes, p21 and p53. Additionally, immunohistochemistry showed that BS promoted p21 expression in the colon. Taken together, the results indicate that BS exhibited anticancer efficacy by modulating apoptosis- and inflammation-related gene expression during colon carcinogenesis in mice, and repetition in baking cycles of BS enhanced its anticancer functionality.

Intake of mulberry 1-deoxynojirimycin prevents colorectal cancer in mice

The effect of 1-deoxynojirimycin, a caloric restriction mimetic, was examined in ICR mice with azoxymethane dextran sodium sulfate-induced colorectal cancer. Azoxymethane is a carcinogen (10 mg/kg body weight), and 2% dextran sodium sulfate (w/v) used as a colitis-inducing agent. Mice were separated into 5 groups: a group without colorectal cancer fed a normal diet (CO– group), and groups with colorectal cancer fed a normal diet (CO+ group), a calorie-restricted diet (caloric restriction group), and diets including 0.02% and 0.1% 1-deoxynojirimycin (l-1-deoxynojirimycin and H-1-deoxynojirimycin groups). The tumor incidence and number were reduced significantly in the caloric restriction group compared to the CO+ group, and were also suppressed in a dose-dependent manner by 1-deoxynojirimycin. mRNA for anti-apoptotic Bcl-2 was decreased and that for pro-apoptotic Bax was increased in the carcinoma tissue of CR, l-1-deoxynojirimycin and H-1-deoxynojirimycin groups. These results suggest that caloric restriction and 1-deoxynojirimycin inhibit growth of colorectal cancer by inducing apoptosis in an induced cancer model in mice.

Simultaneous Assessment of the Efficacy and Toxicity of Marine Mollusc-Derived Brominated Indoles in an In Vivo Model for Early Stage Colon Cancer

The acute apoptotic response to genotoxic carcinogens animal model has been extensively used to assess the ability of drugs and natural products like dietary components to promote apoptosis in the colon and protect against colorectal cancer (CRC). This work aimed to use this model to identify the main chemopreventative agent in extracts from an Australian mollusc Dicathais orbita, while simultaneously providing information on their potential in vivo toxicity. After 2 weeks of daily oral gavage with bioactive extracts and purified brominated indoles, mice were injected with the chemical carcinogen azoxymethane (AOM; 10 mg/kg) and then killed 6 hours later. Efficacy was evaluated using immunohistochemical and hematoxylin staining, and toxicity was assessed via hematology, blood biochemistry, and liver histopathology. Comparison of saline- and AOM-injected controls revealed that potential toxic side effects can be interpreted from blood biochemistry and hematology using this short-term model, although AOM negatively affected the ability to detect histopathological effects in the liver. Purified 6-bromoisatin was identified as the main cancer preventive agent in the Muricidae extract, significantly enhancing apoptosis and reducing cell proliferation in the colonic crypts at 0.05 mg/g. There was no evidence of liver toxicity associated with 6-bromoisatin, whereas 0.1 mg/g of the brominated indole tyrindoleninone led to elevated aspartate aminotransferase levels and a reduction in red blood cells. As tyrindoleninone is converted to 6-bromoisatin by oxidation, this information will assist in the optimization and quality control of a chemopreventative nutraceutical from Muricidae. In conclusion, preliminary data on in vivo safety can be simultaneously collected when testing the efficacy of new natural products, such as 6-bromoisatin from Muricidae molluscs for early stage prevention of colon cancer.

Role of neutral ceramidase in colon cancer

Alterations in sphingolipid metabolism, especially ceramide and sphingosine 1-phosphate, have been linked to colon cancer, suggesting that enzymes of sphingolipid metabolism may emerge as novel regulators and targets in colon cancer. Neutral ceramidase (nCDase), a key enzyme in sphingolipid metabolism that hydrolyzes ceramide into sphingosine, is highly expressed in the intestine; however, its role in colon cancer has not been defined. Here we show that molecular and pharmacological inhibition of nCDase in colon cancer cells increases ceramide, and this is accompanied by decreased cell survival and increased apoptosis and autophagy, with minimal effects on noncancerous cells. Inhibition of nCDase resulted in loss of β-catenin and inhibition of ERK, components of pathways relevant for colon cancer development. Furthermore, inhibition of nCDase in a xenograft model delayed tumor growth and increased ceramide while decreasing proliferation. It is noteworthy that mice lacking nCDase treated with azoxymethane were protected from tumor formation. Taken together, these studies show that nCDase is pivotal for regulating initiation and development of colon cancer, and these data suggest that this enzyme is a suitable and novel target for colon cancer therapy.-García-Barros, M., Coant, N., Kawamori, T., Wada, M., Snider, A. J., Truman, J.-P., Wu, B. X., Furuya, H., Clarke, C. J., Bialkowska, A. B., Ghaleb, A., Yang, V. W., Obeid, L. M., Hannun, Y. A. Role of neutral ceramidase in colon cancer.

