Catenin-δ1, negatively regulated by miR-145, promotes tumour aggressiveness in gastric cancer

Emerging roles of miR-145 in gastrointestinal cancers: A new paradigm

Gastrointestinal (GI) carcinomas are a group of cancers affecting the GI tract and digestive organs, such as the gastric, liver, bile ducts, pancreas, small intestine, esophagus, colon, and rectum. MicroRNAs (miRNAs) are small functional non-coding RNAs (ncRNAs) which are involved in regulating the expression of multiple target genes; mainly at the post-transcriptional level, via complementary binding to their 3'-untranslated region (3'-UTR). Increasing evidence has shown that miRNAs have critical roles in modulating of various physiological and pathological cellular processes and regulating the occurrence and development of human malignancies. Among them, miR-145 is recognized for its anti-oncogenic properties in various cancers, including GI cancers. MiR-145 has been implicated in diverse biological processes of cancers through the regulation of target genes or signaling, including, proliferation, differentiation, tumorigenesis, angiogenesis, apoptosis, metastasis, and therapy resistance. In this review, we have summarized the role of miR-145 in selected GI cancers and also its downstream molecules and cellular processes targets, which could lead to a better understanding of the miR-145 in these cancers. In conclusion, we reveal the potential diagnostic, prognostic, and therapeutic value of miR-145 in GI cancer, and hope to provide new ideas for its application as a biomarker as well as a therapeutic target for the treatment of these cancer.

Integrated bioinformatics analysis of noncoding RNAs with tumor immune microenvironment in gastric cancer

In recent years, molecular and genetic research hotspots of gastric cancer have been investigated, including microRNAs, long noncoding RNAs (lncRNAs) and messenger RNA (mRNAs). The study on the role of lncRNAs may help to develop personalized treatment and identify potential prognostic biomarkers in gastric cancer. The RNA-seq and miRNA-seq data of gastric cancer were downloaded from the TCGA database. Differential analysis of RNA expression between gastric cancer samples and normal samples was performed using the edgeR package. The ceRNA regulatory network was visualized using Cytoscape. KEGG pathway analysis of mRNAs in the ceRNA network was performed using the clusterProfiler package. CIBERSORT was used to distinguish 22 immune cell types and the prognosis-related genes and immune cells were determined using Kaplan-Meier and Cox proportional hazard analyses. To estimate these nomograms, we used receiver operating characteristic and calibration curve studies. The ceRNA regulation network of gastric cancer was built in this study, and the genes in the network were analyzed for prognosis. A total of 980 lncRNAs were differentially expressed, of which 774 were upregulated and 206 were downregulated. A survival study identified 15 genes associated with gastric cancer prognosis, including VCAN-AS1, SERPINE1, AL139002.1, LINC00326, AC018781.1, C15orf54, hsa-miR-145. Monocytes and Neutrophils were associated with the survival rate of gastric cancer. Our research uncovers new ceRNA network for the detection, treatment, and monitoring of gastric cancer.

HRCT1, negatively regulated by miR-124-3p, promotes tumor metastasis and the growth of gastric cancer by activating the ERBB2-MAPK pathway

BACKGROUND

Gastric cancer is the fourth leading cause of cancer-related deaths worldwide. And patient outcomes are poor due to tumor relapse and metastasis. To develop new therapeutic strategies, it is of great importance to explore the mechanism underlying the progression of gastric cancer.

METHODS

Primary gastric cancer samples with lymph node metastases (LNM) and without LNM were subjected to mRNA microarray assay. The differentially expressed genes were confirmed by RT-qPCR. HRCT1 protein expression was further detected using an immunohistochemistry (IHC) assay. In vitro and in vivo assays were performed to investigate the role of HRCT1 in tumor invasion, metastasis, and proliferation. The expressions of the downstream target genes of HRCT1 were detected by microarray, RT-qPCR and Western blot assays. Dual-luciferase reporter and Western blot assays were carried out to identify miRNAs target to HRCT1.

RESULTS

HRCT1 was upregulated in gastric cancer, and high expression of HRCT1 was associated with poor overall survival (OS) and disease-free survival (DFS). Moreover, HRCT1protein expression was an independent predictor for poor OS and DFS. HRCT1 could promote gastric cancer cells' migration, invasion, and proliferation in vitro as well as tumor metastasis and growth in vivo. Notably, our data showed that HRCT1 promoted gastric cancer progression by activating the ERBB2-MAPK signaling pathway. At least partially, the expression of HRCT1 could be negatively regulated by miR-124-3p.

