Repression Of E-cadherin Expression Research Articles

Extracellular vesicles derived from lung cancer cells promote the progression of lung cancer by delivering miR-151a-5p

Extracellular vesicles (EVs) participate in the occurrence and development of lung cancer. MiR-151a-5p has been reported to be highly expressed in the tumor tissues of lung cancer. The aim of this work was to investigate whether EVs can affect lung cancer progression by delivering miR-151a-5p. In this work, we found that miR-151a-5p was highly expressed in serum of lung cancer patients. Up-regulation of miR-151a-5p and down-regulation of Nedd4-binding partner-1 (N4BP1) were observed in lung cancer cell lines. The expression of miR-151a-5p was also increased in H520-derived EVs. H520-derived EVs promoted cell proliferation, inhibited apoptosis of H520 cells by delivering miR-151a-5p. EVs containing miR-151a-5p repressed E-cadherin expression and elevated N-cadherin and Vimentin expression to impede epithelial-mesenchymal transition (EMT) of H520 cells. Additionally, the interaction between miR-151a-5p and N4BP1 was verified by luciferase reporter assay, showing that miR-151a-5p interacted with N4BP1. MiR-151a-5p repressed N4BP1 expression by interacting with N4BP1. EVs containing miR-151a-5p promoted malignant phenotypes of H520 cells by targeting N4BP1. Finally, a tumor-bearing mouse model was constructed by inoculation of H520 cells with miR-151a-5p overexpression or knockdown. Overexpression of miR-151a-5p accelerated tumor growth of lung cancer in vivo, and repressed N4BP1 expression in the tumor tissues. Knockdown of miR-151a-5p caused opposite results. In conclusion, this work demonstrated that lung cancer cell-derived EVs secreted miR-151a-5p to promote cell proliferation, and inhibit apoptosis and EMT of lung cancer cells by targeting N4BP1, thereby accelerating lung cancer progression. Thus, this study suggests that EVs-derived miR-151a-5p may be a potential target for lung cancer treatment.

Hepatitis B virus X protein and hepatitis C virus core protein cooperate to repress E-cadherin expression via DNA methylation

Dual infection of hepatitis B virus (HBV) and hepatitis C virus (HCV) is closely associated with an increased risk of hepatocellular carcinoma; however, the underlying mechanism is poorly understood. In the present study, we found that HBV X protein (HBx) and HCV core protein work together to inhibit E-cadherin expression in human hepatoma cells. For this effect, they additively increased both the level and activity of enzymes, DNA methyltransferase 1, 3a, and 3b to induce promoter hypermethylation of E-cadherin in a p53-dependent fashion. Their additive effect on E-cadherin levels was reproduced in an in vitro HBV/HCV dual infection system using Huh7D-NTCP cells. As a result, HBV and HCV additively upregulated mesenchymal marker such as N-cadherin, Snail, Twist and Vimentin but cooperatively downregulated epithelial markers such as E-cadherin, Slug and Plakoglobin. In addition, the coinfected cells exhibited faster cell migration and higher invasion ability, as compared with monoinfection, which are hallmarks of epithelial-mesenchymal transition required for the initiation of metastasis in cancer progression.

Co‐expression of Zeb‐1 and K17 provides new insights into the role of EMT in pancreatic cancer progression

