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Background & Aims Senescence prevents cellular transformation. We investigated whether vascular endothelial growth factor (VEGF) signaling via its receptor, VEGFR2, regulates senescence and proliferation of tumor cells in mice with colitis-associated cancer (CAC). Methods CAC was induced in VEGFR2 ΔIEC mice, which do not express VEGFR2 in the intestinal epithelium, and VEGFR2 fl/fl mice (controls) by administration of azoxymethane followed by dextran sodium sulfate. Tumor development and inflammation were determined by endoscopy. Colorectal tissues were collected for immunoblot, immunohistochemical, and quantitative polymerase chain reaction analyses. Findings from mouse tissues were confirmed in human HCT116 colorectal cancer cells. We analyzed colorectal tumor samples from patients before and after treatment with bevacizumab. Results After colitis induction, VEGFR2 ΔIEC mice developed significantly fewer tumors than control mice. A greater number of intestinal tumor cells from VEGFR2 ΔIEC mice were in senescence than tumor cells from control mice. We found VEGFR2 to activate phosphatidylinositol-4,5-bisphosphate-3-kinase and AKT, resulting in inactivation of p21 in HCT116 cells. Inhibitors of VEGFR2 and AKT induced senescence in HCT116 cells. Tumor cell senescence promoted an anti-tumor immune response by CD8 + T cells in mice. Patients whose tumor samples showed an increase in the proportion of senescent cells after treatment with bevacizumab had longer progression-free survival than patients in which the proportion of senescent tumor cells did not change before and after treatment. Conclusions Inhibition of VEGFR2 signaling leads to senescence of human and mouse colorectal cancer cells. VEGFR2 interacts with phosphatidylinositol-4,5-bisphosphate-3-kinase and AKT to inactivate p21. Colorectal tumor senescence and p21 level correlate with patient survival during treatment with bevacizumab.

While barrier function and the effects of the intestinal microbiome have only recently moved into the focus of inflammatory bowel disease research, the role of the innate and the adaptive immune system in these gastrointestinal disorders has extensively been studied. Although still not completely understood, the increasing knowledge about the immune system's contribution to the pathophysiology of inflammatory bowel diseases has led to new diagnostic and therapeutic approaches. This review gives a compact overview on this important topic.

Early detection and evaluation of brain tumors during surgery is crucial for accurate resection. Currently cryosections during surgery are regularly performed. Confocal laser endomicroscopy (CLE) is a novel technique permitting in vivo histologic imaging with miniaturized endoscopic probes at excellent resolution. Aim of the current study was to evaluate CLE for in vivo diagnosis in different types and models of intracranial neoplasia. In vivo histomorphology of healthy brains and two different C6 glioma cell line allografts was evaluated in rats. One cell line expressed EYFP, the other cell line was used for staining with fluorescent dyes (fluorescein, acriflavine, FITC-dextran and Indocyanine green). To evaluate future application in patients, fresh surgical resection specimen of human intracranial tumors (n = 15) were examined (glioblastoma multiforme, meningioma, craniopharyngioma, acoustic neurinoma, brain metastasis, medulloblastoma, epidermoid tumor). Healthy brain tissue adjacent to the samples served as control. CLE yielded high-quality histomorphology of normal brain tissue and tumors. Different fluorescent agents revealed distinct aspects of tissue and cell structure (nuclear pattern, axonal pathways, hemorrhages). CLE discrimination of neoplastic from healthy brain tissue was easy to perform based on tissue and cellular architecture and resemblance with histopathology was excellent. Confocal laser endomicroscopy allows immediate in vivo imaging of normal and neoplastic brain tissue at high resolution. The technology might be transferred to scientific and clinical application in neurosurgery and neuropathology. It may become helpful to screen for tumor free margins and to improve the surgical resection of malignant brain tumors, and opens the door to in vivo molecular imaging of tumors and other neurologic disorders.

