Mouse Forestomach Research Articles

Characterization of the gastrointestinal microbiome of the Syrian hamster (Mesocricetus auratus) and comparison to data from mice.

Syrian hamsters (Mesocricetus auratus) have been increasingly used as rodent models in recent years, especially for SARS-CoV-2 since the pandemic. However, the physiology of this animal model is not yet well-understood, even less when considering the digestive tract. Generally, the gastrointestinal microbiome influences the immune system, drug metabolism, and vaccination efficacy. However, a detailed understanding of the gastrointestinal microbiome of hamsters is missing. Therefore, we analyzed 10 healthy 11-week-old RjHan:AURA hamsters fed a pelleted standard diet. Their gastrointestinal content was sampled (i.e., forestomach, glandular stomach, ileum, cecum, and colon) and analyzed using 16S rRNA gene amplicon sequencing. Results displayed a distinct difference in the bacterial community before and after the cecum, possibly due to the available nutrients and digestive functions. Next, we compared hamsters with the literature data of young-adult C57BL/6J mice, another important animal model. We sampled the same gastrointestinal regions and analyzed the differences in the microbiome between both rodents. Surprisingly, we found strong differences in their specific gastrointestinal bacterial communities. For instance, Lactobacillaceae were more abundant in hamsters' forestomach and ileum, while Muribaculaceae dominated in the mouse forestomach and ileum. Similarly, in mouse cecum and colon, Muribaculaceae were dominant, while in hamsters, Lachnospiraceae and Erysipelotrichaceae dominated the bacterial community. Molecular strains of Muribaculaceae in both rodent species displayed some species specificity. This comparison allows a better understanding of the suitability of the Syrian hamster as an animal model, especially regarding its comparability to other rodent models. Thereby, this work contributes to the characterization of the hamster model and allows better experimental planning.

Trametes robiniophila Murr Sensitizes Gastric Cancer Cells to 5-Fluorouracil by Modulating Tumor Microenvironment.

Trametes robiniophila Murr (TRM) is a traditional Chinese medicine which has been used in clinics for enhancing immunity and improving the efficacy of chemotherapy. However, the mechanisms of action of TRM are unknown. In the previous study, we found that the Trametes robiniophila Murr n-butanol extract (TRMBE) comprises the major bioactive components of TRM. In the present study, we aimed to assess the combinational effects of TRMBE and 5-fluorouracil (5-FU) on the treatment of gastric cancer (GC) and explore its mechanism of action. It was found that TRMBE significantly potentiated the anticancer activity of 5-FU and prolonged the survival time of mice bearing Mouse Forestomach Carcinoma (MFC) xenograft tumors. We observed that the combination of TRMBE and 5-FU decreased the risk of liver metastasis in vivo. Furthermore, the combination of TRMBE and 5-FU reduced the levels of immune cytokines IL-6, IL-10, and TGF-β and increased the level of IFN-γ in peripheral blood. This combination therapy also significantly decreased the levels of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) and PD-1-positive CD8+ T cells and increased the levels of NK cells in tumor microenvironment (TME). However, TRMBE treatment was unable to enhance the chemosensitivity of GC to 5-FU in vivo after the depletion of CD8+ T and NK cells. Taken together, our results demonstrate that TRMBE can reshape the TME of GC by regulating PMN-MDSCs, CD8+ T cells, and NK cells, therefore improving the therapeutic effects of 5-FU. This study suggests that the combination of TRMBE and 5-FU could enhance immunity and could be a promising approach for GC treatment.

GATA4 blocks squamous epithelial cell gene expression in human esophageal squamous cells

GATA4 promotes columnar epithelial cell fate during gastric development. When ectopically expressed in the developing mouse forestomach, the tissue emerges as columnar-like rather than stratified squamous with gene expression changes that parallel those observed in the pre-malignant squamous to columnar metaplasia known as Barrett’s esophagus (BE). GATA4 mRNA up-regulation and gene amplification occur in BE and its associated cancer, esophageal adenocarcinoma (EAC), and GATA4 gene amplification correlates with poor patient outcomes. Here, we explored the effect of ectopic expression of GATA4 in mature human esophageal squamous epithelial cells. We found that GATA4 expression in esophageal squamous epithelial cells compromised squamous cell marker gene expression and up-regulated expression of the canonical columnar cell cytokeratin KRT8. We observed GATA4 occupancy in the p63, KRT5, and KRT15 promoters, suggesting that GATA4 directly represses expression of squamous epithelial cell marker genes. Finally, we verified GATA4 protein expression in BE and EAC and found that exposure of esophageal squamous epithelial cells to acid and bile, known BE risk factors, induced GATA4 mRNA expression. We conclude that GATA4 suppresses expression of genes marking the stratified squamous epithelial cell lineage and that this repressive action by GATA4 may have implications in BE and EAC.

