sLeX Expression Research Articles

Altered expression of Sialyl Lewis X in experimental models of Parkinson’s disease

The mechanisms underlying neurodegeneration in Parkinson’s disease (PD) are still not fully understood. Glycosylation is an important post-translational modification that affects protein function, cell-cell contacts and inflammation and can be modified in pathologic conditions. Although the involvement of aberrant glycosylation has been proposed for PD, the knowledge of the diversity of glycans and their role in PD is still minimal. Sialyl Lewis X (sLeX) is a sialylated and fucosylated tetrasaccharide with essential roles in cell-to-cell recognition processes. Pathological conditions and pro-inflammatory mediators can up-regulate sLeX expression on cell surfaces, which has important consequences in intracellular signalling and immune function. Here, we investigated the expression of this glycan using in vivo and in vitro models of PD. We show the activation of deleterious glycation-related pathways in mouse striatum upon treatment with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a toxin-based model of PD. Importantly, our results show that MPTP triggers the presentation of more proteins decorated with sLeX in mouse cortex and striatum in a time-dependent manner, as well as increased mRNA expression of its rate-limiting enzyme fucosyltransferase 7. sLeX is expressed in neurons, including dopaminergic neurons, and microglia. Although the underlying mechanism that drives increased sLeX epitopes, the nature of the protein scaffolds and their functional importance in PD remain unknown, our data suggest for the first time that sLeX in the brain may have a role in neuronal signalling and immunomodulation in pathological conditions.Key messagesMPTP triggers the presentation of proteins decorated with sLeX in mouse brain.MPTP triggers the expression of sLeX rate-limiting enzyme FUT 7 in striatum.sLeX is expressed in neurons, including dopaminergic neurons, and microglia.sLeX in the brain may have a role in neuronal signalling and immunomodulation.

Therapeutic Effects of an Anti-Sialyl Lewis x Antibody in a Murine Model of Acute Lung Injury.

Acute respiratory distress syndrome is a life-threatening acute lung injury (ALI) characterized by the destruction of alveoli leading to pulmonary edema. The infiltration and activation of inflammatory cells and production of inflammatory cytokines are both involved in the pathogenesis of ALI. Here, we show that the infiltration of neutrophils, major inflammatory cells causing ALI, into the lung is mediated by sialyl Lewis x (sLex) glycans, which can be efficiently suppressed by a monoclonal antibody (mAb) against these glycans. In fucosyltransferase-IV and -VII double-deficient mice lacking sLex expression, neutrophil infiltration into the lung was significantly suppressed compared with that observed in wild-type mice in a lipopolysaccharide (LPS)-induced ALI model. Administration of a highly specific anti-sLex mAb F2 3 hours after LPS administration significantly suppressed pulmonary neutrophil infiltration, accompanied by the reduced induction of inflammatory cytokines. It was consistently indicated from ex vivo cell rolling assay that mAb F2 blocked the rolling of mouse neutrophils on P-selectin-expressing cells. Overall, these results indicate that the sLex glycan could serve as a therapeutic target against ALI, and also that mAb F2 would be useful for specific targeting of this glycan.

The Sialyl Lewis X Glycan Receptor Facilitates Infection of Subtype H7 Avian Influenza A Viruses.

Subtype H7 avian influenza A viruses (IAVs) are enzootic in wild aquatic birds and have caused sporadic spillovers into domestic poultry and humans. Here, we determined the distribution of fucosylated α2,3 sialoglycan (i.e., sialyl Lewis X [SLeX]) in chickens and five common dabbling duck species and the association between SLeX and cell/tissue/host tropisms of H7 IAVs. Receptor binding analyses showed that H7 IAVs bind to both α2,3-linked (SA2,3Gal) and α2,6-linked sialic acids (SA2,6Gal), but with a higher preference for SLeX; H7 IAVs replicated more efficiently in SLeX-overexpressed than SLeX-deficient MDCK cells. While chickens and all tested dabbling ducks expressed abundant SA2,3Gal and SA2,6Gal, SLeX was detected in both respiratory and gastrointestinal tissues of chickens and mallard ducks and in only the respiratory tissues of gadwall, green-wing teal, and northern shoveler but not in wood ducks. Viral-tissue binding assays showed that H7 IAVs bind to chicken colon crypt cells that express SLeX but fewer bind to mallard colon crypt cells, which do not express SLeX; H7 IAVs bind efficiently to epithelial cells of all tissues expressing SA2,3Gal. High viral replication was identified in both chickens and mallards infected with an H7 virus, regardless of SLeX expression, and viruses were detected in all cells to the same degree as viruses detected in the viral-tissue binding assays. In summary, this study suggests that SLeX facilitates infection of H7 viruses, but other types of SA2,3Gal glycan receptors shape the tissue/host tropisms of H7 IAVs. IMPORTANCE In addition to causing outbreaks in domestic poultry, subtype H7 IAVs can cause sporadic spillover infections in lower mammals and humans. In this study, we showed that SLeX expression varies among wild dabbling ducks. Although it facilitated virus binding and affected infection of H7 IAV in cells, SLeX expression is not the only determinant of viral replication at either the tissue or host level. This study suggested that access to heterologous SA2,3Gal glycan receptors, including fucosylated α2,3-linked sialoglycans, shape tissue and host tropism of H7 IAVs in aquatic wild birds.

