BACKGROUND: The aim of this study was to investigate the effect of hypoxia on the level of microRNA-18a (miR-18a) and hypoxia-inducible factor 1A (HIF1A) expressed by choroidal endothelial cells through cytological analysis.

MATERIAL AND METHODS: After culturing choroidal endothelial cells (CECs) under normoxia or hypoxia, microRNAs, expressed in different ways, were screened by using GeneChip microRNA array, and the results were confirmed by real-time PCR. The bioinformatics approach was used to screen target genes of target miRNA. In addition, CECs were transfected with target miRNA mimic or inhibitor and then expression levels of targeted miRNA and genes were observed.

RESULTS: The GeneChip microRNA Array detected 14 miRNAs that were expressed differently. Among these miRNAs, 12 miRNAs were identified as being upregulated and 2 miRNAs as being down-regulated. MiR-18a was most significantly down-regulated. Bioinformatics analysis showed that HIF1A was the target gene of miR-18a. In CECs transfected with miR-18a mimic, there was a remarkable decrease in gene expression level and protein level of HIF1A, and thereby, significant reduction in proliferation and migration of CECs. In CECs transfected with miR-18a inhibitor, there was a significant increase in gene and protein expression levels of HIF1A, and enhanced proliferation and migration of CECs.

CONCLUSIONS: We conclude that miR-18a affects the function of CECs by inhibiting the expression of HIF1A.

Keywords: Cell Hypoxia - physiology, Base Sequence, Cell Movement - physiology, Cell Proliferation - physiology, Choroid - cytology, DNA Primers - genetics, Epithelial Cells - physiology, Gene Expression Regulation - physiology, Hypoxia-Inducible Factor 1, alpha Subunit - metabolism, Microarray Analysis, Molecular Sequence Data, Oligonucleotide Array Sequence Analysis