山本 昌美

A 9-y-old male Boxer dog developed a mandibular skin tumor, which histologically had a locally invasive growth pattern composed of bilayered structures of inner eosinophilic cuboidal tumor cells and outer clear polygonal tumor cells with cytoplasm containing glycogen granules. Both cell populations gradually changed from low-grade morphologic features to highly anaplastic ones. Immunohistochemically, the eosinophilic tumor cells were positive for cytokeratin 8, a useful marker for luminal epithelial cells. In contrast, the clear tumor cells expressed several myoepithelial markers, including α-smooth muscle actin, p63, and cytokeratin 14. Based on these histologic and immunohistochemical characteristics, we diagnosed this apocrine sweat gland tumor as a carcinoma-and-malignant myoepithelioma with high-grade transformation of both luminal and myoepithelial cells. Our case may be a helpful reference for the histogenesis of carcinoma-and-malignant myoepithelioma, in which both the luminal epithelial and myoepithelial components are malignant.

Psoriasis is a chronic skin disease with interleukin (IL)-17-dominated inflammation and hyperproliferation of epidermis. Dietary fiber is fermented by the gut microbiome into short-chain fatty acids (SCFAs) that manifest anti-inflammatory effects. We examined if feeding with an inulin-enriched high-fiber diet (HFD) might improve topical imiquimod-induced psoriasis-like dermatitis in mice. HFD reduced thickening and total severity scores of imiquimod-induced dermatitis and reduced epidermal thickness, inflammatory infiltrates, including Ly6G+ neutrophils, and epidermal Ki67+ proliferating cells. HFD reduced mRNA levels of IL-17A, IL-17F, IL-22, IL-1β, tumor necrosis factor (TNF)-α, CXCL1, CXCL2, and keratin 16 and increased those of transforming growth factor (TGF)-β1 and cyclin-dependent kinase inhibitor 1A in imiquimod-induced dermatitis. In 16S rRNA sequencing of the gut microbiome, imiquimod increased relative abundance of phylum Firmicutes, while HFD increased that of phylum Bacteroidota and genus Bacteroides. HFD increased serum and fecal concentrations of SCFA propionate. Oral propionate reduced inflammatory infiltrates and epidermal Ki67+ cells and reduced mRNA levels of IL-17A, IL-17F, IL-17C, IL-22, IL-1β, IL-6, TNF-α, CXCL1, CCL20 and increased those of TGF-β1and IL-10 in imiquimod-indued dermatitis. Dietary inulin supplementation improves imiquimod-induced psoriasis-like dermatitis partially via propionate, and may be a promising adjunctive therapy for psoriasis.

Hemangiosarcoma (HSA) is a malignant neoplasm that occurs in humans and canines with a poor prognosis owing to metastatic spread, despite effective treatment. The frequency of spontaneous HSA development is higher in canines than in humans. Therefore, canine HSA is a useful model of intractable human disease, which requires early detection and an effective therapeutic strategy. A high frequency of the p110α phosphatidylinositol‑4,5‑bisphosphate 3‑kinase catalytic subunit alpha (PIK3CA) mutations is detected in a comprehensive genome‑wide analysis of canine cases of HSA. The present cloned the full‑length cDNA of canine PIK3CA and identified a mutation in codon 1047 from canine cases of HSA and cell lines that were established from these. The enforced expression of the 1047th histidine residue (H1047)R or L mutants of canine PIK3CA in HeLa cells enhanced epidermal growth factor receptor (EGFR) signaling via Akt phosphorylation. PIK3CA mutant canine HSA cell lines exhibited the hyperphosphorylation of Akt upon EGF stimulation as well. Alpelisib, a molecular targeted drug against PIK3CA activating mutations, exerted a significant antitumor effect in canine PIK3CA‑mutated HSA cell lines. By contrast, it had no significant effect on canine mammary gland tumor cell lines harboring PIK3CA mutations. On the whole, the findings of the present study suggest that alpelisib may be highly effective against PIK3CA mutations that occur frequently in canine HSA.

The initial step in bacterial infection is adherence of the bacterium to the target cell surface. Helicobacter pylori exploits the interaction of bacterial adhesin protein HopQ with human epithelial CEACAMs (CEACAM1, 5, and 6) to stably adhere to gastric epithelial cells, which is necessary for delivery of the H. pylori CagA oncoprotein into the epithelial cells via a type IV secretion system. In contrast to human CEACAMs, however, HopQ does not interact with Ceacam1 (mouse CEACAM1) in vitro or in CHO cells ectopically expressing Ceacam1. Since the mouse genome lacks Ceacam5 and Ceacam6, no significant HopQ-Ceacam interaction may occur in mouse gastric epithelial cells. Here, we found that the mouse stomach has a much lower expression level of Ceacam1 than the expression level of CEACAM1 in the human stomach. Consistently, mouse gastric epithelial cells resist CagA delivery by cagA-positive H. pylori, and the delivery is restored by ectopic expression of human CEACAM1 or CEACAM5 in mouse gastric epithelial cells. Thus, despite the fact that mice are routinely used for H. pylori infection studies, a low expression level of Ceacam1 in the mouse stomach together with the loss or greatly reduced interaction of HopQ with Ceacams make the mouse an inappropriate model for studying the role of H. pylori-delivered CagA in gastric pathogenesis, including the development of gastric cancer.

