Epithelial-mesenchymal Transition In Gastric Cancer Research Articles

The effect of Jianpi Yangzheng Xiaozheng Decoction and its components on gastric cancer

Ethnopharmacological relevanceJianpi Yangzheng Xiaozheng Decoction (JPYZXZ) is an empirical compound prescription based on the theory of traditional Chinese medicine. JPYZXZ, which is “Qi-invigorating, spleen-strengthening and stasis-removing,” can improve the quality of life of gastric cancer patients and prolong their survival; however, the exact mechanism underlying the antitumor effects of this compound is still not clear. Aim of the studyThe aim of this study is to clearly define the effect of JPYZXZ and its components, Jianpi Yangzheng Decoction (JPYZ) and Xiao Zheng San Jie Decoction (XZSJ), on inhibiting the progression of gastric cancer. Materials and methodsThe effect of JPYZXZ and its components on the motility of gastric cancer MGC-803 cells was measured by MTT, adhesion, transwell assays and wound-healing assays. JPYZXZ, JPYZ and XZSJ were administered to 615 mice with gastric cancer xenografts, and their effect on the inhibition of subcutaneous transplantation was analyzed. THP-1 monocyte cells were used to establish tumor-associated macrophage (TAM) models. The polarized state of the TAMs was detected by Flow Cytometry, ELISA and Immunohistochemistry. The mRNA and protein expression of tumor epithelial-mesenchymal transition (EMT) and TAM-related genes was determined by Real-time PCR and Western Blot, respectively. ResultsWe determined that both JPYZXZ and its components inhibited the progress of gastric cancer in vitro, and JPYZXZ was clearly more effective than JPYZ or XZSJ. The in vivo results demonstrated that the JPYZXZ and XZSJ group exhibited a significant decrease in the tumor weight compared to the control group. Further analysis indicated that JPYZXZ was more active than JPYZ or XZSJ in inhibiting the gastric cancer EMT transformation both in vivo and in vitro. However, JPYZ was more effective compared with JPYZXZ for inducing the phenotypic change in macrophages from M2 to M1. ConclusionsOur results demonstrate that both JPYZXZ and its components prevent the progress of gastric cancer. JPYZXZ inhibits the gastric cancer EMT more effectively than JPYZ and XZSJ, but JPYZ primarily works to regulate the phenotypic change in macrophages from M2 to M1.

Circular RNA CircCACTIN Promotes Gastric Cancer Progression by Sponging MiR-331-3p and Regulating TGFBR1 Expression

Background: Circular RNAs (circRNAs) are a new class of RNAs that play a significant role in regulating gene expression and biological function. However, the expression profile and function of circRNAs in gastric cancer (GC) remain mostly uncertain. In the present study, we researched the expression profile of circRNAs in human GC tissues and explored the role of circCACTIN (hsa_circ_0092303).Methods: Circular RNA microarray assays were performed to detect circular RNA expression profiles of GC and circCACTIN was identified for further investigation. Quantitative real-time PCR was used to detect the expression of circCACTIN, miR-331-3p and TGFBR1 in GC specimens and cell lines. CircCACTIN was stably silenced and overexpressed in GC cells, and cell proliferation, migration, invasion, epithelial-mesenchymal transition (EMT), as well as tumorigenesis in nude mice were performed to assess the effect of circCACTIN on GC.Results: CircCACTIN expression was obviously up-regulated in GC tissues and cell lines. Knockdown of circCACTIN inhibited GC cells proliferation, migration, invasion and EMT. Enforced-expression of circCACTIN promoted GC cells migration, invasion and EMT, but had no effect on GC cells proliferation. Moreover, in vivo experiments, circCACTIN up-regulation promoted GC tumor growth and EMT, and circCACTIN down-regulation inhibited GC tumor growth and EMT. Binding interactions were detected between circCACTIN and miR-331-3p, and between miR-331-3p and TGFBR1 by Dual-luciferase reporter assays. Mechanistically, we demonstrated that circCACTIN promoted gastric cancer progression by sponging miRNA-331-3p and regulating TGFBR1 mRNA expression.Conclusion: The circCACTIN/miR-331-3p/TGFBR1 axis affected the proliferation, migration, invasion and EMT of GC through the mechanism of competing endogenous RNAs (ceRNA). Furthermore, our results identified circCACTIN as a novel oncogenic circRNA in GC.

