[Plasmablastic lymphoma presenting with plasmacytosis and polyclonal hypergammopathy].

A 72-year-old woman presented with generalized lymphadenopathies and plasmacytosis accompanied by polyclonal hypergammopathy. 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) showed FDG accumulation in the systemic lymph nodes, spleen, and multiple bones. Human immunodeficiency virus antibody was negative. Lymph node histologic findings showed a monotonous population of plasma cells with a starry-sky appearance. The cells were positive for CD19, λ, and Epstein-Barr virus-encoded RNA, and negative for CD20 and CD56. The MIB-1 index was 80%. A diagnosis of plasmablastic lymphoma with plasmacytosis and polyclonal hypergammopathy was made, and complete metabolic response was achieved after six cycles of dose-adjusted-EPOCH therapy (etoposide, prednisolone, vincristine, cyclophosphamide, and doxorubicin).

[Multiple myeloma with myelofibrosis at diagnosis and aggressive extramedullary relapse after autologous stem cell transplantation].

A 66-year-old man was diagnosed with symptomatic IgG-λ multiple myeloma based on the presence of anemia, thrombocytopenia, renal dysfunction, and a tumor on the right sixth rib. Bone marrow aspiration yielded a dry tap and biopsy revealed myelofibrosis grade 2. Partial response was achieved with Bd (bortezomib and dexamethasone) and VRd (bortezomib, lenalidomide, and dexamethasone). The patient received autologous stem cell transplantation, but the myeloma relapsed 3 months later, and liver tumors developed as well. DKd (daratumumab, carfilzomib, and dexamethasone) was administered, but the patient died due to disease progression. Autopsy revealed multiple extramedullary lesions in the liver, spleen, gallbladder, adrenal glands, kidneys, and multiple lymph nodes, as well as ascites.

Gilteritinib as Bridging and Posttransplant Maintenance for Relapsed Acute Myeloid Leukemia with FLT3-ITD Mutation Accompanied by Extramedullary Disease in Elderly.

A 69-year-old woman was diagnosed with acute myeloid leukemia (AML) with an FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) mutation. Complete remission (CR) was achieved after induction therapy, but AML resulted in a hematological relapse two months after the consolidation chemotherapy. Relapse was accompanied by multiple skin lesions that demonstrated leukemic cell infiltration as well as a drooping right eyelid with extroversion of the eye due to right oculomotor palsy. Gilteritinib was started as salvage therapy, and bone marrow blasts decreased to 0.8% after one month. Two months later, the eye symptoms improved, and the patient underwent cord blood transplantation (CBT). The skin lesions disappeared after the conditioning regimen, and the patient achieved CR status with complete donor chimerism at day 28. Gilteritinib was restarted as posttransplant maintenance therapy on day 53 of CBT. No adverse events other than mild hepatotoxicity were observed, and the patient was alive and in CR status, while continuing gilteritinib at one year and seven months after CBT. Bridging and posttransplant maintenance therapy with gilteritinib may be a promising therapeutic option for relapsed AML with the FLT3-ITD mutation in elderly patients.

[Busulfan/thiotepa followed by autologous peripheral blood stem cell transplantation for refractory diffuse large B-cell lymphoma accompanied by hypopyon].

A 54-year-old male patient, who presented with multiple lymphadenopathies, bilateral leg edema, and oscheohydrocele, was diagnosed with diffuse large B-cell lymphoma (DLBCL) stage IVB. His lymphadenopathies disappeared after six courses of R-CHOP therapy, which consist of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone); however, right hypopyon and partly remaining testicular soft tissue masses with fluorodeoxyglucose accumulation were observed. Lymphoma cell infiltration was observed in the aqueous humor of the right anterior chamber and testis, which indicates DLBCL progression. Hypopyon disappeared after the first course of intrathecal chemotherapy combined with R-HDMA therapy, which consists of rituximab and high-dose methotrexate/cytarabine, but recurred in the third course. The patient then underwent busulfan and thiotepa (BuTT) therapy followed by autologous peripheral blood stem cell transplantation (auto-PBSCT) after four courses of R-HDMA therapy. Hypopyon promptly disappeared after BuTT therapy and no hypopyon recurrence was observed 9 months after auto-PBSCT. Therefore, BuTT therapy is effective for hypopyon associated with refractory DLBCL.

