miR-200 family expression is downregulated upon neoplastic progression of Barrett's esophagus

Abstract

Aim: To investigate miR-200 family expression in Barrett's epithelium, gastric and duodenal epithelia, and esophageal adenocarcinoma.

Methods: Real-time reverse transcriptase-polymerase chain reaction was used to measure miR-200, ZEB1 and ZEB2 expression. Ingenuity Pathway Analysis of miR-200 targets was used to predict biological outcomes.

Results: Barrett's epithelium expressed lower levels of miR-141 and miR-200c than did gastric and duodenal epithelia (P < 0.001). In silico analysis indicated roles for the miR-200 family in molecular pathways that distinguish Barrett's epithelium from gastric and duodenal epithelia, and which control apoptosis and proliferation. All miR-200 members were downregulated in adenocarcinoma (P < 0.02), and miR-200c expression was also downregulated in non-invasive epithelium adjacent to adenocarcinoma (P < 0.02). The expression of all miR-200 members was lower in Barrett's epithelium derived high-grade dysplastic cell lines than in a cell line derived from benign Barrett's epithelium. We observed significant inverse correlations between miR-200 family expression and ZEB1 and ZEB2 expression in Barrett's epithelium and esophageal adenocarcinoma (P < 0.05).

Conclusion: miR-200 expression might contribute to the anti-apoptotic and proliferative phenotype of Barrett's epithelium and regulate key neoplastic processes in this epithelium.

Keywords: Apoptosis; Barrett’s esophagus; Epithelial to mesenchymal transition; Epithelium; Esophageal adenocarcinoma; Proliferation; miR-200; miRNA.

Figure 1

Top associated network functions for miR-141 and miR-200c. A: Ingenuity Pathway Analysis predicted that the top associated network functions for miR-141 were gene expression, cell death and cell cycle (P = 1 × 10^-35). B: The top associated network functions for miR-200c were cell morphology, cellular assembly and organization, cellular function and maintenance (P = 1 × 10^-38). Predicted targets of miR-141 or miR-200c are highlighted in grey. Uncolored entries represent molecules that are associated with the pathway but are not predicted miR-141 or miR-200c targets. The P values were derived from a right-tailed Fisher’s exact test to calculate the probability that each predicted miRNA target matches the ascribed network function due to chance alone.

Figure 2

miR-200 family expression in benign Barrett’s and dysplastic cell lines. Relative expression of all miR-141, miR-200a, miR-200b and miR-429, normalized to U44 expression is shown on the left hand y axis. Relative expression of miR-200c is shown on the right hand y axis. The pattern of relative expression of miR-200 members in the Qh (benign Barrett’s) cell line closely resembled that in benign Barrett’s esophagus mucosa (see relative expression values in Table 1).