Schnell, Thomas

Abstract Background: In patients with Barrett's esophagus, chronic reflux injury and inflammation are associated with esophageal adenocarcinoma, one of the most rapidly increasing lethal cancers. Epidemiological and preclinical studies support decreased risk of esophageal adenocarcinoma with NSAID use. Gastroesophageal refluxate contents can promote carcinogenesis in Barrett's metaplasia by activating AKT, which up regulates COX-2 expression and prostaglandin biosynthesis. We recently noted that neoplastic transformation in Barrett's esophagus is associated with increased AKT expression, particularly isoform AKT1. The AIM of this study is to investigate the effect of NSAID (Aspirin) use in patients with Barrett's esophagus on AKT1 expression using frozen tissue from the randomized, phase II trial of aspirin and esomeprazole for esophageal cancer chemoprevention in Barrett's esophagus patients and to assess the functional consequences of AKT1 expression in-vitro. Methods and Results: In a subset of patients (12 of 120 patients) with Barrett's esophagus who were randomized to placebo, lower dose (81 mg) or higher dose (325 mg) Aspirin for 4 weeks, both PCR and Western blot revealed marked reduction in AKT1 expression in patients who received 325 mg of Aspirin daily compared to patients who received placebo. Our in-vitro experiments support that AKT1 expression is functionally relevant to the process of carcinogenesis in Barrett's epithelial cells. Using adenovirus to induce AKT1 expression, we show that increased AKT1 expression increases Barrett's epithelial cell growth, facilitates RAS-mediated transformation of pre-neoplastic epithelial cells and promotes colony formation. Since AKT1 is known as Warburg kinase and regulates cellular glucose uptake to support aerobic glycolysis during growth de-regulation and neoplasia, we examined the uptake of fluorescent deoxyglucose analog (2-NBDG) in Barrett's epithelial cells transduced with AKT1 adenovirus. At 48 hrs, compared to control, AKT1 overexpression resulted in increased glucose uptake both by metaplastic and neoplastic Barrett's epithelial cells. Transcriptional repression of AKT1 abrogated the 2-NBDG uptake by these cells. Finally, we did pathway specific qPCRs and noted that use of Aspirin is associated with altered expression of chromatin remodelers that could down-regulate AKT1 expression. Conclusion: Collectively, our results demonstrate that Aspirin mediated down-regulation of Warburg kinase AKT1 in patients with Barrett?s esophagus is a novel mechanism for the regulation of Barrett?s epithelial cell growth. The in-depth characterization of molecular mechanisms is currently underway. This abstract is also presented as Poster A82. Citation Format: Navtej S. Buttar, Gary W. Falk, Cathrine J. DeMars, Sonia Chowdhury, Ahmed Elebiary, Anamay Sharma, Sidhartha Chaudhry, Nathan R. Foster, Katie L. Allen Ziegler, Yvonne Romero, Norman E. Marcon, Thomas Schnell, Douglas A. Corley, Prateek Sharma, Marcia R. Cruz-Correa, Chin Hur, David E. Fleischer, Amitabh Chak, Kenneth R. DeVault, David S. Weinberg, Gary Della’Zanna, Ellen Richmond, Thomas C. Smyrk, Sumithra Mandrekar, Paul J. Limburg. Aspirin mediated downregulation of Warburg kinase AKT1 in patients with Barrett's esophagus: Implications in neoplastic transformation. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr PR-03.

Abstract Background and Aims: In patients with Barrett's esophagus (BE), reflux-induced injury promotes esophageal adenocarcinoma, presumably through cyclooxygenase 2 (COX-2) related pathways. Proton pump inhibitors (PPIs) and nonsteroidal anti-inflammatory drugs (NSAIDs) may interrupt reflux-associated carcinogenesis by reducing acid exposure and subsequent inflammation. However, clinical trial data regarding the chemopreventive efficacy of a PPI + NSAID combination are limited. The aim of this multi-center, randomized, phase II trial was to assess the effects of a 28-day intervention with esomeprazole 40 mg bid and aspirin 81 mg qd, 325 mg qd, or placebo qd on tissue prostaglandin E2 (PGE2) concentrations in BE patients. Methods: Using the infrastructure of the Cancer Prevention Network, participants (> 18 years) with histologically confirmed non dysplastic BE were randomly assigned to receive one of three interventions for 28 days: (arm A) esomeprazole 40 mg bid+ aspirin 81 mg placebo qd + aspirin 325 mg placebo qd (n=42); (arm B) esomeprazole 40 mg bid+ aspirin 81 mg qd + aspirin placebo 325 qd (n=63); (arm C) esomeprazole 40 mg bid + aspirin 81 mg qd placebo + aspirin 325 mg qd (n=63). Esophageal biopsies were obtained pre- and post-intervention to assess change in PGE2 concentration as the primary endpoint. Results: In total, 122 participants were randomized, 121 (99%) completed the trial per protocol, and 115 (94%) were evaluated for the primary endpoint. Baseline characteristics were similar across intervention arms. The absolute change (mean + SD) in tissue PGE2 concentration was −67.6 (229.68) in Arm A, −120.9 (281.28) in Arm B (p = 0.10 vs Arm A) and −174.9 (263.62) in Arm C (p = 0.02 vs Arm A). Conclusions: In combination with esomeprazole 40 mg twice per day, aspirin 325 mg per day significantly reduced tissue PGE2 concentration in BE patients after a 28-day intervention, as compared to aspirin placebo. Given the relevance of PGE2 pathways in BE-associated carcinogenesis, further evaluation of this chemoprevention strategy in larger, more definitive phase III trials is warranted. Citation Information: Cancer Prev Res 2011;4(10 Suppl):CN06-03.