Phosphoglucose isomerase gene expression as a prognostic biomarker of gastric cancer.

ObjectiveTumor heterogeneity renders identification of suitable biomarkers of gastric cancer (GC) challenging. Here, we aimed to identify prognostic genes of GC using computational analysis.MethodsWe first used microarray technology to profile gene expression of GC and paired nontumor tissues from 198 patients. Based on these profiles and patients’ clinical information, we next identified prognostic genes using novel computational approaches. Phosphoglucose isomerase, also known as glucose-6-phosphate isomerase (GPI), which ranked first among 27 candidate genes, was further investigated by a new analytical tool namely enviro-geno-pheno-state (E-GPS) analysis. Suitability of GPI as a prognostic marker, and its relationship with physiological processes such as metabolism, epithelial-mesenchymal transition (EMT), as well as drug sensitivity were evaluated using both our own and independent public datasets. ResultsWe found that higher expression of GPI in GC correlated with prolonged survival of patients. Particularly, a combination of CDH2 and GPI expression effectively stratified the outcomes of patients with TNM stage II/III. Down-regulation of GPI in tumor tissues correlated well with depressed glucose metabolism and fatty acid synthesis, as well as enhanced fatty acid oxidation and creatine metabolism, indicating that GPI represents a suitable marker for increased probability of EMT in GC cells. ConclusionsOur findings strongly suggest that GPI acts as a novel biomarker candidate for GC prognosis, allowing greatly enhanced clinical management of GC patients. The potential metabolic rewiring correlated with GPI also provides new insights into studying the relationship between cancer metabolism and patient survival.

MiR-129-5p attenuates cell proliferation and epithelial mesenchymal transition via HMGB1 in gastric cancer

BackgroundThe miR-129-5p has been reported to be aberrant expression and exert vital roles in tumor progression of various malignancies. However, the effects on EMT in gastric cancer and its precise molecular mechanism in gastric cancer remain unclear. Methods and materialsRT-qPCR was performed to evaluate the expression level of miR-129-5p and HMGB1 in cell lines. Cell proliferation was detected via CCK-8. The epithelial mesenchymal transition (EMT) related proteins and the expression of HMGB1 were detected by western blot analysis. Luciferase assays were used to validate binding seeds between miR-129-5p and HMGB1. ResultsmiR-129-5p was downregulated in gastric cancer cells compared with GES-1. At the same time EMT was promoted in gastric cancer cells compared to GES-1. Overexpression of miR-129-5p inhibited EMT and proliferation. MiR-129-5p negatively and directly targeted HMGB1. HMGB1 was upregulated in gastric cancer cells and HMGB1 knocked-down inhibited EMT and cell proliferation. ConclusionTaken together, upregulation of miR-129-5p associated with gastric cancer proliferation and EMT, and serves as a potential diagnostic and therapeutic target via miR-129-5p/HMGB1 pathway in gastric cancer.

Circ_0009910 regulates growth and metastasis and is associated with poor prognosis in gastric cancer.

Circular RNAs (circRNAs) have recently shown capabilities as gene regulators in mammals. In this study, we aimed to evaluate the effects and mechanism of circ_0009910 in gastric cancer (GC). Circ_0009910 expression was quantified by Real-time PCR in human GC cell lines and tissues. Association between circ_0009910 levels and clinicopathological factors and patient's prognosis was analyzed. The roles of circ_0009910 in regulating GC cell proliferation, colony formation, migration, and invasion were evaluated in vitro. Western blot analysis was conducted to detect the expressions of molecular markers of epithelial-mesenchymal transition (EMT). Circ_0009910 expression level was elevated in GC tissues and cell lines and associated with clinical stage (p = 0.032), distant metastasis (p = 0.028) and differentiation (p = 0.007). Kaplan-Meier survival analysis indicated that circ_0009910 expression in positive group has a worse overall survival compared to the negative group (p = 0.0013). Multivariate analysis showed that circ_0009910 was an independent risk factor for GC (HR = 2.346, 95% CI: 1.673-3.775, p = 0.006). Knockdown of circ_0009910 expression can suppress BGC823 and AGS cells proliferation, migration and invasion in vitro experiments. The results of Western blot indicated that knockdown of circ_0009910 increased expression of E-cadherin and decreased expression of the mesenchymal markers, snail and N-cadherin. Altogether, we demonstrate that circ_0009910 acts as a prognostic biomarker and promote cell proliferation, migration, invasion and EMT in GC, indicating that circ_0009910 may be a novel potential biomarker and therapeutic target of GC.

