Role of microbiota and Toll-like receptors in progression of esophageal adenocarcinoma (EAC) in a rat reflux model.

Abstract

28 Background: The discovery of the link between H. pylori and gastric cancer may be the most direct proof that bacterial signaling and host response can result in carcinogenesis. Accumulating evidence supports that activation of the Toll-like receptor (TLR) signaling pathway by microbes is associated with the development of GI malignancies. Using the modified Levrat model of gastroduodenojejunal reflux which mimics the physiological and molecular sequence of human EAC in the rat, this study profiles the expression of genes central to TLR-mediated signal transduction as well as characterizes the esophageal microbiome across the spectrum of EAC development. Methods: Modified Levrat’s surgery induced chronic acid reflux in Sprague-Dawley’s with harvest of esophagus 40 weeks post-surgery. Macordissection of normal adjacent epithelium, Barrett’s esophagus (BE), dysplasia and EAC tumor was performed followed by RNA/DNA isolation. Five samples per group were selected for gene expression profiling on the Qiagen TLR Signaling Pathway PCR Array as well as microbiome analysis by IBIS technology. Validation of IBIS was performed by fluorescence in situ hybridization (FISH). Results: Gene expression analysis identified TLRs 1-3 and 6, 7, 9 as significantly upregulated in EAC compared to normal esophagus. TLR 1 and 5 were significantly upregulated in dysplasia. TLR 1 was significantly upregulated in BE and normal adjacent epithelium. Thirty seven genes involved in the TLR signaling pathway were dysregulated in EAC, 30 in dysplasia, 21 in BE and 23 in normal adjacent. IBIS analysis revealed a prevalence of E. coli in BE and EAC which was validated by FISH. Conclusions: Toll-like receptor (TLR) signaling pathway responses to E. coli may participate in the development of EAC. E. coli may be a potential risk factor for EAC requiring further clinical validation.