BACKGROUND: Gastric cancer (GC) is one of the most common cancer worldwide. We analyzed the expression of m6A regulatory genes in GC cohorts and revealed that YTHDF1 was uniquely upregulated in GC as compared with adjacent normal tissues. In this study, we analyzed the role of YTHDF1 in GC cells and modulation of the tumor immune microenvironment. METHODS: Three GC cohorts (cohort 1, n=101; cohort 2, n=278, and the Cancer Genome Atlas cohort, n=375) were analyzed for YTHDF1 expression. Function of YTHDF1 in GC was determined in GC cell lines. Role of YTHDF1 in antitumor immunity was investigated in allograft models. RESULTS: YTHDF1 is upregulated in GC compared with adjacent normal tissues, and high YTHDF1 expression was correlated with poor survival of patients with GC at mRNA (p=0.016) and protein levels (p=0.039). Loss of YTHDF1 in human (AGS, BGC823, MKN74) or mouse (YTN16) GC cell lines inhibited cell growth and colony formation in vitro. Strikingly, syngeneic YTN16 tumors with loss of YTHDF1 underwent complete remission in immunocompetent mice, while a lesser effect was found in immunodeficient mice. Consistently, YTHDF1 loss in GC tumors led to recruitment of mature dendritic cells (DCs) with increased MHCII expression and interleukin-12 (IL-12) secretion, which in turn, promoted CD4+ and CD8+ T cells infiltration with increased interferon-γ (IFN-γ) secretion. Loss of YTHDF1 mediated the overexpression of IFN-γ receptor 1 and JAK/STAT1 signaling pathway in tumor cells, which might contribute to restored sensitivity to antitumor immunity. In addition, pre-emptive exposure of YTN16 tumors with YTHDF1 loss triggered a potent antitumor immune response on rechallenge with wild-type YTN16 cells, implying that YTHDF1 loss induced a lasting systemic antitumor immunity. CONCLUSIONS: YTHDF1 is overexpressed in GC and promotes GC by inducing cell proliferation and repression of DCs-mediated antitumor immune response. YTHDF1 is a promising therapeutic target for GC treatment.

BACKGROUND: Bovine papillomavirus types 1 and 2 (BPV1/2) infection in horses has been associated with the development of equine sarcoids. Previous findings revealed the presence of sarcoid-associated BPV sequence variants that have been proposed as a key factor of cross-species infection in horses. To verify this hypothesis, sarcoid-associated BPV variants should be identified regardless of geographic location. OBJECTIVES: Sequence analyses of BPV1/2 derived from both horses and cattle were conducted to clarify the sarcoid-associated sequence variants. The aim of this study was to clarify the correlation between BPV phylogeny and the geographic origin/host species. STUDY DESIGN: Cross-sectional study. METHODS: Conventional PCR to detect BPV1/2 was performed with genomic DNA extracted from equine sarcoid (n = 10) and bovine papilloma (n = 10) samples collected in Japan. Direct sequencing results were compared between equine and bovine (equine/bovine)-derived BPV to identify sarcoid-associated variants of two early regions (E2, E5), one late region (L1) and the long control region (LCR). Phylogenetic and phylogeny-trait correlation were analysed using Bayesian Markov chain Monte Carlo (MCMC) method and Bayesian tip-association significance testing (BaTS). RESULTS: Seven BPV1 and three BPV2 were identified from equine sarcoids using PCR and direct sequencing. Sequence analysis of equine/bovine-derived samples showed no sarcoid-associated variants in four regions (E2, E5, L1 and LCR) of either BPV1 or BPV2. The phylogenetic tree of BPV1 E2, L1 and LCR tended to cluster within its geographic origins. BaTS analysis demonstrated that BPV1 sequence variability may be due to the geographic origin rather than host species difference. MAIN LIMITATIONS: There was a limitation in sample numbers. CONCLUSIONS: This study supports the geographic-specific hypothesis of sequence variability, suggesting that BPV1 is shared between local equids and bovids. However, more extensively collected sequences worldwide and functional evaluations are needed to verify the geographic-specific sequence variability of BPV1/2 between equine- and bovine-derived sequence.

Nestin, a class VI intermediate filament protein, is known to be expressed in various types of human neoplasms, including breast cancer, and is associated with their progression. However, its expression and role in canine mammary tumors remain unknown. We analyzed nestin expression in canine mammary tumors using in situ hybridization and immunohistochemistry. We also investigated its role in a canine mammary carcinoma cell line using RNA interference. Nestin expression was not observed in luminal epithelial cells of any of the 62 cases of benign mammary lesions examined, although myoepithelial cells showed its expression in most cases. In 16/50 (32%) primary mammary carcinomas and 6/15 (40%) metastases of mammary carcinomas, cytoplasmic nestin expression was detected in luminal epithelial cells. In luminal cells of primary mammary carcinomas, its expression was positively related to several pathological parameters that indicate high-grade malignancy, including histological grading (P < .01), vascular/lymphatic invasion (P < .01), Ki-67 index (P < .01), and metastasis (P < .05). Immunohistochemistry revealed that nestin expression was related to vimentin expression in mammary carcinomas (P < .01). This relationship was confirmed using reverse transcription-quantitative polymerase chain reaction using 9 cell lines derived from canine mammary carcinoma (P < .01). Finally, nestin knockdown in canine mammary carcinoma cells using small interfering RNA inhibited cell proliferation and migration based on WST-8, Boyden chamber, and cell-tracking assays. These findings suggest that nestin may at least partially mediate these behaviors of canine mammary carcinoma cells.

