Circ-EIF4G3 promotes the development of gastric cancer by sponging miR-335

Circular RNAs (circRNAs), a new group of endogenous non-coding RNAs, plays a crucial role in various types of carcinomas. However, there is still limited information on the involvement of circular RNAs in the setting of gastric cancer (GC). In the present study, we aimed to investigate circ-EIF4G3 status in clinical GC patient samples and explored the malignant biological behaviors.

The expression of circ-EIF4G3 was determined by quantitative real time polymerase chain reaction (qRT-PCR). Microarray was performed to detect si-circ-EIF4G3 and unprocessed BGC-823 cells to find a cluster of differently expressed microRNAs (miRNAs) and bioinformatic tools including circinteractome, GO, NHGR1_GWAS, KEGG analyses were used in follow-up analysis. Luciferase reporter, RNA pull down and fluorescence in situ hybridization (FISH) assays were employed to explore the interaction between circ-EIF4G3 and miR-335. SiRNA-mediated knockdown of circ-EIF4G3, proliferation, migration and invasion in vitro were used to evaluate the function of circ-EIF4G3.

An increase level in the circ-EIF4G3 expression was associated with higher TNM stage and lymphatic metastasis. In vitro assays of the GC cell lines AGS and BGC-823 demonstrated that knockdown of circ-EIF4G3 inhibited cell proliferation, invasion and migration significantly. In addition, circ-EIF4G3 was identified as a sponge of miR-335, further promoting the proliferation, invasion and migration of GC cells.

Our study demonstrates that circ-EIF4G3 promotes the proliferation, invasion and migration of gastric cancer via sponging miR-335.