Circular RNA circ-AGFG1 contributes to esophageal squamous cell carcinoma progression and glutamine catabolism by targeting microRNA-497-5p/solute carrier family 1 member 5 axis

Circular RNAs (circRNAs) have been shown to play important regulatory roles in human malignancies. However, the role of circRNA ArfGAP with FG repeats 1 (circ-AGFG1) in esophageal squamous cell carcinoma (ESCC) progression and its associated mechanism are still largely undefined. Cell proliferation was analyzed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and 5-ethynyl-2'-deoxyuridine assay. Cell apoptosis was assessed by flow cytometry analysis. Transwell assay and wound healing assay were used to analyze cell invasion and migration abilities. The uptake of glutamine and the production of α-ketoglutarate and glutamate were analyzed using Glutamine Determination Kit, α-ketoglutarate Assay Kit and Glutamate Determination Kit. A xenograft tumor model was used to analyze the biological role of circ-AGFG1 in vivo . The interaction between microRNA-497-5p (miR-497-5p) and circ-AGFG1 or solute carrier family 1 member 5 (SLC1A5) was verified by dual-luciferase reporter assay. Circ-AGFG1 expression was upregulated in ESCC tissues and cell lines. Circ-AGFG1 silencing suppressed the proliferation, migration, invasion and glutaminolysis and triggered the apoptosis of ESCC cells. Circ-AGFG1 knockdown significantly slowed down tumor growth in vivo . Circ-AGFG1 acted as a sponge for miR-497-5p, and miR-497-5p interacted with the 3' untranslated region (3'UTR) of SLC1A5. miR-497-5p silencing largely abolished circ-AGFG1 silencing-induced effects in ESCC cells. miR-497-5p overexpression-mediated influences in ESCC cells were largely reversed by the addition of SLC1A5 expressing plasmid. Circ-AGFG1 could upregulate SLC1A5 expression by sponging miR-497-5p. In summary, circ-AGFG1 acted as an oncogene to elevate the malignant potential and promote the glutamine catabolism of ESCC cells by targeting the miR-497-5p/SLC1A5 axis.