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Attachment of the PSGL-1 cytoplasmic domain to the actin cytoskeleton is essential for leukocyte rolling on P-selectin.

P-selectin glycoprotein ligand-1 (PSGL-1) serves as the leukocyte ligand for P-selectin, and many of the structural features of its ectodomain required for interactions with P-selectin have been uncovered. In contrast, the function of the highly conserved PSGL-1 cytoplasmic domain has not been explored. Stable transfectants expressing similar levels of either wild-type PSGL-1 or truncated PSGL-1 in which only 4 cytoplasmic residues were retained (designated PSGL-1 Delta cyto), were analyzed. Transfectants expressing full-length PSGL-1 rolled well on P-selectin. In contrast, rolling was almost completely absent in cells transfected with PSGL-1 Delta cyto, even at low shear. Importantly, cells expressing truncated PSGL-1 were able to bind soluble P-selectin and to bind COS cells overexpressing P-selectin, demonstrating that the P-selectin binding site on the PSGL-1 Delta cyto transfectants was intact and was capable of recognizing P-selectin. Impaired rolling by PSGL-1 Delta cyto transfectants was not due to alterations in subcellular localization because both wild-type and truncated PSGL-1 had similar surface distributions on K562 transfectants. Treatment of cells expressing native PSGL-1 with actin cytoskeletal toxins inhibited adhesion in a dose-dependent way. PSGL-1 was associated with the actin cytoskeleton, and this interaction was greatly impaired in PSGL-1 Delta cyto- expressing cells. The PSGL-1 cytoplasmic domain interacted selectively with the ezrin/radixin/moesin (ERM) protein moesin, but not with other ERM proteins or several other cytoskeletal linker proteins. Pharmacologic disruption of interactions between moesin and F-actin in cells expressing PSGL-1 resulted in a dose-dependent inhibition of rolling on P-selectin. Thus, attachment of PSGL-1 to the leukocyte cortical cytoskeleton is essential for leukocyte rolling on P-selectin.

Actins↗

Human mast cell progenitors use alpha4-integrin, VCAM-1, and PSGL-1 E-selectin for adhesive interactions with human vascular endothelium under flow conditions.

Mast cells (MCs) are central to asthma and other allergic diseases, and for responses to infection and tissue injuries. MCs arise from committed progenitors (PrMCs) that migrate from the circulation to tissues by incompletely characterized mechanisms, and differentiate in situ in perivascular connective tissues of multiple organs. PrMCs derived in vitro from human cord blood were examined for adhesion molecule expression and their ability to adhere to human umbilical vein endothelial cells (HUVECs) under conditions that mimic physiologic shear flow. The PrMCs expressed alpha(4)beta(1), low levels of beta7, and the beta2-integrins alphaLbeta2 and alphaMbeta2. The PrMCs also expressed PSGL-1, but not L-selectin. At low (0.5 dynes/cm(2)-1.0 dynes/cm(2)) shear stress, PrMCs attached and rolled on recombinant E-selectin and P-selectin and VCAM-1. An anti-PSGL-1 monoclonal antibody (mAb) blocked essentially all adhesion to P-selectin but reduced adhesion to E-selectin by only 40%, suggesting PrMCs express other ligands for E-selectin. PrMCs adhered strongly to tumor necrosis factor-alpha (TNF-alpha)-activated HUVECs, whereas adhesion to interleukin 4 (IL-4)-activated HUVECs was lower. PrMC adhesion to IL-4-activated HUVECs was totally alpha4-integrin- and VCAM-1-dependent. Adhesion to TNF-alpha-activated HUVECs was blocked by 50% by mAbs against alpha4-integrin, vascular cell adhesion molecule-1 (VCAM-1), E-selectin, or PSGL-1, whereas combinations of mAbs to alpha4-integrin plus PSGL-1, or VCAM-1 plus E-selectin, blocked adhesion by greater than 70%. Thus, PrMCs derived in vitro predominantly use alpha4-integrin, VCAM-1, PSGL-1, and other ligands that bind E-selectin for adhesion to cytokine-activated HUVEC monolayers. These observations may explain the abundance of MCs at sites of mucosal inflammation, where VCAM-1 and E-selectin are important inducible receptors.