Preventive effects of Resveratrol against azoxymethane-induced testis injury in rats

To evaluate the protective effects of Resveratrol (RES) on azoxymethane (AOM)-induced testicular damage using histopathology and biochemical analyses, 28 male rats were randomly divided into four groups. Groups were control, RES, AOM and ARES. At the end of the 7 weeks, following routine tissue processing procedure, testis sections were stained with haematoxylin-eosin and Masson's trichrome. The blood samples were taken for biochemical analysis of testosterone, total oxidative stress, total antioxidant status and oxidative stress index. Degenerative changes in the seminiferous tubules such as atrophy, loss in the number of germ cells and arrested spermatogenic cell, and increase in the connective tissue of the tunica albuginea in the groups with AOM treatment were found. RES treatment (ARES) reduced the number of affected seminiferous tubules significantly (p < .05) compared to AOM alone. The testosterone levels in AOM group were significantly lower than in the control group (p < .05). The total oxidative stress levels were significantly higher in AOM group compared to control group (p < .05). The total antioxidant status levels in ARES group were significantly higher than in the AOM group (p < .05). This study results suggest that an antioxidant like Resveratrol may be useful for decreasing the harmful effects of azoxymethane.

The MUTYH base excision repair gene protects against inflammation-associated colorectal carcinogenesis

MUTYH DNA glycosylase removes mismatched adenine opposite 7, 8-dihydro-8-oxoguanine (8-oxoG), which is the major mutagenic lesion induced by oxidative stress. Biallelic mutations in MUTYH are associated with MUTYH-Associated polyposis (MAP) and increased risk in colorectal cancer (CRC). We investigated cancer susceptibility associated with MUTYH inactivation in a mouse model of inflammation-dependent carcinogenesis induced by azoxymethane (AOM) and dextran sulphate (DSS). Mutyh^−/− mice were more sensitive than wild-type (WT) animals to AOM/DSS toxicity and accumulated DNA 8-oxoG in their gastrointestinal tract. AOM/DSS-induced colonic adenomas were significantly more numerous in Mutyh^−/− than in WT animals, and frequently showed a tubulo-villous feature along with high-grade dysplasia and larger size lesions. This condition resulted in a greater propensity to develop adenocarcinomas. The colon of untreated Mutyh^−/− mice expressed higher basal levels of pro-inflammatory cytokines GM-CSF and IFNγ, and treatment with AOM/DSS induced an early decrease in circulating CD4+ and CD8+ T lymphocytes and an increase in myeloid-derived suppressor cells (MDSCs). Adenomas from Mutyh^−/− mice had a greater infiltrate of Foxp3+ T regulatory cells, granulocytes, macrophages, MDSCs and strong expression of TGF-β-latency-associated peptide and IL6. Our findings indicate that MUTYH loss is associated with an increase in CRC risk, which involves immunosuppression and altered inflammatory response. We propose that the AOM/DSS initiation/promotion protocol in Mutyh^−/− mice provides a good model for MAP.

Comparative DNA adduct formation and induction of colonic aberrant crypt foci in mice exposed to 2-amino-9H-pyrido[2,3-b]indole, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline, and azoxymethane

Considerable evidence suggests that environmental factors, including diet and cigarette smoke, are involved in the pathogenesis of colon cancer. Carcinogenic nitroso compounds (NOC), such as N-nitrosodimethylamine (NDMA), are present in tobacco and processed red meat, and NOC have been implicated in colon cancer. Azoxymethane (AOM), commonly used for experimental colon carcinogenesis, is an isomer of NDMA, and it produces the same DNA adducts as does NDMA. Heterocyclic aromatic amines (HAAs) formed during the combustion of tobacco and high-temperature cooking of meats are also associated with an elevated risk of colon cancer. The most abundant carcinogenic HAA formed in tobacco smoke is 2-amino-9H-pyrido[2,3-b]indole (AαC), whereas 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) is the most potent carcinogenic HAA formed during the cooking of meat and fish. However, the comparative tumor-initiating potential of AαC, MeIQ, and AOM is unknown. In this report, we evaluate the formation of DNA adducts as a measure of genotoxicity, and the induction of colonic aberrant crypt foci (ACF) and dysplastic ACF, as an early measure of carcinogenic potency of these compounds in the colon of male A/J mice. Both AαC and AOM induced a greater number of DNA adducts than MeIQ in the liver and colon. AOM induced a greater number of ACF and dysplastic ACF than either AαC or MeIQ. Conversely, based on adduct levels, MeIQ-DNA adducts were more potent than AαC- and AOM-DNA adducts at inducing ACF. Long-term feeding studies are required to relate levels of DNA adducts, induction of ACF, and colon cancer by these colon genotoxicants.

