Glycoproteins in animal cells contain a variety of glycan structures that are added co- and/or posttranslationally to proteins. Of over 20 different types of sugar-amino acid linkages known, the two major types are N-glycans (Asn-linked) and O-glycans (Ser/Thr-linked). An abnormal mucin-type O-glycan whose expression is associated with cancer and several human disorders is the Tn antigen. It has a relatively simple structure composed of N-acetyl-D-galactosamine with a glycosidic α linkage to serine/threonine residues in glycoproteins (GalNAcα1-O-Ser/Thr), and was one of the first glycoconjugates to be chemically synthesized. The Tn antigen is normally modified by a specific galactosyltransferase (T-synthase) in the Golgi apparatus of cells. Expression of active T-synthase is uniquely dependent on the molecular chaperone Cosmc, which is encoded by a gene on the X chromosome. Expression of the Tn antigen can arise as a consequence of mutations in the genes for T-synthase or Cosmc, or genes affecting other steps of O-glycosylation pathways. Because of the association of the Tn antigen with disease, there is much interest in the development of Tn-based vaccines and other therapeutic approaches based on Tn expression.

Tumor-associated blood vessels differ from normal vessels and proteins present only on tumor vessels may serve as biomarkers or targets for antiangiogenic therapy in cancer. Comparing the transcriptional profiles of blood vascular endothelium from human invasive bladder cancer with normal bladder tissue, we found that the endothelial cell-specific molecule endocan (ESM1) was highly elevated on tumor vessels. Endocan was associated with filopodia of angiogenic endothelial tip cells in invasive bladder cancer. Notably, endocan expression on tumor vessels correlated strongly with staging and invasiveness, predicting a shorter recurrence-free survival time in noninvasive bladder cancers. Both endocan and VEGF-A levels were higher in plasma of patients with invasive bladder cancer than healthy individuals. Mechanistic investigations in cultured blood vascular endothelial cells or transgenic mice revealed that endocan expression was stimulated by VEGF-A through the phosphorylation and activation of VEGFR-2, which was required to promote cell migration and tube formation by VEGF-A. Taken together, our findings suggest that disrupting endocan interaction with VEGFR-2 or VEGF-A could offer a novel rational strategy to inhibit tumor angiogenesis. Furthermore, they suggest that endocan might serve as a useful biomarker to monitor disease progression and the efficacy of VEGF-A–targeting therapies in patients with bladder cancer. Cancer Res; 73(3); 1097–106. ©2012 AACR.

L-selectin expressed on leukocytes is involved in lym-Binding to an isomeric glycosulfopeptide containing three Tyr-SO 3 residues and a core 1-based O-glycan expressing sLe x was reduced by ϳ90%. All three Tyr-SO 3 residues of GSP-6 are required for high affinity binding to L-selectin. Low affinity binding to mono-and disulfated GSPs is largely independent of the position of the Tyr-SO 3 residues, except for some binding preference for an isomer sulfated on both Tyr-48 and -51. These results demonstrate that L-selectin binds with high affinity to the N-terminal region of PSGL-1 through cooperative interactions with three sulfated tyrosine residues and an appropriately positioned C2-O-sLe x O-glycan.

Cancer registries are valuable sources for epidemiological research investigating risk factors underlying different types of cancer incidence. The present study is based on the Swiss Feline Cancer Registry that comprises 51,322 feline patient records, compiled between 1965 and 2008. In these records, 18,375 tumours were reported. The study analyses the influence of sex, neutering status, breed, time and age on the development of the most common tumour types and on their locations, using a multiple logistic regression model. The largest differences between breeds were found in the development of fibrosarcomas and squamous cell carcinomas, as well as in the development of tumours in the skin/subcutis and mammary gland. Differences, although often small, in sex and neutering status were observed in most analyses. Tumours were more frequent in middle-aged and older cats. The sample size allowed detailed analyses of the influence of sex, neutering status, breed and age. Results of the study are mainly consistent with previous analyses; however, some results cannot be compared with the existing literature. Further investigations are necessary, since feline tumours have not been investigated in depth to date. More accurate comparisons would require the definition of international standards for animal cancer registries.

Intercellular adhesion molecule-1 (ICAM-1) occurs as both a membrane and a soluble, secreted glycoprotein (sICAM-1). ICAM-1 on endothelial cells mediates leukocyte adhesion by binding to leukocyte function associated antigen-1 (LFA-1) and macrophage antigen-1 (Mac-1). Recombinant mouse sICAM-1 induces the production of macrophage inflammatory protein-2 (MIP-2) in mouse astrocytes by a novel LFA-1-and Mac-1-independent mechanism. Here we showed that N-glycan structures of sI-CAM-1 influence its ability to induce MIP-2 production. sICAM-1 expressed in Chinese hamster ovary (CHO) cells was a more potent inducer of MIP-2 production than sI-CAM-1 expressed in HEK 293 cells, suggesting that posttranslational modification of sICAM-1 could influence its signaling activity. To explore the roles of glycosylation in sICAM-1 activity, we expressed sICAM-1 in mutant CHO cell lines differing in glycosylation, including Lec2, Lec8, and Lec1 as well as in CHO cells cultured in the presence of the ␣-mannosidase-I inhibitor kifunensine. Signaling activity of sICAM-1 lacking sialic acid was reduced 3-fold compared with sICAM-1 from CHO cells. The activity of sICAM-1 lacking both sialic acid and galactose was reduced 12-fold, whereas the activity of sICAM-1 carrying only high mannose-type N-glycans was reduced 12-26-fold. sICAM-1 glycoforms carrying truncated glycans retained full ability to bind to LFA-1 on leukocytes. Thus, sialylated and galactosylated complex-type N-glycans strongly enhanced the ability of sICAM-1 to induce MIP-2 production in astrocytes but did not alter its binding to LFA-1 on leukocytes. Glycosylation could therefore serve as a means to regulate specifically the signaling function of sICAM-1 in vivo.

