Altered β1,6-GlcNAc branched N-glycans impair TGF-β-mediated epithelial-to-mesenchymal transition through Smad signalling pathway in human lung cancer

Roles of Glyco-Redox in Epithelial Mesenchymal Transition and Mesenchymal Epithelial Transition, Cancer, and Various Diseases

Significance: Reduction-oxidation (redox) regulation is an important biological phenomenon that provides a balance between antioxidants and the generation of reactive oxygen species and reactive nitrogen species under pathophysiological conditions. Structural and functional changes in glycans are also important as post-translational modifications of proteins. The integration of glycobiology and redox biology, called glyco-redox has provided new insights into the mechanisms of epithelial-mesenchymal transition (EMT)/mesenchymal-epithelial transition (MET), cancer, and various diseases including Alzheimer's disease, chronic obstructive lung disease, type 2 diabetes, interstitial pneumonitis, and ulcerative colitis. Recent Advances: Glycans are biosynthesized by specific glycosyltransferases and each glycosyltransferase is either directly or indirectly regulated by oxidative stress and redox regulation. A typical example of glyco-redox is the role of N-glycan referred to as core fucose in superoxide dismutase 3. This glycan was found to be involved in the growth inhibition of cancer cell lines. Critical Issues: The significance of glyco-redox in EMT/MET, cancer, and various diseases was found in major N-glycan branching glycosyltransferases β1,4N-acetylglucosaminyltransferase III, β1,4N-acetylglucosaminyltransferase IV, β1,6N-acetylglucosaminyltransferase V, β1,4-acetylglucosaminyltransfearfse VI, β1,6-acetylglucosaminyltransferase IX, α-1,6 fucosyltransferase, and β-galactoside α-2,6-sialyltransferase 1. Herein, we summarize previous reports on target proteins and how this relates to oxidative stress. We also discuss the products of these processes and their significance to cancer and various diseases. Future Direction: A clear-cut understanding of the significance of glyco-redox in relation to prevention, diagnosis, and therapeutics is required. These studies will open a new road toward glycobiology and redox biology. Antioxid. Redox Signal. 41, 910-926.

Prodigiosin Inhibits Transforming Growth Factor β Signaling by Interfering Receptor Recycling and Subcellular Translocation in Epithelial Cells

Prodigiosin (PG) is a naturally occurring polypyrrole red pigment produced by numerous microorganisms including some Serratia and Streptomyces strains. PG has exhibited promising anticancer activity; however, the molecular mechanisms of action of PG on malignant cells remain ambiguous. Transforming growth factor-β (TGF-β) is a multifunctional cytokine that governs a wide array of cellular processes in development and tissue homeostasis. Malfunctions of TGF-β signaling are associated with numerous human cancers. Emerging evidence underscores the significance of internalized TGF-β receptors and their intracellular trafficking in initiating signaling cascades. In this study, we identified PG as a potent inhibitor of the TGF-β pathway. PG blocked TGF-β signaling by targeting multiple sites of this pathway, including facilitating the sequestering of TGF-β receptors in the cytoplasm by impeding the recycling of type II TGF-β receptors to the cell surface. Additionally, PG prompts a reduction in the abundance of receptors on the cell surface through the disruption of the receptor glycosylation. In human Caucasian lung carcinoma cells and human hepatocellular cancer cell line cells, nanomolar concentrations of PG substantially diminish TGF-β-triggered phosphorylation of Smad2 protein. This attenuation is further reflected in the suppression of downstream target gene expression, including those encoding fibronectin, plasminogen activator inhibitor-1, and N-cadherin. SIGNIFICANCE STATEMENT: Prodigiosin (PG) emerges from this study as a potent TGF-β pathway inhibitor, disrupting receptor trafficking and glycosylation and reducing TGF-β signaling and downstream gene expression. These findings not only shed light on PG's potential therapeutic role but also present a captivating avenue towards future anti-TGF-β strategies.

