MicroRNA profiling of Barrett's oesophagus and oesophageal adenocarcinoma

Background: The genetic changes that drive metaplastic progression from squamous oesophageal mucosa toward intestinal metaplasia and adenocarcinoma are unclear. The aberrant expression of microRNAs (miRNAs) is involved in the development of cancer. This study examined whether miRNAs play a role in the development of oesophageal adenocarcinoma. Methods: RNA was extracted from mucosa of normal oesophageal squamous epithelium, normal gastric epithelium, Barrett's oesophagus with intestinal metaplasia and oesophageal adenocarcinoma obtained from 16 individuals. Expression profiles of 377 human miRNAs were determined by microarray analysis and selected miRNAs were analysed further using real-time reverse transcription polymerase chain reaction (RT-PCR) in tissues from 32 individuals. Results: Microarray analyses identified 44 miRNAs likely to have altered expression between various mucosal samples. Of these, miR-21, miR-143, miR-145, miR-194, miR-203, miR-205 and miR-215 were chosen for validation by real-time RT-PCR. Tissue-specific expression profiles were observed, with miR-21, miR-143, miR-145, miR-194 and miR-215 significantly upregulated in columnar tissues compared with normal squamous epithelium. Expression of miR-143, miR-145 and miR-215 was lower in oesophageal adenocarcinoma than in Barrett's oesophagus. Levels of miR-203 and miR-205 were high in normal squamous epithelium and low in columnar epithelia. MiR-205 levels were lower in gastric epithelium than in both Barrett's oesophagus and adenocarcinoma. Conclusion: Expression of miRNA might define disease states in oesophageal epithelium. Dysregulation of specific miRNAs could contribute to metaplastic and neoplastic processes in the oesophageal mucosa.