Clinical significance of Stathmin1 expression and epithelial-mesenchymal transition in curatively resected gastric cancer.

In our previous study, it was demonstrated that the Stathmin1 (STMN1) is overexpressed in gastric cancer (GC) and that its high expression level is associated with tumor invasion and metastasis. Epithelial-mesenchymal transition (EMT) has also been shown to be critically involved in GC invasion and metastasis. Certain studies have indicated that STMN1 may serve an important role in the EMT process. However, the association between STMN1 expression and EMT-associated markers, as well as clinicopathological characteristics of patients with GC, remains unclear. The aim of the present study was to investigate the clinicopathological significance and prognostic value of STMN1 and EMT-associated markers in GC. The expression of STMN1 and the EMT-associated proteins E-cadherin (E-Cad) and vimentin (VIM) were analyzed by immunohistochemistry in GC and adjacent non-tumorous tissues. Associations between the expression of these markers and clinicopathological parameters were analyzed. The association between STMN1 expression and EMT-associated markers was investigated in the GC cell lines BGC-803 and SGC-7901. The results revealed that STMN1 was expressed in 63.5% of the 167 GC tissues, which was significantly higher than the percentage observed in the adjacent non-tumorous tissues (P=0.003). The STMN1 expression was demonstrated to be positively associated with the VIM levels (P=0.001) and negatively associated with the E-Cad levels (P=0.022) in GC tissues. The STMN1 expression was associated with Lauren's Classification, invasion depth, lymph node metastasis and pathological Tumor-Node-Metastasis (pTNM) stage (P<0.05). In the univariate analyses, the high E-Cad expression was a positive prognostic indicator for overall survival, whereas the high STMN1 and VIM expression was a negative indicator. COX multiple regression analysis demonstrated that the pTNM stage [hazard ratio (HR) 1.912, 95% confidence interval (CI): 1.282–2.851, P=0.001] and E-Cad expression (HR 0.403, 95% CI: 0.249–0.650, P=0.000) were independent prognostic factors. It was also revealed that the expression level of E-Cad decreased, while the expression level of VIM increased by depleting STMN1 levels in GC cells. The present results suggest that the aberrant expression of STMN1 may promote tumor progression through EMT in GC.

Transforming growth factor-β1 regulates epithelial-mesenchymal transition of gastric cancer by inducing Wnt signaling pathway

Objective To investigate the regulatory effect of transforming growth factor-β1 (TGF-β1) via Wnt signaling pathway in gastric cancer cells. Methods Via 5, 10, 20 ng/ml TGF-β1 recombinant protein inducing or TGF-β1 small interfering RNA (siRNA) recombinant plasmid gene silencing in gastric cancer cell MGC803, detect the expression of protein related to the occurrence and progression of gastric cancer by Western blotting. Results In gastric cancer cells, TGF-β1 can induce high expression of Wnt3a, β-catenin and Cyclin D1 , while their expression increase with increased TGF-β1 recombinant protein concentration (Wnt3a control group: 1.000±0.046; 5ng/ml group: 1.233±0.033, P=0.025; 10 ng/ml group: 2.233±0.122, P=0.001; 20 ng/ml group: 3.200±0.151, P=0.000. β-catenincontrol group: 1.000±0.035; 5 ng/ml group: 1.867±0.120, P=0.003; 10 ng/ml group: 2.200±0.153, P=0.002; 20 ng/ml group: 1.967±0.120, P=0.002. Cyclin D1control group: 1.000±0.029; 5 ng/ml group: 1.100±0.100, P=0.435; 10 ng/ml group: 3.167±0.176, P=0.000; 20 ng/ml group: 2.867±0.203, P=0.001). And silencing TGF-β1gene leads to low expression of Wnt3a, β-cateninand Cyclin D1 (Wnt3a control group: 1.000±0.040; siRNA group: 0.400±0.058, P=0.002. β-catenin NC: 1.000±0.046; siRNA group: 0.467±0.033, P=0.001. Cyclin D1 control group: 1.000±0.029; siRNA group: 0.333±0.088, P=0.003). Conclusion TGF-β1 plays a positive role in the Wnt3a/β-catenin signaling pathway in gastric cancer cells, and can regulate the epithelial-mesenchymal transition (EMT) process of gastric cancer cells by activating Wnt3a/β-catenin signaling pathway. Key words: Gastric cancer; Transforming growth factor-β1; Wnt signaling pathway