INTRODUCTIONDespite improvements in screening and therapeutic options, pancreatic ductal adenocarcinoma (PDAC) has the third‐worst mortality rate, highlighting the need for better diagnostic and therapeutic approaches. Epithelial‐mesenchymal transition (EMT) has been conferred with a greater likelihood of metastasis in multiple cancers, specifically identified through markers like Zeb‐1 and Twist‐1. Zeb‐1 (Zinc Finger E‐Box Binding Homeobox 1) was shown to repress E‐cadherin expression, consequently inducing EMT.Our lab has previously identified K17 (Keratin 17) as an independent prognostic biomarker of poor outcomes in PDAC patients. While increasing evidence has suggested that EMT drives pancreatic cancer migration and metastasis, there have not been any well‐established connections between K17 expression and EMT. This study aims to provide new insights into the role of K17 in EMT by evaluating the co‐expression of K17 and Zeb‐1 in human PDAC biopsies. We hypothesized that tumor cells co‐express K17 and Zeb‐1 as a hallmark of EMT in PDAC. In addition, our study aims to establish a novel method of scoring Zeb‐1 expression in stromal fibroblasts via immunofluorescence to remove variability in the stromal constituency.METHODSPDAC tissues obtained from patients who underwent surgical resection between 2013 and 2017 at Stony Brook University (n=20) were selected for serial sectioning. Double immunofluorescence and single immunohistochemical staining were achieved by incubation with Zeb‐1 and K17 antibodies followed by incubation of fluorescent or biotin conjugated secondary antibodies, respectively. Histologic examination was performed using immunofluorescence staining along with H&E and immunohistochemical staining (IHC) to determine concordance.RESULTS● IHC for Zeb‐1 was detected predominantly in the nuclei of centroacinar cells, benign proliferative ducts, and stromal fibroblasts. Focal nuclear staining in tumor epithelial was also detected in some cases.● High levels of K17 and but decreased expression of Zeb‐1 were detected in diffusely infiltrative cells with morphologic features of EMT.● Both high Zeb‐1 and high K17 protein expression were associated with poor survival of PDAC patients.● Using confocal immunofluorescence microscopy, we detected co‐localization of Zeb‐1 and K17 in PDAC.● We quantified Zeb‐1 protein expression in PDAC samples from 20 patients and confirmed significantly higher expression in the tumor‐associated stroma of high‐grade tumors compared to stromal fibroblasts in areas devoid of tumor.CONCLUSIONOur results provide evidence that K17 is upregulated in tumor epithelial cells that show morphologic immunohistochemical properties of EMT. The loss of Zeb‐1 in diffusely infiltrative, K17‐positive tumor cells suggests that EMT upregulates K17, driving tumor aggression. Our results suggest that K17 may enhance PDAC aggression by mediating EMT. Hence, novel therapeutic agents targeting K17 may improve clinical care for this biologically distinct patient subgroup.

Abstract 2901: Pdcd4 inhibits slug translation to suppress E-cadherin expression and invasion in colon tumor cells

Abstract Programmed cell death 4 (Pdcd4) has been demonstrated to function as a tumor suppressor and protein translation inhibitor. We previously reported that knockdown of Pdcd4 down-regulated E-cadherin expression. E-cadherin is a key regulator for tumor cell invasion and metastasis, whose expression is controlled by transcription repressors Snail, Slug, ZEB1/2, and Twist. Both Slug and Snail have been shown to repress E-cadherin expression and contribute to tumor progression in various cancers including colon cancer. Here, we reported that knockdown of Pdcd4 increased Slug protein level but not SLUG mRNA level in colon tumor cells. Conversely, over-expression of Pdcd4 decreased Slug expression. Using sucrose gradient fractionation assays, Pdcd4 knockdown was found to increase the population of SLUG mRNA in the polysomal fractions. These results indicate that Pdcd4 translationally regulates Slug expression. To understand the mechanism by which Pdcd4 regulates Slug translation, the SLUG 5' untranslated region (5'UTR) was cloned and fused with luciferase reporter and named as 5'UTR-Slug-Luc. Knockdown of Pdcd4 significantly enhanced the translation of 5'UTR-Slug-Luc while ectopic expression of Pdcd4 repressed the translation of 5'UTR-Slug-Luc, suggesting that SLUG 5'UTR is an essential element for Pdcd4 to inhibit Slug translation. Moreover, cells treated with silvestrol, an inhibitor for translation initiation factor 4A (eIF4A), significantly suppressed Slug translation. In addition, ectopic expression of Pdcd4 inhibited Slug translation and thereby decreased E-cadherin expression. By contrast, Pdcd4(D418A), a mutant that does not bind with eIF4A, failed to suppress the expression of Slug and E-cadherin. These findings suggest that Pdcd4-inhibited Slug translation is through suppressing eIF4A. Furthermore, knockdown of Slug in Pdcd4 knockdown cells restored the E-cadherin expression and reversed the invasive capacity induced by Pdcd4 knockdown, indicating that up-regulation of Slug contributes to Pdcd4-knockdown enhanced invasion. Taken together, this study demonstrates that Pdcd4 inhibits translation of Slug to regulate E-cadherin expression and invasion in colon tumor cells. Citation Format: Qing Wang, Jiang Zhu, Hsin-Sheng Yang. Pdcd4 inhibits slug translation to suppress E-cadherin expression and invasion in colon tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2901.

