Long noncoding RNAs (lncRNA) are dysregulated in various human cancers and control tumor development and progression. However, the upstream mechanisms underlying their dysregulation remain unclear. Here, we demonstrate that the expression of hepatocyte nuclear factor 1 homeobox A antisense RNA 1 (HNF1A-AS1) is significantly upregulated in gastric cancer tissues. Overexpression of HNF1A-AS1 enhanced cell proliferation and promoted cell-cycle progression, whereas knockdown of HNF1A-AS1 elicited the opposite effects. Early growth response protein 1 (EGR1) directly bound the HNF1A-AS1 promoter region and activated its transcription. Overexpression of EGR1 enhanced cell proliferation and promoted cell-cycle promotion, similar to the function of HNF1A-AS1. HNF1A-AS1 functioned as competing endogenous RNA (ceRNA) by binding to miR-661, upregulating the expression of cell division cycle 34 (CDC34), which is a direct target of miR-661. EGR1 and HNF1A-AS1 enhanced the expression of cyclin-dependent kinase 2 (CDK2), CDK4, and cyclin E1 but inhibited the expression of p21 by promoting CDC34-mediated ubiquitination and degradation of p21. Taken together, these findings suggest that EGR1-activated HNF1A-AS1 regulates various pro- and antigrowth factors to promote the development of gastric cancer, implicating it as a possible target for therapeutic intervention in this disease. This study provides novel insights into mechanisms by which the noncoding RNA HNF1A-AS1 contributes to gastric cancer progression through modulation of the cell cycle. .

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Vascular Endothelial Growth Factor C (VEGF-C) has critical roles in angiogenesis in human cancers; however, the underlying mechanisms regulating VEGF-C expression remain largely unknown. In the present study, VEGF-C protein expression and the density of blood vessels or lymphatic vessels were determined by immunohistochemistry in 103 cases of gastric cancer tissues. Suppression of VEGF-C by miR-27b, miR-101 and miR-128 was investigated by luciferase assays, Western blot and ELISA. The miRNAs expression levels were detected in human gastric cancers by real-time quantitative PCR. Cell proliferation, migration and invasion assays were performed to assess the effect of miRNAs on gastric cancer cells and human umbilical vascular endothelial cells (HUVECs). Our data showed that high VEGF-C expression was significantly associated with increased tumor size, advanced TNM classification and clinical stage, higher microvessel density (MVD) and lymphatic density (LVD), as well as poor survival in patients with gastric cancer. Furthermore, VEGF-C was found to be a direct target gene of miR-27b, miR-101, and miR-128. The expression levels of the three miRNAs were inversely correlated with MVD. Overexpression of miR-27b, miR-101, or miR-128 suppressed migration, proliferation activity, and tube formation in HUVECs by repressing VEGF-C secretion in gastric cancer cells. We conclude that miR-27b, miR-101 and miR-128 inhibit angiogenesis by down-regulating VEGF-C expression in gastric cancers.

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