Refining the migration and engraftment of short-term and long-term HSCs by enhancing homing-specific adhesion mechanisms

AbstractIn contrast to the short-term (ST) CD34+ stem cells, studies have suggested that long-term (LT) hematopoietic stem cells (HSCs) found in the CD34− stem cell pool have trouble migrating and engrafting when introduced through IV. To understand why these deficiencies exist, we set out to fully elucidate the adhesion mechanisms used by ST and LT-HSCs to migrate to the bone marrow(BM). Specifically focusing on murine ST-HSCs (Flk2−CD34+) and LT-HSCs (Flk2−CD34−), we observed a distinctive expression pattern of BM homing effectors necessary for the first step, namely sialyl Lewis-X (sLex) (ligand for E-selectin), and the second step, namely CXCR4 chemokine receptor (receptor for SDF-1). sLex expression was higher on Flk2−CD34+ ST-HSCs (>60%) compared with Flk2−CD34− LT-HSCs (<10%), which correlated to binding to E-selectin. Higher concentrations of CXCR4 were observed on Flk2−CD34+ ST-HSCs compared with Flk2−CD34− LT-HSCs. Interestingly, the expression of CD26, a peptidase known to deactivate chemokines (ie, SDF-1), was higher on Flk2−CD34− LT-HSCs. Given that both E-selectin–binding and CXCR4-mediated migration are compromised in Flk2−CD34− LT-HSCs, we aimed to enhance their ability to migrate using recombinant human fucosyltransferase 6 (rhFTVI) and the CD26 inhibitor, Dip A (diprotin A). To this end, we observed that although LT-HSCs expressed low concentrations of sLex, they were able to engraft when transplanted into recipient mice. Moreover, although both CD26 inhibition and fucosylation enhanced migration of both HSC populations in vitro, only pretreatment of LT-HSCs with Dip A enhanced engraftment in vivo after transplantation into recipient mice. Remarkably, fucosylation of Flk2−CD34+ ST-HSCs consistently led to their ability to transplant secondary recipients. These data suggest that using fucosylation and Dip A to overcome the molecular disparity in adhesion mechanisms among ST-HSCs and LT-HSCs differentially influences their abilities to migrate and engraft in vivo and promotes the ability of ST-HSCs to engraft secondary recipient mice, the gold standard for testing functionality of LT-HSCs.

Neutrophils aid cellular therapeutics by enhancing glycoengineered stem cell recruitment and retention at sites of inflammation

The efficacy of cell-based therapies relies on targeted payload delivery and enhanced cell retention. In vitro and in vivo studies suggest that the glycoengineering of mesenchymal and cardiosphere-derived cells (CDCs) may enhance such recruitment at sites of injury. We evaluated the role of blood cells in amplifying this recruitment. Thus, the human α(1,3)fucosyltransferase FUT7 was stably expressed in CDCs, sometimes with P-selectin glycoprotein ligand-1 (PSGL-1/CD162). Such FUT7 over-expression resulted in cell-surface sialyl Lewis-X (sLeX) expression, at levels comparable to blood neutrophils. Whereas FUT7 was sufficient for CDC recruitment on substrates bearing E-selectin under flow, PSGL-1 co-expression was necessary for P-/L-selectin binding. In both cone-plate viscometer and flow chamber studies, chemokine driven neutrophil activation promoted the adhesion of glycoengineered-CDCs to blood cells. Here, blood neutrophils activated upon contact with IL-1β stimulated endothelial cells, amplified glycoengineered-CDC recruitment. In vivo, local inflammation in a mouse ear elicited both glycoengineered-CDC and peripheral blood neutrophil homing to the inflamed site. Glycoengineering CDCs also resulted in enhanced (~16%) cell retention at 24 h in a murine myocardial infarction model, with CDCs often co-localized with blood neutrophils. Overall, peripheral blood neutrophils, activated at sites of injury, may enhance recruitment of glycoengineered cellular therapeutics via secondary capture mechanisms.

