Background/Aims: Non-coding RNAs including miRNA and lncRNA had been reported to regulate gene expression and were both related to cancer progression. MicroRNA-141 (miR-141) has been reported to play a role in the epithelial to mesenchymal transition (EMT) process and H19 has also been demonstrated to promote malignancy in various cancers. We aimed to determine the correlation between miR-141 and H19 and their roles in gastric cancer in this study. Methods: H19 and miR-141 expression were detected by qRT-PCR. By bioinformatic analysis and luciferase assay we examined the correlation between H19 and miR-141 in vitro. Results: H19 expression was found to be inversely correlated to miR-141 expression in gastric cancer cells and tissues. H19 promotes malignancy including proliferation and invasion whereas miR-141 suppresses malignancy in human cancer cells. MiR-141 binds to H19 in a sequence specific manner, and suppresses H19 expression and functions including proliferation and invasion. MiR-141 could also regulate H19 target genes and miR-141 inhibitor restores H19 siRNA function, while H19 regulates miR-141 target gene ZEB1. Conclusion: These results were the first to demonstrate that H19 and miR-141 could compete with each other and affect their target genes in gastric cancer, which provide important clues for understanding the key roles of lncRNA-miRNA functional network in cancer.

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Gastric cancer (GC) is one of the most common tumors and the molecular mechanism underlying its metastasis is still largely unclear. Here, we show that miR-25 was overexpressed in plasma and primary tumor tissues of GC patients with tumor node metastasis stage (III or IV) or lymph node metastasis. MiR-25 inhibition significantly decreased the metastasis, invasion and proliferation of GC cells in vitro, and reduced their capacity to develop distal pulmonary metastases and peritoneal dissemination in vivo. Furthermore, miR-25 repressed transducer of ERBB2, 1 (TOB1) expression by directly binding to TOB1-3'-UTR, and the inverse correlation was observed between the expressions of miR-25 and TOB1 mRNA in primary GC tissues. Moreover, the loss of TOB1 increased the metastasis, invasion and proliferation of GC cells, and the restoration of TOB1 led to suppressed metastasis, invasion and proliferation. The receiver operating characteristics analysis yielded an area under the curve value of 0.7325 in distinguishing the GC patients with death from those with survival. The analysis of optimal cutoff value revealed poor survival in GC patients with high plasma concentrations of miR-25 (>0.2333 amol/μl). Taken together, miR-25 promotes GC progression by directly downregulating TOB1 expression, and may be a noninvasive biomarker for the prognosis of GC patients.

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