Micro-RNA (miR) Expression in Upper Gastrointestinal Mucosal Tissue: A Potential Target for Understanding and Preventing the Progression of Barrett's Esophagus
The incidence of esophageal adenocarcinoma has increased dramatically over the past three
decades. These adenocarcinomas usually arise from columnar lined epithelium of the
esophagus known as Barrett's esophagus (BE). There is an established association between
gastroesophageal reflux disease (GERD) and the development of BE and esophageal
adenocarcinoma. In an attempt to diagnose esophageal adenocarcinoma at an earlier and more
treatable stage, efforts have been directed at identifying patients with BE and enrolling
them in surveillance protocols. Several authors have challenged this strategy since it has
not yet been proven to save lives and is very expensive. A major unresolved problem is the
fact that the clinical factors considered to be somewhat predictive of the presence or
absence of BE are neither sufficiently sensitive nor specific. In addition, once BE is
identified, predicting who may or may not progress to cancer is far from perfect. A
molecular understanding of why certain patients develop BE and why certain of those progress
to cancer is of obvious importance.
The molecular pathway from normal esophageal mucosa to Barrett's esophagus and on to
adenocarcinoma is not well understood. Micro-RNA (miR) RNAs have recently emerged as
important regulators of carcinogenesis and have not been studied in BE. We seek to confirm
our ability to characterize miR expression in various tissues (esophagus, stomach and
duodenum) obtained from the upper gastrointestinal tract in preparation for the study of MiR
in patients with Barrett's esophagus and other inflammatory conditions of the upper
This study will involve collection of tissue via endoscopic biopsy in 10 patients with
normal endoscopic appearance from the esophagus, stomach and duodenum. Ambion miR
oligonucleotide arrays will be utilized to profile miRs that are specifically expressed in
epithelial biopsies from the duodenum, stomach, and esophagus. Total RNA will be extracted
from independent biopsy samples using the mirVana(R) micro RNA isolation kit from Ambion.
The Ambion Flash PAGE(R) electrophoresis system will be used to resolve mature miRs from the
larger pre-miR species. Mature miRs will be labeled and hybridized to Ambion mirVana
miR(R)arrays, which will be scanned to identify miRs that are regulated under these
circumstances. Signals from the microarrays will be processed using the R functions of
Bioconductor for normalization and background correction and RMA for summarization.
Statistical significance will be determined using Insightful S+ functions and assuming a
least pooled error model. Potential targets will be confirmed by northern blotting. The
routine histology sample will be reviewed simply to exclude other, unexpected microscopic
pathology. Benign histologic findings such as minor inflammation, will not exclude the
patient from inclusion. If there is a wide variation in miR expression, then the histology
might be needed to help explain such variation.
Observational Model: Case-Only, Time Perspective: Prospective
Kenneth R. DeVault,, M.D.
Mayo Clinic, Jacksonville, Florida
United States: Institutional Review Board
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