Aristolochic Acid-Induced Genotoxicity and Toxicogenomic Changes in Rodents.

Aristolochic acid (AA) is a group of structurally related nitrophenanthrene carboxylic acids found in many plants that are widely used by many cultures as traditional herbal medicines. AA is a causative agent for Chinese herbs nephropathy, a term replaced later by AA nephropathy. Evidence indicates that AA is nephrotoxic, genotoxic, and carcinogenic in humans; and it also induces tumors in the forestomach, kidney, renal pelvis, urinary bladder, and lung of rats and mice. Therefore, plants containing AA have been classified as carcinogenic to humans (Group 1) by the International Agency for Research on Cancer. In our laboratories, we have conducted a series of genotoxicity and toxicogenomic studies in the rats exposed to AA of 0.1–10 mg/kg for 12 weeks. Our results demonstrated that AA treatments induced DNA adducts and mutations in the kidney, liver, and spleen of rats, as well as significant alteration of gene expression in both its target and nontarget tissues. AA treatments altered mutagenesis- or carcinogenesis-related microRNA expression in rat kidney and resulted in significant changes in protein expression profiling. We also applied benchmark dose (BMD) modeling to the 3-month AA-induced genotoxicity data. The obtained BMDL10 (the lower 95% confidence interval of the BMD10 that is a 10% increase over the background level) for AA-induced mutations in the kidney of rats was about 7 μg/kg body weight per day. This review constitutes an overview of our investigations on AA-induced genotoxicity and toxicogenomic changes including gene expression, microRNA expression, and proteomics; and presents updated information focused on AA-induced genotoxicity in rodents.

BMP7 Signaling in TGFBR2-Deficient Stromal Cells Provokes Epithelial Carcinogenesis.

Deregulated transforming growth factor-β (TGFβ) signaling is a common feature of many epithelial cancers. Deletion of TGFβ receptor type 2 (TGFBR2) in fibroblast specific protein-1 (FSP1)-positive stromal cells induces squamous cell carcinoma in the murine forestomach, implicating fibroblast-derived hepatocyte growth factor (HGF) as the major driver of the epithelium carcinogenesis. Prior to cancer development, hyperproliferative FSP1+ fibroblasts lacking TGFBR2 accumulate in the forestomach, disrupting the regulatory signaling cross-talk with the forestomach epithelium. Here, concurrent loss in TGFBR2 and SMAD4 completely abrogates the development of forestomach cancer. Bone morphogenic protein-7 (BMP7) was highly upregulated in forestomach cancer tissue, activating Smad1/5/8 signaling, cell proliferation, and HGF production in TGFBR2-deficient FSP1+ fibroblasts. This stimulation by BMP7 was lost in the combined TGFBR2 and SMAD4 double knockout fibroblasts, which included a profound decrease in HGF expression. Thus, Smad4-mediated signaling is required to initiate epithelial carcinogenesis subsequent to TGFBR2 deletion in FSP1+ fibroblasts.Implications: These findings reveal a complex cross-talk between epithelial cells and the stroma, wherein Smad4 is required to elicit squamous cell carcinomas in the forestomach of mice with TGFBR2-deficient stromal cells. Mol Cancer Res; 16(10); 1568-78. ©2018 AACR.