NFIB promotes cell growth, aggressiveness, metastasis and EMT of gastric cancer through the Akt/Stat3 signaling pathway.

Nuclear factorI/B (NFIB) plays a crucial role in the progression of several types of cancers. However, its role in gastric cancer (GC) remains unclear. The present study revealed that NFIB was highly expressed in GC tissues and was positively associated with the clinicopathological features of GC patients. Downregulation of NFIB inhibited the tumor growth, migration and aggression of MKN45 and HGC27 cells invitro. In addition, NFIB expression promoted epithelial‑mesenchymal transition (EMT), which was accompanied with decreased E‑cadherin and increased vimentin expression. Since AKT and Stat3 play an important role in EMT and tumor progression, we examined whether there is a correlation between NFIB and AKT/Stat3 signaling pathways in GC. Our results revealed that NFIB exhibits its oncogenic functions in GC development by regulating the phosphorylation of both AKT and Stat3 molecules. Knocking down the NFIB expression may enhance the phosphorylation of AKT while inhibiting the Stat3 phosphorylation, suggesting that the AKT/Stat3 signaling pathway may be the downstream target of NFIB with which it exerts its roles on GC development. These results revealed that NFIB promotes tumor growth and aggressiveness of GC. In addition, downregulation of NFIB alters the protein kinase B/signal transducers and activators of transcription 3 (AKT/Stat3) axis, which could be a potential molecular mechanism for precise target treatment of GC.

Aldolase A as a prognostic factor and mediator of progression via inducing epithelial-mesenchymal transition in gastric cancer.

Glycolysis is regarded as the hallmark of cancer development and progression, which involves a multistep enzymatic reaction. This study aimed to explore the clinicopathological significance and potential role of glycolytic enzyme aldolase A (ALDOA) in the carcinogenesis and progression of gastric cancer (GC). ALDOA was screened from three paired liver metastasis tissues and primary GC tissues and further explored with clinical samples and in vitro studies. The ALDOA protein level significantly correlated with a larger tumor diameter (P = .004), advanced T stage (P < .001), N stage (P < .001) and lymphovascular invasion (P = .001). Moreover, the expression of ALDOA was an independent prognostic factor for the 5‐year overall survival and disease‐free survival of patients with GC in both univariate and multivariate survival analyses (P < .05). Silencing the expression of ALDOA in GC cell lines significantly impaired cell growth, proliferation and invasion ability (P < .05). Knockdown of the expression of ALDOA reversed the epithelial–mesenchymal transition process. Mechanically, ALDOA could affect the hypoxia‐inducible factor (HIF)‐1α activity as demonstrated by the HIF‐1α response element–luciferase activity in GC cells. Collectively, this study revealed that ALDOA was a potential biomarker of GC prognosis and was important in the carcinogenesis and progression of human GC.

TRPC1/3/6 inhibition attenuates the TGF-β1-induced epithelial-mesenchymal transition in gastric cancer via the Ras/Raf1/ERK signaling pathway.