BACKGROUND: Peritoneal metastasis (PM) in gastric cancer (GC) is characterized by diffusely infiltrating and proliferating cancer cells accompanied by extensive stromal fibrosis in the peritoneal space. The prognosis of GC with PM is still poor regardless of the various current treatments. In order to elucidate the cause of difficulties in PM treatment, we compared the tumor immune microenvironment (TME) in primary and PM lesions in GC. In addition, a PM model with fibrous stroma was constructed using immunocompetent mice to determine whether its TME was similar to that in patients. METHODS: Immuno-histochemical analyses of infiltrating immune cells were performed in paired primary and PM lesions from 28 patients with GC. A C57BL/6 J mouse model with PM was established using the mouse GC cell line YTN16 either with or without co-inoculation of mouse myofibroblast cell line LmcMF with α-SMA expression. The resected PM from each mouse model was analyzed the immunocompetent cells using immunohistochemistry. RESULTS: The number of CD8+ cells was significantly lower in PM lesions than in primary lesions (P < 0.01). Conversely, the number of CD163+ cells (M2 macrophages) was significantly higher in PM lesions than in primary lesions (P = 0.016). Azan staining revealed that YTN16 and LmcMF co-inoculated tumors were more fibrous than tumor with YTN16 alone (P < 0.05). Co-inoculated fibrous tumor also showed an invasive growth pattern and higher progression than tumor with YTN16 alone (P = 0.045). Additionally, YTN16 and LmcMF co-inoculated tumors showed lower infiltration of CD8+ cells and higher infiltration of M2 macrophages than tumors with YTN16 alone (P < 0.05, P < 0.05). These results indicate that LmcMF plays as cancer-associated fibroblasts (CAFs) by crosstalk with YTN16 and CAFs contribute tumor progression, invasion, fibrosis, and immune suppression. CONCLUSIONS: This model is the first immunocompetent mouse model similar to TME of human clinical PM with fibrosis. By using this model, new treatment strategies for PM, such as anti-CAFs therapies, may be developed.

Fibroblast growth factor receptor 4 (FGFR4), one of four tyrosine kinase receptors for FGFs, is involved in diverse cellular processes. Activation of FGF19/FGFR4 signaling is closely associated with cancer development and progression. In this study, we examined the expression and roles of FGF19/FGFR4 signaling in human pancreatic ductal adenocarcinoma (PDAC). In human PDAC cases, FGFR4 expression positively correlated with larger primary tumors and more advanced stages. Among eight PDAC cell lines, FGFR4 was expressed at the highest levels in PK-1 cells, in which single-nucleotide polymorphism G388R in FGFR4 was detected. For inhibition of autocrine/paracrine FGF19/FGFR4 signaling, we used BLU9931, a highly selective FGFR4 inhibitor. Inhibition of signal transduction through ERK, AKT, and STAT3 pathways by BLU9931 reduced proliferation in FGF19/FGFR4 signaling-activated PDAC cells. By contrast, BLU9931 did not alter stemness features, including stemness marker expression, anticancer drug resistance, and sphere-forming ability. However, BLU9931 inhibited cell invasion, in part, by downregulating membrane-type matrix metalloproteinase-1 in FGF19/FGFR4 signaling-activated PDAC cells. Furthermore, downregulation of SIRT1 and SIRT6 by BLU9931 contributed to senescence induction, priming these cells for quercetin-induced death, a process termed senolysis. Thus, we propose that BLU9931 is a promising therapeutic agent in FGFR4-positive PDAC, especially when combined with senolysis (195/200).

Abdominal ultrasonographical and computed tomography examinations of a 12-year-old neutered female toy poodle revealed a protruding mass, approximately 2 cm in diameter, at the apex of the bladder. The mass was firm and haemorrhagic with a homogeneously brownish-yellow cut surface. Microscopically, it was unencapsulated and located in the muscle layer with invasion of the extra-muscular layer. It was composed of spindloid to oval neoplastic cells that formed irregular clefts and diffuse sheets that dissected bundles of collagen. Immunohistochemically, the neoplastic cells were positive for vimentin and lymphatic vessel endothelial hyaluronan receptor 1 antigens, but negative for cytokeratin AE1/AE3, factor VIII-related antigen, CD31, CD34, Prox-1, S100, desmin, α-smooth muscle actin and MyoD1. Negative immunolabelling for laminin antigen supported the absence of evidence of a basal lamina on ultrastructural examination. Based on these findings, this tumour was identified as a lymphangiosarcoma. To the best of our knowledge, this case is the first report of lymphangiosarcoma arising from the bladder in a dog.

Only a small percentage of patients afflicted with gastric cancer (GC) respond to immune checkpoint blockade (ICB). To study the mechanisms underlying this resistance, we examined the immune landscape of GC. A subset of these tumors was characterized by high frequencies of regulatory T (Treg) cells and low numbers of effector T cells. Genomic analyses revealed that these tumors bore mutations in RHOA that are known to drive tumor progression. RHOA mutations in cancer cells activated the PI3K-AKT-mTOR signaling pathway, increasing production of free fatty acids that are more effectively consumed by Treg cells than effector T cells. RHOA mutant tumors were resistant to PD-1 blockade but responded to combination of PD-1 blockade with inhibitors of the PI3K pathway or therapies targeting Treg cells. We propose that the metabolic advantage conferred by RHOA mutations enables Treg cell accumulation within GC tumors, generating an immunosuppressive TME that underlies resistance to ICB.

A 26-year and 6-month-old male sika deer that was kept at the Showa Park, Tokyo, Japan, collapsed and died of severe disease wasting and severe tabefaction. Grossly, numerous masses, 0.3-1.0 cm diameter, were dispersed throughout the liver. The multiple masses were composed of tumor cells, which had hypochromatic nuclei and abundant faintly eosinophilic cytoplasm, arranged in nests of various sizes. Immunohistochemically, tumor cells were positive for cytokeratin, chromogranin A, synaptophysin and gastrin. Ultrastructurally, the cytoplasm of the tumor cells contained abundant membrane-bound electron-dense granules. A metastatic lesion was observed in the renal, hepatic and pancreatic lymph nodes. On the basis of these findings, this tumor was diagnosed as a neuroendocrine carcinoma with metastases to the lymph nodes.