Abstract 4471: Pax9 regulates squamous cell differentiation and alcohol-associated carcinogenesis in the oro-esophageal epithelium

Abstract Pax9 is a transcription factor of the Pax family characterized by a DNA-binding paired domain. Previous studies have suggested a potential role of Pax9 in squamous cell differentiation and carcinogenesis of oro-esophageal epithelium. However, its functional role in differentiation and carcinogenesis remains unclear. In this study, Pax9 deficiency in mouse esophagus promoted cell proliferation, delayed cell differentiation and altered the global gene expression profile. Ethanol exposure down-regulated Pax9 expression in human esophageal epithelial cells in vitro and mouse forestomach and tongue in vivo. We further showed that PAX9 was down-regulated in human oro-esophageal squamous cell carcinoma (OESCC), and its down-regulation was associated with alcohol drinking and promoter hypermethylation. Moreover, ad libitum feeding with an isocaloric Lieber-DeCarli liquid diet containing ethanol for 40 weeks or Pax9 deficiency promoted NMBA-induced squamous cell carcinogenesis in mouse tongue, esophagus, and forestomach. In conclusion, Pax9 regulates squamous cell differentiation in the oro-esophageal epithelium. Alcohol drinking and promoter hypermethylation are associated with PAX9 silencing in human OESCC. Pax9 down-regulation, at least in part, contributes to alcohol-associated oro-esophageal squamous cell carcinogenesis. Citation Format: Zhaohui Xiong, Shuang Ren, Hao Chen, Yao Liu, Caizhi Huang, Yawan Lyvia Zhang, Joab Otieno Odera, Tong Chen, Ralf Kist, Heiko Peters, Katherine Garman, Zheng Sun, Xiaoxin Luke Chen. Pax9 regulates squamous cell differentiation and alcohol-associated carcinogenesis in the oro-esophageal epithelium [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4471.

Transcriptional profiling of male CD-1 mouse lungs and Harderian glands supports the involvement of calcium signaling in acrylamide-induced tumors

Acrylamide (AA) exposure causes increased incidence of forestomach, lung, and Harderian gland tumors in male mice. One hypothesized mode of action (MOA) for AA-carcinogenicity includes genotoxicity/mutagenicity as a key event, possibly resulting from AA metabolism to the direct genotoxic metabolite glycidamide. Alternatively, altered calcium signaling (CS) has been proposed as a central key event in the MOA. To examine the plausibility of these proposed MOAs, RNA-sequencing was performed on tumor target tissues: Harderian glands (the most sensitive tumor target tissue in the rodent 2-year cancer bioassay) and lungs of AA-exposed male CD-1 mice. Animals were exposed to 0.0, 1.5, 3.0, 6.0, 12.0, or 24.0 mg AA/kg bw-day in drinking water for 5, 15, or 31 days. We observed a pronounced effect on genes involved in CS and cytoskeletal processes in both tissues, but no evidence supporting a genotoxic MOA. Benchmark dose modeling suggests transcriptional points of departure (PODs) of 0.54 and 2.21 mg/kg bw-day for the Harderian glands and lungs, respectively. These are concordant with PODs of 0.17 and 1.27 mg/kg bw-day derived from the cancer bioassay data for these tissues in male mice, respectively. Overall, this study supports the involvement of CS in AA-induced mouse carcinogenicity, which is consistent with a recently proposed CS-based MOA in rat thyroid, and with other published reports of aberrant CS in malignant tumors in rodents and humans.

The role of ethyl acrylate induced GSH depletion in the rodent forestomach and its impact on MTD and in vivo genotoxicity in developing an adverse outcome pathway (AOP)

Adverse outcome pathways (AOP) and mode of action (MOA) frameworks help evaluate the toxicity findings of animal studies and their relevance to humans. To effectively use these tools to improve hazard identification and risk assessments for ethyl acrylate (EA), knowledge gaps in metabolism and genotoxicity were identified and addressed. For EA, hypothesized early key events relate to its irritation potential: concentration dependent irritation and cytotoxicity, progressing to regenerative proliferation and forestomach carcinogenicity after repeated oral bolus application in rodents. The current research quantitated glutathione (GSH) depletion to assess a kinetically-derived maximum tolerated dose (MTD) in the target tissue and used this information to conduct an in vivo genotoxicity study using current methods. In the mouse forestomach, gavage doses of EA caused GSH depletion to 47% of control at 20 mg/kg and 28% at 100 mg/kg. Cellular redox changes and histopathology support saturation of metabolism and an MTD of ∼50 mg/kg. No increases in point mutations or deletions occurred in the stomach or liver following a 28 day treatment of gpt delta transgenic mice at gavage doses up to 50 mg/kg/day. These results provide valuable information for evaluating AOP molecular initiating events or MOA key events for EA and other GSH depleting materials.