Gastric cancer (GC) is one of the most common malignancies worldwide. TGF-β1 induces the epithelial-mesenchymal transition (EMT) in GC, mainly through Smad-dependent pathways. Nevertheless, few studies have focused on the activation of non-canonical transduction pathways. TRPC, Ca2+ entry channels, are ubiquitously expressed in various cell types and are involved in many cellular functions. However, their roles in GC are not well elucidated. This study aimed to determine whether TRPC participates in the TGF-β1-induced EMT of GC and to investigate the potential mechanisms. Immunofluorescence staining was performed to examine the distribution and expression of TRPCs and EMT-related proteins in SGC-7901 cells incubated with or without TGF-β1. The expression of TRPC1/3/6 and EMT-related molecules, including E-cadherin, vimentin, and α-SMA, was detected by qRT-PCR and Western blotting. Additionally, the underlying mechanism was determined by treating cells with pharmacological inhibitors and examining the levels of proteins involved in the main signaling cascades using Western blotting. TRPC1/3/6 were expressed at high levels in SGC-7901 cells. Following TGF-β1 stimulation, the expression of vimentin, α-SMA, and TRPC1/3/6 increased and E-cadherin expression decreased, accompanied by activation of the Ras/Raf1/ERK1/2 signaling pathway. Notably, activation of the Ras/Raf1/ERK1/2 signaling cascade was suppressed by SKF96365 and 2-APB. Both TRPC and ERK inhibitors mitigated EMT progression. Based on these results, TRPC1/3/6 inhibition attenuated the TGF-β1-induced EMT in GC by suppressing Ras/Raf1/ERK signal transduction.

MEG3/miR‑21 axis affects cell mobility by suppressing epithelial‑mesenchymal transition in gastric cancer.

The prognosis of patients with gastric cancer remains poor mainly due to distant metastasis. Maternally expressed gene 3 (MEG3), a long non-coding RNA (lncRNA), is downregulated in various tumor tissues and suppresses tumor progression. miR-21 is a microRNA which is expressed highly in tumor tissues. In the present study, we investigated the relationship between MEG3 and miR-21 in regards to the cell mobility of gastric cancer. Our data demonstrated that MEG3 was downregulated while miR-21 was upregulated in gastric cancer tissues and cell lines by qRT-PCR. Overexpression of MEG3 suppressed cell mobility of gastric cancer cells (AGS) by downregulating the expression of MMP-3, MMP-9 and VEGF. As shown by western blot analysis, overexpression of MEG3 also suppressed epithelial-mesenchymal transition (EMT) by increasing the expression of an epithelial marker (E-cadherin) and downregulating the expression of mesenchymal markers (N-cadherin, Snail and β-catenin), indicating that MEG3 suppressed cell mobility through the inhibition of EMT in gastric cancer. The expression of miR-21 was negatively regulated by MEG3 and overexpression of miR-21 promoted cell mobility of AGS through activation of EMT. Co-transfection of lncRNA-MEG3 and miR-21 mimic counteracted the inhibitory effect on the cell mobility attributed to MEG3, suggesting that the MEG3/miR-21 axis affects cell mobility by suppressing EMT in gastric cancer. Using a mouse xenograft tumor model, we found that the overexpression of MEG3 suppressed tumor growth and metastasis while overexpression of miR-21 had the opposite effects. The MEG3/miR-21 axis affected gastric cancer growth and metastasis through inhibition of EMT in vivo. In conclusion, we demonstrated that the MEG3/miR-21 axis participates in the tumor progression and metastasis of gastric cancer through the regulation of EMT.

Small interfering RNA-mediated knockdown of fatty acid synthase attenuates the proliferation and metastasis of human gastric cancer cells via the mTOR/Gli1 signaling pathway.