CONCLUSIONS

The upregulated expression of HRCT1 predicts poor survival for patients with gastric cancer. HRCT1 promotes tumor progression by activating the ERBB2-MAPK pathway. HRCT1, negatively regulated by miR-124-3p, may be a potential therapeutic target for patients with gastric cancer.

lncRNA THAP7-AS1, transcriptionally activated by SP1 and post-transcriptionally stabilized by METTL3-mediated m6A modification, exerts oncogenic properties by improving CUL4B entry into the nucleus

Long noncoding RNAs (lncRNAs) are dysregulated in different cancer types, and thus have emerged as important regulators of the initiation and progression of human cancers. However, the biological functions and the underlying mechanisms responsible for their functions in gastric cancer (GC) remain poorly understood. Here, by lncRNA microarray, we identified 1414 differentially expressed lncRNAs, among which THAP7-AS1 was significantly upregulated in GC tissues compared with non-tumorous gastric tissues. High expression of THAP7-AS1 was correlated with positive lymph node metastasis and poorer prognosis. SP1, a transcription factor, could bind directly to the THAP7-AS1 promoter region and activate its transcription. Moreover, the m6A modification of THAP7-AS1 by METTL3 enhanced its expression depending on the "reader" protein IGF2BP1-dependent pathway. THAP7-AS1 promoted GC cell progression. Mechanistically, THAP7-AS1 interacted with the 1-50 Amino Acid Region (nuclear localization signal) of CUL4B through its 1-442 nt Sequence, and it promoted interaction between nuclear localization signal (NLS) and importin α1, and improved the CUL4B protein entry into the nucleus, repressing miR-22-3p and miR-320a expression by CUL4B-catalyzed H2AK119ub1 and the EZH2-mediated H3K27me3, subsequently activating PI3K/AKT signaling pathway to promote GC progression. Moreover, LV-sh-THAP7-AS1 treatment could suppress GC growth, invasion and metastasis, indicating that THAP7-AS1 may act as a promising molecular target for GC therapies. Taken together, our results show that THAP7-AS1, transcriptionally activated by SP1 and then modified by METTL3-mediated m6A, exerts oncogenic functions, by promoting interaction between NLS and importin α1 and then improving the CUL4B protein entry into the nucleus to repress the transcription of miR-22-3p and miR-320a.

MicroRNAs and 'Sponging' Competitive Endogenous RNAs Dysregulated in Colorectal Cancer: Potential as Noninvasive Biomarkers and Therapeutic Targets

The gastrointestinal (GI) tract in mammals is comprised of dozens of cell types with varied functions, structures, and histological locations that respond in a myriad of ways to epigenetic and genetic factors, environmental cues, diet, and microbiota. The homeostatic functioning of these cells contained within this complex organ system has been shown to be highly regulated by the effect of microRNAs (miRNA). Multiple efforts have uncovered that these miRNAs are often tightly influential in either the suppression or overexpression of inflammatory, apoptotic, and differentiation-related genes and proteins in a variety of cell types in colorectal cancer (CRC). The early detection of CRC and other GI cancers can be difficult, attributable to the invasive nature of prophylactic colonoscopies. Additionally, the levels of miRNAs associated with CRC in biofluids can be contradictory and, therefore, must be considered in the context of other inhibiting competitive endogenous RNAs (ceRNA) such as lncRNAs and circRNAs. There is now a high demand for disease treatments and noninvasive screenings such as testing for bloodborne or fecal miRNAs and their inhibitors/targets. The breadth of this review encompasses current literature on well-established CRC-related miRNAs and the possibilities for their use as biomarkers in the diagnoses of this potentially fatal GI cancer.

MiRNA-145 and Its Direct Downstream Targets in Digestive System Cancers: A Promising Therapeutic Target

MicroRNAs (miRNAs) play a vital role in the onset and development of many diseases, including cancers. Emerging evidence shows that numerous miRNAs have the potential to be used as diagnostic biomarkers for cancers, and miRNA-based therapy may be a promising therapy for the treatment of malignant neoplasm. MicroRNA-145 (miR-145) has been considered to play certain roles in various cellular processes, such as proliferation, differentiation and apoptosis, via modulating the expression of direct target genes. Recent reports show that miR-145 participates in the progression of digestive system cancers, and plays crucial and novel roles in cancer treatment. In this review, we summarize the recent knowledge concerning the function of miR-145 and its direct targets in digestive system cancers. We discuss the potential role of miR-145 as a valuable biomarker for digestive system cancers and how miR-145 regulates these digestive system cancers via different targets to explore the potential strategy of targeting miR-145.

