Inhibited Gastric Cancer Cell Migration Research Articles

Pepsinogen C Interacts with IQGAP1 to Inhibit the Metastasis of Gastric Cancer Cells by Suppressing Rho-GTPase Pathway.

This study systematically explored the biological effects and mechanisms of PGC on gastric cancer (GC) cells in vitro and in vivo. The critical biological roles of PGC in GC were assessed via EdU staining, Hoechst staining, flow cytometry, mouse models, CCK-8, wound healing, transwell, and sphere-forming assays. The interaction study with IQ-domain GTPase-activating protein 1 (IQGAP1) was used by Liquid chromatography-mass spectrometry co-immunoprecipitation, immunofluorescence staining, CHX-chase assay, MG132 assay, and qRT-PCR. PGC inhibited the proliferation, viability, epithelial-mesenchymal transition, migration, invasion, and stemness of GC cells and promoted GC cell differentiation. PGC suppressed subcutaneous tumor growth and peritoneal dissemination in vivo. The interaction study found PGC inhibits GC cell migration and invasion by downregulating IQGAP1 protein and IQGAP1-mediated Rho-GTPase signaling suppression. In addition, PGC disrupts the stability of the IQGAP1 protein, promoting its degradation and significantly shortening its half-life. Moreover, the expression levels of PGC and IQGAP1 in GC tissues were significantly negatively correlated. PGC may act as a tumor suppressor in the development and metastasis of GC. PGC can downregulate its interacting protein IQGAP1 and inhibit the Rho-GTPase pathway, thereby participating in the inhibition of GC cell migration and invasion.

RNA Binding Protein PTBP1 Promotes the Metastasis of Gastric Cancer by Stabilizing PGK1 mRNA.

Gastric cancer (GC) is the most common type of malignant tumor within the gastrointestinal tract, and GC metastasis is associated with poor prognosis. Polypyrimidine tract binding protein 1 (PTBP1) is an RNA-binding protein implicated in various types of tumor development and metastasis. However, the role of PTBP1 in GC metastasis remains elusive. In this study, we verified that PTBP1 was upregulated in GC tissues and cell lines, and higher PTBP1 level was associated with poorer prognosis. It was shown that PTBP1 knockdown in vitro inhibited GC cell migration, whereas PTBP1 overexpression promoted the migration of GC cells. In vivo, the knockdown of PTBP1 notably reduced both the size and occurrence of metastatic nodules in a nude mice liver metastasis model. We identified phosphoglycerate kinase 1 (PGK1) as a downstream target of PTBP1 and found that PTBP1 increased the stability of PGK1 by directly binding to its mRNA. Furthermore, the PGK1/SNAIL axis could be required for PTBP1's function in the promotion of GC cell migration. These discoveries suggest that PTBP1 could be a promising therapeutic target for GC.

Over-Expression of ARID3B Suppresses Tumor Progression and Predicts Better Prognosis in Patients With Gastric Cancer.

ARID3B (AT-rich interaction domain 3B) has been demonstrated to be associated with the progression and patient prognosis of several human tumors. We conducted the present study to investigate the biological behavior and clinical relevance of ARID3B in gastric cancer (GC). Detection of the expression level in GC tissues and cell lines were performed by Western blot and immunohistochemistry. We also retrospectively analyzed the correlation of ARID3B with clinicopathological characteristics and patient prognosis in gastric cancer. The biological functions of ARID3B in GC cells were further explored by transwell migration assays, wound healing assays and cell proliferation assay. The present study suggested that the expression of ARID3B was significantly lower in GC tissues than in adjacent normal tissues. IHC staining in tissues of 406 GC patients from training and validation sets verified that ARID3B over-expression correlated with clinicopathological features, such as degree of differentiation and clinical stage. Meanwhile, ARID3B was proved to be an independent prognostic factor for GC prognosis. Furthermore, over-expression of ARID3B suppressed proliferation in GC cells according CCK8 assay. We found that over-expression of ARID3B inhibited GC cell migration by transwell assay and wound healing assay. Furthermore, EMT markers were detected in ARID3B over-expression GC cells, which showed that ARID3B may inhibit metastasis of GC cells. Our results firstly revealed that the expression level of ARID3B was closely correlated with clinicopathological features and may serve as an independent prognostic factor for GC patients. More importantly, ARID3B could suppress GC progression, including cell proliferation, migration and metastasis.