Editorial expression of concern: Cdc6 expression is induced byHPV16 E6 and E7 oncogenes and represses E-cadherin expression

Editorial expression of concern: Cdc6 expression is induced byHPV16 E6 and E7 oncogenes and represses E-cadherin expression

ZEB1 Collaborates with ELK3 to Repress E-Cadherin Expression in Triple-Negative Breast Cancer Cells.

ZEB1 has intrinsic oncogenic functions that control the epithelial-to-mesenchymal transition (EMT) of cancer cells, impacting tumorigenesis from its earliest stages. By integrating microenvironment signals and being implicated in feedback regulatory loops, ZEB1 appears to be a central switch that determines EMT and metastasis of cancer cells. Here, we found that ZEB1 collaborates with ELK3, a ternary complex factor belonging to the ETS family, to repress E-cadherin expression. ZEB1 functions as a transcriptional activator of ELK3. We first identified that ELK3 and ZEB1 have a positively correlated expression in breast cancer cells by using multiple databases for correlation analysis. Molecular analysis revealed that ZEB1 functions as a transcriptional activator of ELK3 expression. GST pull-down assay and coimmunoprecipitation analysis of wild-type or domain deletion mutants of ZEB1 and ELK3 showed that these 2 proteins directly bound each other. Furthermore, we demonstrated that ZEB1 and ELK3 collaborate to repress the expression of E-cadherin, a representative protein that initiates EMT. Our finding suggested that ELK3 is a novel factor of the ZEB1/E-cadherin axis in triple-negative breast cancer cells. IMPLICATIONS: ELK3 is a novel factor in the ZEB1/E-cadherin axis and ZEB1 has a dual role in ELK3 as a transcriptional activator and as a collaborator to repress E-cadherin expression in triple-negative breast cancer cells.

HSPD1 repressed E-cadherin expression to promote cell invasion and migration for poor prognosis in oral squamous cell carcinoma

Buccal mucosa squamous cell carcinoma (BMSCC) is one of major subsites of oral cancer and is associated with a high rate of metastasis and poor prognosis. Heat shock proteins (HSPs) act as potential prognostic biomarkers in many cancer types. However, the role of HSPD1 in oral cancer, especially in BMSCC, is still unknown. Through data analysis with The Cancer Genome Atlas (TCGA), we found the association of HSPD1 gene expression with tumorigenesis and poor prognosis in oral cancer patients. Our cohort study showed that higher HSPD1 protein level was associated with tumorigenesis and poor prognosis in BMSCC patients with lymph node invasion, suggesting that HSPD1 may be involved in tumor metastasis. Moreover, knockdown of HSPD1 induced E-cadherin expression and decreased the migration and invasion of BMSCC cells. In contrast, ectopic expression of HSPD1 diminished E-cadherin expression and promoted the migration/invasion of BMSCC cells. Further, HSPD1 regulated RelA activation to repress E-cadherin expression, enhancing the migration and invasion of BMSCC cells. Furthermore, HSPD1 protein level was inversely correlated with E-cadherin protein level in tumor tissues and co-expression of high HSPD1/low E-cadherin showed a significant association with poor prognosis in BMSCC patients. Taken together, HSPD1 might repress E-cadherin expression and promote metastatic characters of BMSCC cells for poor prognosis of BMSCC patients.

