Identification of the potential target genes of microRNA-146a induced by PMA treatment in human microvascular endothelial cells.

Phorbol 12-myristate 13-acetate (PMA) is known to activate protein kinase C (PKC) and increase angiogenesis in cultured endothelial cells. Using a microRNA (miRNA) array, we found that PMA induced miR-146a expression in human microvascular endothelial cells. The miR-146a expression was dependent on dose and time and independent of PKC activation. Using a combined approach involving predictions using miRanda algorithm and whole genome microarray experiments with or without inhibition of miR-146a expression by LNA-antimir-146a or LNA-control, 29 potential target genes of miR-146a were identified. Because endothelial cell S phase progression is an early event in the induction of angiogenesis, we evaluated 5 cell cycle-related genes from the 29 target genes and found that the transcripts of 3 genes (CCNA2, PA2G4, and BRCA1) were downregulated after PMA treatment, but their expression was rescued upon miR-146a inhibition. However, inhibition of miR-146a expression failed to alter the cell cycle distribution or angiogenesis induced by PMA treatment. By using a combined approach involving computational prediction and a whole genome microarray experiment in the presence or absence of antimir, the observations in this presented article raise the possibility that antimir strategies might be used to identify the potential miRNA targets.