Three Cases of Esophageal Squamous Papilloma: A Rare and Poorly Understood Lesion

Squamous papilloma is a rare lesion of the esophagus. The estimated prevalence is between 0.07% and 0.45% on endoscopy. The pathogenesis remains uncertain, however underlying inflammation from reflux, as well as chronic mechanical/chemical irritation have been implicated. Further, human papilloma virus has been proposed as a risk factor. Although currently considered a benign lesion, the malignant potential of esophageal squamous papilloma in causing squamous cell carcinoma is controversial.Figure 1Figure 2Figure 3We present three cases of esophageal squamous papilloma. In the first, a 51 year old asymptomatic African American female with multiple sclerosis on dimethyl fumarate underwent esophagogastroduodenoscopy (EGD) for workup of iron deficiency anemia. On exam, the Z-line appeared irregular and a single 2mm white-pink wart like projection was seen in the middle esophagus. Excisional biopsy was performed. Pathology revealed squamous papilloma with biopsies of the distal esophagus showing chronic inflammation. Of note, a recent pap smear was negative for HPV. In the second case, a 28 year old Hispanic male with 2 months of epigastric abdominal pain, and hematemesis was seen for further evaluation. An EGD revealed a single 5mm nonbleeding exophytic projection 33cm from the incisors. Excisional biopsy showed squamous papilloma. In the final case, a 42 year old female underwent evaluation for abdominal pain and melena. EGD demonstrated a single 5mm exophytic nodule in the middle esophagus and diffuse inflammation in the stomach. The lesion was excised and showed a squamous papilloma. The present cases demonstrate the heterogeneity in gender, age, esophageal location, and risk factors of squamous papilloma. Prior reports from Western countries demonstrate a male predominance, average 48 years of age and location in the lower esophagus, thought to be related to reflux disease. However, in the present series two of the three patients were female and had lesions in the middle esophagus. One patient was 28 years of age without any signs of reflux. Moreover, the present series reports the first case of esophageal squamous papilloma in a patient taking dimethyl fumarate, an agent known to increase papillomas and squamous cell carcinomas of the forestomach in mice and rat models. Further studies are needed to understand pathogenesis and risk factors of esophageal papilloma to identify at-risk patients since the natural history and malignant potential remain poorly understood.

Acrylamide in Foods Generated through Heating (Contaminants).

The Food Safety Commission of Japan (FSCJ) conducted a risk assessment on acrylamide (AA) (CAS No. 79-06-1) in foods generated through heating, as a self-tasking risk assessment. In rodent toxicity studies, major adverse effects were observed on neurotoxicity and male reproductive toxicity. Statistically significant increases in incidences were observed in the carcinogenicity studies in Harderian gland, mammary gland, lung and forestomach in mice, and in mammary gland, thyroid and testis in rats. Positive results were also obtained from in vitro and in vivo genotoxicity studies of AA and glycidamide (GA). Therefore, FSCJ recognized AA as a genotoxic carcinogen. Judging from the dietary AA intake among Japanese people, the non-neoplastic risk is extremely low because of sufficient margins of exposure (MOEs). The neoplastic risk, however, could not be excluded due to the insufficient MOEs, although no clear evidence on human health effect have been provided from the epidemiological studies. It is important to note that no consistent relationships between AA exposure and cancer incidences have been observed even in the studies focusing on the highly exposed populations in occupational settings. FSCJ thus concluded that continual efforts are necessary to reduce dietary AA intakes in accordance with the principle of ALARA (as low as reasonably achievable) from the viewpoint of public health.

Characterization of the ecological role of genes mediating acid resistance in Lactobacillus reuteri during colonization of the gastrointestinal tract.

