MiR-769-5p functions as an oncogene by down-regulating RYBP expression in gastric cancer

P.-B. Luan, X.-Z. Jia, J. Yao

Department of General Surgery, Yantaishan Hospital, Yantai, China. yt6709936@163.com

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• Oncology

OBJECTIVE: The purpose of this study was to detect the relative expression level of micro-ribonucleic acid (miR)-769-5p in gastric cancer (GC) tissues and cells, and to investigate the clinical significance, biological function, and mechanism of miR-769-5p in GC.

PATIENTS AND METHODS: The relative expression level in 62 cases of GC tissues and paracancerous tissues was detected by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). The correlation between miR-769-5p expression and clinicopathological characteristics of GC patients was analyzed by Chi-square test. Besides, the relative expression level of miR-769-5p in GC cells and the interference efficiency of si-miR-769-5p were detected by qRT-PCR, and the biological function of miR-769-5p was studied by in vitro experiments [Thiazolyl Blue Tetrazolium Bromide (MTT), flow cytometry, 5-ethynyl-2′-deoxyuridine (EdU)]. Next, the effect of miR-769-5p on the tumorigenicity of GC cells in vivo was investigated by nude mouse tumorigenicity assay. Moreover, the downstream target genes of miR-769-5p were predicted by bioinformatics. Finally, qRT-PCR and Western blotting were used to screen the downstream target genes.

RESULTS: In the 62 cases of GC tissues, the expression of miR-769-5p was upregulated in 48 cases. MiR-769-5p was divided into high-expression group and low-expression group. Chi-square analysis showed that the high expression of miR-769-5p was positively correlated with tumor-node-metastasis (TNM) stage (p=0.005), lymph node metastasis (p=0.010), and infiltration depth (p=0.011) in patients with GC. The results of qRT-PCR indicated that the expression of miR-769-5p was upregulated in GC cells. In vitro experiments (MTT, flow cytometry, EdU) results showed that after interfering in the expression of miR-769-5p, the proliferation ability of GC cells was decreased, and apoptosis was increased. Furthermore, the results of in vivo experiments manifested that the tumorigenic ability of GC cells declined after interference in the expression of miR-769-5p. Finally, the results of qRT-PCR and Western blotting revealed that the expression of RING1 and YY1-binding protein (RYBP) was regulated by miR-769-5p.

CONCLUSIONS: The expression of miR-769-5p is upregulated in GC and positively correlated with TNM stage in GC patients. By regulating the expression of RYBP, the proliferation of GC cells was promoted, and the apoptosis was inhibited.

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