Vitamin D modulation and microRNAs in gastric cancer: prognostic and therapeutic role

Gastric adenocarcinoma arises after a complex interaction between the host and environmental factors. Tumor location and TNM are the tools that currently guide treatment decisions. Surgery is the only curative treatment, but relapse is common. After relapse or advanced staged disease survival is poor and systemic treatment has modestly improved survival. An association between sun exposure, vitamin D status and gastric cancer (GC) incidence and mortality has been reported. The molecular differences of the histological subtypes and the new molecular classifications account for the great heterogeneity of this disease and are the basis for the discovery of new therapeutic targets. New prognostic and predictive factors are essential and microRNAs (miRNAs) are endogenous small non-coding RNA molecules with a great potential for diagnosis, prognosis and treatment of cancer. There are hundreds of miRNAs with altered expression in tumor gastric tissue when compared to normal gastric tissue. Many of these miRNAs are associated with clinicopathological variables and survival in patients with GC. Furthermore, the expression of some of these miRNAs with prognostic importance in CG is influenced by vitamin D and others are mediators of some of the actions of this vitamin. This review aims to update the evidence on several miRNAs with prognostic value and therapeutic potential in GC, whose expression may be influenced by vitamin D or may regulate vitamin D signaling.

Identification of New Genes Involved in Germline Predisposition to Early-Onset Gastric Cancer

The genetic cause for several families with gastric cancer (GC) aggregation is unclear, with marked relevance in early-onset patients. We aimed to identify new candidate genes involved in GC germline predisposition. Whole-exome sequencing (WES) of germline samples was performed in 20 early-onset GC patients without previous germline mutation identified. WES was also performed in nine tumor samples to analyze the somatic profile using SigProfilerExtractor tool. Sequencing germline data were filtered to select those variants with plausible pathogenicity, rare frequency and previously involved in cancer. Then, a manual filtering was performed to prioritize genes according to current knowledge and function. These genetic variants were prevalidated with Integrative Genomics Viewer 2.8.2 (IGV). Subsequently, a further selection step was carried out according to function and information obtained from tumor samples. After IGV and selection step, 58 genetic variants in 52 different candidate genes were validated by Sanger sequencing. Among them, APC, FAT4, CTNND1 and TLR2 seem to be the most promising genes because of their role in hereditary cancer syndromes, tumor suppression, cell adhesion and Helicobacter pylori recognition, respectively. These encouraging results represent the open door to the identification of new genes involved in GC germline predisposition.

Elevated ZBTB7A expression in the tumor invasive front correlates with more tumor budding formation in gastric adenocarcinoma

PURPOSE

Tumor budding (TB) is reported to predict nodal involvement and recurrence in multiple human malignancies. However, it is not clear how TB forms. The purpose of this study is to find markers related to TB formation in gastric cancer and to investigate the underlying mechanisms.

METHODS

TB was scored on hematoxylin-eosin staining slides in 122 gastric cancer cases. Immunostaining score of CREB1, GAGE12I, CTNND1, KIF26B and ZBTB7A both at the invasive front and in the center of the tumor were assigned to each case. Spearman's correlation with the TB score was performed to find the TB-related markers. In vitro study and RNA-seq using gastric cancer cell lines were done to unveil the mechanisms.

RESULTS

TB could predict lymph node metastasis and is negatively associated with overall survival of the patients. The expression of ZBTB7A in the invasive front, rather than the other four markers, was much higher than that in the tumor center and was positively correlated with TB score. ZBTB7A could enhance migration and invasion of gastric cancer cells in vitro. RNA-seq data followed by RT-qPCR and western blot verification demonstrated the activation of EGFR-MAPK-ERK and PI3K-AKT-mTOR pathways and increased expression of EMT related markers upon ZBTB7A over-expression.

CONCLUSION

Higher ZBTB7A expression in the tumor margin may contribute to the dissociation of tumor cells from the tumor mass to form TB by initiating EMT via EGFR-MEK-ERK and PI3K-AKT-mTOR pathway.