Exosomal hsa_circ_0017252 attenuates the development of gastric cancer via inhibiting macrophage M2 polarization.

Gastric cancer (GC) is an aggressive malignant tumor of the digestive system, with high morbidity rates. We previously demonstrated that miR-17-5p can modify tumorigenesis in GC. In addition, other studies have shown that circRNAs can regulate GC progression by sponging various miRNAs. However, the association between circRNAs and miR-17-5p in GC has not yet been explored. Hence, this study aimed to explore the possible interactions between various circRNAs and miR-17-5p using a dual-luciferase assay. CCK-8 was used to determine cell viability, and a Transwell assay was used to measure cell invasion and migration. Gene expression was assessed using quantitative reverse transcription PCR (RT-qPCR), and exosomes were identified using transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA). Annexin V/PI staining was also used to detect cell apoptosis. These investigations collectively revealed that miR-17-5p is a target of the circRNA hsa_circ_0017252 and hsa_circ_0017252 is significantly downregulated in GC tissues. In addition, the overexpression of hsa_circ_0017252 inhibited GC cell migration by sponging of miR-17-5p, and GC cell-secreted exosomal hsa_circ_0017252 effectively inhibited macrophage M2-like polarization, which in turn suppressed GC cell invasion. Notably, exosomes containing hsa_circ_0017252 also suppressed GC tumor growth in vivo. Thus, our data suggest that the overexpression of hsa_circ_0017252 suppresses GC malignancy by sponging miR-17-5p. In addition, exosomal hsa_circ_0017252 excreted from GC cells attenuated GC progression by suppressing macrophage M2-like polarization. These findings improve our basic understanding of GC and open a novel avenue for developing more effective GC treatments.

MiR-548d-3p inhibits the invasion and migration of gastric cancer cells by targeting GKN1.

BackgroundThe aim of this study was to explore the function and mechanism of GKN1 in gastric cancer (GC) progression.MethodsFirstly, we used GEO2R to perform differential gene analysis on GSE26942 and GSE79973 and constructed the protein–protein interaction network of differential genes by STRING. Next, the cytoHubba, Mcode plugins, and GEPIA were used to obtain our follow‐up research object GKN1. Then, the function of GKN1 in GC was verified by scratch and transwell assay in GC cells. We further analyzed the genes related to GKN1 through LinkedOmics, and exported top 100 genes positively or negatively correlated with GKN1. Meanwhile, Metascape was performed on these genes. Finally, we analyzed the miRNAs that bind to GKN1 through the miRDB and verified the correlation between miR‐548d‐3p and GKN1 using dual‐fluorescence and quantitative PCR experiments.ResultsBioinformatics analysis showed that there were 52 differential genes on GSE26942 and GSE79973. In addition, the results of functional assays indicated that overexpressed GKN1 can inhibit GC cell migration and invasion, while GKN1 knockdown demonstrated the opposite effect. Additionally, Metascape analysis results showed that the 3′‐UTR region of mRNA is rich in AU sequences, based on which we infer that mRNA may be regulated by miRNA. Dual‐fluorescence and quantitative PCR assays clarified that miR‐548d‐3p may be one of the target miRNAs of GKN1, which was up‐regulated in GC tissues.ConclusionsIn summary, we clarified that miR‐548d‐3p regulates GKN1 to participate in GC cell migration and invasion, and provides a possible target for the prognostic diagnosis and treatment of GC.

MiR-29c inhibits metastasis of gastric cancer cells by targeting VEGFA.