Exploration of glycosyltransferases mutation status in cervical cancer reveals PARP14 as a potential prognostic marker

This study investigates the potential role of Glycosyltransferases (GTs) in the glycosylation process and their association with malignant tumors. Specifically, the study focuses on PARP14, a member of GTs, and its potential as a target for tumors in the diagnosis and treatment of cervical cancer. To gather data, the study used somatic mutation data, gene expression data and clinical information from TCGA-CESE dataset as well as tissue samples from cervical cancer patients. Further verification was conducted through RT-qPCR and immunohistochemistry staining on cervical cancer tissues to confirm the expression of PARP14. The study utilized Kaplan-Meier for survival analysis of cervical cancer patient and found significant mutational abnormalities in GTs. The high frequency mutated gene was identified as PARP14. RT-qPCR revealed significantly higher mRNA expression of PARP14 compared to precancerous tissue. Using IHC combined with Kaplan-Meier,patients in the PARP14 high expression group had a better prognosis than the low expression group. The study identified PARP14 as a frequently mutated gene in cervical cancer and proposed its potential role in diagnosis and treatment.

Mutual regulation between glycosylation and transforming growth factor-β isoforms signaling pathway

Transforming growth factor-beta (TGF-β) superfamily members orchestrate a wide breadth of biological processes. Through Sma and Mad (Smad)-related dependent or noncanonical pathways, TGF-β members involve in the occurrence and development of many diseases such as cancers, fibrosis, autoimmune diseases, cardiovascular diseases and brain diseases. Glycosylation is one kind of the most common posttranslational modifications on proteins or lipids. Abnormal protein glycosylation can lead to protein malfunction and biological process disorder, thereby causing serious diseases. Previously, researchers commonly make comprehensive systematic overviews on the roles of TGF-β signaling in a specific disease or biological process. In recent years, more and more evidences associate glycosylation modification with TGF-β signaling pathway, and we can no longer disengage and ignore the roles of glycosylation from TGF-β signaling to make investigation. In this review, we provide an overview of current findings involved in glycosylation within TGF-βs and theirs receptors, and the interaction effects between glycosylation and TGF-β subfamily signaling, concluding that there is an intricate mutual regulation between glycosylation and TGF-β signaling, hoping to present the glycosylation regulatory patterns that concealed in TGF-βs signaling pathways.

Aberrant N-glycosylation in cancer: MGAT5 and β1,6-GlcNAc branched N-glycans as critical regulators of tumor development and progression

BACKGROUND

Changes in protein glycosylation are widely observed in tumor cells. N-glycan branching through adding β1,6-linked N-acetylglucosamine (β1,6-GlcNAc) to an α1,6-linked mannose, which is catalyzed by the N-acetylglucosaminyltransferase V (MGAT5 or GnT-V), is one of the most frequently observed tumor-associated glycan structure formed. Increased levels of this branching structure play a pro-tumoral role in various ways, for example, through the stabilization of growth factor receptors, the destabilization of intercellular adhesion, or the acquisition of a migratory phenotype.

CONCLUSION

In this review, we provide an updated and comprehensive summary of the physiological and pathophysiological roles of MGAT5 and β1,6-GlcNAc branched N-glycans, including their regulatory mechanisms. Specific emphasis is given to the role of MGAT5 and β1,6-GlcNAc branched N-glycans in cellular mechanisms that contribute to the development and progression of solid tumors. We also provide insight into possible future clinical implications, such as the use of MGAT5 as a prognostic biomarker.

Overexpression of N-acetylglucosaminyltransferase V promotes human parotid gland acinar cell immortalization via the epidermal receptor activation

The purpose of this study is to maintain the proliferation capability of human parotid gland acinar cells (ACs) in vitro to extend passage number and to study the mechanism that regulates AC stemness. N-acetylglucosaminyltransferase V (GnT-V) is the Golgi enzyme, and it has been reported that the β1,6GlcNAc-branched N-linked glycans are associated with various cell behaviors. Therefore, we modify the gene expression of ACs by transfection of the GnT-V-overexpression plasmid, and we found that upregulation of GnT-V extensively increased ACs proliferation and stemness properties in ACs/GnT-V compared to ACs transfected with Mock plasmid. More importantly, we observed that high levels of GnT-V positively correlated with ALDH1A3 expression via increasing phosphorylation of cell surface receptors and activating the downstream signaling transduction. Hence, the current study suggested that GnT-V is a significant factor for cell immortalization in the ACs model by activating the EGFR/ERK/ALDH1A3 signaling pathway.