Hsa-miR-425-5p promotes tumor growth and metastasis by activating the CTNND1-mediated β-catenin pathway and EMT in colorectal cancer

Colorectal cancer (CRC) is a common malignancy with high mortality. However, the roles of miR-425-5p and its underlying mechanism in CRC remain unknown. Here, RT-qPCR confirmed that miR-425-5p expression was increased by miR-425-5p mimic in SW480 cells and decreased by miR-425-5p inhibitor in LOVO cells. CCK-8, flow cytometry, wound healing and transwell assays revealed that the increased miR-425-5p promoted cell viability, cell cycle entry, migration and invasion in CRC. Besides, miR-425-5p overexpression induced epithelial-mesenchymal transition (EMT) with upregulation of Fibronectin, N-cadherin, Vimentin, and downregulation of E-cadherin. Moreover, miR-425-5p overexpression induced c-myc, Cyclin D1 and MMP7 levels, and promoted β-catenin translocation to the nucleus. Knockdown of miR-425-5p exerted opposite effects. Luciferase reporter assay indicated that miR-425-5p directly targeted CTNND1. Overexpression of miR-425-5p repressed CTNND1 expression at mRNA and protein levels. Silencing of CTNND1 had the inhibitory effect of miR-425-5p inhibitor on cell proliferation, migration, invasion, EMT, and the activation of β-catenin signaling pathway. Furthermore, miR-425-5p promoted tumor growth and metastasis in vivo. In conclusion, miR-425-5p may promote tumorigenesis and metastasis through activating CTNND1-mediated β-catenin pathway, which may provide therapeutic targets for human CRC.

SP1-activated long noncoding RNA lncRNA GCMA functions as a competing endogenous RNA to promote tumor metastasis by sponging miR-124 and miR-34a in gastric cancer

Long noncoding RNAs (lncRNAs) were demonstrated to play important roles in gene regulation and cancer progression. However, the functional roles of lncRNAs and the detailed mechanisms underlying gastric cancer (GC) progression remain largely unclear. Here, we identified a novel cancer-related lncRNA, termed lncRNA GCMA (Gastric Cancer metastasis-associated lncRNA), which was upregulated in GC tissues with lymph node metastasis (LNM) compared with tissues without LNM. High expression of GCMA was significantly associated with poor prognosis of patients with GC. Luciferase assays, bioinformatics analyses and chromatin immunoprecipitation (ChIP) assays indicated that SP1 transcription factor directly bound to the GCMA promoter region and activated its transcription. Functionally, upregulation of GCMA dramatically promoted GC cells proliferation, migration and invasion in vitro, whereas knockdown of GCMA elicited the opposite function. Consistently, stable knockdown of GCMA inhibited tumor proliferation, invasion and metastasis in vivo. Mechanistically, by using bioinformatics analyses, RNA binding protein immunoprecipitation (RIP) assays, luciferase assays and western-blot assays, GCMA was demonstrated to function as a competing endogenous RNA (ceRNA) via competitively absorbing miR-124 and miR-34a to upregulate slug and snail, thereby induced epithelial-mesenchymal transition (EMT) and GC cell metastasis in vitro and in vivo. Collectively, these results demonstrate that GCMA functions as an oncogenic lncRNA that may serve as a potential prognostic biomarker for GC and shed new lights on targeted therapy of GC in the future.

The circular RNA circMAST1 promotes hepatocellular carcinoma cell proliferation and migration by sponging miR-1299 and regulating CTNND1 expression

Circular RNAs (circRNAs) are a class of non-coding RNAs with a loop structure; however, their functions remain largely unknown. Growing evidence suggests that circRNAs play a pivotal role in the progression of malignant diseases. However, the expression profiles and function of circRNAs in hepatocellular carcinoma (HCC) remain unclear. We investigated the expression of microtubule-associated serine/threonine kinase 1 (MAST1) circRNA (circMAST1) in HCC and healthy tissues using bioinformatics, quantitative real-time PCR (qRT-PCR), and fluorescence in situ hybridization. Luciferase reporter assays were performed to assess the interaction between circMAST1 and miR-1299. Proliferation assays, colony formation assays, flow cytometry, transwell assays, and western blotting were also performed. A mouse xenograft model was also used to determine the effect of circMAST1 on HCC growth in vivo. CircMAST1 was upregulated in HCC tissues and cell lines; silencing via small interfering RNA inhibited migration, invasion, and proliferation of HCC cell lines in vitro as well as tumor growth in vivo. Furthermore, the expression of circMAST1 was positively correlated with catenin delta-1 (CTNND1) and negatively correlated with microRNA (miR)-1299 in HCC clinical samples. Importantly, circMAST1 sponged miR-1299 to stabilize the expression of CTNND1 and promoted tumorigenic features in HCC cell lines. We found that circMAST1 may serve as a novel biomarker for HCC. Moreover, circMAST1 elicits HCC progression by sponging miRNA-1299 and stabilizing CTNND1. Our data provide potential options for therapeutic targets in patients with HCC.