Background: Gastric cancer (GC) is characterized by tissue invasion and metastasis, which lead to an aggressive and highly lethal disease. However, the underlying molecular mechanism remains largely unclear. Although multiple miRNAs are known to regulate crucial cellular events during cancer metastasis, their individual roles are still not fully described. Methods: miR-29c overexpressed cell lines were constructed. The wound healing, migration and invasion assays were performed to investigate the effect of miR-29c on metastasis of GC. HUVECs proliferation and tube formation assays were used to test the ability of angiogenesis of miR-29c. The target gene VEGFA was predicted by bioinformatic algorithms and validated by luciferase activity assay. Peritoneal spreading and pulmonary metastasis mice models were applied in vivo. Results: In the current study, we report the results that introduction of exogenous miR-29c inhibits GC cell migration, invasion and angiogenesis. Epithelial-mesenchymal transition (EMT) and cancer stem cells (CSCs) properties are participated in the miR-29c mediated cell metastasis. Furthermore, by performing tumor metastasis PCR array and luciferase reporter assay, we find that the expression of VEGFA is regulated by miR-29c through direct targeting of its 3'-UTR. In addition, we show that the VEGFA/VEGFR2/ERK pathway is involved in this process. Conclusion: These data taken together reveal the crucial functions of miR-29c-VEGFA/VEGFR2/ERK signaling axis in the metastasis progression of GC via regulating EMT and CSCs properties, which make them potential targets for clinical intervention in GC.

SMicroRNA-28-5p acts as a metastasis suppressor in gastric cancer by targeting Nrf2

The transcription factor nuclear factor (erythroid-2)-related factor 2 (Nrf2) can principally serve a mode of protection for both the normal cells and cancer cells from cellular stress, and elevates cancer cell survival. microRNA-28 (miR-28) has been involved in the regulation of Nrf2 expression in breast epithelial cells. However, no comprehensive analysis has been conducted regarding the function of miR-28-5p regulating Nrf2 in gastric cancer (GC). In this study, we aimed to evaluate their interaction and biological roles in the migration and invasion of GC cells. The expression of Nrf2 in the cancer tissues harvested from 42 patients with GC was examined by an array of molecular techniques comprising of Immunohistochemical staining, RT-qPCR and Western blot analysis. Kaplan-Meier method was adopted for analysis of the correlation of Nrf2 with the prognosis of GC patients. Interaction between miR-28-5p and Nrf2 was determined using the bioinformatics analysis and dual luciferase reporter gene assay. Gain- and loss-of-function studies of miR-28-5p and Nrf2 were conducted to elucidate their effects on GC cell migration, invasion and metastasis, as well as expression pattern of several epithelial-mesenchymal transition (EMT)-related proteins. Results indicated that the expression pattern of Nrf2 was significantly upregulated in GC tissues and indicative of poor prognosis of GC patients. miR-28-5p was verified to target Nrf2 and downregulate its expression. GC cells with overexpression of miR-28-5p or Nrf2 knockdown exhibited a marked reduction in the migrated and invasive abilities, along with the N-cadherin expression yet an increase of E-cadherin expression. Furthermore, miR-28-5p exerted an inhibitory function on the metastatic and tumorigenicity of GC cells. In conclusion, miR-28-5p is a comprehensive tumor suppressor that inhibits GC cell migration and invasion through repressing the Nrf2 expression. Therefore, miR-28-5p may serve as a potential biomarker for the prognosis of GC and a novel therapeutic target in advanced GC.

Junctional Adhesion Molecule-Like Protein Promotes Tumor Progression and Metastasis via p38 Signaling Pathway in Gastric Cancer.

