Long non-coding RNA FOXD3-AS1 silencing exerts tumor suppressive effects in nasopharyngeal carcinoma by downregulating FOXD3 expression via microRNA-185-3p upregulation.

Emerging evidence indicates that the incidence of nasopharyngeal carcinoma (NPC) remains high in endemic regions despite changing environmental factors, suggesting that genetic traits contribute to its development. Recently, long non-coding RNA-microRNA-messenger RNA (lncRNA-miRNA-mRNA) axis has been reported to be implicated in the pathophysiological processes of malignancies. Moreover, initial bioinformatic analysis revealed a highly expressed lncRNA Forkhead box D3 antisense RNA1 (FOXD3-AS1) for mechanistic network underlying NPC in this present study. Therefore, this study aims to delineate the ability of lncRNA FOXD3-AS1 to influence the NPC progression. The relationship among lncRNA FOXD3-AS1, miR-185-3p, and FOXD3 was identified with bioinformatics prediction, dual-luciferase reporter gene assays, RNA-binding protein immunoprecipitation, and RNA pull-down assays. Furthermore, effects of lncRNA FOXD3-AS1 on malignant phenotypes in vitro, alongside tumor formation in vivo, of transfected NPC stem-like cells were examined with gain- and loss-of-function experiments. Our findings revealed that lncRNA FOXD3-AS1 and FOXD3 exhibited increased expression levels, while miR-185-3p exhibited diminished levels in NPC. The levels of lncRNA FOXD3-AS1 and FOXD3 were further correlated with tumor node metastasis stage and pathological type of patients with NPC. LncRNA FOXD3-AS1 was also confirmed to negatively regulate the miR-185-3p expression, which further targeted the downstream gene FOXD3. In addition, lncRNA FOXD3-AS1 knockdown repressed cell stemness, colony formation, viability, invasion, migration, and in vivo tumor growth, and accelerated cell apoptosis. Moreover, FOXD3 silencing or miR-185-3p overexpression reversed the effects of lncRNA FOXD3-AS1. Our findings provide evidence indicating that lncRNA FOXD3-AS1 could bind to miR-185-3p to upregulate the FOXD3 expression, thereby promoting the development of NPC.