EVI1 promotes epithelial-to-mesenchymal transition, cancer stem cell features and chemo\u2212/radioresistance in nasopharyngeal carcinoma

BackgroundAberrant EVI1 expression is frequently reported in cancer studies; however, its role in nasopharyngeal carcinoma (NPC) has not been examined in detail. The aim of the present study is to investigate the involvement of EVI1 in progression and prognosis of NPC.MethodsRT-PCR, immunohistochemistry and western blot assays were used to examine the expression of EVI1 in NPC tissues and cell lines. Fluorescence in situ hybridization assay was used to examine the amplification of EVI1 in NPC tissues. The biological effect of EVI1 was determined by both in vitro and in vivo studies. The dual-luciferase reporter assay was performed to confirm that EVI1 bind at E-cadherin andβ-catenin promoters. The ChIP, EMSA, and coimmunoprecipitation combined with mass spectrometry assays were used to analyze the EVI1 regulated proteins.ResultsEVI1 expression level was up-regulated in NPC tissues and cell lines. EVI1 was amplificated in NPC tissues. We observed that EVI1 down-regulation decreased the cell proliferation and invasive capacity of NPC cells in vitro and in vivo. EVI1, snail, and HDAC1 formed a co-repressor complex to repress E-cadherin expression and ultimately contributed to epithelial mesenchymal transition (EMT) phenotype in NPC cells. In another way, EVI1 directly bound at β-catenin promoter and activated its expression. β-catenin mediated EVI1’s function on cancer stem cells (CSCs) properties. EVI1 up-regulation predicted unfavorable prognosis and contributed to chemo/radio-resistance in NPC cells. Finally, we constructed arsenic trioxide-loaded nanoparticles (ALNPs) and revealed that ALNPs exerted anti-tumor effect in NPC cells.ConclusionsOur data indicated that EVI1 played an oncogenic role in NPC growth and metastasis and that EVI1 might serve as a novel molecular target for the treatment of NPC.

Epigenetic suppression of E-cadherin expression by Snail2 during the metastasis of colorectal cancer

BackgroundThe transcription factor Snail2 is a repressor of E-cadherin expression during carcinogenesis; however, the specific mechanisms involved in this process in human colorectal cancer (CRC) remain largely unknown.MethodWe checked the expression of Snail2 in several clinical CRC specimens. Then, we established Snail2-overexpressing and knockdown cell lines to determine the function of Snail2 during EMT and metastasis processes in CRC. In addition, we used luciferase reporter assay to explore how Snail2 inhibits the expression of E-cadherin and induces EMT.ResultsWe found that the expression of Snail2 was higher in clinical specimens of colorectal cancer (CRC) compared to non-cancerous tissues. Overexpression of Snail2 induced migration and metastatic properties in CRC cells in vitro and in vivo. Furthermore, overexpression of Snail2 promoted the occurrence of the epithelial–mesenchymal transition (EMT), downregulating the expression of E-cadherin and upregulating that of vimentin. Specifically, Snail2 could interact with HDAC6 and then recruited HDAC6 and PRC2 to the promoter of E-cadherin and thus inhibited the expression of E-cadherin, promoting EMT and inducing invasion and metastasis of CRC.ConclusionOur study reveals that Snail2 might epigenetically suppress the expression of E-cadherin during CRC metastasis.

T-box Transcription Factor Tbx3 Contributes to Human Hepatocellular Carcinoma Cell Migration and Invasion by Repressing E-Cadherin Expression.

Tbx3, a member of the T-box family of transcription factors, contributes directly to tumor formation, migration, and invasion. However, the role of Tbx3 in the metastasis of HCC remains unclear. In the present study, Tbx3 expression was detected in HCC tissues and cells by Western blot, and Tbx3 expression was regulated by use of siRNAs or lentivirus-mediated vectors. Here we found that Tbx3 protein expression increased in HCC tissues and cell lines. Tbx3 expression was positively associated with multiple tumor nodes, venous infiltration, and advanced TNM tumor stage. Survival analysis demonstrated that Tbx3 expression was an independent prognostic factor for HCC patients. In vitro assays further validated that Tbx3 indeed prompted HCC cell migration and invasion. In addition, Tbx3 expression was negatively related with E-cadherin expression in HCC tissues. Mechanically, Tbx3 inhibited the expression of E-cadherin, and then facilitated epithelial–mesenchymal transition (EMT) of HCC cells. Furthermore, the effect of Tbx3 knockdown on HCC cells was attenuated by E-cadherin knockdown. In conclusion, Tbx3 may be a novel prognostic factor, and it contributes to HCC cell migration, invasion, and EMT by repressing E-cadherin expression. Thus, Tbx3 may be recommended as a therapeutic target for HCC patients.