Antigens, CD↗

L-selectin and intercellular adhesion molecule-1 regulate the development of Concanavalin A-induced liver injury.

Concanavalin A (Con A)-induced hepatitis is a model for human T cell-mediated hepatitis. We evaluated the role of L-selectin and intercellular adhesion molecule-1 (ICAM-1) in this model by injecting Con A intravenously in mice lacking L-selectin (L-selectin-/-), ICAM-1 (ICAM-1-/-), or both (L-selectin/ICAM-1-/-). Blood and liver samples were collected 0, 8, 24, and 48 h after Con A treatment. Increases in plasma transaminase levels, which peaked 8 h after injection, were reduced significantly in L-selectin-/-, ICAM-1-/-, and L-selectin/ICAM-1-/- mice compared with wild-type mice. Liver necrosis was more strongly inhibited in ICAM-1-/- mice than in L-selectin-/- mice but was most prominently reduced in L-selectin/ICAM-1-/- mice, in parallel with decreased plasma transaminase levels. The reduced severity of hepatitis in the mutant mice correlated with decreases in numbers of liver CD4+ T cells but not numbers of CD8+ T cells or neutrophils. Following Con A treatment, L-selectin deficiency reduced liver mRNA expression of tumor necrosis factor-alpha, and ICAM-1 deficiency reduced expression of interleukin-4. By contrast, reductions in liver macrophage inhibitor protein-1alpha mRNA occurred in all mutant mice. These results indicate that L-selectin and ICAM-1 contribute cooperatively to the development of Con A-induced hepatitis by regulating leukocyte infiltration and subsequent cytokine production.

Animals↗

Diminished soluble and total cellular L-selectin in cord blood is associated with its impaired shedding from activated neutrophils.

We have previously shown that surface levels of the adhesive glycoprotein, L-selectin, are diminished on cord blood neutrophils (polymorphonuclear leukocytes, PMN) and associated with impaired adherence to endothelium under flow conditions. To test the hypothesis that diminished surface levels reflect a total cellular deficiency, we measured L-selectin in PMN lysates and plasma from cord and adult blood. L-selectin content was decreased in cord blood PMN lysates compared with those of adults by both Western blot analyses and ELISA (cord blood, 1195 +/- 160 pg/mL; adult, 1870 +/- 260 pg/mL; X +/- SEM; p < 0.05). Soluble L-selectin levels were also decreased in cord blood plasma (324 +/- 24 ng/mL versus 537 +/- 28 ng/mLiter in adult plasma, p < 0.01). To evaluate L-selectin function, we next compared the dose dependent effect of several chemoattractants on shedding of L-selectin from cord blood and adult PMN. Adult PMN showed greater overall shedding of L-selectin as compared with cord blood PMN after stimulation with fMet-Leu-Phe (p < 0.03) and granulocyte-macrophage colony-stimulating factor (p < 0.02). In contrast, shedding of L-selectin was similar between groups after IL-8 tested stimulation. We conclude that cord blood PMN have a decreased cellular content of L-selectin in addition to an impaired ability to shed surface L-selectin in response to specific inflammatory mediators.

Adult↗

Engagement of L-selectin impairs the actin polymerizing capacity of beta 2-integrins on neutrophils.

A sequential activation of L-selectin and beta 2-integrins on neutrophils is crucial for the rolling, adherence and subsequent migration of these cells on the endothelium. However, little is known about a possible interplay between these adhesion receptors in the final regulation of cell motility. The results presented here show that sulfatides themselves (here used as tools to activate L-selectins), have no major effect on the cellular content of filamentous actin (F-actin), but cause a time-related decrease in the beta 2-integrin-induced formation of F-actin. This effect of sulfatides was abolished in cells lacking L-selectin as a result of pretreatment with chymotrypsin. A similar sulfatide-induced activation of L-selectin also caused a pronounced and time-related decrease of a subsequent chemotactic peptide-induced F-actin response. The effect of sulfatides on both beta 2-integrin- and chemotactic peptide-induced F-actin were abolished if L-selectin were blocked by preincubating the cells with specific antibodies to L-selectin. These effects of L-selectin engagement on cellular F-actin content were neither abolished by blocking the cytosolic free Ca2+ signal with bis-(2-amino-5-methylphenoxy)ethane-N,N,N',N'-tetraaceticacid tetraacetoxymethyly ester (MAPT/AM) nor by blocking a cAMP-induced activation of protein kinase A by pretreating the cells with adenosine-3',5'-cyclic monophos-phorothioate (Rp-cAMPS). Instead we found that L-selectin engagement impaired an early beta 2-integrin-induced tyrosine kinase activation, an event shown to be necessary for a normal beta 2-integrin-mediated F-actin response. The present demonstration of a negative feed-back function of L-selectin on beta 2-integrin-induced modulations of the actin cytoskeleton, suggests that the relative distribution and/or density of the respective L-selectin and beta 2-integrin ligands on endothelial cells might be important factors in determining the final site of firm adhesion and extravasation of neutrophils.