Rodent-derived strains of Lactobacillus reuteri densely colonize the forestomach of mice and possess several genes whose predicted functions constitute adaptations towards an acidic environment. The objective of this study was to systematically determine which genes of L. reuteri 100-23 contribute to tolerance towards host gastric acid secretion. Genes predicted to be involved in acid resistance were inactivated, and their contribution to survival under acidic conditions was confirmed in model gastric juice. Fitness of five mutants that showed impaired in vitro acid resistance were then compared through competition experiments in ex-germ-free mice that were either treated with omeprazole, a proton-pump inhibitor that suppresses acid secretion in the stomach, or left untreated. This analysis revealed that the urease cluster was the predominant factor in mediating resistance to gastric acid production. Population levels of the mutant, which were substantially decreased in untreated mice, were almost completely restored through omeprazole, demonstrating that urease production in L. reuteri is mainly devoted to overcome gastric acid. The findings provide novel information on the mechanisms by which L. reuteri colonizes its gastric niche and demonstrate that in silico gene predictions and in vitro tests have limitations for predicting the ecological functions of colonization factors in bacterial symbionts.

Role of hepatic cytochrome P450 enzymes in the detoxication of aristolochic acid I; effects on DNA adduct, mutation, and tumor formation.

IntroductionHepatic cytochrome P450s (CYPs) play an important role in the metabolism of plant carcinogen, aristolochic acid I (AAI). In the present study, we employed hepatic NADPH-cytochrome P450 reductase null (HRN) gpt delta transgenic mice to investigate the role of hepatic CYPs in the metabolism of AAI. DNA adduct formation, gene mutation, and tumor induction in the liver and kidneys were analyzed. Pharmacokinetic analyses were performed and tissue levels of AAI were determined.ResultsPretreatment with β-naphthoflavone in wild type gpt delta transgenic mice (BNF-WT mice) could increase the rate of clearance of AAI in blood and tissues, and decrease the formation of AAI-DNA adducts in kidney. In contrast, there was reduced clearance of AAI in HRN gpt delta mice, which showed increased concentration of AAI in tissues and increased levels of DNA adducts. The mutant frequencies of gpt gene, induced by AAI, in the kidneys of HRN gpt delta mice were significantly higher than that in WT mice. In the tumor induction assay, after treatment for 2 months with daily doses of 5 mg/kg AAI, mice were kept under observation for 7 months. During this period, papillomatous changes occurred in the forestomach of both WT-AAI mice and HRN gpt delta-AAI mice. Squamous cell carcinomas were found in the forestomach of 2 HRN gpt delta-AAI mice, which had also metastasized to other tissues. In addition, adenomas were found in 2 of 8 HRN gpt delta-AAI mice, in the absence of squamous cell carcinomas.ConclusionThese results indicated that the main role of hepatic CYPs is to aid in the excretion of AAI, and to protect the target organs against AAI induced DNA adduct formation, mutagenesis, and tumorigenesis.Electronic supplementary materialThe online version of this article (doi:10.1186/s41021-015-0010-z) contains supplementary material, which is available to authorized users.

Molecular Characterization of Host-Specific Biofilm Formation in a Vertebrate Gut Symbiont

Although vertebrates harbor bacterial communities in their gastrointestinal tract whose composition is host-specific, little is known about the mechanisms by which bacterial lineages become selected. The goal of this study was to characterize the ecological processes that mediate host-specificity of the vertebrate gut symbiont Lactobacillus reuteri, and to systematically identify the bacterial factors that are involved. Experiments with monoassociated mice revealed that the ability of L. reuteri to form epithelial biofilms in the mouse forestomach is strictly dependent on the strain's host origin. To unravel the molecular basis for this host-specific biofilm formation, we applied a combination of transcriptome analysis and comparative genomics and identified eleven genes of L. reuteri 100-23 that were predicted to play a role. We then determined expression and importance of these genes during in vivo biofilm formation in monoassociated mice. This analysis revealed that six of the genes were upregulated in vivo, and that genes encoding for proteins involved in epithelial adherence, specialized protein transport, cell aggregation, environmental sensing, and cell lysis contributed to biofilm formation. Inactivation of a serine-rich surface adhesin with a devoted transport system (the SecA2-SecY2 pathway) completely abrogated biofilm formation, indicating that initial adhesion represented the most significant step in biofilm formation, likely conferring host specificity. In summary, this study established that the epithelial selection of bacterial symbionts in the vertebrate gut can be both specific and highly efficient, resulting in biofilms that are exclusively formed by the coevolved strains, and it allowed insight into the bacterial effectors of this process.