Long Noncoding RNA NEAT1 Promotes Growth and Metastasis of Cholangiocarcinoma Cells.

Long noncoding RNAs (lncRNAs) are known to play important roles in cancers. However, little is known about lncRNAs in cholangiocarcinoma (CCA), a cholangiocyte malignancy with poor prognosis. We investigated the role of nuclear paraspeckle assembly transcript 1 (NEAT1) lncRNA in promoting CCA. qRT-PCR analysis of patient samples showed that NEAT1 expression was higher in CCA tumors than in matched adjacent nontumor tissue. NEAT1 levels were also higher in CCA cell lines than in a normal biliary epithelium cell line (HIBEpic). NEAT1 knockdown in CCA cell lines using shNEAT1 reduced cell proliferation and colony formation in CCK-8 and colony formation assays, respectively. CCA cells transfected with shNEAT1 also exhibited reduced metastasis and invasiveness in Transwell assays. NEAT1 knockdown cells produced smaller tumors, demonstrating that NEAT1 promotes tumor growth in vivo. Silencing of NEAT1 increased E-cadherin expression in vitro, and E-cadherin expression was inversely correlated with NEAT1 expression in CCA tissue samples. RIP and ChIP assays suggest that NEAT1 is recruited to the E-cadherin promoter by EZH2 (enhancer of zeste homolog 2), where it represses E-cadherin expression. These findings indicate that NEAT1 exerts oncogenic effects in CCA. We postulate that NEAT1 is a potentially useful diagnostic and therapeutic target for CCA.

Scleraxis regulates Twist1 and Snai1 expression in the epithelial-to-mesenchymal transition.

Numerous physiological and pathological events, from organ development to cancer and fibrosis, are characterized by an epithelial-to-mesenchymal transition (EMT), whereby adherent epithelial cells convert to migratory mesenchymal cells. During cardiac development, proepicardial organ epithelial cells undergo EMT to generate fibroblasts. Subsequent stress or damage induces further phenotype conversion of fibroblasts to myofibroblasts, causing fibrosis via synthesis of an excessive extracellular matrix. We have previously shown that the transcription factor scleraxis is both sufficient and necessary for the conversion of cardiac fibroblasts to myofibroblasts and found that scleraxis knockout reduced cardiac fibroblast numbers by 50%, possibly via EMT attenuation. Scleraxis induced expression of the EMT transcriptional regulators Twist1 and Snai1 via an unknown mechanism. Here, we report that scleraxis binds to E-box consensus sequences within the Twist1 and Snai1 promoters to transactivate these genes directly. Scleraxis upregulates expression of both genes in A549 epithelial cells and in cardiac myofibroblasts. Transforming growth factor-β induces EMT, fibrosis, and scleraxis expression, and we found that transforming growth factor-β-mediated upregulation of Twist1 and Snai1 completely depends on the presence of scleraxis. Snai1 knockdown upregulated the epithelial marker E-cadherin; however, this effect was lost after scleraxis overexpression, suggesting that scleraxis may repress E-cadherin expression. Together, these results indicate that scleraxis can regulate EMT via direct transactivation of the Twist1 and Snai1 genes. Given the role of scleraxis in also driving the myofibroblast phenotype, scleraxis appears to be a critical controller of fibroblast genesis and fate in the myocardium and thus may play key roles in wound healing and fibrosis. NEW & NOTEWORTHY The molecular mechanism by which the transcription factor scleraxis mediates Twist1 and Snai1 gene expression was determined. These results reveal a novel means of transcriptional regulation of epithelial-to-mesenchymal transition and demonstrate that transforming growth factor-β-mediated epithelial-to-mesenchymal transition is dependent on scleraxis, providing a potential target for controlling this process.