S100A4 (metastasin), a member of the S100 protein family, was initially identified in metastatic cells and is well established as a marker of aggressive human cancer. However, expression and roles of S100A4 in canine mammary tumors have not been clarified. In this study, expression of S100A4 was examined immunohistochemically in normal, hyperplastic, and neoplastic mammary glands of dogs. In all normal and benign lesions, S100A4 was restricted to a few stromal fibroblasts and inflammatory cells. However, in 7 of 57 (12%) of the malignant tumors examined, cytoplasmic and nuclear expression of S100A4 was observed in epithelial tumor cells and stromal cells. Particularly, the frequency of S100A4-positive anaplastic carcinomas was high (4/8 cases, 50%). Next, we established a novel cell line, named NV-CML, from a S100A4-positive canine mammary carcinoma. The cultured NV-CML cells and the tumors that developed in the immunodeficient mice after subcutaneous injection of the cells maintained the immunophenotype of the original tumor, including S100A4 expression. Using this cell line, we examined the cellular functions of S100A4 using RNA interference. S100A4 expression level in NV-CML cells transfected with small interfering RNA (siRNA) targeting canine S100A4 (siS100A4) was reduced to about one-fifth of those with negative-control siRNA (siNeg). Cell proliferation in WST-8 assay and cell migration in Boyden chamber assay were significantly decreased in siS100A4-transfected cells compared with siNeg-transfected cells. These findings suggest that S100A4 may be related to progression of canine mammary carcinomas via its influence on cell growth and motility.

H19 is an oncofetal RNA expressed in the developing embryo as well as in bladder, breast, gastric, pancreatic, hepatocellular, and prostate cancers. Recent studies have shown that H19 enhances cancer invasion and metastasis; however, its roles in cancer remain controversial. In the current study, H19 exhibited the second largest increase (82.4-fold) and represented the only non-protein coding gene among 11 genes identified that were elevated over 10-fold in lung-metastasis-derived pancreatic cancer cells compared with their parental cells using a mouse metastatic model. Subsequently, we further clarified the roles of H19 in pancreatic cancer growth and metastasis using in vitro and in vivo techniques. In situ hybridization showed that H19 was detected in 23 of 139 invasive ductal carcinomas (17%), and that H19 expression positively correlated with higher histological grades (P < 0.0001). Overexpression of H19 in PANC-1 pancreatic cancer cells induced higher motilities, whereas H19 inhibition using shRNA and siRNA showed opposite results; however, cell growth rates were not impacted. Intravenous injection of H19 shRNA vector-transfected PANC-1 cells yielded marked inhibition of metastasis in the liver and lungs of immunodeficient mice. These findings suggest that H19 has important roles in pancreatic cancer metastasis, and that inhibition of H19 represents a novel candidate for pancreatic cancer therapy.

Previously no mouse gastric cancer cell lines have been available for transplantation into C57BL/6 mice. However, a gastric cancer model in immunocompetent mice would be useful for analyzing putative therapies. N-Methyl-N-nitrosourea (MNU) was given in drinking water to C57BL/6 mice and p53 heterozygous knockout mice. Only 1 tumor from a p53 knockout mouse could be cultured and the cells s.c. transplanted into a C57BL/6 mouse. We cultured this s.c. tumor, and subcloned it. mRNA expression in the most aggressive YTN16 subline was compared to the less aggressive YTN2 subline by microarray analysis, and fibroblast growth factor receptor 4 (FGFR4) in YTN16 cells was knocked out with a CRISPR/Cas9 system and inhibited by an FGFR4 selective inhibitor, BLU9931. These transplanted cell lines formed s.c. tumors in C57BL/6 mice. Four cell lines (YTN2, YTN3, YTN5, YTN16) were subcloned and established. Their in vitro growth rates were similar. However, s.c. tumor establishment rates, metastatic rates, and peritoneal dissemination rates of YTN2 and YTN3 were lower than for YTN5 and YTN16. YTN16 established 8/8 s.c. tumors, 7/8 with lung metastases, 3/8 with lymph node metastases and 5/5 with peritoneal dissemination. FGFR4 expression by YTN16 was 121-fold higher than YTN2. FGFR4-deleted YTN16 cells failed to form s.c. tumors and showed lower rates of peritoneal dissemination. BLU9931 significantly inhibited the growth of peritoneal dissemination of YTN16. These studies present the first transplantable mouse gastric cancer lines. Our results further indicate that FGFR4 is an important growth signal receptor in gastric cancer cells with high FGFR4 expression.

With the recent advent of whole genome and transcriptome sequencing technologies, long noncoding RNAs have been brought into the spotlight in molecular biology. H19 was one of the first reported long non-coding RNAs its expression is high in embryonic organs and absent or greatly reduced in most adult tissues. Accumulating evidence suggests that H19 plays crucial roles in embryogenesis. However, its levels are increased in different cancers, including breast, hepato-gastrointestinal, urological, respiratory, and brain tumors. Although there have been several controversial reports as to whether H19 is oncogenic or tumor-suppressive, most studies have indicated that H19 is associated with growth, migration, invasion, and/or metastasis in many cancers however, its reported functional mechanisms vary among cancer types. Furthermore, serum H19 levels in patients with certain cancers have been suggested to be useful for diagnosis and prognosis. Thus, H19 long non-coding RNA might be a candidate for development of promising therapeutic and diagnostic modalities for several cancers. The purpose of this review is to provide an inclusive report on the functional role of H19 in different cancers.

