Circular RNA circ_SKA3 enhances gastric cancer development by targeting miR-520h

Circ_0003356 suppresses gastric cancer growth through targeting the miR-668-3p/SOCS3 axis

BACKGROUND

Circular RNAs (circRNAs) have attracted extensive attention as therapeutic targets in gastric cancer (GC). Circ_0003356 is known to be downregulated in GC tissues, but its cellular function and mechanisms remain undefined.

AIM

To investigate the role of circ_0003356 in GC at the molecular and cellular level.

METHODS

Circ_0003356, miR-668-3p, and SOCS3 expression were assessed via quantitative real time-polymerase chain reaction (qRT-PCR). Wound healing, EdU, CCK-8, flow cytometry and transwell assays were used to analyze the migration, proliferation, viability, apoptosis and invasion of GC cells. The subcellular localization of circ_0003356 was monitored using fluorescence in situ hybridization. The interaction of circ_0003356 with miR-668-3p was confirmed using RIP-qRT-PCR, RNA pull-down, and dual luciferase reporter assays. We observed protein levels of genes via western blot. We injected AGS cells into the upper back of mice and performed immunohistochemistry staining for examining E-cadherin, N-cadherin, Ki67, and SOCS3 expressions. TUNEL staining was performed for the assessment of apoptosis in mouse tumor tissues.

RESULTS

Circ_0003356 and SOCS3 expression was downregulated in GC cells, whilst miR-668-3p was upregulated. Exogenous circ_0003356 expression and miR-668-3p silencing suppressed the migration, viability, proliferation, epithelial to mesenchy-mal transition (EMT) and invasion of GC cells and enhanced apoptosis. Circ_0003356 overexpression impaired tumor growth in xenograft mice. Targeting of miR-668-3p by circ_0003356 was confirmed through binding assays and SOCS3 was identified as a downstream target of miR-668-3p. The impacts of circ_0003356 on cell proliferation, apoptosis, migration, invasion and EMT were reversed by miR-668-3p up-regulation or SOCS3 down-regulation in GC cells.

CONCLUSION

Circ_0003356 impaired GC development through its interaction with the miR-668-3p/SOCS3 axis.

Role of circRNAs in gastric cancer

Circular RNAs (circRNAs) are a large class of non-coding RNAs with single-strand covalently closed loops, formed by reverse splicing, which widely exist in many cell lines and diverse species. Some circRNAs have highly evolutionarily conserved sequences, or tissue-specific or cell-specific expression patterns, and many circRNAs are extremely stable. In the past decades, accumulating evidence has indicated that circRNAs participate in the mechanisms associated with the development of many kinds of tumors, exert important biological functions by acting as microRNA or protein ‘sponges’, transcriptional regulatory factors, and protein translation templates, and play key roles in the occurrence and development of gastric cancer. This review comprehensively summarizes the biogenesis, characteristics, and biological functions of circRNAs, and the molecular mechanisms underlying the role of circRNAs in the carcinogenesis and progression of gastric cancer.