Effect of Acid Suppressants on Non-Helicobacter pylori Helicobacters Within Parietal Cells.

We investigated the effect of increased pH induced by acid suppressants on the viability of non-Helicobacter pylori helicobacters (NHPHs) within parietal cell intracellular canaliculi and fundic glandular lumina by immunohistochemistry, electron microscopy, quantitative PCR, urea breath tests, and using a bilayer culture system. Three months before the experiment, mice were infected with the NHPH H. suis and then treated with famotidine (2 mg/kg body weight [BW], once daily), lansoprazole (30 mg/kg BW, once daily), or vonoprazan (20 mg/kg BW, once daily) for 3 days. Immunohistochemical studies using the TUNEL method, quantitative PCR analysis, and urea breath tests were performed. PCR analysis showed a decrease in the NHPH quantity after vonoprazan treatment. Urea breath tests revealed a significant decrease in the NHPH urease activity after vonoprazan, lansoprazole, and famotidine treatments for 3 days; however, 4 days after the treatment, urease activity reversed to the pretreatment level for each treatment group. Electron microscopy revealed an increase in the damaged NHPH after vonoprazan treatment. The TUNEL method revealed apoptotic NHPH within parietal cells after vonoprazan treatment. The bilayer culture results demonstrated that NHPH moved more quickly at a pH of 4.0 than at a pH of 3.0, 5.0, and 6.5, and electron microscopy revealed a change from the spiral form to the coccoid form under near-neutral pH conditions. We thus proposed that acid suppressants, especially vonoprazan, induce NHPH damage by altering pH.

Chemopreventive Effects of Dietary Isothiocyanates in Animal Models of Gastric Cancer and Synergistic Anticancer Effects With Cisplatin in Human Gastric Cancer Cells.

Naturally occurring isothiocyanates (ITCs) from edible vegetables have shown potential as chemopreventive agents against several types of cancer. The aims of the present study were to study the potential of ITCs in chemoprevention and in potentiating the efficacy of cytotoxic drugs in gastric cancer treatment. The chemoprevention was studied in chemically induced mouse model of gastric cancer, namely N-methyl-N-nitrosourea (MNU) in drinking water, and in a genetically engineered mouse model of gastric cancer (the so-called INS-GAS mice). The pharmacological effects of ITCs with or without cisplatin were studied in human gastric cell lines MKN45, AGS, MKN74 and KATO-III, which were derived from either intestinal or diffused types of gastric carcinoma. The results showed that dietary phenethyl isothiocyanate (PEITC) reduced the tumor size when PEITC was given simultaneously with MNU, but neither when administrated after MNU nor in INS-GAS mice. Treatments of gastric cancer cells with ITCs resulted in a time- and concentration-dependent inhibition on cell proliferation. Pretreatment of gastric cancer cells with ITCs enhanced the inhibitory effects of cisplatin (but not 5-fluorouracil) in time- and concentration-dependent manners. Treatments of gastric cancer cells with PEITC plus cisplatin simultaneously at different concentrations of either PEITC or cisplatin exhibited neither additive nor synergetic inhibitory effect. Furthermore, PEITC depleted glutathione and induced G2/M cell cycle arrest in gastric cancer cells. In conclusion, the results of the present study showed that PEITC displayed anti-cancer effects, particularly when given before the tumor initiation, suggesting a chemopreventive effect in gastric cancer, and that pretreatment of PEITC potentiated the anti-cancer effects of cisplatin, possibly by reducing the intracellular pool of glutathione, suggesting a possible combination strategy of chemotherapy with pretreatment with PEITC.