Actins↗

Soluble leukocyte selectin in the analysis of pleural effusions.

STUDY OBJECTIVES: To determine if soluble leukocyte selectin (sL-selectin) levels in serum and pleural fluid (PF) are an inflammatory marker that differentiates pleural effusion transudates from exudates. DESIGN: sL-selectin PF and serum levels were measured in consecutive patients and compared to established criteria. SETTING: A tertiary-care military medical center. PATIENTS: One hundred twenty patients undergoing diagnostic or therapeutic thoracentesis. INTERVENTIONS: PF and serum samples were collected during thoracentesis and analyzed separately for sL-selectin levels. Results were compared with clinical diagnosis and established PF criteria including the criteria of Light et al, cholesterol ratio, total bilirubin ratio, and albumin gradient. MEASUREMENTS AND RESULTS: sL-selectin levels in PF and serum were determined in 109 patients. By clinical diagnosis, mean +/- SD PF sL-selectin levels were 200.2 +/- 124.3 ng/mL in transudates and 496.8 +/- 379.2 ng/mL in exudates (p < 0.001). By the criteria of Light et al, mean PF sL-selectin levels were 195.7 +/- 105.2 ng/mL in transudates and 448.2 +/- 367.6 ng/mL in exudates (p < 0.001). Mean sL-selectin PF to serum ratios were 0.31 +/- 0.17 in transudates and 0.72 +/- 0.31 in exudates (p < 0.001) by clinical criteria, and 0.31 +/- 0.18 in transudates and 0.64 +/- 0.33 in exudates (p < 0.001) by the criteria of Light et al. No significant difference was noted with serum sL-selectin levels between groups. CONCLUSIONS: sL-selectin is an inflammatory marker that differentiates transudates from exudates in pleural effusions and is a sensitive indicator for PF analysis.

Biomarkers↗

Quantitative measurement of selectin-ligand interactions: assays to identify a sweet pill in a library of carbohydrates.

Soluble oligosaccharides and glycoproteins can inhibit leukocyte adhesion during a range of vascular ailments including inflammation, thrombosis, and cancer metastasis. The design of such molecules in many cases is based on the structure of naturally occurring selectin ligands. In this case, synthetic selectin-ligand mimetics act as competitive inhibitors of cell adhesion. In an alternate approach, cell-permeable, small-molecule oligosaccharides have been shown to alter the metabolic pathways that lead to the biosynthesis of functional selectin-ligands. The addition of such molecules results in glycoproteins that are defective in their ability to bind selectins. Quantitative in vitro testing of the efficacy of the above inhibition strategies ideally requires the application of assays that mimic the in vivo physiological milieu in terms of the valency of selectin and selectin-ligands, the physiological fluid-flow conditions, and the use of blood cells. Assays that are performed in small volumes are preferable when the quantity of available inhibitor is scarce. Finally, the measurements must account for the rapid on- and off-rates of selectin-mediated binding interactions. This chapter addresses these issues by presenting methods to measure selectin function in enzyme-linked immunosorbent assay and flow cytometry-based static assays, cell-adhesion assays performed under shear flow in cone-plate viscometers, and Biacore surface plasmon resonance measurements of molecular-binding kinetics. Examples are presented where such methods are applied to measure the ability of simple oligosaccharides based on sialyl Lewis-X and complex molecules with the core-2 structure to block selectin function. Such methods may be extended to identify potent selectin antagonists in a library of carbohydrates.

Combinatorial Chemistry Techniques↗

Targeting selectin functions in the therapy of psoriasis.