Evidence That Tumor Microenvironment Initiates Epithelial-To-Mesenchymal Transition and Calebin A can Suppress it in Colorectal Cancer Cells

Background: Tumor microenvironment (TME) has a pivotal impact on tumor progression, and epithelial-mesenchymal transition (EMT) is an extremely crucial initial event in the metastatic process in colorectal cancer (CRC) that is not yet fully understood. Calebin A (an ingredient in Curcuma longa) has been shown to repress CRC tumor growth. However, whether Calebin A is able to abrogate TME-induced EMT in CRC was investigated based on the underlying pathways. Methods: CRC cell lines (HCT116, RKO) were exposed with Calebin A and/or a FAK inhibitor, cytochalasin D (CD) to investigate the action of Calebin A in TME-induced EMT-related tumor progression. Results: TME induced viability, proliferation, and increased invasiveness in 3D-alginate CRC cultures. In addition, TME stimulated stabilization of the master EMT-related transcription factor (Slug), which was accompanied by changes in the expression patterns of EMT-associated biomarkers. Moreover, TME resulted in stimulation of NF-κB, TGF-β1, and FAK signaling pathways. However, these effects were dramatically reduced by Calebin A, comparable to FAK inhibitor or CD. Finally, TME induced a functional association between NF-κB and Slug, suggesting that a synergistic interaction between the two transcription factors is required for initiation of EMT and tumor cell invasion, whereas Calebin A strongly inhibited this binding and subsequent CRC cell migration. Conclusion: We propose for the first time that Calebin A modulates TME-induced EMT in CRC cells, at least partially through the NF-κB/Slug axis, TGF-β1, and FAK signaling. Thus, Calebin A appears to be a potential agent for the prevention and management of CRC.

An integrated multi-omics approach to identify regulatory mechanisms in cancer metastatic processes

BACKGROUND

Metastatic progress is the primary cause of death in most cancers, yet the regulatory dynamics driving the cellular changes necessary for metastasis remain poorly understood. Multi-omics approaches hold great promise for addressing this challenge; however, current analysis tools have limited capabilities to systematically integrate transcriptomic, epigenomic, and cistromic information to accurately define the regulatory networks critical for metastasis.

RESULTS

To address this limitation, we use a purposefully generated cellular model of colon cancer invasiveness to generate multi-omics data, including expression, accessibility, and selected histone modification profiles, for increasing levels of invasiveness. We then adopt a rigorous probabilistic framework for joint inference from the resulting heterogeneous data, along with transcription factor binding profiles. Our approach uses probabilistic graphical models to leverage the functional information provided by specific epigenomic changes, models the influence of multiple transcription factors simultaneously, and automatically learns the activating or repressive roles of cis-regulatory events. Global analysis of these relationships reveals key transcription factors driving invasiveness, as well as their likely target genes. Disrupting the expression of one of the highly ranked transcription factors JunD, an AP-1 complex protein, confirms functional relevance to colon cancer cell migration and invasion. Transcriptomic profiling confirms key regulatory targets of JunD, and a gene signature derived from the model demonstrates strong prognostic potential in TCGA colorectal cancer data.

CONCLUSIONS

Our work sheds new light into the complex molecular processes driving colon cancer metastasis and presents a statistically sound integrative approach to analyze multi-omics profiles of a dynamic biological process.

True significance of N-acetylglucosaminyltransferases GnT-III, V and α1,6 fucosyltransferase in epithelial-mesenchymal transition and cancer

It is well known that numerous cancer-related changes occur in glycans that are attached to glycoproteins, glycolipids and proteoglycans on the cell surface and these changes in structure and the expression of the glycans are largely regulated by glycosyl-transferases, glycosidases, nucleotide sugars and their related genes. Such structural changes in glycans on cell surface proteins may accelerate the progression, invasion and metastasis of cancer cells. Among the over 200 known glycosyltransferases and related genes, β 1,6 N-acetylglucosaminyltransferase V (GnT-V) (the MGAT5 gene) and α 1,6 fucosyltransferase (FUT8) (the FUT8 gene) are representative enzymes in this respect because changes in glycans caused by these genes appear to be related to cancer metastasis and invasion in vitro as well as in vivo, and a number of reports on these genes in related to epithelial-mesenchymal transition (EMT) have also appeared. Another enzyme, one of the N-glycan branching enzymes, β1,4 N-acetylglucosaminyltransferase III (GnT-III) (the MGAT3 gene) has been reported to suppress EMT. However, there are intermediate states between EMT and mesenchymal-epithelial transition (MET) and some of these genes have been implicated in both EMT and MET and are also probably in an intermediate state. Therefore, it would be difficult to clearly define which specific glycosyltransferase is involved in EMT or MET or an intermediate state. The significance of EMT and N-glycan branching glycosyltransferases needs to be reconsidered and the inhibition of their corresponding genes would also be desirable in therapeutics. This review mainly focuses on GnT-III, GnT-V and FUT8, major players as N-glycan branching enzymes in cancer in relation to EMT programs, and also discusses the catalytic mechanisms of GnT-V and FUT8 whose crystal structures have now been obtained.