N,N-Dimethyl-p-toluidine, a Component in Dental Materials, Causes Hematologic Toxic and Carcinogenic Responses in Rodent Model Systems

Because of the potential for exposure to N,N-dimethyl-p-toluidine (DMPT) in medical devices and the lack of toxicity and carcinogenicity information available in the literature, the National Toxicology Program conducted toxicity and carcinogenicity studies of DMPT in male and female F344/N rats and B6C3F1/N mice. In these studies, a treatment-related macrocytic regenerative anemia characterized by increased levels of methemoglobin and Heinz body formation developed within a few weeks of DMPT exposure in rats and mice. DMPT induced nasal cavity, splenic, and liver toxicity in rats and mice at 3 months and 2 years. DMPT carcinogenic effects were seen in the liver of male and female rats and mice, the nasal cavity of male and female rats, and the lung and forestomach of female mice. In rodents, DMPT is distributed to many of the sites where toxic and carcinogenic effects occurred. DMPT-induced oxidative damage at these target sites may be one mechanism for the treatment-related lesions. Methemoglobinemia, as seen in these DMPT studies, is caused by oxidation of the heme moiety, and this end point served as an early alert for other target organ toxicities and carcinogenic responses that followed with longer term exposure.

ACB‐PCR measurement of H‐ras codon 61 CAA→CTA mutation provides an early indication of aristolochic acid I carcinogenic effect in tumor target tissues

Aristolochic acid (AA) is a strong cytotoxic nephrotoxin and carcinogen, which induces forestomach and kidney tumors in mice and is associated with development of urothelial cancer in humans. This study sought to gain mechanistic insight into AAI-induced carcinogenesis through analysis of a tumor-relevant endpoint. Female Hupki mice were treated daily with 5 mg AAI/kg body weight by gavage for 3, 12, or 21 days. Histopathology and DNA adduct analysis confirmed kidney and forestomach as target tissues for AAI-induced toxicity. H-ras codon 61 CAA→CTA mutations were measured in mouse kidney and forestomach, as well as liver and glandular stomach (nontarget organs) by allele-specific competitive blocker-PCR (ACB-PCR), because A→T transversion is the predominant mutation induced by AA and this particular mutation was found previously in AA-induced rodent forestomach tumors. Treatment-related differences were observed, with the H-ras mutant fraction (MF) of mouse kidney and forestomach exposed to 5 mg AAI/kg body weight for 21 days significantly higher than that of vehicle-treated controls (Fisher's exact test, P < 0.05). Statistically significant correlations between dA-AAI adduct levels (measured previously in the same animals) and induced H-ras MFs were evident in forestomach of mice treated for 21 days (linear regression, P < 0.05). The significant increase in H-ras MF in kidney and forestomach, along with the correlation between DNA adducts, histopathology, and oncogene mutation, provide definitive evidence that AA induces tumors through a directly mutagenic mode of action. Thus, measurement of tumor-associated mutations is a useful tool for elucidating the mechanisms underlying the tissue specificity of carcinogenesis.

Genetic alteration of stemness factors and p53 in mouse forestomach by chemical carcinogen-induced carcinogenesis

The expression profiles of genes normally enriched in embryonic stem (ES) cells (stemness factors) are associated with poor clinical outcome in solid tumors. However, whether such gene expression is responsible for tumor initiation and progression remains to be determined. The tumor suppressor gene p53 is known to attenuate the expression of Nanog, which is essential for maintaining stem cells in response to DNA damage. On the basis of these findings, we hypothesized that stemness factors and p53 closely correlate with each other and form a network in response to genomic damage in the early phase of carcinogenesis and in the process of tumor progression. In this study, we applied the N-methylbenzylnitrosoamine (NMBA)-induced carcinogenesis model to the mouse forestomach to clarify the role of the stemness factors, c-Myc, Klf4, Sox2, Oct3/4 and Nanog, in cancer development using p53(+/+) (n=26) and p53(+/-) (n=11) C57BL/6J mice. Thirty weeks following NMBA administration, histologically evident squamous cell carcinoma was detected in the forestomachs of p53(+/+) mice, and the percentage of p53-positive nuclei in the forestomach epithelium gradually increased during carcinogenesis. Tumor development in p53(+/-) mice occurred significantly earlier than in p53(+/+) mice. Quantitative real-time PCR analyses revealed a reduced c-Myc and Klf4 expression before evident morphological changes were observed, and an increased expression with the development of squamous cell carcinoma. Sox2 expression remained unchanged until tumor development and increased with the appearance of squamous cell carcinomas. The expression of Oct3/4 and Nanog increased at the early stages following NMBA administration, and Nanog expression in situ was not positively affected by the deficiency of p53. Findings of the present study suggested that Oct3/4 may be involved in the progression of carcinogenesis from normal epithelial cells at early stages, suggesting the potential use of Oct3/4 as a biomarker in forestomach tumor formation at early stages of chemical carcinogenesis.