FUT6 deficiency compromises basophil function by selectively abrogating their sialyl-Lewis x expression

Sialyl-Lewis x (sLex, CD15s) is a tetra-saccharide on the surface of leukocytes required for E-selectin-mediated rolling, a prerequisite for leukocytes to migrate out of the blood vessels. Here we show using flow cytometry that sLex expression on basophils and mast cell progenitors depends on fucosyltransferase 6 (FUT6). Using genetic association data analysis and qPCR, the cell type-specific defect was associated with single nucleotide polymorphisms (SNPs) in the FUT6 gene region (tagged by rs17855739 and rs778798), affecting coding sequence and/or expression level of the mRNA. Heterozygous individuals with one functional FUT6 gene harbor a mixed population of sLex+ and sLex- basophils, a phenomenon caused by random monoallelic expression (RME). Microfluidic assay demonstrated FUT6-deficient basophils rolling on E-selectin is severely impaired. FUT6 null alleles carriers exhibit elevated blood basophil counts and a reduced itch sensitivity against insect bites. FUT6-deficiency thus dampens the basophil-mediated allergic response in the periphery, evident also in lower IgE titers and reduced eosinophil counts.

SLex expression in invasive micropapillary breast carcinoma is associated with poor prognosis and can be combined with MUC1/EMA as a supplementary diagnostic indicator.

Objective:Mucin 1 (MUC1/EMA) and sialyl Lewis X (sLex) indicate polarity reversal in invasive micropapillary carcinoma (IMPC). The purpose of this study was to evaluate the expression of MUC1/EMA and sLex and to assess their diagnostic and prognostic value in patients with IMPC.Methods:The expression of sLex and MUC1/EMA in 100 patients with IMPC and a control group of 89 patients with invasive ductal carcinoma not otherwise specified (IDC-NOS) were analyzed with IHC. Fresh tumor tissues were collected from patients with IMPC or IDC-NOS for primary culture and immunofluorescence analysis.Results:The rate of nodal metastasis was higher in patients with IMPC than those with IDC-NOS, and IMPC cells tended to express more sLex and MUC1/EMA in the cytomembranes (the stroma-facing surfaces of the micropapillary clusters) than IDC-NOS cells. In IMPC, high cytomembrane expression of sLex, but not MUC1/EMA, indicated poor prognosis. In addition, among the 100 patients with IMPC, 10 patients had sLex+/EMA– expression patterns, and 8 patients had sLex–/EMA+ expression patterns. The primary IMPC cells were suspended, non-adherent tumor cell clusters, whereas the primary IDC cells were adherent tumor cells. Immunofluorescence analysis showed that MUC1/EMA and sLex were co-expressed on the cytomembranes in IMPC cell clusters and in the cytoplasm in IDC-NOS cells.Conclusions:sLex can be used as a prognostic indicator and can be combined with MUC1/EMA as a complementary diagnostic indicator to avoid missed IMPC diagnosis.

Terminally sialylated and fucosylated complex N-glycans are involved in the malignant behavior of high-grade glioma.

Gliomas are the most common intracranial primary tumors, for which very few therapeutic options are available. The most malignant subtype is the glioblastoma, a disease associated with a 5-year survival rate lower than 5%. Given that research in glycobiology continues highlighting the role of glycans in tumor cell biology, it offers an interesting niche for the search of new therapeutic targets. In this study, we characterized aberrant glycosylation and its impact on cell biology over a broad panel of high- and low-grade glioma cell lines. Results show high expression of terminal Lewis glycans, mainly SLex, and overexpression of sialyl- and fucosyltransferases involved in their biosynthesis in high-grade glioma cell lines. Moreover, we report an association of complex multi-antennary N-glycans presenting β1,6-GlcNAc branches with the high-grade glioma cells, which also overexpressed the gene responsible for these assemblies, MGAT5. In addition, downmodulation of N-glycosylation by treatment with the inhibitors Tunicamycin/Swainsonine or MGAT5 silencing decreased SLex expression, adhesion and migration in high-grade glioma cells. In contrast, no significant changes in these cell capacities were observed in low-grade glioma after treatment with the N-glycosylation inhibitors. Furthermore, inhibition of histone deacetylases by Trichostatin A provoked an increase in the expression of SLex and its biosynthetic related glycosyltransferases in low-grade glioma cells. Our results describe that aggressive glioma cells show high expression of Lewis glycans anchored to complex multi-antennary N-glycans. This glycophenotype plays a key role in malignant cell behavior and is regulated by histone acetylation dependent mechanisms.

SLeX Expression Delineates Distinct Functional Subsets of Human Blood Central and Effector Memory T Cells.