Advances in the discovery of novel biomarkers for cancer: spotlight on protein N-glycosylation

Progress on glycosylation and tumor markers has not been extensively reported. Glycosylation plays an important part in post-translational modification. Previous research on glycosylation-modified biomarkers has lagged behind due to insufficient understanding of glycosylation-related regulations. However, some new methods and ideas illustrated in recent research may provide new inspirations in the field. This article aims to review current advances in revealing relationship between tumors and abnormal N-glycosylation and discuss leading-edge applications of N-glycosylation in developing novel tumor biomarkers.

Ursolic Acid Attenuates TGF-β1-Induced Epithelial-Mesenchymal Transition in NSCLC by Targeting Integrin αVβ5/MMPs Signaling

Transforming growth factor-β1 (TGF-β1)-induced epithelial-mesenchymal transition (EMT) of non-small cell lung cancer (NSCLC) may contribute to tumor metastasis. TGF-β1-induced EMT in H1975 cells (a human NSCLC cell line) resulted in the adoption of mesenchymal responses that were predominantly mediated via the TGF-β1-integrin signaling pathway. Ursolic acid has been previously reported to inhibit tumor growth and metastasis in several cancers. However, whether ursolic acid can attenuate TGF-β1-induced EMT in H1975 cells and its underlying mechanisms remain unknown. In this study, ursolic acid significantly attenuated the TGF-β1-induced decrease in E-cadherin level and elevated the level of N-cadherin. Furthermore, ursolic acid inhibited the mesenchymal-like responses in H1975 cells, including cell migration, invasion, and activity of matrix metallopeptidase (MMP)-2 and -9. Finally, our new findings provided evidence that ursolic acid could inhibit EMT in NSCLC through TGF-β1 signaling pathway-mediated integrin αVβ5 expression, and this might be the potential mechanism of resveratrol on the inhibition of invasion and metastases in NSCLC. We conclude that ursolic acid attenuated TGF-β1-induced EMT in H1975 cells and thus might be a promising therapeutic agent for treating NSCLC.

Knockdown of aristaless-like homeobox1 inhibits epithelial-mesenchymal transition through Wnt/β-catenin signaling pathway in melanoma cells

Aristaless-like homeobox1 (ALX1), a member of the ALX family, is capable of mediating survival and development of mesenchyme-derived elements in vertebrates and its mutation will prevent the fusion of frontonasal and maxillary elements. Recently, ALX1 has been reported to be associated with cancer progression. However, the specific roles of ALX1 in melanoma remain unclear. In this study, we investigated the expression pattern and biological functions of ALX1 in melanoma. We found that ALX1 was highly expressed in melanoma tissues and cell lines. Knockdown of ALX1 suppressed the proliferation and invasion of melanoma cells. Furthermore, we showed that ALX1 knockdown reversed the epithelial-mesenchymal transition (EMT) process in melanoma cells, which might be attributed to inactivation of the Wnt/β-catenin pathway. Taken together, this study provided a new insight into the role of ALX1 as a therapeutic target for melanoma treatment.

