MicroRNA-374b-5p suppresses osteosarcoma progression via the PDPK1-mediated AKT pathway

MicroRNAs (miRNAs) have been verified to be involved in various biological processes through regulating their target genes, and some previous studies have revealed the antitumour role of microRNA-374b-5p (miR-374b-5p) in several tumours. Therefore, the purpose of this study was to explore the functions and potential mechanisms of miR-374b-5p in osteosarcoma (OS) progression.

The differentially expressed gene miR-374b-5p was discovered in the dataset GSE65071 from the Gene Expression Omnibus (GEO) database via bioinformatics analysis, and its expression levels in OS tissues and cell lines were confirmed by RNA fluorescence in situ hybridization (FISH) staining and quantitative real-time polymerase chain reaction (qRT-PCR). OS cell proliferation ability was evaluated by Cell Counting Kit-8 (CCK-8) assay and colony formation assay, cell migration and invasion abilities were assessed by Transwell assays, and apoptosis was detected by flow cytometry. The underlying mechanisms of miR-374b-5p in regulating OS progression were explored by qRT-PCR, dual-luciferase reporter assay and western blotting. In vivo experiments, a nude mice xenograft tumour model was performed to evaluate the effects of miR-374b-5p on tumour growth and gene expression changes.

In this study, miR-374b-5p expression was confirmed to be significantly down-regulated in OS, and miR-374b-5p overexpression could inhibit the proliferation, migration, and invasion abilities but promote apoptosis of OS cells. Mechanism studies revealed that miR-374b-5p suppressed the AKT pathway via negatively regulating the expression of phosphoinositide-dependent protein kinase 1 (PDPK1). Notably, PDPK1 were highly expressed in OS cell lines, as verified by qRT-PCR, and PDPK1-silencing considerably restrained OS progression. Moreover, the inhibitory effects of miR-374b-5p on OS progression were partially reversed by PDPK1 overexpression both in vitro and in vivo.

MiR-374b-5p was lowly expressed in OS, and its upregulation inhibited the progression of OS by directly targeting PDPK1 to affect the activity of the AKT pathway.