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IL-1β-STAT3 Mediated Up-Regulation of AKT1 Expression in Barrett'sEsophagus: A Potential Link Between Inflammation and CarcinogenesisAnamay N. Sharma, Sonia Chowdhury, Cathrine J. DeMars, Gwen A. Lomberk, Lori S.Lutzke, Prasad G. Iyer, Kenneth K. Wang, Kausilia K. Krishnadath, Raul A. Urrutia,Navtej Buttar

BACKGROUND AND AIM: We have recently shown that, in addition to AKT1 activationthrough its phosphorylation, overall increased expression of AKT1 that is observed duringneoplastic progression in patients with Barrett's also plays a direct role in this injury-inducedoncogenesis. Since pro-inflammatory cytokine IL-1β promotes esophageal adenocarcinomaand its downstream effector STAT3 could bind to the core promoter region of AKT1, it isplausible that IL-1β-STAT3-AKT1 could link inflammation to carcinogenesis in Barrett'sesophagus. The aims of this study were to examine IL-1 β-STAT3 mediated regulation ofAKT1 expression and explore the underlying mechanisms in Barrett's epithelium. METHODSand RESULTS: Using Barrett's epithelial cells, we noted that both IL-1 β and constitutivelyactive STAT3c induced AKT1 promoter activity. Moreover, in a dose and time dependentmanner IL-1β increased AKT1 mRNA expression. Similarly, constitutively active STAT3calso increased AKT1 mRNA expression. We also noted that IL-1 β increased cellular p300levels, a histone acetyl transferase that STAT3 recruits on target promoter chromatin toactivate them by acetylating histone H3. We found that while constitutively active STAT3cincreased AKT1 promoter activity/expression, there was an increased acetylation of AKT1promoter (ChIP using anti H3 K18 and 27 antibody) during neoplastic progression inBarrett's epithelium. Additionally, both IL-1β and STAT3c partially interfered with repressionof AKT1 promoter by anti-inflammatory transcription factor KLF11, a known recruiter ofSin3-HDAC that deacetylates and represses AKT1 promoter. Together, these findings raisea possibility that pro-inflammatory IL-1β, by simultaneously increasing p300 and STAT3activation could direct p300 onto the AKT1 promoter to hyper acetylate and activate AKT1promoter. Alternatively, pro-inflammatory IL-1β-pSTAT3 through antagonizing the anti-inflammatory KLF11-Sin3-histone deacetylase pathway preserve AKT1 promoter acetylationto activate AKT1 promoter/expression. CONCLUSION: Our observations expose an antago-nism between pro-inflammatory IL-1β-STAT3-p300 and anti-inflammatory KLF11-Sin3-HDAC pathways in regulating oncogenic AKT1 during neoplastic transformation in Barrett'sesophagus, providing a potential link between inflammation and carcinogenesis.

389

Racial Differences in the Characteristics of Barrett's Esophagus (BE) andResponse to Radiofrequency Ablation (RFA) Treatment: Results From the U.S.RFA RegistryNan Li, William J. Bulsiewicz, Charles J. Lightdale, Ryan D. Madanick, GeorgeTriadafilopoulos, William D. Lyday, V. Raman Muthusamy, Anthony Infantolino, Bergein F.Overholt, Nicholas J. Shaheen

Background: Racial differences in the incidence of esophageal adenocarcinoma are wellestablished. However, little is known about racial differences in the characteristics of Barrett'sesophagus (BE), and the impact of race on response to radiofrequency ablation (RFA) isunknown. We report the characteristics of BE and response to treatment among races in anational registry of patients. Methods: The U.S. RFA Registry enrolled subjects undergoingRFA at 148 sites. Self-identified race was recorded using NIH categorizations: Caucasian,African American, Hispanic, and Asian (no American Indians or native Hawaiians wereenrolled). Demographics, pre-ablation histology, length of BE, and need for EMR werecompared between the races. Our safety cohort consisted of all treated patients, while ourefficacy cohort was restricted to subjects who had a biopsy performed 12 months or moreafter enrollment. Safety and efficacy outcomes were compared, including rates of stricture,GI bleeding, perforation, hospitalization, complete eradication of intestinal metaplasia (CEIM)and number of treatment sessions to CEIM. Multivariable logistic regression using predictorvariables suggested by the bivariate analysis (p,0.2) was performed to assess for independentassociations between race and stricture or CEIM. Results: Among 5530 patients who receivedRFA, 5134(93%) were Caucasian, 137(2.5%) Hispanic, 82(1.5%) African-American, and40(0.7%) Asian, while 137 patients of unknown race were excluded. There were markedbaseline differences between the groups in sex distribution, BE length, and severity of pre-treatment histology (table). Of note, while Caucasians demonstrated the expected strongpredilection toward male sex, there was a near even distribution between the sexes in AfricanAmericans and Asians. African Americans and Asians were also less likely to demonstratedysplasia, and had shorter segments of BE. In bivariate analysis, efficacy and safety weregenerally similar between races, although strictures were about 3 times as common inAsians (7.5%), and African-Americans (6.1%) compared to Caucasians (2.3%)(p ,0.05).After controlling for sex, presence of dysplasia at baseline, BE length and total RFA treatmentsessions, both Asians (OR 4.8, 95% CI 1.4-16.1) and African-Americans (3.2, 1.3-8.3) hadhigher odds of stricture compared to Caucasians. There were no significant differences inthe rate of CEIM or number of RFA sessions to achieve CEIM in bivariate or multivariableanalysis. Conclusions: In a large U.S. registry of RFA treatment for BE, marked differencesin disease patterns were noted between races, most notable a lack of male sex predilectionfor BE in African Americans and Asians. These groups were less likely to harbor dysplasiaat baseline, and had shorter BE segments. Strictures were more frequent after RFA amongAsians and African-Americans.

