Fucosyltransferase 2 induced epithelial-mesenchymal transition via TGF-β/Smad signaling pathway in lung adenocarcinaoma

Fucosyltransferase 2 (FUT2), the enzyme catalyzing α-1,2-fucosylation in mammals, has been implicated in cancer. The up-regulation of FUT2 has been observed in lung adenocarcinoma (LUAD), and FUT2 can enhance the cell migration and invasion of LUAD cell lines. However, the underlying mechanism of FUT2 in LUAD remains largely unknown. Abundant studies have revealed that epithelial-mesenchymal transition (EMT) played a pivotal role during lung cancer metastasis and progression. In the present study, we showed that knocking down FUT2 in LUAD cell lines increased the expression of E-cadherin and reduced the expression of Vimentin, N-cadherin, TβRII, p-Smad2, p-Smad3 and Snail, which were the makers of EMT. Meanwhile, the expression of E-cadherin was decreased, and the expression of Vimentin was increased by restoring the expression of FUT2 in RNA interference FUT2 (RNAi-FUT2) cells, suggesting that FUT2 enhanced the EMT process in LUAD. Additionally, silencing FUT2 expression can up-regulate E-cadherin and down-regulate Vimentin, significantly attenuated EMT in vivo. Treated with the SIS3, a new-type inhibitor of p-Smad3 of TGF-β signaling, the expression of E-cadherin, Vimentin and Snail were not affected by RNAi-FUT2 cells, indicating that the effect of FUT2 on EMT depended on TGF-β/Smad signaling. Overall, the current results indicated that FUT2 might promote LUAD metastasis through the EMT initiated by TGF-β/Smad signaling. Therefore, FUT2 might be a prognostic factor and therapeutic target for LUAD.

Airway epithelial wound repair: role of carbohydrate sialyl Lewisx

Epithelial repair is a complex cellular and molecular process, the details of which are still not clearly understood. Plasma membrane glycoconjugates can modulate cell function by altering the function of protein and lipids. Sialyl Lewisx (sLex), a fucose-containing tetrasaccharide, decorates membrane-bound and secreted proteins and mediates cell-cell interaction. In the present study we investigated the role of sLex in airway epithelial repair. Using immunohistochemistry, we showed an increased expression of sLex in areas of damaged bronchial epithelium compared with intact regions. Confluent monolayers of airway epithelial cells were mechanically wounded and allowed to close. Wounded monolayers were photographed for wound closure kinetics, fixed for immunocytochemical studies, or subjected to RNA extraction. Examining the expression of different alpha1,3-fucosyltransferases (FucT), enzymes that mediate the final step in the synthesis of sLex, we found that FucT-IV was the common gene expressed in all cell lines and primary airway epithelial cells. We demonstrated an increased expression of sLex over time after mechanical injury. Blocking of sLex with an inhibitory antibody completely prevented epithelial repair. Our data suggest an essential functional role for sLex in epithelial repair. Further studies are necessary to explore the exact mechanism for sLex in mediating cell-cell interaction in bronchial epithelial cells to facilitate epithelial migration and repair.

Enforced fucosylation of neonatal CD34+ cells generates selectin ligands that enhance the initial interactions with microvessels but not homing to bone marrow

Hematopoietic progenitor/stem cell homing to the bone marrow requires the concerted action of several adhesion molecules. Endothelial P- and E-selectins play an important role in this process, but their ligands on a large subset of neonate-derived human CD34+ cells are absent, leading to a reduced ability to interact with the bone marrow (BM) microvasculature. We report here that this deficiency results from reduced α1,3-fucosyltransferase (FucT) expression and activity in these CD34+ cells. Incubation of CD34+ cells with recombinant human FucTVI rapidly corrected the deficiency in nonbinding CD34+ cells and further increased the density of ligands for both P- and E-selectins on all cord blood–derived CD34+ cells. Intravital microscopy studies revealed that these FucTVI-treated CD34+ cells displayed a marked enhancement in their initial interactions with the BM microvasculature, but unexpectedly, homing into the BM was not improved by FucTVI treatment. These data indicate that, although exogenous FucT enzyme activity can rapidly modulate selectin binding avidity of cord blood CD34+ cells, further studies are needed to understand how to translate a positive effect on progenitor cell adhesion in bone marrow microvessels into one that significantly influences migration and lodgement into the parenchyma.