Polyglucosan bodies (PGB) in the prostate of aged dogs without neurological signs were examined by light microscopy, histochemistry and immunohistochemistry. Prostatic PGB were round or oval and slightly basophilic. Most of the bodies were situated within the stromal smooth muscle cells. PGB were intensely positive for PAS, Best's carmine, Lugol's iodine and Grocott's methenamine silver method. Moreover, canine prostatic PGB were immunoreactive for monoclonal antibodies raised against human polyglucosan. The frequency of PGB in the smooth muscle cells was significantly correlated with the age of dogs. The occurrence of PGB in the canine prostate might be a non-specific finding related to ageing.

A young adult, female, free-ranging Japanese raccoon dog (Nyctereutes procyonoides viverrinus) with scabies infection was found dead as a result of traumatic injuries presumed to reflect vehicular trauma. Necropsy showed a large solid mass located on the left ovarian region, occupying a third of the abdominal cavity. Histologically, the mass contained complex tissues derived from three germinal layers, with areas of cuboidal or columnar epithelium, keratinized squamous epithelium, bone, cartilage, and adipose tissue. This paper presents the first morphologic description of ovarian teratoma in a raccoon dog.

Background: Helicobacter pylori (H. pylori) infection and excessive salt intake are known as important risk factors for stomach cancer in humans. However, interactions of these two factors with gene expression profiles during gastric carcinogenesis remain unclear. In the present study, we investigated the global gene expression associated with stomach carcinogenesis and prognosis of human gastric cancer using a mouse model. Methods: To find candidate genes involved in stomach carcinogenesis, we firstly constructed a carcinogen-induced mouse gastric tumor model combined with H. pylori infection and high-salt diet. C57BL/6J mice were given N-methyl-N-nitrosourea in their drinking water and sacrificed after 40 weeks. Animals of a combination group were inoculated with H. pylori and fed a high-salt diet. Gene expression profiles in glandular stomach of the mice were investigated by oligonucleotide microarray. Second, we examined an availability of the candidate gene as prognostic factor for human patients. Immunohistochemical analysis of CD177, one of the up-regulated genes, was performed in human advanced gastric cancer specimens to evaluate the association with prognosis. Results: The multiplicity of gastric tumor in carcinogen-treated mice was significantly increased by combination of H. pylori infection and high-salt diet. In the microarray analysis, 35 and 31 more than two-fold up-regulated and down-regulated genes, respectively, were detected in the H. pylori-infection and high-salt diet combined group compared with the other groups. Quantitative RT-PCR confirmed significant over-expression of two candidate genes including Cd177 and Reg3g. On immunohistochemical analysis of CD177 in human advanced gastric cancer specimens, over-expression was evident in 33 (60.0%) of 55 cases, significantly correlating with a favorable prognosis (P = 0.0294). Multivariate analysis including clinicopathological factors as covariates revealed high expression of CD177 to be an independent prognostic factor for overall survival. Conclusions: These results suggest that our mouse model combined with H. pylori infection and high-salt diet is useful for gene expression profiling in gastric carcinogenesis, providing evidence that CD177 is a novel prognostic factor for stomach cancer. This is the first report showing a prognostic correlation between CD177 expression and solid tumor behavior.

In 2005, a Japanese epidemiological study showed that increase in plasma glucose levels is a risk factor for gastric cancer. However, no animal model has hitherto shown any association between diabetes mellitus and neoplasia in the stomach. Diabetic (db/db) mice have obese and diabetic phenotypes, including hyperglycemia, because of disruption of the leptin receptor. In the present study, effects of hyperglycemia and/or hyperinsulinemia on the development of proliferative lesions were therefore examined in db/db mice given N-methyl-N-nitrosourea (MNU). A total of 120 mice were assigned to four groups: Group A, 40 db/db mice with MNU; Group B, 40 + /db mice with MNU; Group C, 30 misty (wild-type) mice with MNU; Group D, 10 db/db mice without MNU. MNU was given at 60 ppm in drinking water for 20 weeks. Subgroups of animals were sacrificed at weeks 21 and 30 and blood samples were collected to measure glucose, insulin, leptin, and adiponectin concentrations. The removed stomachs were fixed in formalin, and embedded in paraffin for histological examination and immunohistochemistry. At week 30 in Groups A, B, C and D, hyperplasia was observed in 100, 79, 57, and 0%, and dysplasia in 91, 43, 71, and 0%, respectively. Adenocarcinomas and pepsinogen-altered pyloric glands (PAPG), putative preneoplastic lesions, were observed only in Group A, at an incidence of 45%. The serum levels of insulin and leptin were also elevated in Group A. Gastric carcinogenesis by MNU was enhanced in db/db mice, possibly in association with hyperinsulinemia and hyperleptinemia. (Cancer Sci 2009; 100: 1180-1185)

