MiR-181a Targets PHLPP2 to Augment AKT Signaling and Regulate Proliferation and Apoptosis in Human Keloid Fibroblasts

Abstract

Background/Aims: Keloids are fibrous overgrowths induced by cutaneous injury. MicroRNAs (miRNAs) have recently emerged as post-transcriptional gene repressors and participants in a diverse array of pathophysiological processes leading to skin disease. The purpose of the current study was to explore the precise functions of miR-181a in human keloid development and the underlying mechanisms. Methods: A miRNA microarray analysis was performed to compare expression profiles between keloid and normal skin tissues. Quantitative real-time PCR was conducted to estimate miR-181a expression. Cell proliferation was determined using the cell counting kit-8 (CCK-8) and 5-ethynyl-2-deoxyuridine (EdU) assays, and cell cycle and apoptosis were detected with flow cytometry. Direct targets of miR-181a were identified using the luciferase reporter assay. Results: miR-181a was significantly upregulated in human keloid tissues and fibroblasts, compared with their control counterparts. Overexpression of miR-181a enhanced keloid fibroblast DNA synthesis and proliferation and inhibited apoptosis, whereas miR-181a suppression triggered the opposite effects. Moreover, miR-181a suppressed the expression of PH domain leucine-rich repeat protein phosphatase 2 (PHLPP2) through direct interactions with its 3′UTR region and subsequently enhanced AKT activation. Overexpression of PHLPP2 without its 3′UTR attenuated the effects of miR-181a on cell proliferation and apoptosis in keloid fibroblast cells. Furthermore, miR-181a mimics increased normal skin fibroblast proliferation. Conclusions: Our results highlight a novel pathway mediated by miR-181a, which may be effectively used as a therapeutic target for treatment of keloids.