Helicobacter suis Infection in Mouse Induced not Only Gastric, but Hepatic and Pulmonary MALT Lymphoma: Relation to Substance P.

BACKGROUND: The hepatic and pulmonary MALT lymphoma (mucosa-associated lymphoid tissue lymphoma) is clinically occasionally observed but its pathogenesis is unknown and thought to be important to establish the treatment strategy. OBJECTIVES: The present study was designed to clarify the characteristics of these lymphomas and the effect of the Helicobacter eradication regimen and substance P antagonist. METHODS: After the long term infection of Helicobacter suis to the C57BL/6 mice stomach, the whole organ was surveyed pathologically. Histochemical characteristics of the lesion and the localization of bacteria were observed. In addition, the effect of the administration of antibiotics and a proton pump inhibitor or the substance P antagonist was investigated. RESULTS: We have detected the hepatic and pulmonary MALT lymphoma after the long term infection. In situ hybridization study revealed the positive reaction of Helicobacter suis in the hepatic and pulmonary MALT lymphoma. After the administration of antibiotics and a proton pump inhibitor, the bacterial number has significantly decreased and the tumor size in the fundus, liver and lung markedly reduced. Substance P immunoreactivity was clearly shown in the lymphoma cells in the liver and lung, and the spantide II administration induced the marked decrease in the size of tumors. CONCLUSION: By our experiments using the long term infection of Helicobacter suis to the C57BL/6 mice, we have detected the liver and pulmonary MALT lymphoma. In situ hybridization study suggested the direct interaction of this bacterium to the etiology of these lesions. Substance P within the lymphoma cells was suggested to work on the maintenance of the extragastric MALT lymphoma.

MALT Lymphoma, Stress Ulcer and Cholinergic Nerves from the Viewpoint of Bilateral and Unilateral Truncal Vagotomy and Substance P.

BACKGROUND: Vagal nerve plays an important role in the stomach function. The cholinergic nerves are the most abundantly distributed nerves in the gastric tissue. It has recently been reported that the vagal nerve is significantly related to both gastric cancer development and progression. However, its relation to the mesenchymal tumor, including MALT lymphoma, is not known. In this study, we investigated the effect of unilateral truncal vagotomy on gastric MALT lymphoma development by using Helicobacter heilmannii-infected mouse model as well as that of bilateral truncal vagotomy on stress-induced ulcer formation. METHODS: In the first part of this study, the distribution of the cholinergic nerves in the rat gastric mucosa and the effect of bilateral truncal vagotomy, as well as various kinds of agents acting on autonomic nerves in rats, were investigated by the histochemical and macroscopic method. In the second part, we employed MALT lymphoma formation in C57BL/6NCrl mice that were infected with Helicobacter heilmannii. A total of 38 infected mice underwent unilateral vagotomy under microscopy. The mice were randomized into 4 groups from which samples were collected; 2, 3, 4 and 6 months after infection. Both the anterior and posterior sides of the stomachs were sampled from each mouse for pathological and immunohistochemical analyses. RESULTS: The bilateral truncal vagotomy significantly suppressed the restraint-induced gastric ulcer formation in rats, while bethanechol, and 6-hydroxydopamine led to an increase of the gastric ulcer formation. In the unilateral truncal vagotomy study using MALT lymphoma, the thickness of the gastric mucosa was reduced in the vagotomized side compared to the non-vagotomized side. Furthermore, the gastric MALT lymphoma was more prominently found in the vagotomized anterior side of stomach compared with that in the non-vagotomized posterior side of stomach. Substance P-immunoreactive nerves markedly increased surrounding the MALT lymphoma and the neurokinin-1 receptor immunoreactive lymphocytes increased within the MALT lymphoma in the vagotomized side. In conclusion, vagotomy enhanced gastric MALT lymphoma development possibly through the substance P-neurokinin-1 receptor pathway.