Sialyl Lewis X (sLeX) regulates T cell trafficking from the vasculature into skin and sites of inflammation, thereby playing a critical role in immunity. In healthy persons, only a small proportion of human blood T cells express sLeX, and their function is not fully defined. Using a combination of biochemical and functional studies, we find that human blood sLeX+CD4+T cells comprise a subpopulation expressing high levels of Th2 and Th17 cytokines, chemokine receptors CCR4 and CCR6, and the transcription factors GATA-3 and RORγT. Additionally, sLeX+CD4+T cells exclusively contain the regulatory T cell population (CD127lowCD25high and FOXP3+) and characteristically display immune-suppressive molecules, including the coinhibitor receptors PD-1 and CTLA-4. Among CD8+T cells, sLeX expression distinguishes a subset displaying low expression of cytotoxic effector molecules, perforin and granzyme β, with reduced degranulation and CD57 expression and, consistently, marginal cytolytic capacity after TCR engagement. Furthermore, sLeX+CD8+T cells present a pattern of features consistent with Th cell-like phenotype, including release of pertinent Tc2 cytokines and elevated expression of CD40L. Together, these findings reveal that sLeX display is associated with unique functional specialization of both CD4+ and CD8+T cells and indicate that circulating T cells that are primed to migrate to lesional sites at onset of inflammation are not poised for cytotoxic function.

A Atractylodes lancea polysaccharide inhibits metastasis of human osteosarcoma U-2 OS cells by blocking sialyl Lewis X (sLex )/E-selectin binding.

In this study, a new water and alkaline‐soluble polysaccharide (ALP), with an average molecular weight of 6.63 × 104 Da, was successfully purified from the rhizomes of Atractylodes lancea. GC analysis demonstrated that ALP was a kind of glucan. The effect of the ALP on the interaction between E‐selectin and sialyl Lewis X (sLex) was examined in human osteosarcoma U‐2 OS cells. It was obvious that the expression of sLex antigen on the surface of U‐2 OS cells was visible under fluorescence microscopy. The addition of ALP (0.5, 1 and 2 mg/mL) resulted in a marked inhibition on the adhesion, migration and invasion of U‐2 OS cells to human umbilical vein endothelial cells (HUVECs), which was achieved by the decreased sLex expression on U‐2 OS cells. Additionally, the induction of apoptosis can be observed in U‐2 OS cells following ALP treatment using TUNEL staining and Annexin V‐FITC/PI double‐staining analysis on flow cytometry. In conclusion, these results indicated that ALP exerted anti‐metastatic activity towards osteosarcoma cells via inhibition of sLex/E‐selectin binding, which suggested that ALP could be a potent agent for human osteosarcoma intervention.

Abstract 365: The role of protein fucosylation in lung cancer progression

Abstract Lung cancer is the leading cause of cancer-associated deaths worldwide. Metabolic reprogramming facilitates the growth advantage of cancer cells and is a hallmark of cancer. Although multiple studies have investigated the cancer-specific metabolic status of lung cancer, it remains unclear. Aberrant fucosylation, which results from the deficiency or overexpression of fucosyltransferases, is also associated with a variety of cancers, including lung cancer. However, the role and regulatory mechanism(s) of fucosylation in lung cancer remain largely unknown. In order to elucidate the specific metabolic status of human lung cancer tissues, we performed metabolomics profiling of paired tumor and normal tissues from patients with non-small cell lung cancer (NSCLC) using both capillary electrophoresis mass-spectrometry (CE-MS) and imaging mass-spectrometry (I-MS). We used principle component analysis (PCA) to confirm that human lung cancer has distinctive metabolic patterns. We revealed upregulation of the GDP-L-fucose de novo pathway, which regulates the level of fucosylated glycoproteins, in lung cancer tissues compared to the adjacent non-malignant lung tissues. In order to elucidate the mechanisms by which fucosylation is increased in lung cancer tissues, gene expression of fucosyltransferases (FUT1-9) were evaluated. We confirmed that fucosyltransferase 3 (FUT3) expression was increased in a significant proportion of human primary lung adenocarcinoma samples and was correlated with sLeX expression. A fucosylation inhibitor, 6-alkynyl-fucose, inhibited the proliferation and invasion of lung cancer cell lines with high endogenous FUT3 expression in vitro. Exogenous FUT3-overexpressing lung cancer cells did not show increased proliferation, but showed significantly increased invasion and adhesion activities in vitro. In order to confirm whether FUT3 promoted metastasis of A549 cells in an experimental lung metastatic mouse model, A549 lung cancer cells expressing EGFP (A549-EGFP) and A549 lung cancer cells overexpressing FUT3 (A549-FUT3) were intravenously administered to BALB/C nude mice and the numbers of metastatic nodules in the lungs were counted after 8 weeks. In concordance with our observations in vitro, there was no significant difference in tumor growth between the A549-EGFP and A549-FUT3 treatments in vivo. Interestingly, injection of A549-FUT3 resulted in an increase in the number of lung metastases compared to the injection of A549-EGFP, suggesting that FUT3 is a positive regulator of cancer invasion and metastasis. Furthermore, high expression of FUT3 in lung cancer tissues predicted a poorer prognosis for patients with lung adenocarcinoma. These findings highlight the important roles of protein fucosylation in lung cancer progression and provide the preclinical rationale to target this pathway in lung cancer treatment. Citation Format: Keita Masuzawa, Hiroyuki Yasuda, Atsushi Matsuda, Hideki Terai, Yuki Sugiura, Junko Hamamoto, Daisuke Arai, Shizuko Kagawa, Katsura Emoto, Shinnosuke Ikemura, Ichiro Kawada, Kenzo Soejima, Koichi Fukunaga. The role of protein fucosylation in lung cancer progression [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 365.

