Expression of long-form N-acetylglucosamine-6-O-sulfotransferase 1 in human high endothelial venules

Expression of Podocalyxin Potentially Decorated With Low-sulfated Keratan Sulfate in Human Testicular Embryonal Carcinoma

SummaryWe previously demonstrated that among various histological types of human testicular germinal cell tumors (GCTs), embryonal carcinoma (EC) preferentially expresses low-sulfated keratan sulfate (KS) consisting of repeating N-acetyllactosamine (LacNAc) disaccharide units composed of galactose and 6-O-sulfated N-acetylglucosamine (GlcNAc), which is recognized by the R-10G antibody. Recently, we generated another anti-low-sulfated KS monoclonal antibody, 294-1B1. Immunohistochemical analysis of testicular GCTs (n=83) revealed that the low-sulfated KS recognized by 294-1B1 is also preferentially expressed in EC but minimally in other GCT histological types. Moreover, immunolabeling with R-10G and 294-1B1 antibodies was resistant to peptide-N-glycosidase F digestion, and EC was not stained with the MECA-79 antibody, indicating that low-sulfated KS expressed in EC contains mucin-type core 2 O-glycans carrying GlcNAc-6-O-sulfated oligo-LacNAc. Double immunofluorescence staining showed that R-10G and 294-1B1 antibody signals colocalized with those for podocalyxin (PODXL). Furthermore, western blot analysis of recombinant human PODXL•IgG fusion proteins secreted from low-sulfated KS-expressing human embryonic kidney 293T cells revealed that PODXL functions as a core protein for low-sulfated KS. Taken together, these findings strongly suggest that the PODXL glycoform decorated with low-sulfated KS is preferentially expressed in human testicular EC and may therefore serve as a diagnostic marker for this malignancy.

Structural Elucidation and Prognostic Relevance of 297-11A-Sulfated Glycans in Ovarian Carcinoma

Ovarian carcinoma is usually diagnosed at an advanced stage with peritoneal dissemination and/or lymph node metastasis, and the prognosis for such advanced carcinoma is very poor. Therefore, new biomarkers to predict patient prognosis are needed. Miyamoto et al. previously showed that keratan sulfate (KS) detected by the 5D4 monoclonal antibody was expressed in ovarian carcinoma. However, the detailed structure of such KS was not determined, and the biological significance of this finding remained to be clarified. We previously generated the 297-11A monoclonal antibody, which recognizes galactose (Gal)-6-O-sulfated N-acetyllactosamine (LacNAc) located at the nonreducing terminus. Because the 297-11A epitope overlaps with that of 5D4, here we chose to use the 297-11A antibody as a tool to analyze KS and related structures. We conducted immunohistochemical analysis of 98 ovarian carcinoma cases with 297-11A antibody combined with a series of glycosidases and performed mass spectrometry analysis of the human serous ovarian carcinoma cell line OVCAR-3 to deduce the glycan structure of 297-11A-sulfated glycans. We also performed western blot analysis to assess a potential association of 297-11A-sulfated glycans with the mucin core protein mucin 16 (MUC16; also known as cancer antigen 125 (CA125)). Finally, we examined the relationship between 297-11A expression and patient prognosis. Consequently, 297-11A-sulfated glycans were primarily expressed in serous and endometrioid carcinomas and poorly expressed in mucinous and clear cell carcinomas. We reveal that structurally, 297-11A-sulfated glycans expressed in ovarian carcinoma are O-glycans carrying partially sialylated, Gal-6-O-sulfated LacNAc and that these glycans are likely displayed on MUC16 mucin core proteins. Of clinical importance is that expression of 297-11A-sulfated glycans correlated with shorter progression-free survival in patients. Thus, 297-11A-sulfated glycans may serve as a predictor of ovarian carcinoma recurrence.