Severe traumatic brain injury stimulates the release of soluble intercellular adhesion molecule-1 (sICAM-1) into CSF. Studies in cultured mouse astrocytes suggest that sICAM-1 induces the production of macrophage inflammatory protein-2 (MIP-2). In the present study, we investigated the underlying mechanisms for MIP-2 induction. sICAM-1 induced MIP-2 in astrocytes lacking membrane-bound ICAM-1, indicating that its action is due to heterophilic binding to an undescribed receptor rather than homophilic binding to surface ICAM-1. Signal transduction may be mediated by src tyrosine kinases, as the src tyrosine kinase inhibitors herbimycin A and PP2 abolished MIP-2 induction by sICAM-1. Phosphorylation of p42/44 mitogen-activated protein kinase (MAPK), but not of p38 MAPK, occurred further downstream, as evidenced by western blot analysis combined with the use of herbimycin A and specific MAPK inhibitors. By contrast, induction of MIP-2 by tumour necrosis factor-a (TNF-a) involved both p42/44 MAPK and p38 MAPK. Following stimulation with either sICAM-1 or TNF-a, astrocyte supernatants promoted chemotaxis of human neutrophils and incubation of these supernatants with anti-MIP-2 antibodies more efficiently suppressed the migration induced by sICAM-1 than by TNF-a. These results show that sICAM-1 induces the production of biologically active MIP-2 in astrocytes by heterophilic binding to an undefined receptor and activation of src tyrosine kinases and p42/44 MAPK. Keywords: astrocytes, macrophage inflammatory protein-2, p42/44 mitogen-activated protein kinase, soluble intercellular adhesion molecule-1, src tyrosine kinases. Cell surface adhesion molecules play an important role in inflammation and immunosurveillance, mediating extravasation of leucocytes and modulating their effector functions. The migration of leucocytes from the bloodstream into inflamed tissue requires a cascade of events, starting with rolling of leucocytes along the endothelium (Kuby 1997). Upon activation by inflammatory signals such as chemokines, rolling progresses to firmer adhesion mediated by binding of leucocyte integrins to endothelial adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1). The firm adhesion of leucocytes to the endothelium is a prerequisite for their subsequent transendothelial migration. Address correspondence and reprint requests to Vivianne I. Otto, PhD, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, BRC 417, 975 NE. 10th Street, Oklahoma City, OK 73104, USA. E-mail: vivianne-otto@ouhsc.eduAbbreviations used: fMLP, N-formyl-methionyl-leucyl-phenylalanine; ICAM-1, intercellular adhesion molecule-1; ICAM-1-/-, ICAM-1 knockout; IL, interleukin; LFA-1, leucocyte function associated antigen-1; Mac-1, macrophage antigen-1; MAPK, mitogen-activated protein kinase; MIP, macrophage inflammatory protein; PMN, polymorphonuclear granulocytes; RANTES, regulated upon activation, normal T-cell expressed and secreted; sICAM-1, soluble intercellular adhesion molecule...

Summary:The potential role of the chemokine Fractalkine (CX 3 CL1) in the pathophysiology of traumatic brain injury (TBI) was investigated in patients with head trauma and in mice after experimental cortical contusion. In control individuals, soluble (s)Fractalkine was present at low concentrations in cerebrospinal fluid (CSF) (12.6 to 57.3 pg/mL) but at much higher levels in serum (21,288 to 74,548 pg/mL). Elevation of sFractalkine in CSF of TBI patients was observed during the whole study period (means: 29.92 to 535.33 pg/mL), whereas serum levels remained within normal ranges (means: 3,100 to 59,159 pg/mL). Based on these differences, a possible passage of sFractalkine from blood to CSF was supported by the strong correlation between blood-brain barrier dysfunction (according to the CSF-/serum-albumin quotient) and sFractalkine concentrations in CSF (R ‫ס‬ 0.706; P < 0.01). In the brain of mice subjected to closed head injury, neither Fractalkine protein nor mRNA were found to be augmented; however, Fractalkine receptor (CX 3 CR1) mRNA steadily increased peaking at 1 week postinjury (P < 0.05, one-way analysis of variance). This possibly implies the receptor to be the key factor determining the action of constitutively expressed Fractalkine. Altogether, these data suggest that the Fractalkine-CX 3 CR1 protein system may be involved in the inflammatory response to TBI, particularly for the accumulation of leukocytes in the injured parenchyma.

The expression of the chemokines macrophage inflammatory protein (MIP)-2 and MIP-1alpha and of their receptors CXCR2 and CCR5 was assessed in wild type (WT) and TNF/lymphotoxin-alpha knockout (TNF/LT-alpha-/-) mice subjected to closed head injury (CHI). At 4 h after trauma intracerebral MIP-2 and MIP-1alpha levels were increased in both groups with MIP-2 concentrations being significantly higher in WT than in TNF/LT-alpha-/- animals (p < 0.05). Thereafter, MIP-2 production declined rapidly, whereas MIP-1alpha remained elevated for 7 days. Expression of CXCR2 was confined to astrocytes and increased dramatically within 24 h in both mouse types. Contrarily, CCR5 expression remained constitutively low and was mainly localized to microglia. These results show that after CHI, chemokines and their receptors are regulated differentially and with independent kinetics.