Surface fucosylation of human cord blood cells augments binding to P-selectin and E-selectin and enhances engraftment in bone marrow

Murine hematopoietic stem and progenitor cells (HSPCs) home to bone marrow in part by rolling on P-selectin and E-selectin expressed on endothelial cells. Human adult CD34+ cells, which are enriched in HSPCs, roll on endothelial selectins in bone marrow vessels of nonobese diabetic/severe combined immune deficiency (NOD/SCID) mice. Many human umbilical cord blood (CB) CD34+ cells do not roll in these vessels, in part because of an uncharacterized defect in binding to P-selectin. Selectin ligands must be α1-3 fucosylated to form glycan determinants such as sialyl Lewis x (sLex). We found that inadequate α1-3 fucosylation of CB CD34+ cells, particularly CD34+CD38–/low cells that are highly enriched in HSPCs, caused them to bind poorly to E-selectin as well as to P-selectin. Treatment of CB CD34+ cells with guanosine diphosphate (GDP) fucose and exogenous α1-3 fucosyltransferase VI increased cell-surface sLex determinants, augmented binding to fluid-phase P- and E-selectin, and improved cell rolling on P- and E-selectin under flow. Similar treatment of CB mononuclear cells enhanced engraftment of human hematopoietic cells in bone marrows of irradiated NOD/SCID mice. These observations suggest that α1-3 fucosylation of CB cells might be a simple and effective method to improve hematopoietic cell homing to and engraftment in bone marrows of patients receiving CB transplants.

Production of a complement inhibitor possessing sialyl Lewis X moieties by in vitro glycosylation technology

Recombinant soluble human complement receptor type 1 (sCR1) is a highly glycosylated glycoprotein intended for use as a drug to treat ischemia-reperfusion injury and other complement-mediated diseases and injuries. sCR1-sLe(x) produced in the FT-VI-expressing mutant CHO cell line LEC11 exists as a heterogeneous mixture of glycoforms, a fraction of which include structures with one or more antennae terminated by the sialyl Lewis X (sLe(x)) [Neu5Acalpha2-3Galbeta1-4(Fucalpha1-3)GlcNAc]) epitope. Such multivalent presentation of sLe(x) was shown previously to effectively target sCR1 to activated endothelial cells expressing E-selectin. Here, we describe the use of the soluble, recombinant alpha2-3 sialyltransferase ST3Gal-III and the alpha1-3 fucosyltransferase FT-VI in vitro to introduce sLe(x) moieties onto the N-glycan chains of sCR1 overexpressed in standard CHO cell lines. The product (sCR1-S/F) of these in vitro enzymatic glycan remodeling reactions performed at the 10-g scale has approximately 14 N-glycan chains per sCR1 molecule, comprised of biantennary (90%), triantennary (8.5%), and tetraantennary (1.5%) structures, nearly all of whose antennae terminate with sLe(x) moieties. sCR1-S/F retained complement inhibitory activity and, in comparison with sCR1-sLe(x) produced in the LEC11 cell line, contained twice the number of sLe(x) moieties per mole glycoprotein, exhibited a twofold increase in area under the intravenous clearance curve in a rat pharmacokinetic model, and exhibited a 10-fold increase in affinity for E-selectin in an in vitro binding assay. These results demonstrate that in vitro glycosylation of the sCR1 drug product reduces heterogeneity of the glycan profile, improves pharmacokinetics, and enhances carbohydrate-mediated binding to E-selectin.

Discordant expression of selectin ligands and sialyl Lewis x-related epitopes on murine myeloid cells

Murine leukocytes are thought to express alpha2-3-sialylated and alpha1-3-fucosylated selectin ligands such as sialyl Lewis x (sLe(x)), although monoclonal antibodies (mAbs) to sLe(x) or Le(x) reportedly do not bind to murine leukocytes. We observed that P- and E-selectin bound to pronase-sensitive ligands on murine monocytic WEHI-3 cells and murine neutrophils, indicating that the ligands for both selectins are glycoproteins. CSLEX-1, HECA-452, and other widely used mAbs to sLe(x) and Le(x) did not bind to WEHI-3 cells and bound at very low levels to murine neutrophils. Only the anti-sLe(x) mAbs 2H5 and KM93, which also recognize nonfucosylated glycans, bound to WEHI-3 cells. 2H5 and KM93 bound to pronase-resistant structures, indicating that the mAbs did not identify selectin ligands. Treatment of WEHI-3 cells with glycosidases or chlorate demonstrated that sialic acid modifications, alpha1-3-galactosylation, or sulfation did not mask epitopes for mAbs to sLe(x) or Le(x). Compared to human promyelocytic HL-60 cells, WEHI-3 cells and murine neutrophils expressed low alpha1-3-fucosyltransferase activities. Consistent with very low endogenous fucosylation, forced fucosylation of intact WEHI-3 cells or murine neutrophils by exogenous alpha1-3-fucosyltransferase FTVI and GDP-fucose created many new epitopes for anti-sLe(x) mAbs such as HECA-452 and CSLEX-1. Nevertheless, forced fucosylation of intact cells did not significantly augment their ability to bind to fluid-phase P- or E-selectin or to roll on immobilized P- or E-selectin under flow. These data suggest that murine myeloid leukocytes fucosylate only a few specific glycans, which interact preferentially with P- and E-selectin.