As leukocytes play a primary role in the immunopathogenesis of psoriasis, it is a reasonable assumption that preventing those cells from localizing to the sites of cutaneous inflammation can stop the disease process. Selectins, a family of three single-chain transmembrane adhesion molecules, which bind to carbohydrate moieties displayed on other cells, are pivotally involved in the initial steps of leukocyte recruitment, i.e. tethering and rolling along the endothelial lining of blood vessels. Thus, compounds impairing selectin functions have been developed to treat inflammatory disorders, such as psoriasis. Potential strategies to interfere with selectin functions include direct inhibition through monoclonal antibodies or small-molecule compounds, transcriptional regulation of selectin expression, and modulation of the post-transcriptional glycosylation of selectin ligands. More than a dozen different compounds targeting selectin functions are currently under development, several of which have shown promising effects on leukocyte recruitment and the therapy of inflammatory conditions under experimental conditions. However, based on preclinical and early clinical investigations, it appears that in some cases specifically targeting the function of single selectins may not be sufficient to effectively interrupt the inflammatory cascade. This is, at least in part, due to considerable redundancies and overlaps in the functions of the selectins, a notion that is corroborated by the apparently more pronounced therapeutic efficacy of some compounds with broader activity against several selectins. Overall, while targeting selectin functions promises rather selective and pathogenesis-based therapeutic approaches against psoriasis, the clinical value of such strategies, alone or in combination with other therapies, remains to be seen.

Drug Delivery Systems↗

L-selectin shedding is independent of its subsurface structures and topographic distribution.

L-selectin (CD62L), a lectin-like adhesion molecule, mediates lymphocyte homing and leukocyte accumulation at sites of inflammation. Its transmembrane (TM) and intracellular (IC) domains confer clustering of L-selectin on microvilli of resting leukocytes, which is important for L-selectin function. Following activation of protein kinase C (PKC) or calmodulin inhibition, the wild-type (WT) protein is rapidly cleaved in its membrane-proximal ectodomain. To examine whether L-selectin topography or TM/IC domains are involved in this shedding process, we used stable transfectants expressing WT L-selectin (on microvilli) or chimeric molecules consisting of the L-selectin ectodomain linked to the TM/IC domains of CD44 (excluded from microvilli) or CD31 (randomly distributed). PKC activation by PMA altered the cells' surface morphology, but did not induce a redistribution of L-selectin ectodomains. All cell lines shed ectodomains upon PMA activation in a dose-dependent fashion and with similar kinetics. Calmodulin inhibition by trifluoperazine induced shedding in both WT and chimera transfectants. At high trifluoperazine concentrations, shedding of WT L-selectin was significantly more pronounced than that of chimeric molecules. Regardless of the activating stimulus, shedding was blocked by a hydroxamate-based metalloprotease inhibitor, suggesting that ectodomain down-regulation occurred through proteolytic cleavage by identical protease(s). These results show that the recognition site(s) for PKC-induced L-selectin shedding is exclusively contained within the ectodomain; the nature of subsurface structures and surface topography are irrelevant. Shedding induced by calmodulin inhibition has two components: one requires the L-selectin TM/IC domain, and the other is independent of it.

Animals↗

Obligatory requirement of sulfation for P-selectin binding to human salivary gland carcinoma Acc-M cells and breast carcinoma ZR-75-30 cells.

Stimulated endothelial cells and activated platelets express P-selectin, which reacts with P-selectin glycoprotein ligand-1 (PSGL-1) for leukocyte rolling on the stimulated endothelial cells and heterotypic aggregation of the activated platelets on leukocytes. P-selectin also binds to several cancer cells in vitro and promotes the growth and metastasis of human colon carcinoma in vivo. The P-selectin/PSGL-1 interaction requires tyrosine sulfation. However, it is unknown whether sulfation is necessary for P-selectin binding to somatic cancer cells. In this study, we show that P-selectin mediated adhesion of Acc-M cells, a cell line derived from a human adenoid cystic carcinoma of salivary gland. These cells had a moderate expression of heparan sulfate-like proteoglycans, but had no detectable expressions of PSGL-1, CD24, Lewis(x), and sialyl Lewis(x). Treatment with sodium chlorate (a sulfation biosynthesis inhibitor), but not 4-methylumbelliferyl-beta-D-xyloside (a proteoglycan biosynthesis inhibitor) or heparinases, reduced adhesion of these cells to P-selectin. Sodium chlorate also inhibited the P-selectin precipitation of the 160-, 54-, and 36-kDa molecules from the cell surface of Acc-M cells. Furthermore, P-selectin could bind to human breast carcinoma ZR-75-30 cells in a sulfation-dependent manner. Our results thus indicate that sulfation is essential for adhesion of nonblood-borne, epithelial-like human cancer cells to P-selectin.