Background Interferon (IFN)-γ is a central pathogenesis factor in inflammatory bowel disease (IBD) with pleiotropic effects on many different cell types. However, as yet, the immune modulatory functions of IFN-γ in IBD have been predominantly investigated. Based on previous studies showing that IFN-γ acts antiangiogenic in colorectal carcinoma, we investigated the effects of IFN-γ on the vascular system in IBD. Methods Colon tissues of patients with IBD and dextran sulfate sodium-induced colitis in mice were subjected to immunohistochemistry, quantitative real-time polymerase chain reactions, and in situ hybridization to quantify cell activation, angiogenesis, and immune responses. Vascular structure and permeability in mice were analyzed by ultramicroscopy and in vivo confocal laser endomicroscopy. Results We showed a significantly increased blood vessel density in IBD and dextran sulfate sodium colitis. In mice, this was associated with a disorganized blood vessel structure and profound vascular leakage. As compared with genes associated with angiogenesis, genes associated with inflammatory cell activation including IFN-γ were more strongly upregulated in colitis tissues. IFN-γ exerted direct effects on endothelial cells in IBD tissues in vivo, as indicated by the expression of IFN-γ-induced guanylate binding protein 1 (GBP-1). Neutralization of IFN-γ in the acute dextran sulfate sodium colitis model demonstrated that this cytokine exerts endogenous angiostatic activity in IBD and contributes to increased vascular permeability. Conclusions The dissection of the pleiotropic activities of IFN-γ in IBD provides new insights to the pathological functions of this cytokine and may be of high relevance for the optimization of combination therapy approaches.

Helicobacter pylori CagA is delivered into H. pylori-adherent gastric epithelial cells through a bacterial type IV secretion system. The delivered CagA is tyrosine-phosphorylated at the EPIYA motifs by the host cell kinases, and then binds and aberrantly-activate Src homology 2 domain-containing protein tyrosine phosphatase 2 (SHP-2) and partitioning-defective 1 (PAR1), thereby acting as an epigenetic oncoprotein that promotes gastric cancer development in its early phase. Recently, Ishikawa et al. reported that the biological half-life of CagA is about 200 min in the gastric epithelial cells (FEBS Lett.,583:2414,2009). This report showed that the action of CagA as an epigenetic oncoprotein was not sustained for a prolonged period of time in the normal condition. In fact, the stability of CagA in the gastric epithelial cells is important for its further oncogenesis. The present study was designed to examine the degradation mechanisms of CagA in the gastric epithelial cells. Methods: MKN28 cells were transfected with CagA expression vectors (the pTet-Off and pTRE2hyg-Wild-typecagA-HA) (WT-A10 cells), and then CagA in the WT-A10 cells was induced for 24 h. H. pylori ATCC700392 was infected with AGS cells for 5 h. At 5 h after the infection, the AGS cells were incubated with 400 μg/mL kanamycin and harvested at 4, 12 and 24 h. 50 μM Z-Leu-Leu-Leu-al (MG132) and 20 μM lactacystin were used as the 26S-proteasome inhibitor, 5 mM3-methyladenine and 50 nMwortmannin as the inhibitors of autophagy, and rapamycin as the inducer of autophagy. Intracellular CagA was evaluated by westernblotting and immunocytochemistry. Results: After the induction of CagA in the WT-A10 cells for 24 h, significantly increase by 2-fold of the intracellular level of CagA was observed following treatment with the proteasome inhibitors, but not following that with the inhibitors of autophagy. On the other hand, degradation of CagA in the WT-A10 cells was promoted in a dose-dependent manner by induction of autophagy with rapamycin. In addition, ubiquitinated-CagA was detected in the WT-A10 cells by immunoprecipitation and the TUBE reaction method. Although the levels of intracellular CagA in the AGS cells decreased in a timedependent manner after H. pylori infection, the rate of CagA degradation in the AGS cells was attenuated to 60% under treatment with proteasome inhibitors at 4 h, and further was attenuated to 70% under treatment with the autophagy inhibitors at 24 h. In addition, conversion of LC3-I to LC3-II, which shows autophagy, was detected in the AGS cells at 24 h. Conclusion: Intracellular CagA was initially targeted for proteasomal degradation, and then it was extensively degraded by the induction of autophagy.