Overcoming a Critical Obstacle Towards Effective and Safe CAR T-Cell Therapeutics

▪Chimeric Antigen Receptor (CAR) T-cells have shown great promise in achieving stable remission of B cell acute lymphoblastic leukemia and are being utilized to treat a variety of other hematologic and non-hematologic malignancies. However, this therapy is associated with significant adverse effects (e.g., cytokine release syndrome and neurotoxicity), largely related to the high cell doses requisite for achieving therapeutic response(s). E-selectin, an endothelial molecule expressed on microvessels of bone marrow and tumors, is critical for extravasation of blood-borne cells. E-selectin binds to sialyl Lewis X (sLeX), a sialofucosylated tetrasaccharide motif decorating specialized glycoproteins and glycolipids on circulating cells. Given that better site-specific delivery of administered CAR T-cells would yield more efficacious immunotherapy while limiting off-target effects, we sought to determine whether these cells express E-selectin ligands.CAR T-cells targeting glioblastoma were created by lentiviral transduction of human T-cells with anti-EGFR-BBz-mCherry CAR construct. Transduced cells (T) and untransduced cells (UT) were subjected to stimulation with anti-CD3/CD28 microbeads followed by culture expansion in presence of interleukin-2 (IL2) for 10 days (“10”). In some cases, cells were expanded for 7 additional days by co-culturing with irradiated U87 glioblastoma cell line (“17”). These cells were compared to resting T-cells (non-expanded; NE). Expression of sLeX on each T-cell population (NE, T10, T17, UT10 or UT17) was measured by flow cytometry.We observed that NE T-cells display moderate expression of sLeX as previously reported in literature (Silva, Fung et al., J. Immunol., 2017). T10 CAR T-cells display significantly lower sLeX compared to NE T-cells, while T17 CAR T-cells completely lack sLeX. Similar pattern of sLeX expression was observed on UT10 and UT17 populations, indicating that culture expansion progressively depletes sLeX expression on T-cells, regardless of transduction with a CAR construct.To analyze the capacity of CAR T-cells to bind E-selectin under hemodynamic shear conditions, we utilized a microfluidic flow chamber wherein T-cells are perfused over human umbilical vein endothelial cell (HUVEC) monolayers treated with TNFα to induce E-selectin expression. Consistent with the observed cell surface sLeX levels, NE T-cells display robust rolling interactions on TNFα-stimulated HUVECs, whereas T10 and T17 CAR T-cells exhibit essentially no endothelial interactions. To overcome this shortfall, we assessed whether sLeX expression can be enforced on the CAR T-cell surface via glycoengineering using glycosyltransferase programmed stereosubstitution (GPS), i.e., fucosyltransferase-mediated α(1,3)-fucose installation that converts terminal sialylated type 2 lactosamines to sLeX. GPS engenders markedly increased CAR T-cell sLeX expression, yielding full (100%) sLeX -expression of the CAR T-cell populations, while increasing sLeX expression from a baseline of 20-30% to maximally 60-70% of the NE T-cell populations. The glycoengineered CAR T-cells display markedly enhanced (>20 fold) adhesive interactions on TNFα-stimulated endothelial cells compared to that of unfucosylated CAR T-cells. Collectively, our data indicate that culture expansion induces down-regulation of endogenous α(1,3)-fucosylation, and, importantly, the missing fucose can be restored via GPS. Finally, to assess whether the enforced E-selectin binding has a meaningful biologic effect, we examined homing of GPS-modified cells to an E-selectin bearing bed (marrow) within 24 hours of intravenous administration. We consistently observed >3-fold increase in marrow infiltrates of culture-expanded GPS-modified T-cells compared to their unmodified counterparts.Overall, these results draw attention to an inherent inability of CAR T-cells to migrate to sites where they are needed. Our data reveal that culture expanded T-cells lack E-selectin binding capacity, however, sLeX display can be enforced by cell surface glycoengineering. Improved E-selectin binding yields superior tissue colonization. As such, glycoengineering CAR T-cells may translate into lowering of cell dosing, thereby improving both the efficacy and safety, and reducing both cell expansion and clinical care costs, of this promising therapeutic approach. DisclosuresMaus:kite therapeutics: Consultancy, Research Funding; windmil therapeutics: Consultancy; crispr therapeutics: Consultancy, Research Funding; agentus: Consultancy, Research Funding; novartis: Consultancy; adaptimmune: Consultancy. Sackstein:Warrior Therapeutics LLC: Equity Ownership, Patents & Royalties.

