The knockdown of lncRNA DLGAP1‐AS2 suppresses osteosarcoma progression by inhibiting aerobic glycolysis via the miR‐451a/HK2 axis

Abstract

Osteosarcoma (OS) is one of the most aggressive bone tumors worldwide. Emerging documents have shown that long noncoding RNAs (lncRNAs) elicit crucial regulatory functions in the process of tumorigenesis. LncRNA DLGAP1‐AS2 is recognized as a regulator in several types of cancers, but its biological functions and molecular mechanisms in OS remain to be elucidated. RT‐qPCR and In situ hybridization (ISH) were used to evaluate DLGAP1‐AS2 expression in OS samples. Western blotting was used for the measurement of the protein levels of hexokinase 2 (HK2) and epithelial–mesenchymal transition (EMT)‐related markers. The proliferation of OS cells was determined using a CCK‐8 assay and EdU assay. TUNEL assay and flow cytometry were performed to assess OS cell apoptosis. Glucose metabolism in vitro assays were used. The binding relations among miR‐451a, HK2, and DLGAP1‐AS2 were validated by luciferase reporter assay. The cellular distribution of DLGAP1‐AS2 in OS cells was determined by FISH and subcellular fractionation assays. Mouse xenograft models were established to perform the experiments in vivo. We found that DLGAP1‐AS2 expression was upregulated in OS tissues and cells. Downregulation of DLGAP1‐AS2 expression suppressed the malignancy of OS cells by restraining cell proliferation, the EMT process, invasiveness, migration, and aerobic glycolysis and accelerating apoptotic behaviors. Of note, silenced DLGAP1‐AS2 restrained tumor growth and metastasis in vivo. However, DLGAP1‐AS2 overexpression accelerated the progression of OS. We further found that DLGAP1‐AS2 upregulation was induced by hypoxia and low glucose. Additionally, DLGAP1‐AS2 bound to miR‐451a to upregulate HK2 expression. Rescue assays revealed that the DLGAP1‐AS2/miR‐451a/HK2 axis contributed to OS cell malignancy by promoting aerobic glucose metabolism. Overall, these findings revealed a new regulatory pathway where DLGAP1‐AS2 upregulated HK2 expression by sponging miR‐451a to accelerate OS development.

Decoding the Impact of Tumor Microenvironment in Osteosarcoma Progression and Metastasis

“…In a recent contribution by Zheng et al, hypoxia's role in metabolic reprogramming was spotlighted. Their work demonstrated that suppressing lncRNA DLGAP1-AS2 hinders OS progression by inhibiting aerobic glycolysis through the miR-451a/HK2 axis [153]. Recently, Subasinghe mapped hypoxia in real time in in vivo orthotopic syngeneic tumors to improve radiographic mapping, which is critical to the study of cancer and a wide range of diseases [154].…”

Emerging roles of long non-coding RNAs in osteosarcoma

“…To date, over 50,000 genes have been identified to generate lncRNAs, with tissue-, lineage-, and spatiotemporalspecific patterns (Iyer et al, 2015). Certain lncRNAs, such as HOTAIR, MALAT1 and H19, have been implicated in OS oncogenesis and progression by modulating signaling pathways (Wang B. et al, 2015;Li E. et al, 2017;Li H. et al, 2023). Furthermore, lncRNAs are associated with the response of OS patients to chemotherapy (Hahne and Valeri, 2018).…”