S-75 AGA Abstracts

390

High Fat Diet During the Perinatal Period Decreases Vagal EfferentMotoneuron Excitability and Response to Cholecystokinin Even in theAbsence of ObesityRuchi Bhagat, Kirsteen N. Browning

Several studies have highlight obesity-induced alterations in the properties of peripheralvagal afferent (sensory) neurons and fibers, but little attention has been paid to the effectsof either diet or obesity on central vagal neurocircuits. The perinatal period is crucial in thedevelopment of brain regions responsible for the control of satiety and food intake. Wehypothesized that exposure to a high fat diet (HFD) during the perinatal period alters theproperties of central vagal neurocircuits, making them less responsive to normal satietysignaling. Rats were fed a HFD (60%kcal from fat; N=18) from embryonic day 13. Electro-physiological recordings were made subsequently from identified gastric projecting dorsalmotor nucleus (DMV) neurons in thin brainstem slices from rats 28-42 days of age. PerinatalHFD rats were of a similar weight to rats fed a control diet (13.5% kcal from fat; N-20;197± 2g vs 229±7g P.0.05). DMV neurons from perinatal HFD rats were less excitablethan control DMV neurons. Specifically, perinatal HFD neurons had a lower input resistance(360±24MΩ vs 501±25MΩ; N=68 and 99, respectively, P,0.05) a higher membrane capaci-tance (113±5pF vs 95±3pF, P,0.05) and fired fewer action potentials in response to injectionof depolarizing current (3±0.3Hz and 10±1Hz compared to 4±0.3Hz and 16±1Hz in responseto 30pA and 270pA current injection, respectively; P ,0.05 for each). In part, the sloweraction potential firing frequency may be due to the larger afterhyperpolarization observedin perinatal HFD fed neurons (17.0±0.5mV vs 15.0±0.4mV, P ,0.05). Superfusion withcholecystokinin (CCK; 100nM) induced an increase in action potential firing rate in 7/10control DMV neurons, which was unaltered by perinatal HFD (11/12 neurons responsive;P.0.05). In contrast, while CCK increased the frequency of miniature excitatory currents(mEPSC) in 3/7 neurons, 0/13 perinatal HFD neurons responded to CCK with an increasein mEPSC (P,0.05). These results suggest that high fat diet, even in the absence of obesity,decreases the excitability of central vagal efferent motoneurons as well as their responsivenessto the satiety neurohormone CCK and that exposure to HFD during the perinatal alterscentral vagal neurocircuitry. Further studies will be required to determine whether suchalterations are permanent or whether postnatal dietary modification can restore normal vagalneurocircuit regulation. Supported by NSF IOS 1148978

391

11βHsd1: A Molecular Link Between Food Intake and Myenteric NerveActivityKatrien Lowette, Jan F. Tack, Pieter Vanden Berghe

Chronic stress can profoundly affect gastrointestinal (GI) function and may alter appetite.However, acute stress, though even moderate as during hunger, is a vital phenomenonthat modulates, via corticosterone (CORT), the synaptic input onto hypothalamic appetiteneurons. Furthermore, 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1) (Webster etal., 2012), the enzyme that regulates intracellular CORT levels, is expressed in the arcuatenucleus, suggesting involvement in appetite control. To date, it is unknown whether the11βHSD1-CORT pathway is involved in regulating activity in the enteric nervous system(ENS), which is thought to control GI function in synchrony with hunger and feeding cycles.Therefore, we aim to investigate the expression of 11 βHSD1 as well as the role of CORTon murine ENS in relation to food intake. Plasma CORT levels were determined using EIA.11βHSD1 expression was studied by immunoreactivity (IR) and RT-PCR using mRNAextracted from ileum of control (C), fasted (F, 20h), refed (RF, 3h) mice and CORT-incubated(100nM, 20min and 20h) ileal tissue. In addition, myenteric neurons were isolated andgrown in culture to which CORT or vehicle was added 20min prior to Ca2+-imaging (Fluo-4). Neurons were depolarized with high K+ or electrically stimulated to monitor changesin intracellular Ca2+ concentrations. Finally, pressure-induced responses in intestinal motilitypatterns were investigated using video imaging. Fasted and refed CORT levels were signifi-cantly higher than in control mice (C=6.4±3.1 10-9M, F=5.3 ±2 10-7M, RF=4.6±2.3 10-8M, P,0.01). 11βHSD1 IR was present in a subset of myenteric neurons throughout the

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