Fatty acid synthase (FASN), the main enzyme involved in de novo lipogenesis, is overexpressed in several types of tumor tissues. In addition, it is associated with tumor cell proliferation, metastasis, epithelial-mesenchymal transition (EMT) and a poor prognosis. However, the precise functions and internal mechanisms of FASN with regard to the proliferation, metastasis and EMT in gastric cancer (GC) cells remain elusive. The present study investigated FASN protein expression in 18 randomly selected pairs of GC tumors and matched normal tissues by western blot analysis. FASN-specific small interfering RNA (siRNA) was then transfected into SGC-7901 cells to examine the effect of FASN on proliferation and migration in vitro. Western blotting was used to detect the protein expression of FASN, EMT-related markers and key signaling molecules of the mechanistic target of rapamycin/zinc finger protein GLI1 (mTOR/Gli1) pathway. Reverse transcription-quantitative polymerase chain reaction was conducted to detect the mRNA expression of FASN and EMT-related markers. The FASN level was higher in the GC tissues compared with that in the surrounding normal tissues. Knockdown of FASN suppressed GC cell proliferation and metastasis in vitro. The silencing of FASN expression using siRNA reversed EMT at the protein and mRNA levels and decreased the expression of Gli1 via regulation of AMP-activated protein kinase/mTOR and protein kinase B/mTOR signaling in GC cells. Inhibition of FASN suppresses GC proliferation and metastasis through targeting of the mTOR/Gli1 signaling pathway, indicating that it may serve as a potential target for the treatment of GC.

LDH-Apromotes epithelial-mesenchymal transition by upregulating ZEB2 in intestinal-type gastric cancer.

IntroductionEpithelial-mesenchymal transition (EMT) is regarded as a crucial process of invasion and metastasis, which contribute greatly to cancer-related relapse and death. Based on research results that hypoxia can trigger gastric cancer EMT and decreasing lactate production can selectively kill hypoxic cancer cells, we infer that lactate dehydrogenase A (LDH-A) transforming pyruvate into lactate is at least in part responsible for poor prognosis of gastric cancer.Materials and methodsWe used siRNA to knock down LDH-A in intestinal-type gastric cancer (ITGC) cell lines SGC7901 and BGC823. Western blot and RT-PCR were applied to detect mRNA and protein expression of EMT-related genes, respectively. Transwell invasion assay and migration assay were applied to study invasive and migratory abilities, respectively. Survival analysis was used to evaluate prognostic values.Results and conclusionThe results of in vitro experiment demonstrated that LDH-A facilitates ITGC cells’ invasion and migration by upregulating ZEB2. The positive correlation between LDH-A and ZEB2 was verified in 371 ITGC specimens. Survival analysis indicated that co-expression of LDH-A/ZEB2 had synergetic power to predict overall survival. Thus, we conclude that the close relationship between LDH-A and ZEB2 may offer a potential therapeutic strategy for ITGC.

Astragaloside IV inhibits TGF-β1-induced epithelial-mesenchymal transition through inhibition of the PI3K/Akt/NF-κB pathway in gastric cancer cells.

Astragaloside IV (AS-IV) has been reported to possess anti-metastasis activity in cancer cells. However, it is unknown whether AS-IV could inhibit epithelial-mesenchymal transition (EMT), a cellular de-differentiation program that promotes metastasis, in cancer cells. The aim of this study was to study the effect and mechanism of AS-IV on EMT in gastric cancer (GC) cells. The results showed that AS-IV significantly inhibited cell viability, invasion, and migration of GC cells. The E-cadherin to N-cadherin switch and expression of Vimentin and metastasis-related genes were induced by transforming growth factor β1 (TGF-β1), whereas AS-IV reversed the induction. In addition, AS-IV inhibited TGF-β1-induced activation of PI3K/Akt/NF-κB. Inhibition of the PI3K/Akt/NF-κB pathway reversed TGF-β1-induced EMT. In conclusion, AS-IV inhibited TGF-β1-induced EMT through inhibition of the PI3K/Akt/NF-κB pathway in GC cells. AS-IV might be an effective candidate for the treatment for GC.