Junctional adhesion molecule-like protein (JAML), a newly discovered junctional adhesion molecule (JAM), mediates the adhesion and migration processes of various immune cells and endothelial/epithelial cells, ultimately regulating inflammation reaction. However, its role in tumors remains to be determined. The expression of JAML was examined in gastric cancer (GC) and peritumoral tissues from 63 patients. The relationship between JAML expression and clinical characteristics was also observed. In vitro, GC cell migration and proliferation were assessed by wound healing assay, transwell migration assay and EdU incorporation assay. Immunohistochemical staining results showed that JAML expression level was higher in GC tissues than in peritumoral tissues. High expression of JAML in cancer tissues was associated with worse cell differentiation, local lymph node involvement, deep infiltration, and advanced stage. In vitro, we found that JAML silencing inhibited GC cell migration and proliferation, while JAML overexpression promoted GC cell migration and proliferation, partially via p38 signaling. Taken together, our study revealed a critical role for JAML to promote GC cell migration and proliferation. JAML might be a novel diagnostic biomarker and therapeutic target for GC.

Tumor suppressor lnc-CTSLP4 inhibits EMT and metastasis of gastric cancer by attenuating HNRNPAB-dependent Snail transcription

Tumor metastasis is a crucial impediment to the treatment of gastric cancer (GC), and the epithelial-to-mesenchymal transition (EMT) program plays a critical role for the initiation of GC metastasis. Thus, the aim of this study is to investigate the regulation of lnc-CTSLP4 in the EMT process during GC progression. We found that lnc-CTSLP4 was significantly downregulated in GC tumor tissues compared with adjacent non-tumor tissues, and its levels in GC tumor tissues were closely correlated with tumor local invasion, TNM stage, lymph node metastasis, and prognosis of GC patients. Loss- and gain-of-function assays indicated that lnc-CTSLP4 inhibited GC cell migration, invasion, and EMT in vitro, as well as peritoneal dissemination in vivo. Mechanistic analysis demonstrated that lnc-CTSLP4 could bind with Hsp90α/heterogeneous nuclear ribonucleoprotein AB (HNRNPAB) complex and recruit E3-ubiquitin ligase ZFP91 to induce the degradation of HNRNPAB, thus suppressing the transcriptional activation of Snail and ultimately reversing EMT of GC cells. Taken together, our results suggest that lnc-CTSLP4 is significantly downregulated in GC tumor tissues and inhibits metastatic potential of GC cells by attenuating HNRNPAB-dependent Snail transcription via interacting with Hsp90α and recruiting E3 ubiquitin ligase ZFP91, which shows that lnc-CTSLP4 could serve as a prognostic biomarker and therapeutic target for metastatic GC.

Elevated microRNA-7 inhibits proliferation and tumor angiogenesis and promotes apoptosis of gastric cancer cells via repression of Raf-1

ABSTRACT Objective Since the essential involvement of microRNAs (miRNAs) in the development and progression of GC, the study was for the exploration of the value of microRNA-7 (miR-7) in the evaluation of neoadjuvant chemotherapy for gastric cancer (GC) and its effects on apoptosis, proliferation and angiogenesis of GC. Methods miR-7 expression in serum of GC patients before and after neoadjuvant chemotherapy were detected to explore its role in neoadjuvant chemotherapy of GC. The GC cells were transfected with miR-7 mimics/inhibitors, or siRNA-Raf-1 to figure out their roles in proliferation, migration, invasion, cycle distribution and apoptosis. Tumor xenograft was conducted to test tumor growth. Microvessel density (MVD) in tumors was tested by immunohistochemical staining. Results miR-7 expression in serum of GC patients was lower than that of healthy controls while it was elevated after neoadjuvant chemotherapy. Moreover, higher miR-7 expression was exhibited in chemotherapy-effective patients rather than chemotherapy-ineffective patients (P < 0.01). miR-7 expression in serum was connected with tumor size, degree of differentiation, TNM stage and lymphatic metastasis.miR-7 was decreased and Raf-1 was elevated in GC cells (both P < 0.05). Elevated miR-7 or declined Raf-1 inhibited GC cell migration, proliferation and invasion, cell cycle entry, xenografted tumor growth and MVD and stimulated apoptosis (all P < 0.05). Down-regulated Raf-1 reversed the impacts of miR-7 knockdown on GC cells (all P < 0.05). Conclusion Our study highlights that elevated miR-27a indicates the good efficacy of neoadjuvant chemotherapy in GC and miR-7 targets Raf-1 to suppress tumor development and angiogenesis of GC cells.