Antigens, CD↗

P-selectin binding promotes the adhesion of monocytes to VCAM-1 under flow conditions.

This study examined the adhesive interaction of peripheral blood monocytes with VCAM-1 and analyzed the effect of P-selectin binding to monocytes on the adhesive interaction with VCAM-1 under flow conditions. P-selectin glycoprotein ligand-1 is expressed on most monocytes. Furthermore, most monocytes bind soluble P-selectin derived from platelets. P-selectin binding to monocytes did not alter the amount of expression of alpha4 integrin on monocytes. However, the mean channel fluorescence value for binding Cy2-conjugated soluble VCAM-1 to P-selectin-bound monocytes was slightly more than that for binding Cy2-conjugated soluble VCAM-1 to untreated monocytes. Under flow conditions, the number of P-selectin-bound monocytes bound to VCAM-1 was much higher than that of untreated monocytes bound to VCAM-1. These bindings were abolished by pretreatment of untreated monocytes and P-selectin-bound monocytes with anti-VCAM-1 mAb or anti-alpha4 integrin mAb. Furthermore, P-selectin binding to monocytes increased shear resistance and thus increased the adhesive strength of monocytes to VCAM-1. These findings indicate that P-selectin binding to monocytes enhances the adhesive interaction of monocytes with VCAM-1. It is suggested that P-selectin glycoprotein ligand-1/P-selectin interaction and alpha4 integrin/VCAM-1 interaction can act sequentially in the adhesion cascade that regulates monocyte trafficking to inflammatory and atherosclerotic lesion.

Blood Flow Velocity↗

Expression of L-selectin on Th1 cells is regulated by IL-12.

L-selectin has become established as a key molecule in the recirculation of naïve T cells from the blood to peripheral lymph nodes, yet little is known about its role in the migration of effector or memory cells. While differentiating naïve CD4+ T cells into Th1 and Th2 subsets in vitro, it was noted that L-selectin levels were maintained on the Th1 subset of cells. The expression of L-selectin on the Th1 cells appeared to be dependent on the presence of IL-12. Th2 cells, differentiated in the absence of IL-12, failed to maintain L-selectin expression. Coculture with IL-12, IL-18, IL-4, TNF-alpha, or IFN-alpha, -beta, or -gamma demonstrated a dependence on IL-12 alone for L-selectin expression. In addition, the inclusion of heat-killed Listeria monocytogenes in the cultures also maintained L-selectin expression on the Th1 cells. In all cultures, the maintenance of L-selectin on the T cell surface could be blocked by the inclusion of anti-IL-12 Abs. Analysis of the mRNA levels for L-selectin in T cells, differentiated in the presence or absence of IL-12, showed that the cytokine appears to exert its effect on L-selectin at the transcriptional level. Given the key role played by IL-12 in the differentiation of naïve T cells into the Th1 subset, the observation that IL-12 can also regulate L-selectin expression has implications for the migration of Th1 effector cells both through the lymphatic system and to sites of inflammation.

Adjuvants, Immunologic↗

Leukocyte entry into sites of inflammation requires overlapping interactions between the L-selectin and ICAM-1 pathways.