MicroRNA-96-5p represses breast cancer proliferation and invasion through Wnt/β-catenin signaling via targeting CTNND1

Low miR-96-5p expression is characteristic of many cancers but its role in breast cancer (BCa) remains poorly defined. Here, the role of miR-96-5p in BC development was assessed. We demonstrate that exogenously expressing miR-96-5p inhibits the proliferative, migratory and invasive capacity of BCa cells. Mechanistically, miR-96-5p in BCa cells was found to target and downregulate catenin delta 1 (CTNND1) leading to decreased β-catenin expression, a loss of WNT11 signaling, reduced cyclin D1 levels and lower MMP7 expression. Exogenously expressing CTNND1 alleviated these effects. In summary, we are the first to reveal that miR-96-5p inhibits the proliferative, invasive and migratory phenotypes of BCa cells the targeting of CTNND1 and subsequent Wnt/β-catenin signaling. These data highlight miR-96-5p as a novel target for BC treatment.

MicroRNA-4472 Promotes Tumor Proliferation and Aggressiveness in Breast Cancer by Targeting RGMA and Inducing EMT

BACKGROUND

Breast cancer is the most common cause of cancer-related death in women worldwide. MicroRNA (miRNA) ectopic expression has been reported to be involved in the regulation of gene expression in breast cancer. We screened several differentially expressed miRNAs associated with breast cancer chemoresistance, growth, and metastasis using a miRNA microarray. Increased expression of miR-4472 has been associated with larger breast tumors and chemoresistance. However, the biologic function of miR-4472 and its molecular mechanisms in cancer progression have not yet been reported.

MATERIALS AND METHODS

Real-time quantitative polymerase chain reaction was used to measure the expression of miR-4472 in breast cancer tissue and cell lines. The biologic functions of miR-4472 and its target gene were explored using Transwell, cell proliferation, and flow cytometry assays. Bioinformatics tools, dual-luciferase reporter assays, and Western blot were used to identify the target genes of miR-4472. Western blot was used to explain the participation of miR-4472 and target gene in epithelial-to-mesenchymal transition.

RESULTS

miR-4472 was significantly upregulated in highly metastatic breast cancer tissues, and its expression was positively associated with larger tumor size and advanced pTNM stage. miR-4472 promoted breast cancer cell metastasis and growth. Repulsive guidance molecule A (RGMA) was a direct target gene of miR-4472. RGMA was identified as a suppressor in cancer metastasis. miR-4472 downregulated expression of RGMA and promoted epithelial-to-mesenchymal transition by suppressing E-cadherin and initiating vimentin, β-catenin, and Slug.

CONCLUSIONS

miR-4472 contributes to the progression of breast cancer by regulating RGMA expression and inducing epithelial-to-mesenchymal transition, indicating that miR-4472/RGMA might serve as a therapeutic target for breast cancer.

MicroRNA-145 performs as a tumor suppressor in human esophageal squamous cell carcinoma by targeting phospholipase C epsilon 1

Esophageal squamous cell carcinoma (ESCC) is the leading pathologic type in China. miR-145 has been reported to be downregulated in multiple tumors. This study was aimed to investigate the role of miR-145 in ESCC. miR-145 expression was investigated in 65 ESCC samples as well as four ESCC cell lines by quantitative real-time polymerase chain reaction (qRT-PCR). Targetscan 6.2 website (http://www.targetscan.org/) was used to predict the targets of miR-145. Expression of phospholipase C epsilon 1 (PLCE1) messenger RNA and protein was detected by qRT-PCR or Western blot. MTT and wound healing assay were conducted to explore the effects of miR-145 on the proliferation and migration of ESCC cell lines, respectively. miR-145 was significantly decreased in ESCC tissues. An inverse correlation between miR-145 and invasion depth and TNM stage were observed. PLCE1 was a direct target of miR-145, and the expression of PLCE1 was inversely correlated with miR-145 expression in ESCC tissues. In addition, overexpression of miR-145 suppressed cell proliferation and migration in ESCC cells. The enforced expression of PLCE1 partially reversed the suppressive effect of miR-145. These results prove that miR-145 may perform as a tumor suppressor in ESCC by targeting PLCE1.

