CRF injection), similar to stress, induced plasma corticosterone rise followed by the return of corticosterone level to baseline in 4 h after indomethacin administration. Indomethacin- induced corticosterone rise was inhibited by NBI 27914 injection and these results confirm the critical role of CRF1 receptors in the activation of the HPA axis. Both astressin and astressin2-B injection resulted in a delay of the recovery to basal circulating corticosterone levels. The impaired termination of corticosterone response to indomethacin caused by astressin2-B was followed by aggravation of indomethacin-induced gastric injury. Conclu- sions: The results suggest that CRF injected into the periphery at the dose, which markedly increased plasma corticosterone levels, may induce protection against indomethacin-pro- duced gastric injury through both CRF1 and CRF2 receptors. CRF2 receptor signaling pathway contributes to the appropriate termination of indomethacin-induced corticosterone secretion and the maintainance of gastric mucosal integrity during ulcerogenic action of indomethacin in rats. The study was supported by grants from RFBR N13-04-01680a and PRAS 5 and 7. Su1917 Chronic Omeprazole Treatment Induces Weight Gain in Mice When Combined to High Energy Diet Milena Saqui-Salces, Amy C. Tsao, Juanita L. Merchant Background: In response to chronic use of proton-pump inhibitors, e.g. omeprazole, plasma gastrin levels increase as feedback to restore acid secretion. Moreover, circulating gastrin contributes to diet-induced insulin secretion. We have reported that feeding mice with a high-fat diet for 3 weeks reduces gastric acid and increases plasma gastrin. In addition, higher body weight, adiposity and increased plasma insulin was observed in genetically- modified mice that are hypochlorhydric and hypergastrinemic. Aim: To test whether the development of obesity and insulin resistance correlated with acid suppression, we evaluated the metabolic outcome of wild-type mice treated chronically with omeprazole. Methods: Female and male C5BL/6 mice (n=3 per gender per diet) were fed for 24 weeks with (A) standard chow (STD) (LabDiet 5LOD, 4.07 kcal/g) (B) STD supplemented with 200 ppm omeprazole (STD+O), (C) High-Energy chow (HiE) (LabDiet 5LJ5, 4.68 kcal/g) and (D) HiE supplemented with 200 ppm omeprazole (HiE+O). Glucose oral tolerance tests (OGTT) were done at week 18 and tissues collected at week 24. In a separate experiment (n=8 per gender per diet) oxygen consumption, carbon dioxide production, spontaneous motor activity and food intake were measured after 8 weeks on the respective diets using the Comprehensive Laboratory Monitoring System (CLAMS). Body fat, lean mass and free fluids were measured using an NMR analyzer (Minispec LF90II). Results: Gastrin expression was significantly higher in the HiE+O group (2.6- and 3.2-fold increase for females and males respectively). Omeprazole treatment combined with STD chow did not affect the weight gain of the females or males. As expected, mice on the HiE gained more weight than on STD chow. However, mice on HiE+O gained almost twice the weight as those on HiE only (males: 12.4±2.4 g vs. 4.4±1.2 g, females: 8.2±2.1 vs. 5.1±1.1 g). Mice on HiE and HiE+O ate less than mice on STD and STD+O diets. OGTT's showed that mice on all diets had similar fasting glucose and cleared glucose to basal levels. However, mice on HiE+O had higher basal and secreted more insulin than mice on the other diets. In an independent experiment, metabolic analysis was performed after 8 weeks on the diets, when weight differences were not yet significant. Although mice on HiE and HiE+O had increased adiposity and lower lean body mass compared to STD diets, this was statistically different only for males on the HiE+O. Females and males on HiE+O showed significantly lower energy expenditure and a trend towards lower ambulatory activity. Conclusion: Chronic treatment with omeprazole induced higher weight gain in mice when combined with a high caloric diet. This weight gain was not associated with hyperphagia or higher dietary fat but instead correlated with diminished energy expenditure, suggesting a role for gastric acid regulation on metabolism. Su1918 Molecular Mechanisms of Cellular Stress Responses in Gastric Cancer Pål Vange, Vidar Beisvag, Arnar Flatberg, Wahida Afroz, Ivar S. Nordrum, Øystein Sørdal, Gunnar Qvigstad, Liv Thommesen, Astrid