Bittersweet tumor development and progression: Emerging roles of epithelial plasticity glycosylations

Altered metabolism is one of the hallmarks of cancer. The best-known cancer metabolic anomaly is an increase in aerobic glycolysis, which generates ATP and other basic building blocks, such as nucleotides, lipids, and proteins to support tumor cell growth and survival. Epithelial plasticity (EP) programs such as the epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET) are evolutionarily conserved processes that are essential for embryonic development. EP also plays an important role during tumor progression toward metastasis and treatment resistance, and new roles in the acceleration of tumorigenesis have been found. Recent evidence has linked EMT-related transcriptomic alterations with metabolic reprogramming in cancer cells, which include increased aerobic glycolysis. More recent studies have revealed a novel connection between EMT and altered glycosylation in tumor cells, in which EMT drives an increase in glucose uptake and flux into the hexosamine biosynthetic pathway (HBP). The HBP is a side-branch pathway from glycolysis which generates the end product uridine-5'-diphosphate-N-acetylglucosamine (UDP-GlcNAc). A key downstream utilization of UDP-GlcNAc is for the post-translational modification O-GlcNAcylation which involves the attachment of the GlcNAc moiety to Ser/Thr/Asn residues of proteins. Global changes in protein O-GlcNAcylation are emerging as a general characteristic of cancer cells. In our recent study, we demonstrated that the EMT-HBP-O-GlcNAcylation axis drives the O-GlcNAcylation of key proteins such as c-Myc, which previous studies have shown to suppress oncogene-induced senescence (OIS) and contribute to accelerated tumorigenesis. Here, we review the HBP and O-GlcNAcylation and their putative roles in driving EMT-related cancer processes with examples to illuminate potential new therapeutic targets for cancer.

The Function of Fucosylation in Progression of Lung Cancer

Lung cancer is a disease that influences human health and has become a leading cause of cancer mortality worldwide. However, it is frequently diagnosed at the advanced stage. It is necessary by means of biology to identify specific lung tumor biomarkers with high sensitivity. Glycosylation is one of the most important post-translational modifications and is related to many different diseases. It is involved in numerous essential biological processes, such as cell proliferation, differentiation, migration, cell-cell integrity and recognition, and immune modulation. However, little was known about deregulation of glycosylation in lung cancer and contribution to tumor–microenvironment interactions. Among the numerous glycosylations, fucosylation is the most common modification of glycoproteins and glycosylated oligosaccharides. Increased levels of fucosylation have been detected in various pathological conditions, as well as in lung cancer. In this article, we reviewed the role of fucosylation in lung cancer. We highlighted some of the fucosylation alterations currently being pursued in sera or tissues of lung cancer patients. Moreover, we elaborated on the regulation mechanism of fucosylation in proliferative invasion and metastasis of lung tumor cells. In summary, alterations in fucosylation provide potential biomarkers and therapeutic targets in lung cancer.

TBL1XR1 as a potential therapeutic target that promotes epithelial-mesenchymal transition in lung squamous cell carcinoma

Transducin (β)-like 1 X-linked receptor 1 (TBL1XR1) has been demonstrated to serve a vital role in tumor progression. However, the biological role and molecular mechanisms of TBL1XR1 in lung squamous cell carcinoma (SCC) remain largely unknown. The purpose of the present study was to investigate the biological role of TBL1XR1 and its mechanism in lung SCC. TBL1XR1 was expressed in a human bronchial epithelial cell line and in lung SCC cell lines. The present study analyzed TBL1XR1-induced proliferation, invasion and migration abilities in vitro using the cell counting kit-8 assay, cell invasion assay and wound healing assay, respectively. This study examined the effects of TBL1XR1 on epithelial-mesenchymal transition (EMT) in lung SCC cells and activation of the transforming growth factor (TGF)-β/mothers against decapentaplegic homolog (Smad) signaling pathway by western blotting. The results indicated that TBL1XR1 was upregulated in lung SCC cells. Overexpression of TBL1XR1 increased the rate of cell proliferation compared with the control group. In vitro, overexpression of TBL1XR1 promoted cell invasion and migration ability compared with the control group. In addition, overexpression of TBL1XR1 produced a mesenchymal phenotype, while cells with downregulated TBL1XR1 produced an epithelial phenotype. Overexpression of TBL1XR1 significantly increased E-cadherin protein expression whilst snail family transcriptional repressor 1 (SNAI1), zinc finger E-box binding homebox 1 (ZEB1), p-Smad2/3, Smad2 and Smad3 protein expression was significantly reduced, compared with the control group. Downregulation of TBL1XR1 produced the opposite results. The present study indicated that TBL1XR1 contributed to lung SCC development and progression, and therefore TBL1XR1 may be a potential therapeutic target. TBL1XR1 may induce EMT of lung SCC cells through activation of the TGF-β/Smad signaling pathway.