Pharmacological effects of curcumin

Curcumin (1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione, Cm) is a natural product, which possesses antioxidant, anti-inflammatory, and anti-tumor activities. Curcumin (diferuloylmethane), a low molecular weight polyphenol, derived from the rhizomes of Curcuma spp., has been shown to prevent cancer in the skin, forestomach, duodenum, and colon of mice and in the tongue, colon, mammary glands, and sebaceous glands of rats. Curcumin is a member of curcuminoids isolated from Curcuma longa (turmeric). Currently, it is one of the investigational new drug substances that have great clinical potential. It was used against several ailments in India. Ever since its isolation (mid Nineteenth century), several groups from all over the world worked on its pharmacology.

Cell Wall Polysaccharides of Candida albicans Induce Mast Cell Degranulation in the Gut.

We investigated Candida albicans-induced mast cell degranulation in vitro and in vivo. Cell wall fraction but not culture supernatant and cell membrane fraction prepared from hyphally grown C. albicans induced β-hexosaminidase release in RBL-2H3 cells. Cell wall mannan and soluble β-glucan fractions also induced β-hexosaminidase release. Histological examination of mouse forestomach showed that C. albicans gut colonization induces mast cell degranulation. However, intragastric administration of cell wall fraction failed to induce mast cell degranulation. We propose that cell wall polysaccharides are responsible for mast cell degranulation in the C. albicans-colonized gut.

Resource partitioning in relation to cohabitation of Lactobacillus species in the mouse forestomach

Phylogenetic analysis of gut communities of vertebrates is advanced, but the relationships, especially at the trophic level, between commensals that share gut habitats of monogastric animals have not been investigated to any extent. Lactobacillus reuteri strain 100-23 and Lactobacillus johnsonii strain 100-33 cohabit in the forestomach of mice. According to the niche exclusion principle, this should not be possible because both strains can utilise the two main fermentable carbohydrates present in the stomach digesta: glucose and maltose. We show, based on gene transcription analysis, in vitro physiological assays, and in vivo experiments that the two strains can co-exist in the forestomach habitat because 100-23 grows more rapidly using maltose, whereas 100-33 preferentially utilises glucose. Mutation of the maltose phosphorylase gene (malA) of strain 100-23 prevented its growth on maltose-containing culture medium, and resulted in the numerical dominance of 100-33 in the forestomach. The fundamental niche of L. reuteri 100-23 in the mouse forestomach can be defined in terms of 'glucose and maltose trophism'. However, its realised niche when L. johnsonii 100-33 is present is 'maltose trophism'. Hence, nutritional adaptations provide niche differentiation that assists cohabitation by the two strains through resource partitioning in the mouse forestomach. This real life, trophic phenomenon conforms to a mathematical model based on in vitro bacterial doubling times, in vitro transport rates, and concentrations of maltose and glucose in mouse stomach digesta.

Styrene exposure and risk of cancer

Styrene is widely used in the manufacture of synthetic rubber, resins, polyesters and plastics. Styrene and the primary metabolite styrene-7,8-oxide are genotoxic and carcinogenic. Long-term chemical carcinogenesis bioassays showed that styrene caused lung cancers in several strains of mice and mammary cancers in rats and styrene-7,8-oxide caused tumours of the forestomach in rats and mice and of the liver in mice. Subsequent epidemiologic studies found styrene workers had increased mortality or incidences of lymphohematopoietic cancers (leukaemia or lymphoma or all), with suggestive evidence for pancreatic and esophageal tumours. No adequate human studies are available for styrene-7,8-oxide although this is the primary and active epoxide metabolite of styrene. Both are genotoxic and form DNA adducts in humans.