RETRACTED ARTICLE: The POU2F1/miR-4490/USP22 axis regulates cell proliferation and metastasis in gastric cancer

PurposeGrowing evidence indicates that aberrant expression of microRNAs contributes to tumor development. However, the biological role of microRNA-4490 (miR-4490) in gastric cancer (GC) remains to be clarified.MethodsTo explore the function of miR-4490 in GC, we performed colony formation, EdU incorporation, qRT-PCR, Western blotting, in situ hybridization (ISH), immunohistochemistry (IHC), flow cytometry, ChIP and dual-luciferase reporter assays. In addition, the growth, migration and invasion capacities of GC cells were evaluated.ResultsWe found that miR-4490 was significantly downregulated in primary GC samples and in GC-derived cell lines compared with normal controls, and that this expression level was negatively correlated with GC malignancy. Exogenous miR-4490 expression not only reduced cell cycle progression and proliferation, but also significantly inhibited GC cell migration, invasion and epithelial-mesenchymal transition (EMT) in vitro. Mechanistically, we found that miR-4490 directly targets USP22, which mediates inhibition of GC cell proliferation and EMT-induced metastasis in vitro and in vivo. Moreover, we found through luciferase and ChIP assays that transcription factor POU2F1 can directly bind to POU2F1 binding sites within the miR-4490 and USP22 promoters and, by doing so, modulate their transcription. Spearman’s correlation analysis revealed a positive correlation between USP22 and POU2F1 expression and negative correlations between miR-4490 and USP22 as well as miR-4490 and POU2F1 expression in primary GC tissues.ConclusionBased on our results we conclude that miR-4490 acts as a tumor suppressor, and that the POU2F1/miR-4490/USP22 axis plays an important role in the regulation of growth, invasion and EMT of GC cells.

LncRNA PVT1 promotes the migration of gastric cancer by functioning as ceRNA of miR-30a and regulating Snail.

Although the incidence and mortality of gastric cancer (GC) are slowly decreasing, the overall prognosis of GC patients with distal metastasis remains dismal. Long non-coding RNA PVT1 has been verified to function as a tumor promoter in several types of cancer. However, the role of PVT1 in GC metastasis remains obscure. Herein, we found that PVT1 was highly expressed in GC tissues and high PVT1 level was associated with tumor stage, lymph node metastasis, and poor prognosis. Overexpression of PVT1 significantly elevated epithelial-to-mesenchymal transition (EMT) marker (N-cadherin, ZEB1, and ZEB2) levels and promoted GC cell EMT process and tumor metastasis in vitro and in vivo. Mechanistically, Snail was identified as a direct target of miR-30a. PVT1 could bind with miR-30a and increase the expression of Snail by acting as a competing endogenous RNA, whereas re-expression of miR-30a in GC cells rescued the EMT markers, decreased Snail level, and inhibited GC cell migration. Taken together, these findings provide a new light on PVT1 in the pathogenesis and development of GC and an important implication for future therapy of the GC.

Upregulation of BCAM and its sense lncRNA BAN are associated with gastric cancer metastasis and poor prognosis.