N-glycosylation by N-acetylglucosaminyltransferase V enhances the interaction of CD147/basigin with integrin β1 and promotes HCC metastasis

While the importance of protein N-glycosylation in cancer cell migration is well appreciated, the precise mechanisms by which N-acetylglucosaminyltransferase V (GnT-V) regulates cancer processes remain largely unknown. In the current study, we report that GnT-V-mediated N-glycosylation of CD147/basigin, a tumor-associated glycoprotein that carries β1,6-N-acetylglucosamine (β1,6-GlcNAc) glycans, is upregulated during TGF-β1-induced epithelial-to-mesenchymal transition (EMT), which correlates with tumor metastasis in patients with hepatocellular carcinoma (HCC). Interruption of β1,6-GlcNAc glycan modification of CD147/basigin decreased matrix metalloproteinase (MMP) expression in HCC cell lines and affected the interaction of CD147/basigin with integrin β1. These results reveal that β1,6-branched glycans modulate the biological function of CD147/basigin in HCC metastasis. Moreover, we showed that the PI3K/Akt pathway regulates GnT-V expression and that inhibition of GnT-V-mediated N-glycosylation suppressed PI3K signaling. In summary, β1,6-branched N-glycosylation affects the biological function of CD147/basigin and these findings provide a novel approach for the development of therapeutic strategies targeting metastasis. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

The role of N-glycans in colorectal cancer progression: potential biomarkers and therapeutic applications

Changes in glycosylation, which is one of the most common protein post-translational modifications, are considered to be a hallmark of cancer. N-glycans can modulate cell migration, cell-cell adhesion, cell signaling, growth and metastasis. The colorectal cancer (CRC) is a leading cause of cancer-related mortality and the correlation between CRC progression and changes in the pattern of expression of N-glycans is being considered in the search for new biomarkers. Here, we review the role of N-glycans in CRC cell biology. The perspectives on emerging N-glycan-related anticancer therapies, along with new insights and challenges, are also discussed.

Vasohibin 2 as a potential predictor of aggressive behavior of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a subtype breast cancer with aggressive behavior, advanced disease status and poor prognosis. Because of the lack of targeting agents and limited therapeutic options, treatment of TNBC remains a great clinical challenge. Vasohibin 2 (VASH2) was previously identified as an angiogenic factor, but its role in TNBC tumorigenesis is unknown. Using quantitative PCR and western blot analyses, we found that VASH2 is overexpressed in TNBC cells and tissues. Knockdown of VASH2 via siRNA inhibited the proliferation of the TNBC cell lines by delaying cell cycle progression and increasing apoptosis. Further analyses showed that the VASH2-mediated increase in the transcription of fibroblast growth factor-2, vascular endothelial growth factor and vasohibin 1 may be the mechanism underlying these effects. Taken together, these data indicate that VASH2 is abnormally expressed in TNBC, indicating a novel and important role for VASH2 in TNBC malignant transformation.

Glycosylation is a global target for androgen control in prostate cancer cells

Changes in glycan composition are common in cancer and can play important roles in all of the recognised hallmarks of cancer. We recently identified glycosylation as a global target for androgen control in prostate cancer cells and further defined a set of 8 glycosylation enzymes (GALNT7, ST6GalNAc1, GCNT1, UAP1, PGM3, CSGALNACT1, ST6GAL1 and EDEM3), which are also significantly upregulated in prostate cancer tissue. These 8 enzymes are under direct control of the androgen receptor (AR) and are linked to the synthesis of important cancer-associated glycans such as sialyl-Tn (sTn), sialyl LewisX (SLeX), O-GlcNAc and chondroitin sulfate. Glycosylation has a key role in many important biological processes in cancer including cell adhesion, migration, interactions with the cell matrix, immune surveillance, cell signalling and cellular metabolism. Our results suggest that alterations in patterns of glycosylation via androgen control might modify some or all of these processes in prostate cancer. The prostate is an abundant secretor of glycoproteins of all types, and alterations in glycans are, therefore, attractive as potential biomarkers and therapeutic targets. Emerging data on these often overlooked glycan modifications have the potential to improve risk stratification and therapeutic strategies in patients with prostate cancer.