Cultured human gastric explants: a model for studies of bacteria-host interaction during conditions of experimental Helicobacter pylori infection

The unique environment of the human stomach makes it difficult to establish representative in vitro models for Helicobacter pylori that mimic the natural infection. The in vitro explant culture (IVEC) technique is based on coculture of human gastric explants with H. pylori, where bacteria-host interaction is studied on the basis of interleukin (IL)-8 secretion of the explant tissue in response to infection. In this study, it was shown that H. pylori attachment to gastric epithelial tissue was required for induction of representative inflammatory responses, assessed here by IL-8 production. Furthermore, IL-8 production by the explant tissue in response to H. pylori infection demonstrated that the explants were adequately responsive. The IVEC technique for studies of the interplay between H. pylori and the human gastric mucosa during conditions of experimental infections in vitro could add knowledge to our understanding of the complex bacteria-host cross-talk in vivo.

Immature mouse dendritic cells enter inflamed tissue, a process that requires E- and P-selectin, but not P-selectin glycoprotein ligand 1

Inflammatory processes are associated with the rapid migration of dendritic cells (DCs) to regional lymph nodes and depletion of these potent antigen-presenting cells (APCs) from the inflamed tissue. This study examined whether sites of cutaneous inflammation can be repopulated with DCs from a pool of immature DCs circulating in the blood. In adoptive transfer experiments with ex vivo-generated radioactively labeled primary bone marrow-derived DCs injected into mice challenged by an allergic contact dermatitis reaction, immature DCs were actively recruited from the blood to sites of cutaneous inflammation, whereas mature DCs were not. Immature, but not mature, DCs were able to adhere specifically to immobilized recombinant E- and P-selectin under static as well as under flow conditions. P-selectin-dependent adhesion of immature DCs correlates with their higher level of expression of the carbohydrate epitope cutaneous lymphocyte-associated antigen (CLA) and is blocked by a novel inhibitory antibody against mouse P-selectin glycoprotein ligand 1 (PSGL-1). Surprisingly, however, emigration of immature DCs into inflamed skin is retained in the presence of this anti-PSGL-1 antibody and is also normal when immature DCs are generated from fucosyltransferase (Fuc-T) Fuc-TVII-deficient mice. By contrast, emigration of wild-type immature DCs is reduced by adhesion-blocking anti-E- and P-selectin antibodies, and immature DCs generated ex vivo from Fuc-TVII/Fuc-TIV double-deficient mice emigrate poorly. Thus, fucosylated ligands of the endothelial selectins, determined in part by Fuc-TIV, and independent of PSGL-1, are required for extravasation of DCs into sites of cutaneous inflammation.

Differential requirements for the O-linked branching enzyme core 2 beta1-6-N-glucosaminyltransferase in biosynthesis of ligands for E-selectin and P-selectin

Selectins are carbohydrate-binding adhesion molecules that play important roles in control of leukocyte traffic. Glycosyltransferases involved in selectin ligand biosynthesis include the alpha1,3-fucosyltransferases FucT-VII and FucT-IV, one or more sialyltransferases, and at least one O-linked branching enzyme. Previous studies have shown that core 2 beta1-6-N-glucosaminyltransferase (C2GlcNAcT-I; EC 2.4.1.102) is required for functional modification of PSGL-1, the leukocyte P-selectin ligand, but have been ambiguous on whether this enzyme is involved in E-selectin ligand formation. Using an attachment and rolling assay under defined shear flow in vitro, this study shows that C2GlcNAcT-I(-) lymphoid cells stably transfected with FucT-VII complementary DNA attach and roll well on E-selectin at 1.5 dynes/cm.(2) Further, attachment and rolling on P-selectin of neutrophils is sharply reduced and that of short- term polarized Th1 cells is virtually abolished, with leukocytes from C2GlcNAcT-I(-/-) mice. In contrast, both neutrophils and Th1 cells from C2GlcNAcT-I(-/-) mice attach and roll as well as wild-type cells on E-selectin. These results show that C2GlcNAcT-I is selectively required for biosynthesis of ligands for P-selectin, but is not essential for at least some E-selectin ligands. Distinct requirements for C2GlcNAcT-I in the formation of ligands for E-selectin versus P-selectin represents a novel level of regulation of expression of selectin ligands and lymphocyte traffic. (Blood. 2001;97:3806-3811)