Six2 is negatively correlated with good prognosis and decreases 5-FU sensitivity via suppressing E-cadherin expression in hepatocellular carcinoma cells

This work aims to study the roles and related mechanisms of six2 in 5-FU sensitivity of hepatocellular carcinoma (HCC) cells. KM-Plotter analysis showed that HCC patients with higher six2 expression levels had shorter overall survival. Six2 expression was higher in clinical HCC tissues than in normal tissues, and was negatively correlated with E-cadherin expression. Additionally, six2 overexpression decreased the sensitivity of HCC cells to 5-Fu, characterized as attenuating 5-FU-induced cell apoptosis and downregulation of cell viability, and promoted HCC cells stemness. Mechanistically, six2 overexpression repressed E-cadherin expression via stimulating promoter methylation of the E-cadherin. And E-cadherin overexpression rescued six2-induced decrease of 5-FU sensitivity and promotion on HCC cells stemness. Therefore, our results suggest that Six2 is negatively correlated with good prognosis and decreases 5-FU sensitivity via suppressing E-cadherin expression in HCC cells.

Lysyl oxidase-like protein 2 (LOXL2) modulates barrier function in cholangiocytes in cholestasis

The lysyl oxidase-like protein 2 (LOXL2) promotes stabilization of the extracellular matrix, chemotaxis, cell growth and cell mobility. We aimed to (i) identify stimuli of LOXL2 in cholangiopathies, (ii) characterize the effects of LOXL2 on biliary epithelial cells' (BECs) barrier function, (iii) compare LOXL2 expression in primary sclerosing cholangitis (PSC), primary biliary cholangitis, and disease controls, and (iv) to determine LOXL2 expression and its cellular sources in four mouse models of cholangiopathies. Cultured murine BECs were challenged with well-known triggers of cellular senescence, hypoxia, phospholipid-deficient Abcb4-/- mouse bile and chenodeoxycholic acid and investigated for LOXL2, SNAIL1 and E-cadherin expression and transepithelial electrical resistance with and without LOX-inhibition. In vivo, LOXL2 expression was studied in PSC livers, and controls and mouse models. We compared LOXL2 serum levels in patients with PSC, secondary SC, primary biliary cholangitis, and controls. Cellular senescence, hypoxia, Abcb4-/- bile and chenodeoxycholic acid induced LOXL2 and SNAIL1 expression, repressed E-cadherin expression, and significantly reduced transepithelial electrical resistance in BECs. Notably, all of the pathological changes could be recovered via pharmacological LOX-inhibition. Mouse models showed induced LOXL2 expression in the portal region and in association with ductular reaction. LOXL2 serum levels were significantly elevated in patients with cholangiopathies. In PSC, LOXL2 expression was located to characteristic periductal onion skin-type fibrosis, ductular reaction, Kupffer cells, and fibrotic septa. Importantly, in PSC, LOXL2 overexpression was paralleled by E-cadherin loss in BECs from medium-sized bile ducts. Reactive BECs produce LOXL2, resulting in increased tight junction permeability, which can be ameliorated by pharmacological LOX-inhibition in vitro. Reactive BECs, portal myofibroblasts, and Kupffer cells are the main sources of LOXL2 in cholangiopathies. In this study, we investigate the role of lysyl oxidase-like protein 2 (LOXL2), an enzyme pivotal in the development of organ fibrosis, in the pathogenesis of cholangiopathies (diseases of bile ducts), such as primary sclerosing cholangitis. We found LOXL2 to be expressed in association with bile duct epithelial injury and uncovered mechanisms for its upregulation and the subsequent effects in vitro and in vivo. Our findings support testing of anti-LOXL2 treatment strategies for patients with primary sclerosing cholangitis.

Possible effect of SNAIL family transcriptional repressor 1 polymorphisms in non-syndromic cleft lip with or without cleft palate.