Long noncoding RNA UCA1 promotes the proliferation, invasion, and migration of nasopharyngeal carcinoma cells via modulation of miR-145

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a common malignant tumor characterized by highly malignant local invasion and distant metastasis. Recently, increasing attention has been paid to long noncoding RNAs (lncRNAs), which play significant roles in tumorigenesis and progression. However, little is known about the potential role of the lncRNA urothelial carcinoma-associated 1 (UCA1) in NPC cell invasion and migration.

METHODS

Real-time quantitative PCR was used to analyze the expression of lncRNA UCA1 in NPC cell lines and NP69. lncRNA UCA1 knock-down nasopharyngeal carcinoma cell line models were established through siRNA. Cell viability was evaluated by Cell counting kit-8 and Colony forming assay. The migration and invasion capacities were evaluated by wound healing and transwell migration and invasion assays. Western blot analysis were used to examine protein changes followed by UCA1 knock-down.

RESULTS

Our study confirmed that UCA1 was upregulated in NPC cell lines and involved in NPC tumorigenesis according to our established UCA1-associated competing endogenous RNA network. Moreover, functional analyses indicated that the downregulation of UCA1 exerted inhibitory effects on cell proliferation, invasion, and migration. Mechanistic analyses revealed that UCA1 was the target of miR-145 and functioned as a sponge to repress miR-145 expression. Rescue experiments suggested that lncRNA UCA1 reversed the miR-145-mediated inhibition on oncogene ADAM17 expression, thus promoting the proliferation, invasion, and migration of NPC cells.

CONCLUSION

LncRNA UCA1 functions as a tumor promoter in NPC. UCA1 promotes the proliferation and invasion of NPC cells by sponging miR-145, functionally altering ADAM17 expression targeted by miR-145. Our exploration of the underlying mechanism of UCA1 in NPC may provide novel therapeutic targets for NPC.

Genome-wide identification of a novel miRNA-based signature to predict recurrence in patients with gastric cancer

The current tumor node metastasis (TNM) staging system is inadequate for identifying high-risk gastric cancer (GC) patients. Using a systematic and comprehensive-biomarker discovery and validation approach, we attempted to build a microRNA (miRNA)-recurrence classifier (MRC) to improve the prognostic prediction of GC. We identified 312 differentially expressed miRNAs in 446 GC tissues compared to 45 normal controls by analyzing high-throughput data from The Cancer Genome Atlas (TCGA). Using a Cox regression model, we developed an 11-miRNA signature that could successfully discriminate high-risk patients in the training set (n = 372; P < 0.0001). Quantitative real-time polymerase chain reaction-based validation in an independent clinical cohort (n = 88) of formalin-fixed paraffin-embedded clinical GC samples showed that MRC-derived high-risk patients succumb to significantly poor recurrence-free survival in GC patients (P < 0.0001). Cox and stratification analysis indicated that the prognostic value of this signature was independent of clinicopathological risk factors. Time-dependent receiver operating characteristic (ROC) analysis revealed that the area under the curve of this signature was significantly larger than that of TNM stage in the TCGA (0.733 vs. 0.589 at 3 years, P = 0.004; 0.802 vs. 0.635 at 5 years, P = 0.005) and validation cohort (0.835 vs. 0.689 at 3 years, P = 0.003). A nomogram was constructed for clinical use, which integrated both MRC and clinical-related variables (depth of invasion, lymph node status and distance metastasis) and did well in the calibration plots. In conclusion, this novel miRNA-based signature is superior to currently used clinicopathological features for identifying high-risk GC patients. It can be readily translated into clinical practice with formalin-fixed paraffin-embedded specimens for specific decision-making applications.

RETRACTED: MicroRNA-298 represses hepatocellular carcinoma progression by inhibiting CTNND1-mediated Wnt/β-catenin signaling

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/policies/article-withdrawal). This article has been retracted at the request of the authors, who have informed the Editor-in-Chief that the wrong cell line was inadvertently used to perform transwell assays in Figure 3, as verified by a review of the laboratory notebooks. In addition, the authors were unable to repeat the western blot results in Figure 6B under the same conditions described in the paper. The authors no longer have confidence in the reliability of the results and would like to apologize for any inconvenience caused. The Editor-in-Chief agreed to retract the article.