FAT4 functions as a tumor suppressor in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer that is often associated with biologic behavior with frequent distant metastasis. FAT tumor suppressor homolog 4 (FAT4), a cadherin-related protein, is involved in a variety of biological processes as a tumor suppressor; however, the role of FAT4 in TNBC is still unclear. The aim of our study was to identify the role of FAT4 in TNBC and examine the underlying molecular mechanisms. The expression of FAT4 was evaluated by immunohistochemistry, western blotting, and qRT-PCR in a series of TNBC tissues. The effects of FAT4 on the ability of cell proliferation, migration, and invasion were assessed by MTT assay and migration and invasion assays. We demonstrated that the repression of FAT4 by shRNA could promote TNBC progression. Taken together, our findings provide evidence for a role of the FAT4 cluster as a tumor suppressor in TNBC patients and may serve as potential novel targets for the treatment of TNBC.

Sialylated β1, 6 branched N-glycans modulate the adhesion, invasion and metastasis of hepatocarcinoma cells

The mouse hepatocarcinoma cell lines Hca-F and Hca-P have been derived from hepatocarcinoma in mice and metastasize only to the lymph node. Hca-F cells displayed greater lymphatic metastasis ability than Hca-P cells. When the two cell lines were compared for cell surface sialylated β1,6 branched N-glycans by flow cytometry using L-PHA and SNA, Hca-F cells were found to express significantly higher levels. To explore the effect of increased sialylated β1,6 branched N-glycans on hepatocarcinoma progression, we inhibit their expression in Hca-F cells by using swainsonine treatment and RNA interference. We found that swainsonine treatment or GnT-V-shRNA transfection significantly inhibited the formation of β1,6 branched N-glycans, and partially inhibited the expression of α2,6 sialic acids. Knockdown of sialylated β1,6 branched N-glycans significantly attenuated the invasive and metastatic capability both in vitro and in vivo. Blockade of α2,6 sialic acid expression on Hca-F cell surface by the treatment with neuraminidase caused reduction in cellular adherence to lymph node. In addition, knockdown of sialylated β1,6 branched N-glycans could decrease the expression of Notch1, NICD1, NICD2 and HES1 in Hca-F cells. Collectively, these findings suggest that increased sialylated β1,6 branched N-glycans may contribute to hepatocarcinoma progression by altering the adhesive, invasive and metastatic ability to lymph node via Notch signaling pathway.

Silencing of Prrx1b suppresses cellular proliferation, migration, invasion and epithelial-mesenchymal transition in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a highly aggressive tumour subtype associated with poor prognosis. The mechanisms involved in TNBC progression remains largely unknown. To date, there are no effective therapeutic targets for this tumour subtype. Paired-related homeobox 1b (Prrx1b), one of major isoforms of Prrx1, has been identified as a new epithelial-mesenchymal transition (EMT) inducer. However, the function of Prrx1b in TNBC has not been elucidated. In this study, we found that Prrx1b was significantly up-regulated in TNBC and associated with tumour size and vascular invasion of breast cancer. Silencing of Prrx1b suppressed the proliferation, migration and invasion of basal-like cancer cells. Moreover, silencing of Prrx1b prevented Wnt/β-catenin signaling pathway and induced the mesenchymal-epithelial transition (MET). Taken together, our data indicated that Prrx1b may be an important regulator of EMT in TNBC cells and a new therapeutic target for interventions against TNBC invasion and metastasis.

Meta-Analysis of EMT Datasets Reveals Different Types of EMT

As a critical process during embryonic development, cancer progression and cell fate conversions, epithelial-mesenchymal transition (EMT) has been extensively studied over the last several decades. To further understand the nature of EMT, we performed meta-analysis of multiple microarray datasets to identify the related generic signature. In this study, 24 human and 17 mouse microarray datasets were integrated to identify conserved gene expression changes in different types of EMT. Our integrative analysis revealed that there is low agreement among the list of the identified signature genes and three other lists in previous studies. Since removing the datasets with weakly-induced EMT from the analysis did not significantly improve the overlapping in the signature-gene lists, we hypothesized the existence of different types of EMT. This hypothesis was further supported by the grouping of 74 human EMT-induction samples into five distinct clusters, and the identification of distinct pathways in these different clusters of EMT samples. The five clusters of EMT-induction samples also improves the understanding of the characteristics of different EMT types. Therefore, we concluded the existence of different types of EMT was the possible reason for its complex role in multiple biological processes.