Lægreid, Arne K. Sandvik, Torunn Bruland, Ingunn Bakke Although the role of cellular stress responses is increasingly recognized to play a role in carcinogenesis as well as in cell homeostasis and inflammation, little is examined in gastric cancer. Cellular stresses like e.g., hormones, chronic inflammation, oxidative stress and chemotherapy induce stress pathways that regulate the balance between survival and apoptosis. One hallmark of cancers is the evasion of apoptosis in response to severe stress stimuli, which contributes to both tumorigenesis and treatment resistance. To modulate the outcome of cellular stress towards cell death in pre-cancerous cells and during cancer treatment, a better understanding of cellular stress responses in normal cells and their aberrations in cancer cells is required, both from a molecular and clinical perspective. The hormone gastrin plays a prominent role in growth and differentiation of the gastric mucosa. We have by genome-wide gene expression time series experiments recently revealed novel gastrin-responsive genes that are important in mucosal homeostasis and known to be stress effectors in carcinogenesis. Among these are endoplasmic reticulum (ER)-stress related acti- vating transcription factor 4 (Atf4), and molecular chaperones such as Grp78 and the pro- survival factor secretory clusterin (sClu). We recently were the first to show that the sCLU protein is important in the anti-apoptotic effect of gastrin in adenocarcinoma cells, and we have now used a translational approach combining results from cell model systems, experimental animals and human material to further elucidate the role of these cellular stress proteins in gastric oxyntic mucosa. By methods like RNAscope® in situ hybridization and double immunofluorescence we have delineated cellular expression patterns in normal and hypergastrinemic rats, in Mongolian gerbils chronically infected with Helicobacter Pylori in combination with a gastrin receptor blocker, as well as in normal human mucosa and in different gastric tumors. The results are related to our whole genome transcriptome analysis of a cohort of gastric cancers showing e.g. a significant variance in clusterin expression between histologically different cancers. Also, using real time monitoring of cellular events (xCelligence) and survival assays on cancer cell lines with and without specific gene knock- down, we show involvement of cellular stress proteins in gastrin induced pro-metastatic S-501 AGA Abstracts processes. Overall, our results indicate that gastrin induced cellular stress proteins are involved in the balance between cell survival and apoptosis in gastric mucosa and provide new insight into cellular stress responses in gastric cancer. Su1919 Low Level Light Therapy (Cold Laser) Produced an Inhibitory Growth Response on Colorectal Adenocarcinoma Cells Philip Brondon, Mohana Nagda, Elliot B. Tapper, Saurabh Sethi, Myron Falchuk, Simon C. Robson Introduction: Low-level light therapy (LLLT), also known as cold laser therapy, was developed shortly after the discovery of the laser. Today LLLT is utilized in several treatment modalities including: treating non-healing ulcers, promoting nerve regeneration and reducing inflamma- tion. LLLT is performed by exposing tissue to low energy densities of red or infrared light. This treatment modality has also been referred to in the literature, as cold laser therapy because the amount of energy used is significantly less than is required for cutting or coagulating tissue. Prior in vitro studies have shown that LLLT can affect the proliferation rates of epidermal cell lines. Experimental evidence suggests that the electron transport chain in the mitochondria serves as the photoreceptor responding by stimulating the production of ATP as well as transcription factors, which alter cellular proliferation and oxygen utilization. This study was designed to show that colonic mucosal cells will demonstrate a similar photobiological effect to LLLT as has been shown with other human cell lines. Methods: CACO-2 cells were cultured in the usual fashion using MEM media without phenol red, maintained in an incubator with 5% CO2. The experimental design consisted of one control group, which received no LLLT and were maintained in a dark incubator. The four treatment groups were exposed to 5J, 10J, 15J and 20J of LLLT treatment each day respectively for a total of 10 days. 96 well culture plates were used and 1000 CACO-2 cells were cultured in each well at the beginning of the experiment. 