Promoter Methylation-Regulated miR-145-5p Inhibits Laryngeal Squamous Cell Carcinoma Progression by Targeting FSCN1

Laryngeal squamous cell carcinoma (LSCC) is a common form of head and neck cancer with poor prognosis. However, the mechanism underlying the pathogenesis of LSCC remains unclear. Here, we demonstrated increased expression of fascin actin-bundling protein 1 (FSCN1) and decreased expression of microRNA-145-5p (miR-145-5p) in a clinical cohort of LSCC. Luciferase assay revealed that miR-145-5p is a negative regulator of FSCN1. Importantly, low miR-145-5p expression was correlated with TNM (tumor, node, metastasis) status and metastasis. Moreover, cases with low miR-145-5p/high FSCN1 expression showed poor prognosis, and these characteristics together served as independent prognostic indicators of survival. Gain- and loss-of-function studies showed that miR-145-5p overexpression or FSCN1 knockdown inhibited LSCC migration, invasion, and growth by suppressing the epithelial-mesenchymal transition along with inducing cell-cycle arrest and apoptosis. Additionally, hypermethylation of the miR-145-5p promoter suggested that repression of miR-145-5p arises through epigenetic inactivation. LSCC tumor growth in vivo could be inhibited by using miR-145-5p agomir or FSCN1 small interfering RNA (siRNA), which highlights the potential for clinical translation. Collectively, our findings indicate that miR-145-5p plays critical roles in inhibiting the progression of LSCC by suppressing FSCN1. Both miR-145-5p and FSCN1 are important potential prognostic markers and therapeutic targets for LSCC.

Construction and Comprehensive Analysis for Dysregulated Long Non-Coding RNA (lncRNA)-Associated Competing Endogenous RNA (ceRNA) Network in Gastric Cancer

Long non-coding RNA (lncRNA) is a kind of non-coding RNA with transcripts more than 200 bp in length. LncRNA can interact with the miRNA as a competing endogenous RNA (ceRNA) to regulate the expression of target genes, which play a significant role in the initiation and progression of tumors. In this study, we explored the functional roles and regulatory mechanisms of lncRNAs as ceRNAs in gastric cancer, and their potential implications for prognosis. The lncRNAs, miRNAs, and mRNAs expression profiles of 375 gastric cancer tissues and 32 non-tumor gastric tissues were downloaded from The Cancer Genome Atlas (TCGA) database. Differential expression of RNAs was identified using the DESeq package. Survival analysis was estimated based on Kaplan-Meier curve analysis. KEGG pathway analysis was performed using KOBAS 3.0. The dysregulated lncRNA-associated ceRNA network was constructed in gastric cancer based on bioinformatics generated from miRcode and miRTarBase. A total of 237 differentially expressed lncRNAs and 198 miRNAs between gastric cancer and matched normal tissues were screened in our study with thresholds of |log2FC| >2 and adjusted P value <0.01. Eleven discriminatively expressed lncRNAs may be correlated with tumorigenesis of gastric cancer. Seven out of 11 dysregulated lncRNA were found to be significantly associated with overall survival in gastric cancer (P value <0.05). The newly identified ceRNA network includes 11 gastric cancer-specific lncRNAs, 9 miRNAs, and 41 mRNAs. Collectively, our study will contribute to improving the understanding of the lncRNA-associated ceRNA network regulatory mechanisms in the pathogenesis of gastric cancer and provide and identify novel lncRNAs as candidate prognostic biomarkers or potential therapeutic targets.

Prognostic Value of microRNA Signature in Patients with Gastric Cancers

The occurrence of lymph node metastases (LNM) after endoscopic submucosal dissection (ESD) in patients with gastric cancer (GC) leads to poor prognosis. However, few biomarkers are available to predict LNM in GC patients. Thus, we measured expression of 6 cancer-related miRNAs using real-time RT-PCR in 102 GC samples that were randomized into a training set and a testing set (each, 51 cases). Using logistic regression, we identified 4-miRNA (miR-27b, miR-128, miR-100 and miR-214) signatures for predicting LNM in GC patients. Patients with high-risk scores for the 4-miRNA signature tended to have higher LNM than those with low-risk scores. Meanwhile, the ROC curve of the 4-miRNA signature was better for predicting LNM in GC patients. In addition, Cox regression analysis indicated that a 2-miRNA signature (miR-27b and miR-214) or a miR-214/N stage signature was predictive of survival for GC patients. This work describes a previously unrecognized 4-miRNA signature involved in LNM and a 2-miRNA signature or miR-214/N stage signature related to GC patients’ survival.