Orofacial development is a complex process subjected to failure impairing. Indeed, the cleft of the lip and/or of the palate is among the most frequent inborn malformations. The JARID2 gene has been suggested to be involved in non-syndromic cleft lip with or without cleft palate (nsCL/P) etiology. JARID2 interacts with the polycomb repressive complex 2 (PRC2) in regulating the expression patterns of developmental genes by modifying the chromatin state. Genes coding for the PRC2 components, as well as other genes active in cell differentiation and embryonic development, were selected for a family-based association study to verify their involvement in nsCL/P. A total of 632 families from Italy and Asia participated to the study. Evidence of allelic association was found with polymorphisms of SNAI1; in particular, the rs16995010-G allele was undertransmitted to the nsCL/P cases [P = 0.004, odds ratio = 0.69 (95% C.I. 0.54-0.89)]. However, the adjusted significance value corrected for all the performed tests was P = 0.051. The findings emerging by the present study suggest for the first time an involvement of SNAI1 in the nsCL/P onset. Interestingly, SNAI1 is known to promote epithelial to mesenchymal transition by repressing E-cadherin expression, but it needs an intact PRC2 to act this function. Alterations of this process could contribute to the complex etiology of nsCL/P.

The TET2/E-cadherin/β-catenin regulatory loop confers growth and invasion in hepatocellular carcinoma cells

The poor outcome of hepatocellular carcinoma (HCC) is mainly due to the development of fast growth, invasion and metastasis. The role of TET2 has been implicated in some cancer types, but its role and mechanisms in HCC remains elusive. In this study, our findings indicated that TET2 expression frequently increased in HCC and that TET2 expressional upregulation correlated with HCC progression. TET2 knockdown inhibited HCC cells proliferation in vitro and growth in vivo, and inhibited the invasion potential of HCC cells. Mechanically, TET2 knockdown upregulated E-cadherin expression and then attenuated β-catenin transactivation in HCC cells. TET2 repressed E-cadherin expression via recruited HDAC1 to E-cadherin promoter to reduce the H3K9Ac and H4K16Ac levels. Moreover, β-catenin signaling transcriptionally regulated TET2 expression to form a positive feedback in HCC cells. These findings indicate that the dysregulation of TET2/E-cadherin/β-catenin regulatory loop is a critical oncogenic event in HCC progression.

Aberrant expression of STYK1 and E-cadherin confer a poor prognosis for pancreatic cancer patients.

Previous studies showed that aberrant Serine/threonine/tyrosine kinase 1 (STYK1, also known as NOK) or/and E-cadherin were involved in the progression of some types of human cancers. However, whether they contributed to the development of pancreatic cancer was unknown. Here, we investigated the prognostic significance of aberrant STYK1 and E-cadherin in pancreatic cancer. Our results showed that STYK1 expression increased while E-cadherin decreased in pancreatic cancer tissues compared with normal pancreas tissues. STYK1 level was positively correlated with lymph node metastasis and clinical stage in pancreatic cancer patients. E-cadherin expression was inversely correlated with STYK1 expression in pancreatic cancer tissue samples. Patients with high STYK1 and low E-cadherin expression had the worst prognosis. In addition, STYK1 knockdown in pancreatic cancer cell lines inhibited cell proliferation, enhanced cell apoptosis, induced cell cycle arrest, and prohibited cell migration, while STYK1 over-expression showed the opposite effects. Silencing STYK1 also increased E-cadherin expression and inhibited epithelial-to-mesenchymal transition (EMT) and p-p38 expression in vitro. Over-expression had showed the opposite trends, and treatment with p38 inhibitor, SB203580, could reverse the trends. Thus, STYK1 repressed E-cadherin expression and promoted EMT, mediated by p38 MAPK signaling pathway, which was the possible mechanism for STYK1-mediated pancreatic cancer cell proliferation and migration. In summary, our results showed that STYK1 might be a prognostic marker for pancreatic cancer patients and might be a novel strategy for the treatment of pancreatic cancer.

HOX transcript antisense intergenic RNA represses E-cadherin expression by binding to EZH2 in gastric cancer.