K19-C2mE transgenic (Tg) mice, simultaneously expressing cyclooxygenase-2 (COX-2) and microsomal prostaglandin E synthase-1 (mPGES-1) in the gastric mucosa under the cytokeratin 19 gene promoter, were here treated with N-methyl-N-nitrosourea (MNU) and inoculated with Helicobacter pylori (H. pylori) to investigate gastric carcinogenesis. Wild-type (WT) and Tg mice undergoing MNU treatment frequently developed tumors in the pyloric region (100% and 94.7%, respectively); multiplicity in Tg was higher than that in WT (P &lt; 0.05) with H. pylori infection. Larger pyloric tumors were more frequently observed in Tg than in WT (P &lt; 0.05). In addition, Tg developed fundic tumors, where WT did not. No gastric tumors were observed without MNU treatment. Transcripts of TNF-alpha, iNOS, IL-1 beta, and CXCL14 were up-regulated with H. pylori infection in both genotypes and were also increased more in Tg than in WT within H. pylori-inoculated animals. Immunohistochemical analysis demonstrated significantly greater beta-catenin accumulation in pyloric tumors, compared with those in the fundus (P &lt; 0.01) with mutations of exon 3; 18.2% and 31.6% in MNU-alone and MNU + H. pylori-treated WT, whereas 21.4% and 62.5% was observed in the Tg, respectively; the latter significantly higher (P &lt; 0.05), suggesting the role of H. pylori in Wnt activation. In conclusion, K19-C2mE mice promoted gastric cancer in both fundic and pyloric regions. Furthermore beta-catenin activation may play the important role of pyloric carcinogenesis especially in H. pylori-infected Tg. Induction of various inflammatory cytokines in addition to overexpression of COX-2/mPGES-1 could be risk factors of gastric carcinogenesis and may serve as a better gastric carcinogenesis model. (Cancer Sci 2008; 99: 2356-2364).

p53 knockout mice have been utilized for the functional analysis of p53 in carcinogenic processes and for the evaluation of the carcinogenic potential of chemicals. In this study, we established that p53 knockout mice have an elevated susceptibility to the induction of histiocytic sarcoma (HS) by N-bis(2-hydroxy-propyl)nitrosamine (BHP). p53 heterozygous (+/-) and wild-type (+/+) mice were treated with 20 or 200 ppm BHP in their drinking water for 15 weeks or with 20 ppm BHP for 40 weeks. An additional group of p53 nullizygous (-/-) mice were treated with 20 ppm BHP for 15 weeks. In a 15-week experiment, hepatic HSs were unexpectedly observed in BHP-treated p53 (-/-) mice (30.8%) but not in p53 (+/-) and (+/+) mice and untreated (-/-) mice, indicating that a complete loss of p53 dramatically accelerates the genesis of HS. In a 40-week experiment, HSs were significantly increased in female p53 (+/-) mice (37.5%) as compared with female (+/+) mice (5.0%). Additionally, PCR-SSCP and sequencing analysis revealed a high frequency of p53 gene mutations in HSs, demonstrating the involvement of p53 gene mutations in HS development. Our data add to the understanding of the carcinogenic susceptibility of p53 knockout mice, and may help to elucidate the pathogenesis of HS development.

p53 knockout mice are now being frequently used to identify the carcinogenic potential of chemicals, thus it is important to precisely assess the susceptibility of the animals to various test chemicals. In the present study the susceptibility of p53 nullizygous((-/-)), heterozygous((+/-)), and wild-type((+/+)) mice to 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) was investigated. Mice of all three genotypes were first fed a diet containing 100 or 300 p.p.m. IQ for 15 weeks in a short-term experiment. p53((+/-)) and ((+/+)) mice were then treated with IQ for 40 weeks and maintained without further treatment for an additional 12 weeks in the long-term experiment. In the forestomach, the incidence of squamous cell hyperplasia was significantly higher in p53((-/-)) than in ((+/-)) and ((+/+)) mice at 15 weeks and higher in ((+/-)) mice than ((+/+)) mice with long-term IQ treatment, indicating an elevated susceptibility of p53 knockout mice. In contrast, in the liver, various hepatocellular lesions developed mainly in female mice with long-term IQ exposure but no significant differences were evident between p53 knockout and wild-type mice, indicating a lack of elevated susceptibility in the knockout animals. Furthermore, polymerase chain reaction-single strand conformation polymorphism and sequencing analysis revealed relatively high (13/30) and low (1/15) incidences of p53 mutations (exons 5-8) in squamous cell hyperplasia and hepatocellular tumors, respectively. These results clearly indicate that the susceptibility of p53 knockout mice is organ-dependent, coinciding to some extent with the likelihood of p53 gene alteration in the induced tumors.

Considerable rodent strain differences have been documented with regard to susceptibility to colon carcinogens. To clarify mechanisms, chimeras of susceptible strain C3H and relatively resistant strain C57BL/6N (B6) mice were exposed to a colonotropic carcinogen, 1,2-dimethylhydrazine (DMH) and tumor incidence and multiplicity were assessed. In the chimeras, incidence was as high as the C3H level. Multiplicity of lesions of B6 cells was also increased (P &lt; 0.001), but maintenance of the strain difference. When tumor localization was analyzed, tumors of B6 genotype in chimeras demonstrated a greater spread of distribution than in the parental case. The chimeric environment may thus stimulate tumor initiation but cell autonomous suppressive factors may be retained. (c) 2005 Elsevier Ireland Ltd. All rights reserved.

To elucidate which is the major determinant of susceptibility of p53 deficient mice, the carcinogen or the target organ, N-bis(2-hydroxypropyl)nitrosamine was administered to induce tumors multi-organs. In a 15-week experiment. the incidences of both lung and hepatic vascular tumors were found to be significantly higher in p53 nullizygous (-/-) than in heterozygous (+/-) and wild-type (+/+) mice, indicating universal susceptibility of p53 (-/-) mice. In a 40-week experiment, p53 (+/-) mice showed increased susceptibility only with regard to vascular tumors, coinciding with significantly more frequent (60%) p53 gene mutations, in comparison with lung tumors with their low Mutation rate (10.8%) (P &lt; 0.005). These results indicate that the target organ may be a more important factor than the carcinogen in determining susceptibility of p53 mice. (c) 2005 Elsevier Ireland Ltd. All rights reserved.