S-Nitrosocaptopril prevents cancer metastasis in vivo by creating the hostile bloodstream microenvironment against circulating tumor cells.

A perfect microenvironment facilitates the activated circulating tumor cells (CTCs) to spark the adhesion-invasion-extravasation metastatic cascade in their premetastatic niche. Platelet-CTC interaction contributes to the progression of tumor malignancy by protecting CTCs from shear stress and immunological assault, aiding CTCs entrapment in the capillary bed, enabling CTCs to successfully exit the bloodstream and enter the tissue, inducing epithelial-mesenchymal-like transition (EMT), and assisting in the establishment of metastatic foci. To prevent the cascade from sparking, we show that, the multifunctional S-nitrosocaptopril (CapNO) acts on both CTCs and platelets to interrupt platelet/CTCs interplay and adhesion to endothelium, thus inhibiting CTC-based pulmonary metastasis in vivo. The activated platelets cloak cancer HT29 cells, resulting in HT29-exhibiting platelet biomarkers CD61 and P-selectin positive. CapNO inhibits both sialyl Lewisx (Slex) expression on HT29 and ADP-induced activation of platelets through P-selectin- and GPIIb/IIIa-dependent mechanisms, confirmed by the corresponding antibody assay. CapNO inhibits platelet- or interleukin (IL)-1β-mediated adhesion between HT29 and endothelial cells, and micrometastatic formation in the lungs of immunocompetent syngeneic mouse models. CapNO have also shown the effects of vasodilation, anticoagulation, inhibition of matrix metalloproteinase-2 (MMP2) expression on cancer cells, and inhibition of cell adhesion molecules (CAMs) expression on vascular endothelium. Due to a series of the beneficial effects of CapNO, CTCs remain exposed to the hostile bloodstream environment and are vulnerable to death induced by shear stress and immune elimination. This new discovery provides a basis for CapNO used for cancer metastatic chemoprevention, and might suggest regulation of the CTCs bloodstream microenvironment as a new avenue for cancer metastatic prevention.

Optimizing human Treg immunotherapy by Treg subset selection and E-selectin ligand expression

While human Tregs hold immense promise for immunotherapy, their biologic variability poses challenges for clinical use. Here, we examined clinically-relevant activities of defined subsets of freshly-isolated and culture-expanded human PBMC-derived Tregs. Unlike highly suppressive but plastic memory Tregs (memTreg), naïve Tregs (nvTreg) exhibited the greatest proliferation, suppressive capacity after stimulation, and Treg lineage fidelity. Yet, unlike memTregs, nvTregs lack Fucosyltransferase VII and display low sLeX expression, with concomitant poor homing capacity. In vitro nvTreg expansion augmented their suppressive function, but did not alter the nvTreg sLeX-l°w glycome. However, exofucosylation of the nvTreg surface yielded high sLeX expression, promoting endothelial adhesion and enhanced inhibition of xenogeneic aGVHD. These data indicate that the immature Treg glycome is under unique regulation and that adult PBMCs can be an ideal source of autologous-derived therapeutic Tregs, provided that subset selection and glycan engineering are engaged to optimize both their immunomodulation and tropism for inflammatory sites.

Clinicopathological implications to micropapillary bladder urothelial carcinoma of the presence of sialyl Lewis X-decorated mucin 1 in stroma-facing membranes