Expression of low-sulfated keratan sulfate in non-mucinous ovarian carcinoma

Keratan sulfate glycosaminoglycan is composed of repeating N-acetyllactosamine (LacNAc) disaccharide units consisting of galactose (Gal) and N-acetylglucosamine (GlcNAc), both often 6-O-sulfated. Sulfate contents of keratan sulfate are heterogeneous depending upon the origins. In this study, keratan sulfate is classified as either highly sulfated (in which both GlcNAc and Gal residues are 6-O-sulfated) or low-sulfated (in which only GlcNAc residues are 6-O-sulfated). It is reported that highly sulfated keratan sulfate detected by the 5D4 monoclonal antibody is preferentially expressed in normal epithelial cells lining the female genital tract and in their neoplastic counterparts; however, expression of low-sulfated keratan sulfate in either has not been characterized. In the present study, we generated the 294-1B1 monoclonal antibody, which selectively recognizes low-sulfated keratan sulfate, and performed precise glycan analysis of sulfated glycans expressed on human serous ovarian carcinoma OVCAR-3 cells. We found that OVCAR-3 cells do not express highly sulfated keratan sulfate but rather express low-sulfated form, which was heterogeneous in 294-1B1 reactivity. Comparison of mass spectrometry spectra of sulfated glycans in 294-1B1-positive versus -negative OVCAR-3 cells indicated that the 294-1B1 epitope is likely at least 2, and possibly 3 or more, tandem GlcNAc-6-O-sulfated LacNAc units. Then, using the 294-1B1 antibody, we performed quantitative immunohistochemical analysis of 40 specimens from patients with ovarian cancer, consisting of 10 each of serous, endometrioid, clear cell, and mucinous carcinomas, and found that among them low-sulfated keratan sulfate was widely expressed in all but mucinous ovarian carcinoma.

Paradoxical Expression of R-10G-reactive Antigen in Human Testicular Embryonal Carcinoma

Thus far, several monoclonal antibodies directed against cell-surface carbohydrate antigens have been generated. Among them, R-10G reportedly reacts selectively with human embryonic stem and induced pluripotent stem cells, but not with embryonal carcinoma (EC) cells. However, EC cells derived from patients' EC tumors may exhibit varying levels of R-10G-reactive antigen expression. Thus, we asked whether human EC tissues or germ cell tumor (GCT) tissues other than EC express R-10G-reactive antigen. To do so, we quantitatively analyzed R-10G-reactive antigen expression in 83 testicular GCT surgical specimens containing a total of 125 various GCT components. Accordingly, in all EC components examined, the EC cell plasma membrane was immunolabeled with R-10G, while most seminoma components were R-10G-negative. In non-seminomatous GCT (NSGCT) other than EC (non-EC NSGCT), R-10G-reactive antigen expression was variable, but signal distribution was focal, and the average intensity was weaker than that seen in EC. The percentages of R-10G-positive cells in these three groups varied with high statistical significance (p<0.001 for all combinations). These findings indicate that the R-10G-reactive antigen is preferentially expressed in human testicular EC tissues and, thus, could be used as a diagnostic marker for this malignancy.

CHST2-mediated sulfation of MECA79 antigens is critical for breast cancer cell migration and metastasis

Snail is a denoted transcriptional repressor that plays key roles in epithelial-mesenchymal transition (EMT) and metastasis. Lately, a plethora of genes can be induced by stable expression of Snail in multiple cell lines. However, the biological roles of these upregulated genes are largely elusive. Here, we report identification of a gene encoding the key GlcNAc sulfation enzyme CHST2 is induced by Snail in multiple breast cancer cells. Biologically, CHST2 depletion results in inhibition of breast cancer cell migration and metastasis, while overexpression of CHST2 promotes cell migration and lung metastasis in nude mice. In addition, the expression level of MECA79 antigen is elevated and blocking the cell surface MECA79 antigen with specific antibodies can override cell migration mediated by CHST2 upregulation. Moreover, the sulfation inhibitor sodium chlorate effectively inhibits the cell migration induced by CHST2. Collectively, these data provide novel insights into the biology of Snail/CHST2/MECA79 axis in breast cancer progression and metastasis as well as potential therapeutic strategy for the diagnosis and treatment of breast cancer metastasis.