Vagal Blocking for Obesity Control: a Possible Mechanism-Of-Action.

BACKGROUND: Recently, the US FDA has approved "vagal blocking therapy or vBLoc® therapy" as a new treatment for obesity. The aim of the present study was to study the mechanism-of-action of "VBLOC" in rat models. METHODS: Rats were implanted with VBLOC, an intra-abdominal electrical device with leads placed around gastric vagal trunks through an abdominal incision and controlled by wireless device. Body weight, food intake, hunger/satiety, and metabolic parameters were monitored by a comprehensive laboratory animal monitoring system. Brain-gut responses were analyzed physiologically. RESULTS: VBLOC reduced body weight and food intake, which was associated with increased satiety but not with decreased hunger. Brain activities in response to VBLOC included increased gene expression of leptin and CCKb receptors, interleukin-1ß, tumor necrosis factor, and transforming growth factor ß1 in the brainstem; increased CCK, somatostatin, and tyrosine hydroxylase in the hippocampus; increased NPY, AgRP, and Foxa2 in the hypothalamus; and reduced CCKb receptor, melanocortin 4 receptor, and insulin receptor in the hypothalamus. Plasma concentrations of CCK, gastrin, glucagon, GLP-1, and PYY and gastric acid secretion were unchanged in response to VBLOC. CONCLUSIONS: Based on the present study, we may suggest that VBLOC induces satiety through vagal signaling, leading to reduced food intake and loss of body weight.

Gene expression profiling of gastric mucosa in mice lacking CCK and gastrin receptors.

The stomach produces acid, which may play an important role in the regulation of bone homeostasis. The aim of this study was to reveal signaling pathways in the gastric mucosa that involve the acid secretion and possibly the bone metabolism in CCK1 and/or CCK2 receptor knockout (KO) mice. Gastric acid secretion was impaired and the ECL cell signaling pathway was inhibited in CCK2 receptor KO mice but not in CCK1 receptor KO mice. However, in CCK1+2 receptor double KO mice the acid secretion in response to pylorus ligation-induced vagal stimulation and the ECL cell pathway were partially normalized, which was associated with an up-regulated pituitary adenylate cyclase-activating polypeptide (PACAP) type 1 receptor (PAC1). The basal part of the gastric mucosa expressed parathyroid hormone-like hormone (PTHLH) in a subpopulation of likely ECL cells (and possibly other cells) and vitamin D3 1α hydroxylase probably in trefoil peptide2-immunoreactive cells. In conclusion, mice lacking CCK receptors exhibited a functional shift from the gastrin-CCK pathways to the neuronal pathway in control of the ECL cells and eventually the acid secretion. Taking the present data together with previous findings, we suggest a possible link between gastric PTHLH and vitamin D and bone metabolism.

Denervation suppresses gastric tumorigenesis.

The nervous system plays an important role in the regulation of epithelial homeostasis and has also been postulated to play a role in tumorigenesis. We provide evidence that proper innervation is critical at all stages of gastric tumorigenesis. In three separate mouse models of gastric cancer, surgical or pharmacological denervation of the stomach (bilateral or unilateral truncal vagotomy, or local injection of botulinum toxin type A) markedly reduced tumor incidence and progression, but only in the denervated portion of the stomach. Vagotomy or botulinum toxin type A treatment also enhanced the therapeutic effects of systemic chemotherapy and prolonged survival. Denervation-induced suppression of tumorigenesis was associated with inhibition of Wnt signaling and suppression of stem cell expansion. In gastric organoid cultures, neurons stimulated growth in a Wnt-mediated fashion through cholinergic signaling. Furthermore, pharmacological inhibition or genetic knockout of the muscarinic acetylcholine M3 receptor suppressed gastric tumorigenesis. In gastric cancer patients, tumor stage correlated with neural density and activated Wnt signaling, whereas vagotomy reduced the risk of gastric cancer. Together, our findings suggest that vagal innervation contributes to gastric tumorigenesis via M3 receptor-mediated Wnt signaling in the stem cells, and that denervation might represent a feasible strategy for the control of gastric cancer.