Patients with metastatic gastric cancer (GC) have a poor prognosis; however, the molecular mechanism of GC metastasis remains unclear. Here, we employed bioinformatics to systematically screen the metastasis‐associated genes and found that the levels of basal cell adhesion molecule (BCAM) were significantly increased in GC tissues from patients with metastasis, as compared to those without metastasis. The upregulation of BCAM was also significantly associated with a shorter survival time. Depletion of BCAM inhibited GC cell migration and invasion. Knockout (KO) of BCAM by the CRISPR/Cas9 system reduced the invasion and metastasis of GC cells. To explore the mechanism of BCAM upregulation, we identified a previously uncharacterized BCAM sense lncRNA that spanned from exon 6 to intron 6 of BCAM, and named it as BCAM‐associated long noncoding RNA (BAN). Knockdown of BAN inhibited BCAM expression at both mRNA and protein levels. Knockdown of BAN suppressed GC cell migration and invasion, which was effectively rescued by ectopic expression of BCAM. Further clinical data showed that BAN upregulation was associated with GC metastasis and poor prognosis. Importantly, BAN expression was also significantly associated with that of BCAM in GC tissues. Taken together, these results indicate that increased expression of BCAM and its sense lncRNA BAN promote GC cell invasion and metastasis, and are associated with poor prognosis of GC patients.

Upregulation of circular SMAD7 inhibits tumorigenesis of gastric cancer by reversing epithelial-to-mesenchymal transition.

Gastric cancer (GC) is one of the most ordinary malignant tumors. Recent studies have revealed that circular RNAs (circRNAs) play an important role in the progression of tumorigenesis. In this research, circ-SMAD7 was selected to identify how it functions in the progression of GC. Circ-SMAD7 expression in paired GC patients' tissue samples and cell lines was detected by Real Time-quantitative Polymerase Chain Reaction (RT-qPCR). The role of circ-SMAD7 in the metastasis of GC was detected through wound healing assay and transwell assay. Western blot assay and RT-qPCR were used to discover the function of circ-SMAD7 in epithelial-to-mesenchymal transition (EMT) process. Furthermore, tumor metastasis assay was also performed in vivo. In this study, RT-qPCR results showed that circ-SMAD7 expression was significantly lower in GC tissues compared to that in adjacent ones. Cell migration and invasion of GC were inhibited via upregulation of circ-SMAD7. Moreover, the results of further experiments revealed that the EMT-related proteins were regulated via upregulation of circ-SMAD7 in GC. Furthermore, tumor metastasis of GC was inhibited via upregulation of circ-SMAD7 in nude mice. These results indicate that upregulation of circ-SMAD7 inhibits GC cell migration and invasion via reversing the EMT process.

The POU2F1/miR-4490/USP22 Axis Regulates Cell Proliferation and Metastasis in Gastric Cancer

Background: Gastric cancer (GC) remains the fourth most common cancer and the miRNAs can function as tumor suppressors or oncogenes.The biological role of miR-4490 has not yet been reported in the context of cancer. Methods: To explore the function of miR-4490, we performed colony formation assays, EdU incorporation assays, qRT-PCR, Western blotting, In situ hybridization (ISH), immunohistochemistry (IHC), flow-cytometry assays, ChIP and dual-luciferase reporter assays. The growth, migration, and invasive capacity of GC cells were evaluated. Findings: microRNA-4490 (miR-4490) was significantly downregulated in GC tumor samples and cell lines compared with that in normal controls and that its expression level was negatively correlated with the aggressiveness of GC. Ectopic miR-4490 expression not only reduced cell-cycle transition and proliferation but also significantly inhibited GC cell migration, invasion, and epithelial-mesenchymal transition (EMT) in vitro. Mechanistically, we confirmed that miR-4490 directly targeted USP22, which mediates the inhibition of proliferation and EMT-induced metastasis in vitro and in vivo. Moreover, we determined through luciferase and ChIP assays that the transcription factor POU2F1 directly bound to potential POU2F1 binding sites in the miR-4490 promoters and modulated their transcription. Spearman's correlation analysis showed a positive correlation between USP22 and POU2F1 and negative correlations between miR-4490 and USP22 as well as between miR-4490 and POU2F1 expression in GC tissues. Interpretation: Our findings suggest that POU2F1/miR-4490/USP22 axis plays an important role in the development and progression of human GC. Funding: National Natural Science Funds of China (Nos.81672875 and 81772964). Declaration of Interest: The authors declare that they have no competing interests. Ethical Approval: This study was reviewed and approved by the Medical Ethics Committee of Nanfang Hosital (NFEC-2017-062), Southern Medical University, Guangzhou, China. All animal studies were approved by the Institutional Animal Care and Use Committee of Committee of Nanfang Hosital.