Sulfated Glycans Recognized by S1 Monoclonal Antibody can Serve as a Diagnostic Marker for Malignant Pleural Mesothelioma

PURPOSE

Malignant pleural mesothelioma (MPM) is a malignant neoplasm of the pleura caused by asbestos exposure. For diagnosis of MPM, immunohistochemistry using multiple markers is recommended to rule out differential diagnoses, such as pulmonary adenocarcinoma. However, the specificity of currently used markers is not fully satisfactory. We previously developed a monoclonal antibody named S1, which recognizes 6-sulfo sialyl Lewis x, an L-selectin ligand expressed on high endothelial venules. During the screening process, we discovered that this antibody stained normal pleural mesothelium. This finding prompted us to hypothesize that the epitope recognized by S1 might serve as a new diagnostic marker for MPM.

METHODS

To test this hypothesis, we immunostained human MPM (n = 22) and lung adenocarcinoma (n = 25) tissues using S1 antibody.

RESULTS

77.3% of MPM were S1 positive, and if limited to epithelioid type, the positivity rate was 100%, while that of lung adenocarcinoma was only 36.0%. Statistical analysis revealed a significant difference in the S1 positivity rate between each disease. Furthermore, immunohistochemistry using a series of anti-carbohydrate antibodies combined with glycosidase digestion revealed the structure of sulfated glycans expressed in MPM to be 6-sulfo sialyl N-acetyllactosamine attached to core 2-branched O-glycans.

CONCLUSION

We propose that the S1 glycoepitope could serve as a new diagnostic marker for MPM.

The Conspicuousness of High Endothelial Venules in Angioimmunoblastic T-cell Lymphoma Is Due to Increased Cross-sectional Area, Not Increased Distribution Density

Angioimmunoblastic T-cell lymphoma (AITL) is a T-cell lymphoma of follicular helper T-cell origin. Histologically, neoplastic T-cells proliferate to form clusters adjacent to or between arborizing high endothelial venules (HEVs). HEVs in normal lymph nodes express sulfated glycans called peripheral lymph node addressin (PNAd); however, it remains unclear whether PNAd is also expressed on HEVs in AITL. Furthermore, although it is widely accepted that HEVs are conspicuous in AITL due to their proliferation, quantitative histological support for this concept is lacking. To investigate these issues, we employed monoclonal antibodies recognizing PNAd, namely, MECA-79, HECA-452, and 297-11A, and performed quantitative immunohistochemical analysis of HEVs in 36 AITL-affected and 67 normal lymph nodes. Staining with all three antibodies confirmed that AITL HEVs express PNAd. Moreover, AITL HEVs were bound calcium-dependently by L-selectin-IgM fusion proteins, indicating that they function in the recruitment of L-selectin-expressing lymphocytes. Unexpectedly, HEV distribution density was not increased but rather decreased in AITL compared with normal lymph nodes, but HEV cross-sectional area in AITL was significantly greater than that seen in normal lymph nodes. Overall, these results indicate that the prominence of AITL HEVs is likely due to increased cross-sectional area rather than increased distribution density.

Apical Membrane Expression of Distinct Sulfated Glycans Is a Characteristic Feature of Ductules and Their Reactive and Neoplastic Counterparts

Intrahepatic bile ducts transport bile between bile canaliculi and the extrahepatic bile duct. The luminal surface of this tract is lined by a layer of biliary epithelial cells, or cholangiocytes, which secrete mucins consisting of scaffold proteins and O-glycosidically linked carbohydrate side chains. Although mucin core proteins have been extensively investigated, the structure and function of carbohydrate side chains have not. Here, we demonstrate that distinct sulfated glycans positive for MECA-79, R-10G, and 297-11A, but not 5D4, monoclonal antibodies are expressed in the cytoplasm of cells of large-sized ducts and in the apical membrane of cells in ductules, and that R-10G immunolabeling is partially eliminated by endo-β-galactosidase digestion, supporting the presence of N-acetylglucosamine-6-O-sulfated N-acetyllactosamine structures. We observed comparable apical membrane-predominant staining in ductular reactions seen during regeneration that occurs in various liver diseases and in cholangiolocarcinoma, a subtype of small duct-type intrahepatic cholangiocarcinoma (iCCA). Apical membrane expression of distinct sulfated glycans in large duct-type iCCA was negligible. Intriguingly, under pathological conditions, endo-β-galactosidase digestion almost completely eliminated R-10G immunoreactivity. These findings suggest that apical membrane expression of distinct sulfated glycans is a characteristic feature of ductules and their reactive and neoplastic counterparts.

