miRNA and mRNA expression profiling identifies members of the miR-200 family as potential regulators of epithelial-mesenchymal transition in pterygium

Abstract

The current study investigates whether microRNA (miRNA) regulators of epithelial-mesenchymal transition (EMT), tissue fibrosis, and angiogenesis are differentially expressed in human primary pterygium. Genome-wide miRNA and mRNA expression profiling of paired pterygium and normal conjunctiva was performed in the context of conventional excision of pterygium with autotransplantation of conjunctiva (n = 8). Quantitative real time polymerase chain reaction (qRT-PCR) was used to validate the expression of key molecules previously detected by microarray. In pterygium, 25 miRNAs and 31 mRNAs were significantly differentially expressed by more than two-fold compared to normal conjunctiva. 14 miRNAs were up-regulated (miR-1246, -486, -451, -3172, -3175, -1308, -1972, -143, -211, -665, -1973, -18a, 143, and -663b), whereas 11 were down-regulated (miR-675, -200b-star, -200a-star, -29b, -200b, -210, -141, -31, -200a, -934, and -375). Unsupervised hierarchical cluster analysis demonstrated that members of the miR-200 family were coexpressed and down-regulated in pterygium. The molecular and cellular functions that were most significant to the miRNA data sets were cellular development, cellular growth and proliferation, and cellular movement. qRT-PCR confirmed the expression of 15 of the 16 genes tested and revealed that miR-429 was down-regulated by more than two-fold in pterygium. The concerted down-regulation of four members from both clusters of the miR-200 family (miR-200a/-200b/-429 and miR-200c/-141), which are known to regulate EMT, and up-regulation of the predicted target and mesenchymal marker fibronectin (FN1), suggest that EMT could potentially play a role in the pathogenesis of pterygium and might constitute promising new targets for therapeutic intervention in pterygium.

Keywords: ACTA; AQP1; CCL19; CDH1; COL3A1; COL4A2; CTGF; E-Cadherin; EFEMP1; EGF containing fibulin-like extracellular matrix protein 1; EMT; FDR; FN1; IKB; Ingenuity Knowledge Base; LTBP2; MMP2; NOTCH1; NR4A1; PECAM1; Q-RT-PCR; Quantitative real-time reverse transcription polymerase chain reaction; SNAI; SPARC; TGB2; UTR; VIM; VWF; ZEB; Zinc finger E-box binding homeobox; actin, alpha 2, smooth muscle, aorta; aquaporin 1 (Colton blood group); chemokine (C–C motif) ligand 19; collagen, type III, alpha 1; collagen, type IV, alpha 2; connective tissue growth factor; epithelial–mesenchymal transition; false discovery rate; fibronectin 1; gene microarray; latent transforming growth factor beta binding protein 2; mRNA; matrix metallopeptidase 2; miR-200 family; miRNA; microRNA; notch 1; nuclear receptor subfamily 4, group A, member 1; platelet/endothelial cell adhesion molecule 1; pterygium; secreted protein acidic cysteine-rich; snail homolog (Drosophila); transforming growth factor beta 2; untranslated region; vimentin; von Willebrand factor.