AIMTo clarify the mechanisms of HOX transcript antisense intergenic RNA (HOTAIR) in gastric cancer (GC) migration and invasion.METHODSQuantitative real-time polymerase chain reaction (qPCR) was used to detect the expression level of HOTAIR in GC tissues. The correlation of its expression with clinicopathological features was analyzed. Area under receiver operating characteristic curve (AUCROC) was constructed to evaluate the diagnostic value of HOTAIR. Wound-healing assay and Transwell assay were performed to detect the biological effects of HOTAIR in GC cells. qPCR, western blot and immunohistochemistry were used to evaluate the mRNA and protein expression of E-cadherin. RNA-binding protein immunoprecipitation was used for the analysis of EZH2 interactions with HOTAIR. Chromatin immunoprecipitation assay was performed to investigate direct interactions between EZH2 and E-cadherin.RESULTSThe expression of HOTAIR was up-regulated in GC tumorous tissues compared with the para-tumorous tissues (P < 0.001). Its over-expression was correlated with tumor-node-metastasis (TNM) stage (P = 0.024), tumor invasion (P = 0.018), lymph node metastasis (P = 0.023), and poor prognosis (P < 0.001). Multivariate Cox regression analysis confirmed expression of HOTAIR as an independent predictor of overall survival (P = 0.033), together with TNM stage (P = 0.002) and lymph node metastasis (P = 0.002). The AUCROC was up to 0.709 (95%CI: 0.623-0.785, P < 0.001). Knockdown of HOTAIR by siRNA in GC cells suppressed the migration and invasion of GC cells. Significantly negative correlation between HOTAIR and E-cadherin was found in GC tissues and cell lines, and HOTAIR contributed to the regulation of E-cadherin through binding to EZH2 with the E-cadherin promoter.CONCLUSIONHOTAIR may play a pivotal role in tumor cell migration and invasion. It can be used as a potential diagnostic and prognostic biomarker for GC.

Nicotinic acid inhibits glioma invasion by facilitating Snail1 degradation

Malignant glioma is a formidable disease that commonly leads to death, mainly due to the invasion of tumor cells into neighboring tissues. Therefore, inhibition of tumor cell invasion may provide an effective therapy for malignant glioma. Here we report that nicotinic acid (NA), an essential vitamin, inhibits glioma cell invasion in vitro and in vivo. Treatment of the U251 glioma cells with NA in vitro results in reduced invasion, which is accompanied by a loss of mesenchymal phenotype and an increase in cell-cell adhesion. At the molecular level, transcription of the adherens junction protein E-cadherin is upregulated, leading to accumulation of E-cadherin protein at the cell-cell boundary. This can be attributed to NA’s ability to facilitate the ubiquitination and degradation of Snail1, a transcription factor that represses E-cadherin expression. Similarly, NA transiently inhibits neural crest migration in Xenopus embryos in a Snail1-dependent manner, indicating that the mechanism of action for NA in cell migration is evolutionarily conserved. We further show that NA injection blocks the infiltration of tumor cells into the adjacent brain tissues and improves animal survival in a rat model of glioma. These results suggest that NA treatment may be developed into a potential therapy for malignant glioma.

Pentabromophenol suppresses TGF-\u03b2 signaling by accelerating degradation of type II TGF-\u03b2 receptors via caveolae-mediated endocytosis

Pentabromophenol (PBP), a brominated flame retardant (BFR), is widely used in various consumer products. BFRs exert adverse health effects such as neurotoxic and endocrine-disrupting effects. In this study, we found that PBP suppressed TGF-β response by accelerating the turnover rate of TGF-β receptors. PBP suppressed TGF-β-mediated cell migration, PAI-1 promoter-driven reporter gene activation, and Smad2/3 phosphorylation in various cell types. Furthermore, PBP abolished TGF-β-mediated repression of E-cadherin expression, in addition to the induction of vimentin expression and N-cadherin and fibronectin upregulation, thus blocking TGF-β-induced epithelial–mesenchymal transition in A549 and NMuMG cells. However, this inhibition was not observed with other congeners such as tribromophenol and triiodophenol. TGF-β superfamily members play key roles in regulating various biological processes including cell proliferation and migration as well as cancer development and progression. The results of this in vitro study provide a basis for studies on the detailed relationship between PBP and modulation of TGF-β signalling. Because PBP is similar to other BFRs such as polybrominated diphenyl ethers (PBDEs), additional laboratory and mechanistic studies should be performed to examine BFRs as potential risk factors for tumorigenesis and other TGF-β-related diseases.