In an in vivo 5-week initiation assay model, chemical hepatectomy by hepatotoxicant administration was utilized as a cell proliferation stimulus as an alternative to the two-thirds partial hepatectomy. The study investigated the effect of an intraperitoneal (i.p.) injection of D-galactosamine (D-gal) for this purpose in a medium-term liver bioassay, with a further focus on cell proliferation kinetics and cytochrome P450 (CYP) expression. In experiment I, cell proliferation in rat liver after a single administration Of D-gal (700 mg kg(-1), i.p.) was analysed by the bromodeoxyuridine (BrdU) labeling method, and CYP isozymes were quantified by immunoblotting. In experiment II, the induction of glutathione S-transferase placental form (GST-P) positive foci by 1,2-dimethylhydrazine (DNIH) was evaluated in a modified in vivo 5-week initiation assay model. At 84 hours after single administration Of D-gal (i.p.) the BrdU index was markedly elevated (27.5% +/- 9.5%). Although CYP 2E1 and 1A2 apoprotein contents decreased transiently to less than 20% of the control level, subsequently they recovered to 60% and 40% of the control level, respectively, at 84 hours. Induction of GST-P positive foci in the group given DMH at 84 hours after a single administration Of D-gal was significantly greater than in the control group, correlating with the kinetics of cell proliferation. In conclusion, the sensitivity of the present initiation assay using D-gal i.p. is high, so that D-gal i.p. can be considered an effective cell proliferation stimulus. Copyright (c) 2005 John Wiley & Sons, Ltd.

The hepatocarcinogenic potential of 9-(4'-aminophenyl)-9H-pyrido[3,4-b]indole (aminophenylnorharman, APNH) was investigated using male and female p53 deficient mice. Incidence of oval cell hyperplasia was 2/14 (14.3%), 14/23 (60.9%), and 2/10 (20%) in p53 nullizygous (-/-), heterozygous (+/-), and wild type (+/+) mice, respectively, exposed to 30 ppm APNH for 15 weeks, while hepatocellular anisonucleosis was observed only in APNH-treated p53 (-/-) mice. At 40 weeks, hepatocellular carcinomas had developed in 16/46 (34.8%) and 10/27 (37.0%) of female p53 (+/-) and (+/+) mice in contrast to only 1/45 (2.2%) and 2/12 (16.7%) in their male counterparts, respectively, without any detectable p53 gene mutations. Dose-dependent APNH-DNA adduct formation and transcriptional induction of CYP 1A1, but not CYP 1A2, was revealed with 7-day APNH treatment using female C57BL/6J mice. These results suggested hepatocarcinogenicity of APNH in mice could be linked to the liver microenvironment including hormonal milieu but independent of p53 expression and p53 gene mutations. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

The initiation effects of the novel heterocyclic amine, 9-(4′-aminophenyl)-9H-pyrido[3,4-b]indole (aminophenylnorharman, APNH) on carcinogenesis were investigated in an in vivo five-week assay system. A total of 65 F344 male rats, 7 weeks old, were subjected to two-thirds partial hepatectomy (PH) and administered APNH intragastrically at doses of 10, 3, 1, and 0 mg/kg body weight (b.w.) (groups 1, 2, 3, and 5, respectively) twice, at 12 and 30 h after PH. Then the rats were fed diet containing 0.015% 2-acetylaminofluorene and given a single dose of CCl4 at week 3. Group 4 received 10 mg/kg b.w. APNH without 2-AAF and CCl4 treatment. Analysis of glutathione S-transferase placental form (GST-P) positive foci in liver sections revealed areas in groups 1, 2, and 3 to be increased in a dose dependent manner to 3.43 ± 1.38, 2.18 ± 1.41, and 0.94 ± 0.51 mm2/cm2, respectively, compared with the control value (0.22 ± 0.20 in group 5) (groups 1-3 vs. group 5, P<0.001; groups 1 vs. 2, P<0.05; groups 2 vs. 3, P<0.01). The numbers of GST-P positive foci in groups 1, 2, and 3 were, 19.34 ± 7.20, 22.75 ± 8.16 and 13.61 ± 4.92 foci/cm2 and were significantly higher than in the controls (2.67 ± 1.27 in group 5). These data suggested initiation activity of APNH. Furthermore, the area of GST-P positive foci in group 4 was increased to 0.59 ± 0.31 mm2/cm2 (P<0.05 vs. group 5) indicating promoting activity of APNH for hepatotumorigenesis. In conclusion, the above results provide evidence of initiating carcinogenic potential for APNH.

Aberrant Wnt/beta-catenin signaling caused by mutations in exon 3 of the beta-catenin gene has been identified in a number of human malignancies, including stomach cancer. However, studies of mutation frequency have yielded conflicting results, and timing during progression remains largely unknown. In this study, we utilized an animal model to address this question. A total of 20 ACl male rats were treated with N-methyl-N'-nitro-N-nitrosoguanicline (MINING) in the drinking water and 22 induced differentiated adenocarcinomas were histopathologically and immunohistochemically evaluated for beta-catenin localization. Fourteen tumors (63.6%) that showed homogeneous low-grade morphology, preserving cell polarity, were found to harbor beta-catenin protein on the cell membranes (M). Eight tumors exhibited regions of high-grade morphology among areas with low-grade morphology, and they were characterized by denser cell growth and loss of cell polarity. Among these 8 tumors, 4 (18.2%) showed cytoplasmic localization (C) of beta-catenin in small regions. The remaining 4 tumors (18.2%) contained more dysplastic regions that displayed nuclear (N) beta-catenin staining. Analysis of DNA obtained by microdissection demonstrated that all of 4 regions with C staining and 20 with M staining, as well as 17 samples of surrounding normal mucosa (S) had wild-type beta-catenin. In contrast, all of 3 regions with N staining featured mutations (3 of 3=100%; N vs. C, P&lt;0.05; N vs. M and IN vs. S, P&lt;0.001, Fisher's exact test) in exon 3, at glycine 34, threonine 41, and serine 45, which affected phosphorylation sites. In conclusion, beta-catenin mutations appear to be associated with the late progression stage of adenocarcinoma development in rat stomach carcinogenesis, in contrast to the case of colorectal cancers, in which mutations appear to occur in the early stages.