Long non-coding RNA LINC01314 represses cell migration, invasion, and angiogenesis in gastric cancer via the Wnt/\u03b2-catenin signaling pathway by down-regulating KLK4

BackgroundIn recent years, gastric cancer (GC) has become a major cause of mortality among various malignancies worldwide with high incidence rates. Long non-coding RNA (lncRNAs) may serve as oncogenes and tumor suppressors in cancers. Therefore, we investigated the effect of LINC01314 on the development of GC cells in relation to the Wnt/β-catenin signaling pathway.MethodsMicroarray data analysis was conducted to screen GC-related differentially expressed lncRNAs, followed by determination of the binding interaction between LINC01314 and kallikrein 4 (KLK4). Human GC cell line SGC-7901 was treated with over-expressed or silenced LINC01314 or KLK4 to investigate the mechanism LINC01314 affecting GC cellular activities. The levels of KLK4, Wnt-1, β-catenin, cyclin D1, N-cadherin and E-cadherin were measured, and cell invasion and migration were evaluated. Next, the tumor weight, micro-vessel density (MVD) and the expression of VEGF-C and VEGFR-3 in transplanted tumors were measured.ResultsLINC01314 was poorly expressed in GC cells and KLK4 was revealed to be a direct target gene of LINC01314. Overexpressed LINC01314 or silencing of KLK4 led to inhibited GC cell migration and invasion, corresponding to decreased Wnt-1, β-catenin, cyclin D1 and N-cadherin while increased E-cadherin. Also, in response to over-expression of LINC01314 or silencing of KLK4, tumor weight and the MVD of transplanted tumors were reduced and angiogenesis was suppressed, which was indicated by down-regulated positive expression of VEGF-C and VEGFR-3.ConclusionThe findings indicated that over-expression of LINC01314 down-regulated KLK4 to inhibit the activation of the Wnt/β-catenin signaling pathway, thus suppressing migration, invasion, and angiogenesis in GC cells, which provides new insight for the treatment of GC.

Downregulation of Long Non-coding RNA FALEC Inhibits Gastric Cancer Cell Migration and Invasion Through Impairing ECM1 Expression by Exerting Its Enhancer-Like Function.

Long non-coding RNAs (lncRNAs) have been shown to play important roles in many human diseases. However, their functions and mechanisms in tumorigenesis and development remain largely unknown. Here, we demonstrated that focally amplified lncRNA in epithelial cancer (FALEC) was upregulated and significantly correlated with lymph node metastasis, TNM stage in gastric cancer (GC). Further experiments revealed that FALEC knockdown significantly inhibited GC cells migration and invasion in vitro. Mechanistic investigations demonstrated that small interfering RNA-induced silencing of FALEC decreased expression of the nearby gene extracellular matrix protein 1 (ECM1) in cis. Additionally, ECM1 and FALEC expression were positively correlated, and high levels of ECM1 predicted shorter survival time in GC patients. Our results suggest that the downregulation of FALEC significantly inhibited the migration and invasion of GC cells through impairing ECM1 expression by exerting an enhancer-like function. Our work provides valuable information and a novel promising target for developing new therapeutic strategies in GC.

Reduced USP33 expression in gastric cancer decreases inhibitory effects of Slit2-Robo1 signalling on cell migration and EMT.

