Background: Signaling by IL-4 and IL-13 is transduced via a receptor complex of IL-13Rα1 and IL-4Rα chains. However, contribution of a putative decoy receptor of IL-13, IL-13Rα2, is not clear. The aim of this study was to determine the significance of Th2-type cytokines in the gastrointestinal (GI) epithelial cell repair system. Methods: We compared the tissue recovery in wild type (WT) and IL-4 receptor a deficient (IL-4R KO) mice following mucosal damage induced by 3 Gy-whole body γ-irradiation. The expression of IL-4, IL-13 and related molecules in the regenerative process were assessed. Results: Expression of IL-13Rα2 dramatically increased in myofibroblasts and fibroblasts on day 3. In contrast, in IL-4R KO mice, intestinal tissue repair after irradiation was delayed, and the transient upregulation of IL-13Rα2 was not seen. Injection of a soluble IL-13Rα2-immunoglobulin chimeric protein to both of WT and IL-4R KO mice resulted in the improvement of tissue recovery. Addition of IL-13 into primary tissue culture of the jejunum induced epithelial cell damage with decreased expression of membrane bound β-catenin. Conclusions: Our study demonstrated that IL-13 has a potential to induce epithelial cell damage, and IL-13Rα2 functions as a regulatory factor in the regeneration of intestinal epithelial cells.

抄録全体を表示

The growth of tumors transplanted into organs, particularly the extent of peritoneal dissemination from these tumors, cannot be evaluated extracorporeally, unlike the growth of subcutaneous tumors. We recently established a mouse model of peritoneal dissemination of human stomach cancer, including the formation of ascites, by orthotopic transplantation of cultured stomach cancer cells. To clarify the processes of expansion of the tumors in this model, nude mice were sacrificed and autopsied at different points of time after the orthotopic transplantation of the tumor cells for macroscopic and histopathological examination of the tumors. The tumor cells grew actively in the gastric submucosa and invaded the deeper layers to reach the serosal plane. The cancer cells then underwent exfoliation and became free, followed by the formation of metastatic lesions initially in the greater omentum, and subsequent colonization and proliferation of the tumors on the peritoneum. While this model allowed the detection of even minute metastases, it was not satisfactory from the viewpoint of quantitative and objective evaluation. To resolve these problems, we introduced a luciferase gene into this cancer cell line with a high metastasizing potential and carried out in vivo imaging analysis. This imaging technique was found to allow objective and quantitative evaluation of the progression of peritoneal dissemination on a real-time basis. This animal metastatic model is useful for monitoring the responses of tumors to anti-cancer agents.

抄録全体を表示

To elucidate molecular mechanism of multi-step carcinogenesis, we have identified genes specifically expressed in renal carcinomas from Eker rat model by differential cloning approach. Niban is one of such genes and is expressed even in the earliest pre-neoplastic lesion (phenotypically altered tubule) . Human NIBAN homologue is specifically expressed in malignancies such as renal or thyroid cancers. We recently found that Niban is a member of a protein family. From the expression profile of Niban/NIBAN, the importance of Niban protein function during carcinogenesis is anticipated. However, its function has been totally unkown. To analyze function of Niban, we generated Niban knockout mouse. So far, we have obtained evidences for the relation between Niban and ER stress as well as eIF2α and S6K/4E-BP1 phosphorylation.

抄録全体を表示

Prostaglandin E2 (PGE₂) and Wnt signaling are two indispensable pathways for gastrointestinal tumorigenesis. As a downstream product of cyclooxygenase 2 (COX-2), PGE₂ plays a key role in gastric tumorigenesis. The Wnt pathway also plays a causal role in gastric carcinogenesis. However, crosstalk or cooperation of these pathways for tumorigenesis remains poorly understood yet. To investigate their roles in gastric cancer development, we have generated two transgenic lines that activate either of two pathways in the gastric epithelial cells. First, we constructed K19-C2mE mice that expressed COX-2 and mPGES-1 simultaneously using the keratin 19 (K19) promoter. K19-C2mE mice showed increased PGE₂ level in the gastric mucosa that caused mucous cell metaplasia and hyperplasia. We next constructed K19-Wnt1 transgenic mice expressing Wntl in the gastric mucosa driven by K19 promoter. K19- Wnt1 mice had a significant suppression of epithelial differentiation, and developed small preneoplastic lesions consisting of undifferentiated epithelial cells with macrophage accumulation. However, K19-Wnt1 mice did not develop gastric tumors. We then crossed K19-Wnt1 mice with K19-C2mE to obtain K19-Wnt1/C2mE compound transgenic mice. Importantly, simultaneous activation of PGE₂ and Wnt pathways converted the preneoplastic lesions in the K19-Wntl mice into malignant gastric tumors by 20 weeks of age. Notably, we found mucous cell metaplasia in the glandular stomach of the compound K19-Wnt1/ C2mE mice as early as 5 weeks of age, before the dysplastic tumor development. These results indicate that cooperation of Wnt and PGE₂ pathways causes malignant gastric tumor development through the metaplasia-carcinoma sequence. Accordingly, K19- Wnt1/ C2mE mouse model is a useful tool to study the genetic mechanism of gastric carcinogenesis through activation of the Wnt and PGE₂ pathways.

