Micro RNA-9 inhibits the gastric cancer cell proliferation by targeting TNFAIP8.

Background and objectives Micro RNA-9 is frequently dysregulated in many human carcinoma types, including gastric cancer (GC). Previous studies demonstrated that the expression of TNFAIP8 in GC is correlated with tumour occurrence, development, invasion, metastasis and prognosis. However, till now, the relationship between Micro RNA-9 and TNFAIP8 in GC has not been reported. Materials and methods Levels of miR-9 and TNFAIP8 expression in GC tissues and in human GC cell lines were studied using qualitative real-time PCR ( qRT- PCR) and Western blotting. Cell viability was detected using the CCK-8 and clone formation assays. A dual-luciferase reporter system was used to confirm the target gene of miR-9. Results We found that the expression level of Micro RNA-9 in GC tissues and cell lines was significantly lower than that in adjacent non-cancerous tissues and human immortalized gastric epithelial cell (GES) line, respectively. In addition, overexpression of Micro RNA-9 markedly inhibited GC cell proliferation in vitro and tumour growth in vivo. Further experiments revealed that TNFAIP8 was a direct and functional target of Micro RNA-9 in GC and overexpression of Micro RNA-9 obviously down-regulated the expression of TNFAIP8, which was involved in the gastric carcinogenesis and cancer progression. Conclusion Our results suggested that Micro RNA-9- TNFAIP8 might represent a promising diagnostic biomarker for GC patients and could be a potential therapeutic target in the prevention and treatment of GC. [ABSTRACT FROM AUTHOR]