ObjectivesBladder urothelial carcinoma (UC) comprises more than 90% of all bladder cancers. Among several UC variants, micropapillary UC (MPUC) is a rare one with high potential for lymphovascular invasion and subsequent lymph node metastasis. Histologically, MPUC is characterized by the presence of small papillary carcinoma cell clusters surrounded by lacunar spaces. Immunohistochemically, the outer circumference of these clusters, that is, the stroma-facing membrane of carcinoma cells, is reportedly almost invariably positive for mucin 1 (MUC1) protein and to a lesser extent for sialyl Lewis X (sLeX) carbohydrates; however, the clinicopathological implications of these expression patterns have not been fully investigated. Materials and methodsWe performed immunohistochemical analysis of MPUC (n = 11) and conventional UC (n = 57) for MUC1 and sLeX to determine whether these factors immunolocalized. Dual immunofluorescence staining was also carried out to assess MUC1 and sLeX colocalization. We also performed Western blot analysis of Chinese hamster ovary cells misexpressing both recombinant epitope-tagged MUC1 and glycosyltransferases enabling sLeX biosynthesis. ResultsMPUC samples preferentially exhibited both MUC1 protein and sLeX carbohydrate expression on the stroma-facing membrane of carcinoma cells. Based on univariate analysis, MUC1 expression in that pattern was positively correlated with tumor extension, lymphovascular invasion, lymph node metastasis, disease stage, and relatively poor patient prognosis. A comparable sLeX expression pattern also correlated positively with tumor extension and nodal metastasis. Based on multivariate analysis, localization of MUC1 and sLeX on the stroma-facing side of the membrane was positively correlated with lymph node metastasis. ConclusionsOverall, our immunofluorescence findings as well as immunoprecipitation analyses of Chinese hamster ovary cell transfectants strongly suggest that MUC1 is a potential scaffold protein for sLeX carbohydrates in MPUC. Both MUC1 and sLeX may cooperatively contribute to MPUC histogenesis and clinicopathological characteristics.

Inhibition of adhesion and metastasis of HepG2 hepatocellular carcinoma cells in vitro by DNA aptamer against sialyl Lewis X.

The sialyl Lewis X (SLex) antigen encoded by the FUT7 gene is the ligand of endotheliam-selectin (E-selectin). The combination of SLex antigen and E-selectin represents an important way for malignant tumor metastasis. In the present study, the effect of the SLex-binding DNA aptamer on the adhesion and metastasis of hepatocellular carcinoma HepG2 cells in vitro was investigated. Reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescence staining were conducted to detect the expression of FUT7 at both transcriptional and translational levels. The SLex expression in HepG2 cells treated with different concentrations of SLex-binding DNA aptamer was detected by flow cytometry. Besides, the adhesion, migration, and invasion of HepG2 cells were measured by cell adhesion assay, and the Transwell migration and invasion assay. The results showed that the FUT7 expression was up-regulated at both mRNA and protein levels in HepG2 cells. SLex-binding DNA aptamer could significantly decrease the expression of SLex in HepG2 cells. The cell adhesion assay revealed that the SLex-binding DNA aptamer could effectively inhibit the interactions between E-selectin and SLex in the HepG2 cells. Additionally, SLex-binding DNA aptamers at 20 nmol/L were found to have the similar effect to the monoclonal antibody CSLEX-1. The Transwell migration and invasion assay revealed that the number of penetrating cells on the down-side of Transwell membrane was significantly less in cells treated with 5, 10, 20 nmol/L SLex-binding DNA aptamer than those in the negative control group (P<0.01). Our study demonstrated that the SLex-binding DNA aptamer could significantly inhibit the in vitro adhesion, migration, and invasion of HepG2 cells, suggesting that the SLex-binding DNA aptamer may be used as a potential molecular targeted drug against metastatic hepatocellular carcinoma.

A Glycovariant of Human CD44 is Characteristically Expressed on Human Mesenchymal Stem Cells.

The clinical effectiveness of systemically administered human mesenchymal stem cells (hMSCs) depends on their capacity to engage vascular endothelium. hMSCs derived from bone marrow (BM-hMSCs) natively lack endothelial binding capacity, but express a CD44 glycovariant containing N-linked sialyllactosamines that can be α(1,3)-fucosylated using fucosyltransferase-VI (FTVI) to enforce sLeX decorations, thereby creating hematopoietic cell E-/L-selectin ligand (HCELL). HCELL expression programs potent shear-resistant adhesion of circulating cells to endothelial beds expressing E-selectin. An alternative source of hMSCs is adipose tissue (A-hMSCs), and we assessed whether A-hMSCs bind E-selectin and/or possess sialyllactosamine-decorated CD44 accessible to α(1,3)-fucosylation. Similar to BM-hMSCs, we found that A-hMSCs natively lack E-selectin ligands, but FTVI-mediated cell surface α(1,3)-fucosylation induces sLeX expression and robust E-selectin binding secondary to conversion of CD44 into HCELL. Moreover, treatment with the α(1,3)-fucosyltransferase-FTVII also generated expression of HCELL on both BM-hMSCs and A-hMSCs, with sLeX decorations created on N-linked glycans of the "standard" CD44 (CD44s) isoform. The finding that hMSCs from both source tissues each lack native E-selectin ligand expression prompted examination of the expression of glycosyltransferases that direct lactosaminyl glycan synthesis. These studies reveal that both types of hMSCs conspicuously lack transcripts encoding α(1,3)-fucosyltransferases, but equally express glycosyltransferases critical to creation of sialyllactosamines. Collectively, these data indicate that assembly of a sialyllactosaminyl-decorated CD44s glycovariant is a conserved feature of hMSCs derived from adipose tissue and marrow, thus identifying a CD44 glycosignature of these cells and supporting the applicability of cell surface α(1,3)-fucosylation in programming migration of systemically administered A-hMSCs to sites of tissue injury/inflammation. Stem Cells 2017;35:1080-1092.

