MiR-18a-5p Promotes NPC Cell Proliferation, Invasion, Migration, and EMT by Targeting SMAD2
Abstract Background: Nasopharyngeal carcinoma (NPC) is the most common malignant tumor in the head and neck that is characterized by high local malignant invasion and distant metastasis. miR-18a-5p reportedly plays an important role in tumorigenesis and development. However, little is known about the mechanism underlying miR-18a-5p’s role in NPC.Methods:Quantitative real-time PCR was used to detect the expression of miR-18a-5p in NPC tissues and cell lines. MTT assay and plate clone formation assay were used to detect the effect of miR-18a-5p on NPC cell proliferation. Woundhealing assays and Transwell assays were used to detect the effect of miR-18a-5p on NPC cell invasion and migration. The expressions of epithelialmesenchymal transition (EMT)-related proteins N-cadherin, Vimentin, and E-cadherin were detected by Westernblot. Bioinformatics and dual-luciferase reporter assay were used to detect the targeting interaction between miR-18a-5p and SMAD2. Xenotransplantation and metastasis model were used to detect the effect of miR-18a-5p on NPC growth and metastasis in vivo.Results:miR-18a-5p was highly expressed in NPC tissues and cell lines. Overexpression of miR-18a-5p promotedNPC cell proliferation, invasion, migration, and EMT process, whereas inhibition of miR-18a-5p expression led to the oppositeresults. Results of dual-luciferase reporter assay showed that SMAD2 was the target gene of miR-18a-5p, and SMAD2 could reverse the effect of miR-18a-5p on NPC cell line. Xenotransplantation and metastasis model experiments in nude mice showed that miR-18a-5p promotesNPC growth and metastasis in vivo.Conclusions:Targeting SMAD2 downregulated miR-18a-5p expression, thereby promoting NPC cell proliferation, invasion, migration, and EMT.