MiR-520b/e Regulates Proliferation and Migration by Simultaneously Targeting EGFR in Gastric Cancer

165

176

Background/Amis: Long non-coding RNAs (lncRNAs), a novel class of transcripts, have been shown to play critical roles in diverse cellular biological processes, including tumorigenesis. Small nucleolar RNA host gene 6 (SNHG6) regulates various biological processes in cancer cells. However, the biological role of SNHG6 in gastric cancer still remains to be explored. The aim of this study is to investigate the characteristic of the SNHG6 in gastric cancer. Methods: Quantitative real-time polymerase chain reaction (qRT-PCR) was used to measure the expression of SNHG6 in gastric cancer tissues and cell lines. MTT assays, colony formation assays were used to determine the impact of SNHG6 on tumorigenesis . Flow cytometric analysis of cell cycle and apoptosis was performed to measure the effect of SNHG6 on cell cycle and apoptosis rate. Transwell assay was performed to measure the effect of SNHG6 on cell migration. Western blotting and immunofuorescence were utilized to examine the effect of SNHG6 on epithelial-mesenchymal transition (EMT) of GC cells. Chromatin immunoprecipitation (ChIP), RNA immunoprecipitation (RIP), RNA-pulldown and luciferase reporter assays were employed to dissect molecular mechanisms. Results: In this study, we revealed that SNHG6 was overexpressed in gastric cancer tissues and cell lines. High expression levels of SNHG6 wereassociated with invasion depth, lymph node metastasis, distant metastasis and tumor/node/metastasis (TNM) stage, and predicted poor prognosis. Loss-of-function assays revealed that silenced SNHG6 obviously inhibited gastric cancer cell growth, weakened cell migration capacity and suppressed the EMT processes of gastric cancer cells. Additionally, ChIP, RIP, RNA-pulldown and luciferase reporter assays evidenced that SNHG6 could epigenetically silenced p27 and could competitively sponging miR-101-3p thereby regulating zinc finger E-box-binding homeobox 1 (ZEB1). Conclusion: In summary, our findings demonstrated that SNHG6 acted as an oncogene in gastric cancer cells through regulating miR-101-3p/ZEB1 at a post-transcriptional level and silencing expression at a transcriptional level by recruiting enhancer of zeste homolog 2 (EZH2) to the promoter of p27. SNHG6 might serve as a candidate prognostic biomarker and a target for novel therapies of gastric cancer patients.

Section: Discussionmentioning

confidence: 99%

LncRNA SNHG6 is Associated with Poor Prognosis of Gastric Cancer and Promotes Cell Proliferation and EMT through Epigenetically Silencing p27 and Sponging miR-101-3p

Yan

Tian

Shi

et al. 2017

165

176

“…Previous studies showed that miRNAs play vital roles in GC carcinogenesis [32][33][34]. In addition, miR-19b regulates hTERT mRNA expression by targeting PITX1 mRNA in melanoma cells [26], and enhanced miR-886-3p expression regulates cell migration, proliferation, and apoptosis by targeting PITX1 in clear cell renal cell carcinoma [35].…”

Section: Cellular Physiology and Biochemistrymentioning

confidence: 98%

Downregulated PITX1 Modulated by MiR-19a-3p Promotes Cell Malignancy and Predicts a Poor Prognosis of Gastric Cancer by Affecting Transcriptionally Activated PDCD5

Qiao

Gong

Song

et al. 2018

Background/Aims: PITX1 has been identified as a potential tumor-suppressor gene in several malignant tumors. The molecular mechanism underlying PITX1, particularly its function as a transcription factor regulating gene expression during tumorigenesis, is still poorly understood. Methods: The expression level and location of PITX1 were determined by quantitative reverse transcription PCR (qRT-PCR) and immunohistochemical staining in gastric cancer (GC). The effect of PITX1 on the GC cell proliferation and tumorigenesis was analyzed in vitro and in vivo. To explore how PITX1 suppresses cell proliferation, we used PITX1-ChIP-sequencing to measure genome-wide binding sites of PITX1 and assessed global function associations based on its putative target genes. ChIP-PCR, electrophoretic mobility shift assay, and promoter reporter assays examined whether PITX1 bound to PDCD5 and regulated its expression. The function of PDCD5 in GC cell apoptosis was further examined in vitro and in vivo. The relationship between the PITX1 protein level and GC patient prognosis was evaluated by the Kaplan-Meier estimator. Meanwhile, the expression level of miR-19a-3p, which is related to PITX1, was also detected by luciferase reporter assay, qRT-PCR, and western blotting. Results: The expression level of PITX1 was decreased in GC tissues and cell lines. Elevated PITX1 expression significantly suppressed the cell proliferation of GC cells and tumorigenesis in vitro and in vivo. PITX1 knockdown blocked its inhibition of GC cell proliferation. PITX1 bound to whole genomewide sites, with these targets enriched on genes with functions mainly related to cell growth and apoptosis. PITX1 bound to PDCD5, an apoptosis-related gene, during tumorigenesis, and cis-regulated PDCD5 expression. Increased PDCD5 expression in GC cells not only induced GC cell apoptosis, but also suppressed GC cell growth in vitro and in vivo. Moreover, PITX1 expression was regulated by miR-19a-3p. More importantly, a decreased level of PITX1 protein was correlated with poor GC patient prognosis. Conclusion: Decreased expression of PITX1 predicts shorter overall survival in GC patients. As a transcriptional activator, PITX1 regulates apoptosis-related genes, including PDCD5, during gastric carcinogenesis. These data indicate PDCD5 to be a novel and feasible therapeutic target for GC.

“…Recent studies have shown that miRNA is deregulated in various cancers, and miRNA expression is relevant to the diagnosis and prognosis of many diverse tumors [18, 19]. Various publications have associated miRNA with cancer; however, the relationship between miR-212-5p and TNBC remains unknown.…”

Section: Discussionmentioning

confidence: 99%

MiR-212-5p Suppresses the Epithelial-Mesenchymal Transition in Triple-Negative Breast Cancer by Targeting Prrx2

Yang

Liu

et al. 2017

Background/Aims: Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype. Our study investigated the functional role of miR-212-5p in TNBC. Methods: Realtime PCR was used to quantify miR-212-5p expression levels in 30 paired TNBC samples and adjacent normal tissues. Wound healing and Transwell assays were used to evaluate the effects of miR-212-5p expression on the invasiveness of TNBC cells. Luciferase reporter and Western blot assays were used to verify whether the mRNA encoding Prrx2 is a major target of miR-212-5p. Results: MiR-212-5p was downregulated in TNBC, and its expression levels were related to tumor size, lymph node status and vascular invasion in breast cancer. We also observed that the miR-212-5p expression level was significantly correlated with a better prognosis in TNBC. Ectopic expression of miR-212-5p induced upregulation of E-cadherin expression and downregulation of vimentin expression. The expression of miR212-5p also suppressed the migration and invasion capacity of mesenchymal-like cancer cells accompanied by a morphological shift towards the epithelial phenotype. Moreover, our study observed that miR-212-5p overexpression significantly suppressed Prrx2 by targeting its 3’-untranslated region (3’-UTR) region, and Prrx2 overexpression partially abrogated miR-212-5p-mediated suppression. Conclusions: Our study demonstrated that miR-212-5p inhibits TNBC from acquiring the EMT phenotype by downregulating Prrx2, thereby inhibiting cell migration and invasion during cancer progression.