Epigenetic roles in the malignant transformation of gastric mucosal cells

Gastric carcinogenesis occurs when gastric epithelial cells transition through the initial, immortal, premalignant, and malignant stages of transformation. Epigenetic regulations contribute to this multistep process. Due to the critical role of epigenetic modifications , these changes are highly likely to be of clinical use in the future as new biomarkers and therapeutic targets for the early detection and treatment of cancers. Here, we summarize the recent findings on how epigenetic modifications, including DNA methylation, histone modifications, and non-coding RNAs, regulate gastric carcinogenesis, and we discuss potential new strategies for the diagnosis and treatments of gastric cancer. The strategies may be helpful in the further understanding of epigenetic regulation in human diseases.

Interaction between Wnt/β-catenin pathway and microRNAs regulates epithelial-mesenchymal transition in gastric cancer (Review)

Gastric cancer (GC) is the third primary cause of cancer-related mortality and one of the most common type of malignant diseases worldwide. Despite remarkable progress in multimodality therapy, advanced GC with high aggressiveness always ends in treatment failure. Epithelial-mesenchymal transition (EMT) has been widely recognized to be a key process associating with GC evolution, during which cancer cells go through phenotypic variations and acquire the capability of migration and invasion. Wnt/β-catenin pathway has established itself as an EMT regulative signaling due to its maintenance of epithelial integrity as well as tight adherens junctions while mutations of its components will lead to GC initiation and diffusion. The E-cadherin/β-catenin complex plays an important role in stabilizing β-catenin at cell membrane while disruption of this compound gives rise to nuclear translocation of β-catenin, which accounts for upregulation of EMT biomarkers and unfavorable prognosis. Additionally, several microRNAs positively or negatively modify EMT by reciprocally acting with certain target genes of Wnt/β-catenin pathway in GC. Thus, this review centers on the strong associations between Wnt/β-catenin pathway and microRNAs during alteration of EMT in GC, which may induce advantageous therapeutic strategies for human gastric cancer.

High expression of cAMP-responsive element-binding protein 1 (CREB1) is associated with metastasis, tumor stage and poor outcome in gastric cancer

cAMP responsive element binding protein 1 (CREB1) has been reported to be implicated in tumor development and progression of human cancers. However, the clinical significance and regulatory mechanisms of CREB1 expression in gastric cancer remain largely unknown. In the present study, immunohistochemistry was performed to detect the expression of CREB1 protein in 185 primary gastric cancer tissues, 50 secondary lymph node metastatic foci and 50 nontumorous gastric tissues. A prognostic model combining CREB1 expression with TNM tumor stage was constructed by logistic regression analysis. Regulation of CREB1 by miRNAs was investigated by luciferase reporter assay and Western blot. It was shown that CREB1 was highly expressed and correlated with lymph node metastasis, distant metastasis and tumor stage and poor outcome in gastric cancer. The prognostic model was proven to be an independent prognosis predictor and performed better than CREB1 or tumor stage alone. CREB1 was identified as a direct target of miR-27b and miR-200b, and down-regulated by miR-27b/miR-200b. We conclude that CREB1 is a promising biomarker to predict tumor metastasis and patient outcome in gastric cancer, and the miR-27b/miR-200b-CREB1 pathway may serve as a potential molecular target for the treatment of gastric cancer.

C/EBPα-induced miR-100 expression suppresses tumor metastasis and growth by targeting ZBTB7A in gastric cancer

MicroRNAs have been reported to play key roles in various human cancers, including gastric cancer. However, understanding of the expression of miR-100 and its regulatory mechanisms in human gastric cancer remains elusive. In this study, we reveal that miR-100 is downregulated in gastric cancer samples and gastric cancer cell lines. Furthermore, lower miR-100 expression was found in primary gastric cancer samples with lymphatic metastasis compared to those without lymphatic metastasis. Overexpression of miR-100 suppressed tumor growth in vivo and inhibited gastric cancer invasion and metastasis in vitro and in vivo. Furthermore, we demonstrated that miR-100 reduced gastric cancer aggressiveness by directly targeting ZBTB7A. Knockdown of ZBTB7A by siRNA disrupted gastric cancer progression by impairing tumor invasion and metastasis. High expression of ZBTB7A was significantly correlated with poorer prognosis in gastric cancer patients. Our results also showed that the transcription factor CCAAT/enhancer-binding protein alpha (C/EBPα) could induce the expression of miR-100 by binding to the putative promoter region of miR-100. This study demonstrated that miR-100 could be induced by C/EBPα and may act as a tumor suppressor gene by inhibiting ZBTB7A.