Leukocyte interactions with vascular endothelium during inflammation depend on cascades of adhesion molecule engagement, particularly during selectin-mediated leukocyte rolling. Leukocyte rolling is also facilitated by members of the integrin and Ig families. Specifically, leukocyte rolling velocities during inflammation are significantly increased in ICAM-1-deficient mice, with ICAM-1 expression required for optimal P- and L-selectin-mediated rolling. Elimination of ICAM-1 expression in L-selectin-deficient mice significantly reduces leukocyte rolling. Whether disrupted leukocyte rolling in L-selectin and ICAM-1 double-deficient (L-selectin/ICAM-1-/-) mice affects leukocyte entry into sites of inflammation in vivo was assessed in the current study by using experimental models of inflammation; thioglycollate-induced peritonitis, chemokine-induced neutrophil migration to the skin, delayed-type hypersensitivity responses, rejection of allogeneic skin grafts, and septic shock. In many cases, the loss of both L-selectin and ICAM-1 expression dramatically reduced leukocyte migration into sites of inflammation beyond what was observed with loss of either receptor alone. In fact, the effects from loss of both L-selectin and ICAM-1 effectively eliminated multiple chronic inflammatory responses in L-selectin/ICAM-1-/- mice. By contrast, the combined loss of L-selectin and ICAM-1 expression had minimal effects on the generation of Ag-specific T cell responses or humoral immunity. Thus, members of the selectin and Ig families function synergistically to mediate optimal leukocyte rolling and entry into tissues, which is essential for the generation of effective inflammatory responses in vivo.

Animals↗

[Behavior of soluble L-selectin in HIV infected children].

L-selectin is an adhesion molecule that is responsible for the initial attachment of leukocytes to endothelium. After leukocyte activation L-selectin is endoproteolytically released from the cell surface. In order to analyze the relationship between soluble L-selectin (sL-selectin) and parameters of immune activation and disease progression, 51 HIV infected children and 15 healthy controls were studied. Serum L-selectin concentrations were significantly higher in HIV infected children than in the control group. Levels of sL-selectin were higher in HIV infected patients with severe immunologic suppression than in those with moderate or no evidence of suppression. A positive correlation between sL-selectin levels and LTCD8 counts, sL-selectin and soluble intercellular adhesion molecule-1 (sICAM-1) and immunogobulin A (IgA) levels was detected. On the contrary sL-selectin concentration did not correlate with plasmatic viral load. The correlation with parameters of immune activation may implicate involvement of sL-selectin in the immunopathogenesis of HIV infection.

CD8-Positive T-Lymphocytes↗

Plasma soluble L-selectin following cardiopulmonary bypass (CPB) in children: is it a marker of the postoperative course?

BACKGROUND: There is increasing evidence that cytokine-inducible leukocyte-endothelial adhesion molecules are instrumental in the postoperative inflammatory response following cardiopulmonary bypass (CPB). L-selectin was shown to be one of those neutrophil-endothelial cell adhesion molecules. This study aimed to investigate the relationship of the soluble adhesion molecule, sL-selectin, and the postoperative course in children undergoing CPB. MATERIAL/METHODS: To determine the time course of sL-selectin after CPB, serial blood samples of 9 children undergoing CPB were collected from the arterial line or from the bypass circuits preoperatively, on initiation of CPB and 1, 6, 12, 18, 24, and 48 hours postoperatively. Plasma was recovered immediately, aliquoted and frozen at -70 degrees C until use. Circulating sL-selectin molecules were measured with a sandwich enzyme-linked immunoabsorbent assay (ELISA) technique. There were significant changes in plasma levels of sL-selectin in patients following CPB, and these levels were associated with patient characteristics, operative variables and postoperative course. Low values of sL-selectin significantly correlated with inotropic support, low PRISM score, postoperative hypotension and fever. There was a significant association between the development of postoperative sepsis and low sL-selectin levels. No correlation was found between sL-selectin values and lactate concentration or neutrophil count. CONCLUSIONS: Our results suggest a relation between CPB-induced mediators and both early and late clinical effects. Although the mechanism for the changes of sL-selectin remains undetermined, the down-regulation of sL-selectin indicates neutrophil activation and supports the possibility that anti-adhesion therapies might participate in the prevention and treatment of the inflammatory response associated with CPB.

Biomarkers↗

High serum soluble E-selectin levels are associated with postoperative haematogenic recurrence in esophageal squamous cell carcinoma patients.