Preferential expression of sialyl 6'-sulfo N-acetyllactosamine-capped O-glycans on high endothelial venules in human peripheral lymph nodes

Lymphocyte "homing", the physiologic trafficking of lymphocytes from the circulation to secondary lymphoid organs, is regulated by sequential adhesive interactions between lymphocytes and endothelial cells that constitute high endothelial venules (HEVs). Initial lymphocyte "rolling" is mediated by relatively weak, transient adhesive interactions between L-selectin expressed on lymphocytes and sulfated mucin-type O-glycans expressed on HEVs. Keratan sulfate galactose (Gal)-6-O-sulfotransferase (KSGal6ST) catalyzes 6-O-sulfation of Gal in keratan sulfate glycosaminoglycan chains but also transfers sulfate to Gal in much shorter glycan chains, such as sialylated N-acetyllactosamine (LacNAc)-capped O-glycans. In mice, KSGal6ST is reportedly expressed in HEVs and functions in synthesizing 6-sulfo Gal-containing O-glycans on HEVs. However, in humans, the presence of 6-sulfo Gal-containing O-glycans on HEVs is not reported. Employing the newly developed monoclonal antibody 297-11A, which recognizes non-sialylated terminal 6'-sulfo LacNAc, we demonstrate that sialyl 6'-sulfo (and/or 6,6'-disulfo) LacNAc-capped O-glycans are preferentially displayed on HEVs in human peripheral lymph nodes (PLNs) and to a lesser extent in mesenteric LNs (MLNs) but not in Peyer's patches (PPs). We also found that the scaffold protein mucosal addressin cell adhesion molecule 1 (MAdCAM-1), which is expressed on HEVs in PPs and MLNs but not PLNs, was modified by 297-11A-positive sulfated glycans less efficiently than was CD34. Moreover, 297-11A-positive sulfated glycans were also displayed on HEV-like vessels induced in tumor-infiltrating lymphocyte (TIL) aggregates formed in various cancers. These findings collectively indicate that 297-11A-positive sulfated glycans potentially play a role in physiologic lymphocyte homing as well as in lymphocyte recruitment under pathologic conditions.

Induction of peripheral lymph node addressin in human nasal mucosa with eosinophilic chronic rhinosinusitis

Eosinophilic chronic rhinosinusitis (ECRS) is characterised by formation of nasal polyps with prominent eosinophilic infiltration; however, how eosinophils are recruited in this pathological setting remains unclear. In the present study, we carried out quantitative immunohistochemical analysis of nasal polyps associated with ECRS (n=30) and non-ECRS (n=30) to evaluate expression of an L-selectin ligand peripheral lymph node addressin (PNAd) on vascular endothelial cells. We found that PNAd was induced primarily on the luminal surface of venular vessels present in nasal mucosa in both ECRS and non-ECRS, while the number of PNAd-expressing vessels in ECRS significantly exceeded that seen in non-ECRS. Moreover, the number of eosinophils attached to the luminal surface of PNAd-expressing vessels in ECRS was significantly greater than that in non-ECRS, while the number of neutrophils and lymphocytes attached did not differ significantly between conditions. Furthermore, eosinophils, which express cell surface L-selectin, adhered to PNAd-expressing Chinese hamster ovary (CHO) cells in a calcium-dependent manner, and that adhesion was significantly inhibited by pretreatment of eosinophils with DREG-56, an anti-human L-selectin monoclonal antibody. These findings combined suggest that interaction between L-selectin and PNAd plays at least a partial role in eosinophil recruitment in human nasal mucosa with ECRS.

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

OBJECTIVES

Bladder 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 METHODS

We 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.

RESULTS

MPUC 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.

CONCLUSIONS

Overall, 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.