High expression of hnRNPA1 promotes cell invasion by inducing EMT in gastric cancer

Advanced gastric cancer (GC) has a poor prognosis and its treatment strategies are not very efficient. Heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1) has emerged as a plausible GC marker, however the role and molecular mechanism of hnRNPA1 in cell invasion and migration remains unknown. In the present study, the gene expression across normal and tumor tissue (GENT) database was used to evaluate the mRNA expression of hnRNPA1 in various types of cancer. Western blot analysis (WB) and immunohistochemistry (IHC) were performed to detect the protein expression of hnRNPA1 in GC tissues and adjacent non-tumor tissues. The expression of multiple oncogenes was detected by western blot analysis and quantitative RT-PCR in hnRNPA1 overexpressing GC cells. Soft agar colony formation, EdU incorporation, wound healing and invasion assays were applied to verify the role of hnRNPA1 in anchorage-independent cell growth, migration and invasion in GC cells. Epithelial-to-mesenchymal transition (EMT) markers were detected by immunofluorescence, western blot analysis and IHC in vitro. A nude mice model of metastasis carcinoma was established to confirm the role of hnRNPA1 during EMT in vivo. Our results revealed that hnRNPA1 was significantly upregulated in GC tissue. HnRNPA1 overexpression significantly induced cell growth, migration and invasion ability in GC cells. In addition, hnRNPA1 promoted EMT of GC cells in vitro and in vivo. These findings indicated that hnRNPA1 is highly expressed in GC and promoted invasion by inducing EMT transition in GC cells. Thus, hnRNPA1 may be a potential therapeutic target for GC.

FBXO31 Suppresses Gastric Cancer EMT by Targeting Snail1 for Proteasomal Degradation.

The F-box protein FBXO31, a component of the Skp1/Cul1/F-box (SCF) E3 ubiquitin ligase complex, plays an important regulatory role in neuronal development, stress response, and tumorigenesis. Our recent report indicates that FBXO31 functions as a tumor suppressor in gastric cancer, and the loss of FBXO31 protein is associated with a higher malignant phenotype and poorer prognosis. However, little is known about the underlying mechanism. In this study, FBXO31 inhibits gastric cancer progression by suppressing the epithelial-mesenchymal transition (EMT). FBXO31 overexpression decreases, whereas its inhibition increases, the protein level of the EMT transcription factor Snail1 (SNAI1), respectively. Further evidence demonstrates that FBXO31 interacts with Snail1 and mediates the ubiquitin- and proteasome-dependent degradation of Snail1 in gastric cancer. The F-box domain of FBXO31 and the phosphorylation of Snail1 are necessary for the molecular interaction between FBXO31 and Snail1. Mouse modeling experiments reveal that FBXO31 overexpression inhibits in vivo colonization of gastric cancer cells. Furthermore, a highly significant negative correlation between FBXO31 and Snail1 is validated in human gastric cancer clinical specimens. Taken together, these findings identify Snail1 as a new target protein of FBXO31 in gastric cancer and substantiate a novel regulatory role of FBXO31 on gastric cancer progression and metastasis.Implication: These findings demonstrate that FBXO31 exerts the tumor-inhibitory role in gastric cancer by ubiquitin-mediated degradation of Snail1, which represents a viable strategy of FBXO31 activators in the prevention and therapy of gastric cancer. Mol Cancer Res; 16(2); 286-95. ©2017 AACR.

Testes-specific protease 50 (TSP50) promotes invasion and metastasis by inducing EMT in gastric cancer

BackgroundTSP50 (testes-specific protease 50) has been reported to be a candidate oncogene and is overexpressed in various cancers. Our previous study demonstrated that TSP50 protein is elevated in gastric cancer, and its high expression is associated with unfavorable prognosis and lymph node metastasis. However, the role of TSP50 in gastric cancer remains elusive.MethodsqRT-PCR, western blot were used to determine TSP50 expression in gastric cancer cell lines. Role of TSP50 in proliferation and invasion was examined by BrdU incorporation assay, cell count, wound healing and transwell assay. Immunohistochemistry and western blot were performed to identify the potential mechanisms involved.ResultsTSP50 was highly expressed in most of the gastric cancer cell lines at both mRNA and protein levels. Up-regulation of TSP50 in gastric cancer cells enhanced proliferation and invasiveness, whereas down-regulation of TSP50 by its specific shRNA decreased it. A negative correlation between TSP50 and E-Cadherin was found in gastric cancer tissues, and combination of them improves the prediction for prognosis and lymph node metastasis. Mechanistic studies revealed that overexpression of TSP50 increased the expression of epithelial-to-mesenchymal transition (EMT) markers including Vimentin, and Twist, and decreased the epithelial marker E-Cadherin. NF-κB signaling pathway is involved in the regulatory effects of TSP50 on EMT, migration and invasion in gastric cancer cells.ConclusionTSP50 promotes the proliferation, migration and invasion of gastric cancer cells involving NF-κB dependent EMT activation. Targeting TSP50 may provide a novel therapeutic strategy for the management of gastric cancer.