Two E-selectin ligands, BST-2 and LGALS3BP, predict metastasis and poor survival of ER-negative breast cancer

Distant metastases account for the majority of cancer-related deaths in breast cancer. The rate and site of metastasis differ between estrogen receptor (ER)-negative and ER-positive tumours, and metastatic fate can be very diverse even within the ER-negative group. Characterisation of new pro-metastatic markers may help to identify patients with higher risk and improve their care accordingly. Selectin ligands aberrantly expressed by cancer cells promote metastasis by enabling interaction between circulating tumour cells and endothelial cells in distant organs. These ligands consist in carbohydrate molecules, such as sialyl-Lewis x antigen (sLex), borne by glycoproteins or glycolipids on the cancer cell surface. We have previously demonstrated that the molecular scaffold presenting sLex to selectins (e.g. glycolipid vs. glycoproteins) was crucial for these interactions to occur. Moreover, we reported that detection of sLex alone in breast carcinomas was only of limited prognostic value. However, since sLex was found to be carried by several glycoproteins in cancer cells, we hypothesized that the combination of the carbohydrate with its carriers could be more relevant than each marker independently. In this study, we addressed this question by analysing sLex expression together with two glycoproteins (BST-2 and LGALS3BP), shown to interact with E-selectin in a carbohydrate-dependent manner, in a cohort of 249 invasive breast cancers. We found both glycoproteins to be associated with distant metastasis risk and poorer survival. Importantly, concomitant high expression of BST-2 with sLex defined a sub-group of patients with ER-negative tumours displaying higher risks of liver and brain metastasis and a 3-fold decreased survival rate.

Synthesis of three fluorescent boronic acid sensors for tumor marker Sialyl Lewis X in cancer diagnosis

Sialyl Lewis X (sLex) is a carbohydrate that is considered not only a marker for cancer, but also an antigen associated with the malignant behavior of cancerous cells. We have synthesized three fluorescent boronic acid sensors as potential sensors for sLex. Photoinduced electron transfer by a fluorescence analyzer was used to assess sensor-sLex antigen binding. The reaction was carried out in mixed aqueous solution, and Sensor 3 was identified as showing the strongest fluorescence enhancement upon binding to sLex at 10nM. In cell-line culture experiments, Sensor 1 was shown to label sLex expression positively for HepG2, Colo 205, and COS-7 cells, and negatively for MDA-MB-231 cells; Sensor 2 did so positively for HepG2, PLC/PRF/5, and Colo 205 cells, and negatively for MDA-MB-231 and COS7 cells; and Sensor 3 did so positively for PLC/PRF/5 and HepG2 cells, and negatively for MDA-MD-231 and COS7 cells. MTT cytotoxicity experiment results showed that the three sensors are nontoxic, and Hoechst 33258 experiments showed that no apoptosis occurred.

B4GALNT2 gene expression controls the biosynthesis of Sda and sialyl Lewis X antigens in healthy and cancer human gastrointestinal tract

The histo blood group carbohydrate Sda antigen and its cognate biosynthetic enzyme B4GALNT2 show the highest level of expression in normal colon. Their dramatic down regulation previously observed in colon cancer tissues could play a role in the concomitant elevation of the selectin ligand sLex, involved in metastasis. However, down regulation of sLex expression by B4GALNT2 has been so far demonstrated in vitro, but not in tissues. The human B4GALNT2 gene specifies at least two transcripts, diverging in the first exon, never studied in normal and cancer tissues. The long form contains a 253 nt exon 1L; the short form contains a 38 nt exon 1S. Using qPCR, we showed that cell lines and normal or cancerous colon, expressed almost exclusively the short form, while the long form was mainly expressed by the embryonic colon fibroblast cell line CCD112CoN. Immunochemistry approaches using colon cancer cells permanently expressing either B4GALNT2 cDNAs as controls, led to the observation of several protein isoforms in human normal and cancerous colon, and cell lines. We showed that tissues expressing B4GALNT2 protein isoforms were able to induce Sda and to inhibit sLex expression; both of which are expressed mainly on PNGase F-insensitive carbohydrate chains. Concomitant expression of B4GALNT2 and siRNA-mediated inhibition of FUT6, the major fucosyltransferase involved in sLex synthesis in colon, resulted in a cumulative inhibition of sLex. In normal colon samples a significant relationship between sLex expression and the ratio between FUT6/B4GALNT2 activities exists, demonstrating for the first time a role for B4GALNT2 in sLex inhibition in vivo.