Whether miR-181a possesses the ability to inhibit cell invasion, transwell invasion assay was performed. As expected, there was significant reduction in cell invasiveness after miR-181a inhibitor transfection in both HGC-27 and MGC-803cell lines (Fig. 4 f ). Taken together, these results indicated PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/26509685 the oncogenic roles ofDiscussion Maternally expressed gene 3 (MEG3) is an imprinted gene belonging to the imprinted DLK1 EG3 locus located at chromosome 14q32.3 in human genome. Its mouse ortholog, Meg3, also known as gene trap locus 2 (Gtl2), is located at distal chromosome 12 [25]. Mice CI-1011 site carrying the maternal deletion of the Meg3 region died perinatally and had major skeletal muscle defects. MEG3 is expressed in many normal tissues, and the loss of MEG3 expression has been found in various types of human tumors, including in 25 of neuroblastomas, 81 of hepatocellular cancers, and 82 of gliomas [26, 27]. However, the involvement of MEG3 in gastric cancer has not been reported. Our findings indicated that MEG3 was down-regulated in GC tissues, and a lower level of MEG3 was associated with tumor stage and metastasis. Functional analysis confirmed the pleiotropic effects of MEG3 on GC cell proliferation, migration and invasion. Therefore, lncRNA MEG3 was determined as a novel tumor suppressor in human GC. Although a vast set of lncRNA transcripts are differentially expressed during development where many of them play critical roles, most of them have not yet been studied in mechanistic details. Till now, a majority of the lncRNAs have been linked with epigenetic modulation of gene expressions, they can also regulate gene expression by transcriptional or post transcriptional modes. In recent years it has been discovered that endogenous lncRNAs can influence post-transcriptional regulation by interfering with the miRNA pathways, by acting as competing endogenous RNAs (ceRNAs) [28?0]. ThesePeng et al. Journal of Experimental Clinical Cancer Research (2015) 34:Page 8 ofFig. 4 The functional analysis of miR-181a in GC cells. a Relative miR-181a expression level in GC tissues and adjacent normal regions; The expression of level of miR-181a was detected in 50 GC patients by RT-qPCR. b miR-181a level were detected in HGC-27 and MGC-803 cells after treatment with miR-181a inhibitor (25 nM) or inhibitor control (25 nM) by RT-qPCR; c Cell proliferation assay of HGC-27 and MGC-803 cells after treatment with miR-181a inhibitor or inhibitor control by using CCK-8; d Flow cytometry was applied to examine the apoptosis of HGC-27 and MGC-803 cells after treatment with miR-181a inhibitor or inhibitor control and stianed with apoptosis markers (FITC-Annexin V and PI). In the apoptosis map, FITC-Annexin V+/PI+ indicates late apoptosis, FITC-Annexin V+/PI- indicates early apoptosis, and FITC-Annexin V-/PI- indicates normal live cells. e Wound healing assays of HGC-27 and MGC-803 cells after treatment with miR-181a inhibitor or inhibitor control, The relative ratio of wound closure per field was shown in the right; f Transwell analysis of HGC-27 and MGC-803 cells after treatment with miR-181a inhibitor or inhibitor control, The relative ratio of invasive cells per field was shown right. For all quantitative results, the data are presented as the mean ?SEM, and the error bars represent the standard deviation obtained from three independent experiments. *p < 0.05; **p < 0.lncRNAs have miRNA responsive elements (MRE) and act as miRNA sponges to control endogenous.