Epithelial-to-Mesenchymal Transition of RPE Cells In Vitro Confers Increased β1,6-N-Glycosylation and Increased Susceptibility to Galectin-3 Binding

Epithelial-to-mesenchymal transition (EMT) of retinal pigment epithelial cells is a crucial event in the onset of proliferative vitreoretinopathy (PVR), the most common reason for treatment failure in retinal detachment surgery. We studied alterations in the cell surface glycan expression profile upon EMT of RPE cells and focused on its relevance for the interaction with galectin-3 (Gal-3), a carbohydrate binding protein, which can inhibit attachment and spreading of human RPE cells in a dose- and carbohydrate-dependent manner, and thus bares the potential to counteract PVR-associated cellular events. Lectin blot analysis revealed that EMT of RPE cells in vitro confers a glycomic shift towards an abundance of Thomsen-Friedenreich antigen, poly-N-acetyllactosamine chains, and complex-type branched N-glycans. Using inhibitors of glycosylation we found that both, binding of Gal-3 to the RPE cell surface and Gal-3-mediated inhibition of RPE attachment and spreading, strongly depend on the interaction of Gal-3 with tri- or tetra-antennary complex type N-glycans and sialylation of glycans but not on complex-type O-glycans. Importantly, we found that β1,6 N-acetylglucosaminyltransferase V (Mgat5), the key enzyme catalyzing the synthesis of tetra- or tri-antennary complex type N-glycans, is increased upon EMT of RPE cells. Silencing of Mgat5 by siRNA and CRISPR-Cas9 genome editing resulted in reduced Gal-3 binding. We conclude from these data that binding of recombinant Gal-3 to the RPE cell surface and inhibitory effects on RPE attachment and spreading largely dependent on interaction with Mgat5 modified N-glycans, which are more abundant on dedifferentiated than on the healthy, native RPE cells. Based on these findings we hypothesize that EMT of RPE cells in vitro confers glycomic changes, which account for high affinity binding of recombinant Gal-3, particularly to the cell surface of myofibroblastic RPE. From a future perspective recombinant Gal-3 may disclose a therapeutic option allowing for selectively targeting RPE cells with pathogenic relevance for development of PVR.

Glycans and cancer: role of N-glycans in cancer biomarker, progression and metastasis, and therapeutics

Glycosylation is catalyzed by various glycosyltransferase enzymes which are mostly located in the Golgi apparatus in cells. These enzymes glycosylate various complex carbohydrates such as glycoproteins, glycolipids, and proteoglycans. The enzyme activity of glycosyltransferases and their gene expression are altered in various pathophysiological situations including cancer. Furthermore, the activity of glycosyltransferases is controlled by various factors such as the levels of nucleotide sugars, acceptor substrates, nucleotide sugar transporters, chaperons, and endogenous lectin in cancer cells. The glycosylation results in various functional changes of glycoproteins including cell surface receptors and adhesion molecules such as E-cadherin and integrins. These changes confer the unique characteristic phenotypes associated with cancer cells. Therefore, glycans play key roles in cancer progression and treatment. This review focuses on glycan structures, their biosynthetic glycosyltransferases, and their genes in relation to their biological significance and involvement in cancer, especially cancer biomarkers, epithelial-mesenchymal transition, cancer progression and metastasis, and therapeutics. Major N-glycan branching structures which are directly related to cancer are β1,6-GlcNAc branching, bisecting GlcNAc, and core fucose. These structures are enzymatic products of glycosyltransferases, GnT-V, GnT-III, and Fut8, respectively. The genes encoding these enzymes are designated as MGAT5 (Mgat5), MGAT3 (Mgat3), and FUT8 (Fut8) in humans (mice in parenthesis), respectively. GnT-V is highly associated with cancer metastasis, whereas GnT-III is associated with cancer suppression. Fut8 is involved in expression of cancer biomarker as well as in the treatment of cancer. In addition to these enzymes, GnT-IV and GnT-IX (GnT-Vb) will be also discussed in relation to cancer.