Purpose. The susceptibility of male p53 nullizygote (-/-), heterozygote (+/-), and wild-type (+/+) mice to 1,2-dimethylhydrazine (DMH) induction of colon carcinogenesis was investigated. Methods. In a preliminary short-term experiment, male mice of three genotypes were given s.c. of 20 mg/kg DMH once weekly for 5 weeks. In a medium-term experiment, mice were given weekly s.c. of DMH for 15 weeks. In a long-term experiment, male p53 (+/-) and (+/+) mice were given weekly injections of DMH for 15 weeks, and killed at week 30. Results. In the medium-term experiment, carcinomas were observed in 70% of p53 (-/-) mice, although there were no carcinomas in p53 (+/+) and (+/-) mice. In the long-term experiment, there was no significant difference in incidences of adenomas and carcinomas between p53 (+/+) and (+/-) mice. PCR-single strand conformation polymorphism analysis of exons 5-8 of p53 gene revealed four mutations in one focal atypia, one adenoma, and two carcinomas, out of 56 colonic proliferative lesions in the medium- and long-term experiments. Conclusions. These results suggest that p53 might not be a direct target of DMH but complete loss of p53 might elevate susceptibility to DMH-induced colorectal carcinogenesis.

Initiating activities of 26 chemicals were investigated in an in vivo 5 week initiation assay model with evaluation of the induction of glutathione S-transferase placental form (GST-P) positive foci as end-point lesions. With the five genotoxic hepatocarcinogens (diethylnitrosamine, dimethylnitrosamine, 2-acetylaminofluorene, N-bis(2-hydroxypropyl)-nitrosamine and safrole) and 11 genotoxic non-hepatocarcinogens, (2-(2-furyl)-3-(5-nitro-2-furyl)-acrylamide, benzo[a]pyrene, N-butyl-N-(4-hydroxybutyl)nitrosamine, 7,12-dimethylbenz[a]anthracene, 1,2-dimethylhydrazine, N-ethyl-N-hydroxyethylnitrosamine, 3-methylcholanthrene, N-methyl-N-nitrosourea, N-methyl-N'-nitro-N-nitrosoguanidine, 4-nitroquinoline 1-oxide and 8-hydroxyquinoline), the numbers of GST-P positive foci were significantly higher than in the controls. On the other hand, the mutagenic non-carcinogens (quercetin, p-phenylenediamine dihydrochloride, 2-chloroethanol and 6-hydroquinoline) did not cause a significant increase. Similarly, non-genotoxic hepatocarcinogens of the hepatopromotor class and promotors which target organs other than the liver did not induce GST-P positive foci. The specificity was thus remarkable. Moreover, regardless of the target organ, mutagenic carcinogens were detected by this in vivo 5 week initiation assay, which therefore constitutes a powerful method for screening for carcinogenic potential, especially in the initiation stage of carcinogenesis. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

Mutations of the p53 tumor suppressor gene constitute one of the most frequent molecular changes in a wide variety of human cancers, including those in the esophagus. Mice deficient in p53 have recently attracted attention for their potential to identify chemical genotoxins. In this study we investigated the susceptibility of p53 nullizygous (-/-), heterozygous (+/-) and wild-type (+/+) mice to methyl-N-amylnitrosamine (MNAN), which specifically induces esophageal tumors in mice and rats. The p53 (+/-) and (+/+) mice were treated with 5 or 15 p.p.m. MNAN in their drinking water for 8 weeks then maintained without further treatment for an additional 7 or 17 weeks, being killed at experimental weeks 15 or 25. An additional group of p53 (-/-) mice were given 5 p.p.m. MNAN for 8 weeks and killed at week 15. At 15 weeks in the 5 p.p.m. groups, squamous cell carcinomas (SCCs) were observed in 10/12 (83.3%) p53 (-/-) and 1/15 (6.7%) p53 (+/-) mice, but in none of the p53 (+/+) mice. In the animals receiving 15 p.p.m., 2/14 (14.3%) p53 (+/-) and 1/11 (9.1%) p53 (+/+) mice developed SCCs. At 25 weeks, the incidence of SCCs was 7/16 (43.8%) and 8/14 (57.1%) in p53 (+/-) mice and 1/13 (7.7%) and 2/10 (20.0%) in p53 (+/+) mice at 5 and 15 p.p.m., respectively. Of the SCCs examined by PCR-single strand conformation polymorphism analysis, 61% (14/23) from p53 (+/-) and 50% (6/12) from p53 (+/+) mice demonstrated mutations in the p53 gene (exons 5-8). These results indicate the order of susceptibility to MNAN-induced esophageal tumorigenesis to be as follows: nullizygotes (-/-) &gt; heterozygotes (+/-) &gt; wild-type (+/+), and provide strong evidence of involvement of p53 mutations in the development of esophageal SCCs.