E-selectin has been reported to be associated with haematogenic metastasis in various cancer patients. In order to evaluate the risk of postoperative haematogenic recurrence of esophageal squamous cell carcinoma (SCC) patients, we examined the preoperative serum levels of soluble E-selectin and clinicopathological data of the patients. Preoperative serum was obtained from 135 esophageal SCC patients who received esophagectomies from 1990 to 1998. Serum soluble E-selectin levels were measured by means of enzyme linked immunoreactive synthesis assay (ELISA). The expression of sialyl Lewis A and X antigens were evaluated in 58 out of 135 patients. Thirty-five patients (25.9%) had haematogenic recurrence in their postoperative course. Serum soluble E-selectin levels of the haematogenic recurrence group (mean 55.6 ng/ml) were significantly higher than those of the non-haematogenic recurrence group (mean 41.1 ng/ml). When the cut-off level of soluble E-selectin was 56 ng/ml, the logistic regression analysis showed that high serum soluble E-selectin levels, lymph node metastasis and intraepithelial spread were associated with postoperative haematogenic recurrence of the esophageal SCC patients (OR 2.99, p=0.047, OR 4.94, p=0.009 and OR 5.0, p=0.019. respectively). Univariate analysis revealed that the patients with a high serum soluble E-selectin level tended to have poor survival (p=0.078) and Cox multivariate analysis revealed that a high serum soluble E-selectin level was a prognostic factor in esophageal SCC patients (RR 1.84, p=0.065). The patients with a high serum soluble E-selectin concomitant with expression of sialyl Lewis antigens had a significant risk of postoperative haematogenic recurrence (p=0.005). These results indicated that preoperative high serum soluble E-selectin was a risk factor in the development of postoperative haematogenic recurrence and was a prognostic factor in esophageal SCC patients.

Biomarkers, Tumor↗

[L-arginine decreases P-selectin expression in traumatic shock].

OBJECTIVE: To investigate the changes of P-selectin distribution in the vital organs and plasma during traumatic shock and explore the significance of these changes. METHODS: Twenty-four normal SD rats were randomly assigned into 3 groups (n=8), namely traumatic shock group, L-arginine (L-Arg) treatment and control group. The rats in the former 2 groups were subjected to traumatic shock with L-Arg treatment group given 100 mg/kg L-Arg during resuscitation while the other receiving no medication. The control group received only intubation without trauma or phlebotomy. P-selectin expression in the vital organs including the heart, lungs, spleen, liver and small intestine was determined by means of streptavidin-biotin (SABC) immunocytochemical staining technique and serum P-selectin level assayed by enzyme-linked immunosorbent assay. RESULTS: Before traumatic shock, P-selectin was scarcely detected in the vital organs except the lungs, and the serum was positive for P-selectin expression. Four hours after shock, intense P-selectin expression was observed in almost all the vital organs and the serum P-selectin level was significantly higher than that of the control group. In L-Arg treatment group, P-selectin levels were significantly lowered than those of shock group. CONCLUSIONS: P-selectin expression in the vital organs and serum is up-regulated during traumatic shock in rats, possibly due to severe microcirculatory disorder and endothelial dysfunction in this condition. L-Arg may decrease the expression of P-selectin very likely through promoting endothelial NO synthesis.

Animals↗

E-selectin up-regulation allows for targeted drug delivery in prostate cancer.

We have used the Eos Hu03 GeneChip array, which represents over 92% of the transcribed human genome, to measure gene expression in a panel of normal and diseased human tissues. This analysis revealed that E-selectin mRNA is selectively overexpressed in prostate cancer epithelium, a finding that correlated strongly with E-selectin protein expression as assessed by immunohistochemistry. Antibodies against E-selectin that blocked function failed to impede cancer cell growth, suggesting that overexpression of E-selectin was not essential for cell growth. However, a novel auristatin E-based antibody drug conjugate (ADC), E-selectin antibody valine-citrulline monomethyl-auristatin E, was a potent and selective agent against E-selectin-expressing cancer cell lines in vitro, with the degree of cytotoxicity varying with surface antigen density. Interestingly, sensitivity to the ADC differed among cell lines from different tissues expressing similar amounts of E-selectin and was found to correlate with sensitivity to free auristatin E. Furthermore, E-selectin-expressing tumors grown as xenografts in severe combined immunodeficient mice were responsive to treatment with E-selectin antibody valine-citrulline monomethyl-auristatin E in vivo, with more than 85% inhibition of tumor growth observed in treated mice. These findings demonstrate that an E-selectin-targeting ADC has potential as a prostate cancer therapy and validates a genomics-based paradigm for the identification of cancer-specific antigens suitable for targeted therapy.

Animals↗