Mechanistic comparison between gastric bypass vs. duodenal switch with sleeve gastrectomy in rat models.

BACKGROUND: Both gastric bypass (GB) and duodenal switch with sleeve gastrectomy (DS) have been widely used as bariatric surgeries, and DS appears to be superior to GB. The aim of this study was to better understand the mechanisms leading to body weight loss by comparing these two procedures in experimental models of rats. METHODS: Animals were subjected to GB, DS or laparotomy (controls), and monitored by an open-circuit indirect calorimeter composed of comprehensive laboratory animal monitoring system and adiabatic bomb calorimeter. RESULTS: Body weight loss was greater after DS than GB. Food intake was reduced after DS but not GB. Energy expenditure was increased after either GB or DS. Fecal energy content was increased after DS but not GB. CONCLUSION: GB induced body weight loss by increasing energy expenditure, whereas DS induced greater body weight loss by reducing food intake, increasing energy expenditure and causing malabsorption in rat models.

Immunohistochemical evidence for an impairment of autophagy in tumorigenesis of gastric carcinoids and adenocarcinomas in rodent models and patients.

BACKGROUND/AIM: Autophagy has dual roles in tumorigenesis: tumor-promoting or tumor-suppressing. The aim of the present study was to examine autophagy-related markers by immunohistochemistry in gastric carcinoids and adenocarcinomas in rodent models and patients. METHODS: Gastric carcinoids in Mastomys were induced by loxtidine treatment. Spontaneously developed gastric adenocarcinomas in Japanese cotton rats and INS-GAS transgenic mice were included. Patient tissue samples of gastric carcinoids or adenocarcinomas were collected. Immunohistochemistry was performed against autophagy-related gene protein-6 (ATG-6, also called beclin-1), ATG-5 and ATG-16. RESULTS: In tumor-free Mastomys, ATG-5, ATG-16 and beclin-1 were immunepositive in the gastric mucosa. In tumor-bearing Mastomys, ATG-5 and ATG-16 were negative in the tumors, whereas beclin-1 was positive in four of five animals. In carcinoid patients, ATG-5 was negative in six of ten, ATG-16 negative in nine of ten, and beclin-1 negative in three of ten patients. In cotton rats, ATG-5 and ATG-16 were negative in all tumors. Beclin-1 was negative in three of five rats. In INS-GAS mice, ATG-5 and beclin-1 were positive in the tumor area, but the numbers of immunopositive cells per gland were reduced by about 50% in comparison with wild-type mice. In adenocarcinoma patients, ATG-5 and ATG-16 were negative in eight of ten, and beclin-1 positive in all ten patients. CONCLUSIONS: An impaired autophagy took place at the stage of formation of ATG-5-ATG-12-ATG-16 complex in both gastric carcinoids and adenocarcinoma of both rodent models and patients. ATG-5 and ATG-16 might be better markers than beclin-1 in assessing autophagy in these lesions.

Eating behavior and glucagon-like peptide-1-producing cells in interposed ileum and pancreatic islets in rats subjected to ileal interposition associated with sleeve gastrectomy.