Apical membrane expression of distinct sulfated glycans represents a novel marker of cholangiolocellular carcinoma

Intrahepatic cholangiocarcinoma (ICC) is the second most common primary liver neoplasm, followed by hepatocellular carcinoma. ICC can be further subclassified as (i) perihilar and (ii) peripheral types, the latter histologically resembling small-sized intrahepatic bile ducts, such as interlobular bile ducts, cholangioles/ductules and the canals of Hering. Cholangiolocellular carcinoma (CoCC), now classified by the World Health Organization as a subtype of combined hepatocellular-cholangiocarcinoma, is currently regarded as a subtype of peripheral-type ICC. The present study was undertaken to determine whether sulfated glycans recognized by the MECA-79 monoclonal antibody could serve as a CoCC marker. Using immunohistochemistry, we show that MECA-79 sulfated glycans are preferentially expressed at the apical membrane of cholangiocytes found in small-sized intrahepatic bile ducts in normal liver and in canalicular structures formed in CoCC. We also report that apical membrane MECA-79 sulfated glycan expression colocalizes with that of mucin 1 (MUC1) core proteins. We also present immunoblotting of Chinese hamster ovary cells overexpressing FLAG-tagged MUC1 to show that MUC1 serves as a MECA-79 scaffold. Furthermore, we report that SSP-25 human ICC cells overexpressing N-acetylglucosamine-6-O-sulfotransferase 2 (GlcNAc6ST-2), but not GlcNAc6ST-1, exhibit membrane expression of MECA-79 sulfated glycans, suggesting that GlcNAc6ST-2 catalyzes MECA-79 epitope biosynthesis in cholangiocytes. Moreover, both wild-type and GlcNAc6ST-1 knockout mice exhibit apical membrane MECA-79 expression in small-sized intrahepatic bile ducts, namely interlobular bile ducts, whereas MECA-79 expression was completely absent in comparable tissues from GlcNAc6ST-1 and GlcNAc6ST-2 double knockout mice. These data collectively indicate that apical membrane localization of MUC1 proteins decorated with GlcNAc6ST-2-dependent MECA-79 sulfated glycans may mark cholangiocytes with cholangiolar/ductular differentiation and could serve as a useful CoCC marker.

Keratan sulfate: biosynthesis, structures, and biological functions

Keratan sulfate is a glycosaminoglycan that has been investigated in the cornea and skeletal tissues for decades. Endoglycosidases and monoclonal antibodies specific for keratan sulfate have been developed. These materials have facilitated the analysis of keratan sulfate biosynthesis and structures. Likewise, they have expedited study of the biological roles of keratan sulfate in vitro and in vivo. It has been shown that keratan sulfate is also expressed in the central nervous system and functions as a regulator of neuronal regeneration/sprouting. Here, we describe methods to determine the enzymatic activity of GlcNAc6ST, which is involved in keratan sulfate biosynthesis, and to extract and prepare ocular keratan sulfate for a disaccharide composition analysis. Immunohistochemistry for an anti-keratan sulfate epitope in the brain is also described.

Periductal induction of high endothelial venule-like vessels in type 1 autoimmune pancreatitis

OBJECTIVES

Type 1 autoimmune pancreatitis (AIP) is histologically characterized by dense lymphoplasmacytic infiltration and marked storiform fibrosis, manifestations associated with pancreatic ducts. Such periductal lymphocyte recruitment is thought to be elicited by dysregulation of mechanisms governing physiological lymphocyte homing. The present study was undertaken to determine whether vascular addressins including peripheral lymph node addressin and mucosal addressin cell adhesion molecule 1 (MAdCAM-1) play a role in type 1 AIP histogenesis.

METHODS

Tissue sections of type 1 AIP and tumor-associated non-AIP chronic pancreatitis, as well as normal pancreas, were subjected to immunohistochemical analysis using vascular addressin-related antibodies.

RESULTS

The number of periductal mouse endothelial cell antigen 79-positive high endothelial venule (HEV)-like vessels was increased in type 1 AIP relative to that seen in non-AIP chronic pancreatitis, whereas the number of MAdCAM-1-positive HEV-like vessels did not differ between the 2 conditions. Mouse endothelial cell antigen 79 antigens are expressed on duct-forming epithelial cells not only in pancreas but also in salivary glands, which often harbor extrapancreatic lesions in type 1 AIP.

CONCLUSIONS

Type 1 AIP can be characterized by periductal induction of MECA-79-positive HEV-like vessels. MECA-79-positive 6-sulfo sialyl Lewis X-related carbohydrate antigens expressed on duct-forming epithelial cells could be associated with type 1 AIP pathogenesis.