ObjectivesGastric cancer (GC) is one of the most common cancers in the world, causing a large number of deaths every year. The Slit‐Robo signalling pathway, initially discovered for its critical role in neuronal guidance, has recently been shown to modulate tumour invasion and metastasis in several human cancers. However, the role of Slit‐Robo signalling and the molecular mechanisms underlying its role in the pathogenesis of gastric cancer remains to be elucidated.Materials and methodsSlit2, Robo1 and USP33 expressions were analysed in datasets obtained from the Oncomine database and measured in human gastric cancer specimens. The function of Slit2‐Robo1‐USP33 signalling on gastric cancer cells migration and epithelial‐mesenchymal transition (EMT) was studied both in vitro and in vivo. The mechanism of the interaction between Robo1 and USP33 was explored by co‐IP and ubiquitination protein analysis.ResultsThe mRNA and protein levels of Slit2 and Robo1 are lower in GC tissues relative to those in adjacent healthy tissues. Importantly, Slit2 inhibits GC cell migration and suppresses EMT process in a Robo‐dependent manner. The inhibitory function of Slit2‐Robo1 is mediated by ubiquitin‐specific protease 33 (USP33) via deubiquitinating and stabilizing Robo1. USP33 expression is decreased in GC tissues, and reduced USP33 level is correlated with poor patient survival.ConclusionsOur study reveals the inhibitory function of Slit‐Robo signalling in GC and uncovers a role of USP33 in suppressing cancer cell migration and EMT by enhancing Slit2‐Robo1 signalling. USP33 represents a feasible choice as a prognostic biomarker for GC.

Transcriptional activation of ANO1 promotes gastric cancer progression

The prognosis of gastric cancer (GC) remains poor due to local invasion and distal metastasis. The GC-related molecular mechanisms underlying invasion and metastasis are not well understood. In this study, we investigated the functional role of ANO1 in GC progression. We found that ANO1 is overexpressed in GC tissues and correlated with GC tumor-node-metastasis stage. Knockdown of ANO1 significantly inhibited GC cell migration and invasion in vitro, and loss of ANO1 resulted in inhibition of tumor metastasis in vivo. Mechanistically, SP1 increased ANO1 transcription, recruited MLL1 to the ANO1 promoter region, facilitated H3K4 trimethylation, and subsequently promoted ANO1 expression. Together, our findings provide a mechanistic assessment of ANO1 overexpression, which represents a GC progression-related molecule and a potentially valuable target for future research.

TES functions as a Mena-dependent tumor suppressor in gastric cancer carcinogenesis and metastasis

BackgroundIn our previous study, we identified a candidate tumor suppressor gene, testin LIM domain protein (TES), in primary gastric cancer (GC). TES contains three LIM domains, which are specific interacting regions for the cell adhesion and cytoskeleton regulatory proteins. Mena is a known cytoskeleton regulator that regulates the assembly of actin filaments and modulates cell adhesion and motility by interacting with Lamellipodin (Lpd). Therefore, we hypothesized that TES plays a role as tumor suppressor in GC through interacting with Mena. This study aimed to investigate the tumor suppressive functions of TES in GC.MethodsWe explored the tumor suppressive effect of TES in GC by in vitro cell proliferation assay, colony formation assay, cell cycle analysis, Transwell assays, and in vivo tumorigenicity and metastasis assays. The interaction of TES and Mena was investigated through immunoprecipitation-based mass spectrometry. We also analyzed the expression of TES and Mena in 172 GC specimens using immunohistochemistry and investigated the clinicopathological and prognostic significance of TES and Mena in GC.ResultsTES suppressed GC cell proliferation and colony formation, induced cell cycle arrest, and inhibited tumorigenicity in vitro. Additionally, it inhibited GC cell migration and invasion in vitro and suppressed metastasis in vivo. TES interacted with Mena, and inhibited the interaction of Mena with Lpd. Transwell assays suggested that TES suppressed migration and invasion of GC cells in a Mena-dependent fashion. In GC patients with high Mena expression, the expression of TES was associated with tumor infiltration (P = 0.005), lymph node metastasis (P = 0.003), TNM stage (P = 0.003), and prognosis (P = 0.010). However, no significant association was observed in GC patients with low Mena expression.ConclusionsWe believe that TES functions as a Mena-dependent tumor suppressor. TES represents a valuable prognostic marker and potential target for GC treatment.