BACKGROUND: Ileal interposition-sleeve gastrectomy (II-SG) has been developed as a metabolic surgery based on the hindgut hypothesis. The aim of the present study was to test this hypothesis by studying the eating behavior, metabolic changes, and glucagon-like peptide-1 (GLP-1)-producing cells in rat models. METHODS: Male Sprague-Dawley rats were subjected to laparotomy, II, SG, or II-SG. Eating behavior and metabolic parameters were monitored by an open-circuit indirect calorimeter designed for a comprehensive laboratory animal monitoring system. GLP-1-producing cells were examined by quantitative immunohistochemistry. RESULTS: After II alone, satiety ratio, i.e., intermeal interval/meal size, was reduced, while calorie intake was increased at 2 and 6 weeks postoperatively. Respiratory exchange ratio, VCO(2)/VO(2), was increased to above 1.0 (i.e., carbohydrate metabolism) during both daytime and nighttime at 2 weeks postoperatively. After SG alone, GLP-1-producing cells were increased in the pancreatic islets (in terms of volume density), but not in the ileum (number/mm). After II-SG, the rate of eating was reduced, while meal duration (min) was increased during both daytime and nighttime at 2 weeks postoperatively. GLP-1-producing cells were increased by about 2.5-fold in the interposed ileum and also increased to the same extent in the pancreatic islets as seen after SG alone. The increased GLP-1-producing cells in the pancreatic islets after SG or II-SG were located around the insulin-producing ß cells. CONCLUSIONS: The present study provides evidence supporting the hindgut hypothesis. II-SG increased GLP-1 production both in the interposed ileum and in the pancreatic islets, leading to metabolic beneficial effects and altered eating behavior.

Topical application of acetic acid in cytoreduction of gastric cancer. A technical report using mouse model.

BACKGROUND AND AIM: Application of acetic acid topically to the mucosal or serosal side of the stomach has been well used to create a chronic gastric ulcer model. The aim of the present study was to apply it as a new cytoreductive approach in a mouse model of gastric cancer. METHODS: A total of 43 genetically engineered mice, the so-called (INS-GAS) mice that develop spontaneously gastric cancer at 10-14 months of age, were included. Acetic acid-induced ulcer method was applied to mice under isofluran anesthesia. The ulcer at the cancer side was made by exposing either the anterior serosal or posterior mucosal side of gastric wall to 0.1 mL of 60% or 100% acetic acid for 30 or 60 s with a cylindrical metal mold (4 mm ID). Route to the serosal side was intra-abdominal and one to the mucosal side was through a small hole made in the forestomach. The opposite side of gastric wall (no treatment with acetic acid) was used as the corresponding control. After the mice were sacrificed, the stomachs were collected 1, 3, 6 h or 1, 3 and 7 days, postoperatively, and evaluated by visual inspection and histology. RESULTS: Gastric cancer was found in both the anterior and posterior walls of the corpus in all 43 mice. Intraluminal pH value was between 11 and 13. Severe necrosis in the cancer was observed in the side exposing to acetic acid, but not in the control side, shortly after the treatment (i.e. within 30 or 60 min). The muscularis mucosa and muscle layers were less damaged, regardless of the side of the treatment. Ulcer formation in the cancer took place 1, 3 or 7 days later. The ulcer depth was sometimes at the muscularis mucosa and muscle layers. At 3 and 7 days, regeneration of epithelial cells was clearly observed in the ulcer margin in the stomach of mice. CONCLUSIONS: Topical application of acetic acid either from mucosal or serosal surface promptly caused the necrosis of tumor, suggesting the potential approach of this simple and reliable method as a cytoreductive treatment of gastric cancer in patients through endoscopy or laparoscopy.

Eating behavior in rats subjected to vagotomy, sleeve gastrectomy, and duodenal switch.