Long Non-Coding RNA RP11-789C1.1 Suppresses Epithelial to Mesenchymal Transition in Gastric Cancer Through the RP11-789C1.1/MiR-5003/E-Cadherin Axis

Background/Aims: Gastric cancer (GC) is a common malignancy with a global incidence that ranks fourth among all tumor types. Epithelial-to-mesenchymal transition (EMT) is a tumor biological process with a role in GC cell metastasis. Long non-coding RNAs (lncRNAs) and microRNAs possess important regulatory functions at the cellular level and in diverse pathophysiological processes. This study was conducted to investigate whether lncRNA RP11-789C1.1 regulates EMT in GC by mediating the miR-5003/E-cadherin pathway. Methods: RP11-789C1.1 and miR-5003 expression was detected in GC specimens and cell lines by quantitative real-time PCR. Western blotting and immunohistochemistry were performed to detect EMT markers in GC. Cell Counting Kit 8 assays were carried out to explore cell proliferation. Wound healing and Transwell assays were conducted to determine the migration and invasion of GC cells. To clarify the correlation between RP11-789C1.1, miR-5003, and E-cadherin, dual-luciferase reporter assays were applied. Results: LncRNA RP11-789C1.1 was significantly down-regulated in GC patients and cell lines, along with the concomitant up-regulation of miR-5003. Silencing RP11-789C1.1 and over-expressing miR-5003 significantly promoted the tumor behavior of GC cells. Dual-luciferase reporter assays confirmed that miR-5003 was the target of both RP11-789C1.1 and E-cadherin. Furthermore, at both the mRNA and protein level, silencing RP11-789C1.1 remarkably reduced the expression of E-cadherin and promoted EMT, which were reversed by knocking down miR-5003. Conclusions: LncRNA RP11-789C1.1 inhibited EMT in GC through the RP11-789C1.1/miR-5003/E-cadherin axis, which could be a promising therapeutic target for GC.

Claudin-7 (CLDN7) is overexpressed in gastric cancer and promotes gastric cancer cell proliferation, invasion and maintains mesenchymal state.

Gastric cancer (GC) ranks as the fourth most common cancer worldwide and is among the most aggressive types of cancer. Claudin-7 (CLDN7) has been found to be aberrantly expressed in some types of cancers. However, the expression and role of CLDN7 on gastric cancer (GC) remain largely unknown. In this study, we have performed the largest expression analysis study to date of CLDN7 in 113 pairs of human GC tissues and non-tumorous adjacent tissues. We found CLDN7 expression is significantly elevated in GC tissues, and the overexpression of CLDN7 is closely related to lymph node metastasis. Furthermore, we observed that CLDN7 executes an oncogenic function, promoting cancer cell proliferation, invasion, and epithelial-mesenchymal transition in GC. Given this oncogenic role of CLDN7 in GC formation and progression, CLDN7 may have an indispensable potential for future anti-metastatic and therapeutic applications.

Roles of Long Noncoding RNAs in Regulating Epithelial-Mesenchymal Transition Process in Gastric Cancer

Gastric Cancer (GC) is one of the most three reasons related to death caused by cancer, especially in East Asia area, where many people have been suffering in this disease. Although there are significant improvements in surgical techniques and medical standards, the five-year survival rate of GC patients is still low. Epithelial- Mesenchymal Transition (EMT) plays a key role in the process of metastasis, which is a biological process that epithelial cells lose their polarity and turn into mesenchymal phenotype. It also enjoys a potential effect on invasion and migration of multiple malignancies, including that of gastric cancer. Accumulating evidences in literature suggest that long noncoding RNAs (lncRNAs) play an important role in the process of EMT. In this review, roles of lncRNAs in GC EMT are highlighted and pathways of lncRNAs in regulating EMT in GC is clarified.