Polysaccharides Extracted from (Oliv.) Diels Relieve the Malignant Characteristics of Glioma Cells through Regulating the MiR-373-3p-Mediated TGF-/Smad4 Signaling Pathway.

Objectives: polysaccharide (ASP) is a traditional herbal medicine accompanied by antitumor potential. This study aims to explore the therapeutic potential of ASP on glioma, as well as the underlying mechanisms involving microRNA-373-3p (miR-373-3p) and the TGF-/Smad4 signaling pathway.

Methods: U251 cells (a human glioma cell line) were treated with different concentrations of ASP. miR-373-3p was silenced in U251 cells by the transfection of the miR-373-3p inhibitor. Cell viability and apoptosis were measured by CCK-8 assay and flow cytometry, respectively. Cell migration and invasion were detected by wound healing and transwell assays, respectively. The miR-373-3p expression was measured by RT-qPCR. The protein expressions of TGF- and Smad4 were evaluated by both western blotting and immunofluorescence.

Results: ASP inhibited the viability, migration, and invasion, and enhanced the apoptosis of U251 cells in a dose-dependent manner. ASP increased miR-373-3p expression and decreased TGF- and Smad4 expressions in U251 cells. Silencing of miR-373-3p weakened the effects of ASP on inhibiting cell viability, migration, and invasion, as well as promoting cell apoptosis. In addition, deleting miR-373-3p weakened the inhibiting effects of ASP on the TGF-/Smad4 pathway in U251 cells.

Conclusions: ASP suppresses the malignant progression of glioma via regulating the miR-373-3p-mediated TGF-/Smad4 pathway.