BACKGROUND/AIM: Food intake, eating behavior, and metabolic parameters in rats that underwent bilateral truncal vagotomy, sleeve gastrectomy, and duodenal switch procedures were examined. METHODS: Rats were subjected to bilateral truncal vagotomy plus pyloroplasty (VTPP), pyloroplasty (PP), laparotomy, sleeve gastrectomy (SG), or duodenal switch (DS; with and without SG). RESULTS: VTPP, but neither PP nor laparotomy, reduced body weight (BW; 10%) transiently (1 week postoperatively). SG reduced BW (10%) for 6 weeks, while DS alone or SG followed by DS led to a continuous BW loss from 15% at 1 week to 50% at 8 weeks postoperatively. Food intake was higher and the satiety ratio was lower during the night than the day for all groups of surgeries. Neither VTPP nor SG had measurable effect on food intake, eating behavior and metabolic parameters. DS reduced daily food intake by more than 50%, which was associated with hypercholecystokinin(CCK)emia, reduced meal size and increased satiety ratio, and increased fecal energy content (measured at 8 weeks). CONCLUSIONS: Weight loss after VTPP, SG, or DS differed in terms of degree, duration, and underlying mechanisms. DS without SG was most effective in the long-term, probably due to hyperCCKemia-induced reduction in food intake and long-limb intestinal bypass-induced malabsorption.

Cancer immunoediting from immunosurveillance to tumor escape in microvillus-formed niche: a study of syngeneic orthotopic rat bladder cancer model in comparison with human bladder cancer.

Cancer cells can develop an attenuated immunogenicity and/or create an immunosuppressive microenvironment to prevent tumor eradication by host immune system, the so-called "cancer immunoediting" hypothesis. The aim of the present study was to find evidence for this hypothesis by using a rat orthotopic bladder cancer model. Fisher rats were inoculated with AY-27 cells (a Fisher rat bladder cancer cell line). Cultured cancer cells, rat and human bladder cancer tissues, and publicly available microarray data from human bladder cancer were analyzed by means of bioinformatics and morphology. Results showed that 12 of 24 differentially expressed pathways were concordant in connection to cell cycle and proliferation between rats and humans (both non-muscle-invasive and muscle-invasive tumors) and that 11 of the 24 pathways, including major histocompatibility complex, were related to host immunosurveillance with activations of T cells and natural killer cells in rats. The altered pathways and morphogenesis of this rat model corresponded more closely with those of human muscle-invasive rather than non-muscle-invasive tumors. A unique ultrastructure displaying microvillus-formed niches was found in small areas within the tumor of both rats and humans. These niches were interconnected with desmosomes between cancer cells and without infiltration of lymphocytes. The expression of E-cadherin, selectins, PGP9.5, vascular endothelial growth factor, caspase-3, CD133, Oct-4, nestin, CD3, and CD45RA was lower in the tumor than in the adjacent normal epithelium. We suggest that the microvillus-formed niche that harbors a few implanted cancer cells might be the compartment that prevents the tumor eradication by the host immune system.

A rat model of intravesical delivery of small interfering RNA for studying urinary carcinoma.

PURPOSE: siRNA has been used successfully in loss-of-function studies in vitro, but neither in vivo nor in clinical applications. The aims of the present study were (1) to establish rat models for in vivo delivery of siRNA to bladder cancer, and (2) to identify potential targets for siRNA. METHODS: The rat models of human urinary carcinoma and rat urinary carcinoma cell line (AY-27) were induced by tobacco-related chemical carcinogens, either N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) or N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN). A syngeneic orthotopic bladder cancer model was established by inoculation of AY-27 cells. A fluorescence-labelled negative control siRNA with cationic and neutral liposomes was tested both in vitro (AY-27 cells) and in vivo. RESULTS: siRNA was highly accumulated in the cancer cells as early as 12 h and remained at least for 24 h after a single dose in vivo. Numerous CD3+ T cells appeared mainly in the periphery area of the tumour. Bioinformatics analysis revealed a list of concordantly highly expressed genes, possible siRNA targets, in the animal models as well as human urinary carcinoma. Literature search on siRNA and bladder cancer provided a list of genes used as siRNA targets. CONCLUSION: The methodology and data presented in the present study provide a number of opportunities for basic research on urinary carcinogenesis and for translational research on evaluation of siRNA therapeutic strategies for urinary carcinoma in the native organ, where hormonal, neural and immunological processes more closely resemble the clinical situation.