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Targeting the COX1/2-Driven Thromboxane A2 Pathway Suppresses Barrett's Esophagus and Esophageal Adenocarcinoma Development
58 Pages Posted: 24 Jun 2019
More...Abstract
Background: Barrett's esophagus (BE), a complication of gastroesophageal reflux disease (GERD), predisposes patients to esophageal adenocarcinoma (EAC). Reliable biomarkers for early detection and discovery of potential drug targets are urgently needed for improved BE and EAC patient outcomes.
Methods: Patient biopsy samples were evaluated for COX1, COX2, and thromboxane A2 synthase (TBXAS) expression. Circulating prostaglandins biosynthesis was determined using enzyme immunoassay kits. Anchorage-independent cell growth assay, crystal violet staining assay, and xenograft experiments were conducted to assess BE and EAC cell growth. A surgical mouse model of reflux (i.e., esophagoduodenostomy) was established and samples were analyzed using an enzyme immunoassay kit, immunohistochemistry, immunoblotting, or RT-PCR. Esophageal biopsy samples (pre- and post-intervention) were obtained from a randomized clinical trial in which participants were administered esomeprazole (40 mg) twice daily in combination with an aspirin placebo or 81 or 325 mg aspirin for 28 days. Esophageal biopsy specimens before and after the intervention period were analyzed.
Findings: COX2 and TBXAS are highly expressed in BE and EAC patients accompanied by a pronounced elevation of circulating TXA2 levels. Aspirin suppressed BE and EAC growth by targeting the TXA2 pathway. Additionally, biopsies from 49 patients (with similar baseline characteristics) showed that aspirin substantially decreased serum TXA2 levels, resulting in reduced inflammation.
Interpretation: This study establishes the importance of the COX1/2-driven TXA2 pathway in BE and EAC pathophysiology and lays the groundwork for introducing a TXA2-targeting strategy for EAC prevention and early detection.
Funding Statement: This work was supported by the Hormel Foundation and National Institutes of Health grants CA166011, CA187027, and CA196639 (Z. Dong).
Declaration of Interests: The authors declare no potential conflicts of interest.
Ethics Approval Statement: All animal studies were approved by the University of Minnesota Institutional Animal Care and Use Committee (IACUC).
Keywords: thromboxane A2 pathway; aspirin; Barrett's Esophagus; esophageal adenocarcinoma
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