Cimetidine and Clobenpropit Attenuate Inflammation-Associated Colorectal Carcinogenesis in Male ICR Mice

Histamine and histamine receptors (Hrhs) have been identified as critical molecules during inflammation and carcinogenesis. This study was conducted to determine the effects of Hrh1-Hrh3 antagonists on inflammation-associated colorectal carcinogenesis. Male ICR mice were treated with azoxymethane (AOM, 10 mg/kg bw, i.p.) and 1.5% dextran sodium sulfate (DSS, drinking water for 7 days) to induce colorectal carcinogenesis. The mice were then fed diets containing test chemical (500 ppm terfenadine, 500 ppm cimetidine or 10 ppm clobenpropit) for 15 weeks. At week 18, feeding with the diets containing cimetidine (Hrh2 antagonist) and clobenpropit (Hrh3 antagonist/inverse agonist) significantly lowered the multiplicity of colonic adenocarcinoma. Terfenadine (Hrh1 antagonist) did not affect AOM-DSS-induced colorectal carcinogenesis. Adenocarcinoma cells immunohistochemically expressed Hrh1, Hrh2, Hrh3 and Hrh4 with varied intensities. Because clobenpropit is also known to be a Hrh4 receptor agonist, Hrh2, Hrh3 and Hrh4 may be involved in inflammation-related colorectal carcinogenesis. Additional data, including the mRNA expression of pro-inflammatory cytokines and inducible inflammatory enzymes in the colonic mucosa, are also presented.

Manipulation of the Gut Microbiota Reveals Role in Colon Tumorigenesis

Mounting evidence indicates that alterations to the gut microbiota, the complex community of bacteria that inhabits the gastrointestinal tract, are strongly associated with the development of colorectal cancer. We used antibiotic perturbations to a murine model of inflammation-driven colon cancer to generate eight starting communities that resulted in various severities of tumorigenesis. Furthermore, we were able to quantitatively predict the final number of tumors on the basis of the initial composition of the gut microbiota. These results further bolster the evidence that the gut microbiota is involved in mediating the development of colorectal cancer. As a final proof of principle, we showed that perturbing the gut microbiota in the midst of tumorigenesis could halt the formation of additional tumors. Together, alteration of the gut microbiota may be a useful therapeutic approach to preventing and altering the trajectory of colorectal cancer.

There is growing evidence that individuals with colonic adenomas and carcinomas harbor a distinct microbiota. Alterations to the gut microbiota may allow the outgrowth of bacterial populations that induce genomic mutations or exacerbate tumor-promoting inflammation. In addition, it is likely that the loss of key bacterial populations may result in the loss of protective functions that are normally provided by the microbiota. We explored the role of the gut microbiota in colon tumorigenesis by using an inflammation-based murine model. We observed that perturbing the microbiota with different combinations of antibiotics reduced the number of tumors at the end of the model. Using the random forest machine learning algorithm, we successfully modeled the number of tumors that developed over the course of the model on the basis of the initial composition of the microbiota. The timing of antibiotic treatment was an important determinant of tumor outcome, as colon tumorigenesis was arrested by the use of antibiotics during the early inflammation period of the murine model. Together, these results indicate that it is possible to predict colon tumorigenesis on the basis of the composition of the microbiota and that altering the gut microbiota can alter the course of tumorigenesis.

IMPORTANCE Mounting evidence indicates that alterations to the gut microbiota, the complex community of bacteria that inhabits the gastrointestinal tract, are strongly associated with the development of colorectal cancer. We used antibiotic perturbations to a murine model of inflammation-driven colon cancer to generate eight starting communities that resulted in various severities of tumorigenesis. Furthermore, we were able to quantitatively predict the final number of tumors on the basis of the initial composition of the gut microbiota. These results further bolster the evidence that the gut microbiota is involved in mediating the development of colorectal cancer. As a final proof of principle, we showed that perturbing the gut microbiota in the midst of tumorigenesis could halt the formation of additional tumors. Together, alteration of the gut microbiota may be a useful therapeutic approach to preventing and altering the trajectory of colorectal cancer.

TGR5 signaling reduces neuroinflammation during hepatic encephalopathy

Hepatic encephalopathy (HE) is a serious neurological complication of acute and chronic liver failure. Expression of the neurosteroid/bile acid receptor Takeda G protein-coupled receptor 5 (TGR5) has been demonstrated in the brain and is thought to be neuroprotective. However, it is unknown how TGR5 signaling can influence the progression and associated neuroinflammation of HE. HE was induced in C57Bl/6 mice via intraperitoneal injection of azoxymethane (AOM) and tissue was collected throughout disease progression. TGR5 expression was elevated in the frontal cortex following AOM injection in mice. The cellular localization of TGR5 was found in both neurons and microglia in the cortex of C57Bl/6 mice. Central infusion of the TGR5 agonist, betulinic acid, prior to AOM injection delayed neurological decline, increased cortical cyclic adenosine monophosphate concentrations, reduced microglia activation and proliferation, and reduced proinflammatory cytokine production. Betulinic acid treatment in vitro reduced the neuronal expression of chemokine ligand 2, a chemokine previously demonstrated to contribute to HE pathogenesis. Lastly, treatment of the microglia cell line EOC-20 with conditioned media from betulinic acid-treated primary neurons decreased phagocytic activity and cytokine production. Together, these data identify that activation of TGR5, which is up-regulated during HE, alleviates neuroinflammation and improves outcomes of AOM-treated mice through neuron and microglia paracrine signaling.