Overexpression of alpha(1,3)-fucosyltransferase VII is sufficient for the acquisition of lung colonization phenotype in human lung adenocarcinoma HAL-24Luc cells

Metastatic human lung adenocarcinoma HAL-8Luc cells display an enhanced expression of alpha(1,3)-fucosyltransferases (alpha(1,3)-Fuc-Ts) compared with their non-metastatic counterpart HAL-24Luc cells. This correlates with an increased surface expression of Lewis(x) (Le(x))- and Lewis(a) (Le(a))-related molecules and an in vitro enhanced adhesive capacity to E-selectin-expressing endothelial cells (Martin-Satué et al (1998). Cancer Res 58: 1544-1550). In the present work we have stably transfected HAL-24Luc cells with the cDNAs for the alpha(1,3)-Fuc-TIV and VII enzymes and analysed by flow cytometry the expression of Le(x), sialyl-Le(x), sialyl-Le(x) dimeric, Le(a) and sialyl-Le(a). Fuc-TVII transfectants exclusively overexpress sialyl-Le(x) while Fuc-TIV-transfected cells only overexpress the Le(x) oligosaccharide. We show that solely Fuc-TVII transfectants are able to adhere to interleukin-1beta-stimulated HUVEC monolayers. We also demonstrate that Fuc-TVII overexpression in HAL-24Luc cells is sufficient for the acquisition of the lung colonization phenotype. This is the first report directly showing the contribution of an alpha(1,3)-Fuc-T to the metastatic behaviour of human lung adenocarcinoma cells.

Expression of Rhizobium chitin oligosaccharide fucosyltransferase in zebrafish embryos disrupts normal development

In this report we present data about the effect of the Rhizobium NodZ enzyme on zebrafish development. We injected zebrafish embryos with a plasmid expressing NodZ protein, and we confirmed that the enzyme is active and has chitin oligosaccharide fucosyltransferase (NodZ) activity in vitro. In addition, the embryos injected with the NodZ-expressing plasmid, but not with a control plasmid, showed malformations or bends in the tail, and in some cases shunted tail structures and fused somites. These results clearly indicate that the likely substrates for this enzyme, chitin oligosaccharides and free N-glycans, have essential functions during early vertebrate embryogenesis.

Down-regulation of Gal alpha(1,3)Gal expression by alpha1,2-fucosyltransferase: further characterization of alpha1,2-fucosyltransferase transgenic mice

BACKGROUND

In pig-to-primate transplantation, antibody-mediated hyperacute rejection is the consequence of binding of natural antibodies to Gal alpha(1,3)Gal on pig endothelium. The elimination of the Gal alpha(1,3)Gal antigen from pig cells should prevent hyperacute rejection. Using in vitro techniques, we have previously reported that using the alpha1,2-fucosyltransferase gene induces the preferential expression of H substance with a concomitant reduction in the expression of Gal alpha(1,3)Gal. The aim of the present study was to examine the effect of expressing the alpha1,2-fucosyltransferase gene in vivo on Gal alpha(1,3)Gal.

METHODS

Three alpha1,2-fucosyltransferase transgenic lines of mice were produced and characterized serologically and histologically.

RESULTS

Immunohistological studies showed heavy staining for H substance in liver, spleen, kidney, and heart, with a reduction in staining for Gal alpha(1,3)Gal. In addition, there was a reduction in the binding of human anti-Gal alpha(1,3)Gal antibody to lymphocytes from alpha1,2-fucosyltransferase transgenic mice and a substantial decrease in complement-mediated cytolysis of alpha1,2-fucosyltransferase transgenic lymphocytes when compared with that obtained with normal mice.

CONCLUSIONS

The findings have important implications, in that alpha1,2-fucosyltransferase transgenic pigs could be produced as a source for humans. Such pigs should have a reduced expression of Gal alpha(1,3)Gal.