Mechanisms Underlying the Protective Effects of Piperine on Retinal Pigment Epithelium Cells

Purpose: To investigate the mechanisms underlying the protective effects of piperine on retinal pigment epithelium (RPE) cells under high-glucose and hypoxic conditions. Methods: A model of diabetes was established by treating D407 cells with high glucose (25 mM) and hypoxia (5% O₂ for 24 h). The mRNA and protein expression levels of the long noncoding RNA (lncRNA), plasmacytoma variant translocation 1 (PVT1), miR-128, pigment epithelium-derived factor (PEDF), and vascular endothelial growth factor C (VEGFC) were assessed by RT-qPCR, western blotting, and immunofluorescence staining. Wound-healing assays were performed to evaluate cell migration. The role of PVT1 was explored using siRNA-mediated knockdown, and the interactions among lncRNA PVT1, miR-128, and VEGFC were predicted and validated by dual-luciferase reporter assays. Results: Under high-glucose and hypoxic conditions, lncRNA PVT1 and VEGFC mRNA transcription were upregulated, whereas miR-128 and PEDF mRNA expression were downregulated. VEGFC protein levels were increased, PEDF protein levels were decreased, and cell migration was impaired. Treatment with piperine or knockdown of lncRNA PVT1 via siRNA partially reversed these effects. Dual-luciferase reporter assays further confirmed the interactions among PVT1, miR-128, and VEGFC. Conclusion: Piperine may protect RPE cells by modulating the lncRNA PVT1/miR-128 signaling pathway and promoting PEDF expression.

diabetes mellitus; lncRNA PVT1/miR-128 pathway; pigment epithelium-derived factor; piperine; vascular endothelial growth factor C.