10 wells were used each for the control and experimental groups. LLLT was delivered using a Quantum Warp 10 device, which delivers 5J/cm2 of 670nm light per dose (Quantum Devices, Barneveld, WI). Each dose is delivered over 88 seconds. Cellular proliferation measurements were taken at 24 hours increments for a total of 10 days using the Cell Counting Kit -8 (Dojindo Laboratories). This test is a sensitive colorimetric assay that has been proven to determine the number of viable cells in proliferation. Results: LLLT inhibited the growth of the CACO-2 cell line when compared to the control group reaching statistical significance via Mann-Whitney Test at day 6 through day 9 of the experiment. ANOVA was performed between the means of all experimental groups and found statistical significance between each. Statistical significance was not observed between the LLLT treatment groups. Conclusions: This is the first experi- mental investigation to show that intestinal mucosal cells display a photobiological response to LLLT. The exact mechanism by which this inhibitory response is occurring is not yet clear although activation of apoptosis is suspected. LLLT may prove to be an exciting new treatment modality for colonic carcinomas as well as adjunctive therapy to reduce inflamma- tion in IBD. Su1929 Delineating the Mechanism for Disruption of Autophagy Maturation by the Helicobacter pylori Vacuolating Cytotoxin a Laura K. Greenfield, Martin T. Smith, Esther Galindo-Mata, Steven R. Blanke, John L. Rubinstein, Peter K. Kim, Nicola L. Jones Infection with Helicobacter pylori is considered the most important risk factor for the develop- ment of gastric cancer. The vacuolating cytotoxin A (VacA) is a major virulence determinant of H. pylori, but exactly how the toxin promotes disease is unclear. Current evidence suggests that autophagy, an evolutionarily conserved process wherein cytosolic proteins, organelles and pathogens are sequestered and degraded within the cell, plays a role in carcinogenesis. Work from our lab has demonstrated that acute exposure to VacA induces autophagy, but prolonged exposure disrupts autophagy by preventing autophagosomes from acquiring cathepsin D, an important degradative enzyme. Previous studies suggest that VacA causes mitochondrial damage and increased reactive oxygen species (ROS) in host cells, which can trigger autophagy. We found that while purified VacA triggered mitochondrial fragmentation in human gastric epithelial (AGS) cells, VacA+ conditioned culture media supernatants (CCMS), which induced robust autophagy, did not provoke the same morphological changes. Furthermore, AGS cells treated with the antioxidant N-acetyl cysteine reduced ROS, but did not alter VacA induced autophagy. Similarly, over-expression of SOD2 did not prevent autophagy. Taken together these studies indicate that VacA induces autophagy independent of mitochondrial damage or ROS. Next we assessed the role of changes in the novel sorting receptor sortilin, which is implicated in the trafficking of cathepsin D to lysosomes. Prolonged exposure of AGS cells to VacA+ CCMS resulted in reduced protein and mRNA levels of sortilin. These findings suggest that VacA-mediated reduction in sortilin prevents autophagosome maturation and provides a potential therapeutic target for modulating disease during chronic infection. Su1930 Differences in Molecular Alterations and Cellular Phenotype in Background Mucosa of Early Gastric Cancer With and Without H. pylori Infection Maki Kawanaka, Jiro Watari, Takahisa Yamasaki, Takashi Kondo, Fumihiko Toyoshima, Jun Sakurai, Hisatomo Ikehara, Noriko Kamiya, Toshihiko Tomita, Tadayuki Oshima, Hirokazu Fukui, Kiron M. Das, Hiroto Miwa Background and Aim: Many studies, including meta-analyses, show that Helicobacter pylori (H. pylori) eradication reduces gastric cancer (GC). Although eradication of H. pylori has been reported to reduce development of metachronous GC (MGC) after endoscopic resection (ER), recent studies have not corroborated those results. As GC occurs to some degree in patients without H. pylori infection, either previously treated with anti-H. pylori therapy or natural eradication, this raises the question of whether H. pylori eradication actually AGA Abstracts