抄録全体を表示

Pancreatic ductal adenocarcinoma is one of the most debilitating malignancies in humans with median survival times after treatment being less than 12 months. For the improvement of survivals, development of appropriate animal models which biologically mimic the human lesion is urgently required. Recent studies indicated that biological characteristics of tumor is dependent on cells in which a tumor grows, termed cancer stem cells. Although the data have been provided to support this theory in human tumors of blood, brain, and breast cancers, the identity of pancreatic cancer stem cells has not been determined. Although, pancreas ductal carcinomas were induced by induction of activated K-ras gene into the precursor gene in mouse, the responsible cells are not directly indicated. We conducted the study to determine if targeted activation of a human oncogenic-ras transgene in rat fully developed pancreas cell would induce carcinomas correspondent to human pancreatic ductal adenocarcinomas. Thus, transgenic (Hras250) rats in which expression of a human Ha-ras^G12V oncogene is regulated by the Cre/lox system is established. Targeted pancreatic activation of the transgene was accomplished by injection of Cre carrying adenovirus into the pancreatic ducts and acini through the common bile duct. Adenoviral infection of injected animals was exclusive to the pancreas; infected cells could be identified in duct, intercalated duct, centroacinar, and, less frequently, acinar cells, but not in endocrine islet cells. Four weeks after injection, proliferative lesions were exclusively observed in the duct epithelium, intercalated ducts, and centroacinar cells, but not acinar cells. Most lesions, including atypical duct proliferative lesions, PanIN-like lesions, and carcinomas, were positive for cyokeratins 19 and 7, cyclooxigenase 2, and MMP-7 but negative for amylase and chymotrypsin. Many adenocarcinoma lesions were positive for EGF and EGFR. Duct epithelial and atypical duct proliferative lesions and carcinoma lesions were all positive for transduced Ha-ras^G12V oncogene expression. This model exhibits close similarities to the human lesions and promises to advance our understanding of biological characteristics of pancreas adenocarcinomas. Results indicate that pancreatic duct epithelium, intercalated duct cells and centroacinar cells are possible candidate of cancer stem cells pancreas duct carcinomas.

抄録全体を表示

Tumor hypoxia is a potential therapeutic problem because it is closely associated with resistance to anti-cancer therapies and with the phenomenon of malignant progression. Therefore, although hypoxic tumor cells account for a very limited area in a solid tumor, conquering tumor hypoxia is crucial for treatment of malignant tumors. To image hypoxic tumor cells in vivo, we isolated a transfectant clone HeLa/5HRE-Luc, whose luciferase activity under hypoxic conditions was more than 100-fold of the one under aerobic conditions, and monitored the luciferase activity in HeLa/5HRE-luc xenografts with an in vivo real-time imaging system. To target tumor hypoxia, we recently constructed a fusion protein POP33, which is composed of the protein transduction domain (PTD), a part of HIF-1 α ODD and the dormant form of caspase-3, procaspase-3. PTD fusion proteins are previously demonstrated to be delivered to every cell in the whole body. POP33 did not affect well-oxygenized cells but efficiently increased caspase-3 activity and induced cell death to hypoxic cells in vitro. To investigate if POP33 can target hypoxic tumor cells in vivo, we monitored the luciferase activity in orthotopically transplanted human pancreatic cancer cells during POP33 treatment. The metastasis of the pancreatic cancer was significantly suppressed and their lucif erase activity was reduced during the sequential administration of POP33. These data demonstrate that POP33 specifically targets tumor hypoxia and provide direct evidence that hypoxic tumor cells play a crucial role in t metastasis of pancreatic cancers.

抄録全体を表示

Background: Signaling by IL-4 and IL-13 is transduced via a receptor complex of IL-13Rα1 and IL-4Rα chains. However, contribution of a putative decoy receptor of IL-13, IL-13Rα2, is not clear. The aim of this study was to determine the significance of Th2-type cytokines in the gastrointestinal (GI) epithelial cell repair system. Methods: We compared the tissue recovery in wild type (WT) and IL-4 receptor α deficient (IL-4R KO) mice following mucosal damage induced by 3 Gy-whole body γ-irradiation. The expression of IL-4, IL-13 and related molecules in the regenerative process were assessed. Results: Expression of IL-13Rα2 dramatically increased in myofibroblasts and fibroblasts on day 3. In contrast, in IL-4R KO mice, intestinal tissue repair after irradiation was delayed, and the transient upregulation of IL-13Rα2 was not seen. Injection of a soluble IL-13Rα2-immunoglobulin chimeric protein to both of WT and IL-4R KO mice resulted in the improvement of tissue recovery. Addition of IL-13 into primary tissue culture of the jejunum induced epithelial cell damage with decreased expression of membrane bound β-catenin. Conclusions: Our study demonstrated that IL-13 has a potential to induce epithelial cell damage, and IL-13Rα2 functions as a regulatory factor in the regeneration of intestinal epithelial cells.

抄録全体を表示