Overexpression of FOXD2-AS1 enhances proliferation and impairs differentiation of glioma stem cells by activating the NOTCH pathway via TAF-1.

Abstract

Emerging data have highlighted the importance of long noncoding RNAs (lncRNAs) in exerting critical biological functions and roles in different forms of brain cancer, including gliomas. In this study, we sought to investigate the role of lncRNA FOXD2 adjacent opposite strand RNA 1 (FOXD2‐AS1) in glioma cells. First, we used sphere formation assay and flow cytometry to select U251 glioma stem cells (GSCs). Then, we quantified the expression of lncRNA FOXD2‐AS1, TATA‐box binding protein associated factor 1 (TAF‐1) and NOTCH1 in glioma tissues and GSCs, as well as the expression of GSC stem markers, OCT4, SOX2, Nanog, Nestin and CD133 in GSCs. Colony formation assay, sphere formation assay, and flow cytometry were used to evaluate GSC stemness. Next, the correlations among lncRNA FOXD2‐AS1, TAF‐1 and NOTCH1 were investigated. LncRNA FOXD2‐AS1, TAF‐1 and NOTCH1 were found to be elevated in glioma tissues and GSCs, and silencing lncRNA FOXD2‐AS1 inhibited stemness and proliferation, while promoting apoptosis and differentiation of GSCs. LncRNA FOXD2‐AS1 overexpression also led to increased NOTCH1 by recruiting TAF‐1 to the NOTCH1 promoter region, thereby promoting stemness and proliferation, while impairing cell apoptosis and differentiation. Mechanistically, lncRNA FOXD2‐AS1 elevation promoted glioma in vivo by activating the NOTCH signalling pathway via TAF‐1 upregulation. Taken together, the key findings of our investigation support the proposition that downregulation of lncRNA FOXD2‐AS1 presents a viable and novel molecular candidate for improving glioma treatment.