Selectins and Associated Adhesion Proteins in Inflammatory disorders

Cancer metastasis is facilitated by cell-cell interactions between cancer cells and endothelial cells in distant tissues. In addition, cancer cell interactions with platelets and leukocytes contribute to cancer cell adhesion, extravasation, and the establishment of metastatic lesions. Selectins are carbohydrate-binding molecules that bind to sialylated, fucosylated glycan structures, and are found on endothelial cells, platelets and leukocytes. There are three members of the selectin family: P-selectin expressed on activated platelets and endothelial cells, L-selectin present on leukocytes and E-selectin expressed on activated endothelial cells. Besides the accepted roles of selectins in physiological processes, such as inflammation, immune response and hemostasis, there is accumulating evidence for the potential of selectins to contribute to a number of pathophysiological processes, including cancer metastasis. Cancer cell interactions with selectins are possible due to a frequent presence of carbohydrate determinants--selectin ligands on the cell surface of tumor cells from various type of cancer. The degree of selectin ligand expression by cancer cells is well correlated with metastasis and poor prognosis for cancer patients. Initial adhesion events of cancer cells facilitated by selectins result in activation of integrins, release of chemokines and are possibly associated with the formation of permissive metastatic microenvironment. While E-selectin has been evaluated as one of the initiating adhesion events during metastasis, it is becoming apparent that P-selectin and L-selectin-mediated interactions significantly contribute to this process as well. In this review we discuss the current evidence for selectins as potential facilitators of metastasis. Copyright © 2010 Elsevier Ltd. All rights reserved.

Current evidence supports that inflammation is a major driving force underlying the initiation of coronary plaques, their unstable progression, and eventual disruption; patients with a more pronounced vascular inflammatory response have a poorer outcome. Biomarkers are generally considered to be proteins or enzymes - measured in serum, plasma, or blood - that provide independent diagnostic and prognostic value by reflecting an underlying disease state. In the case of coronary artery disease (CAD), inflammatory biomarkers, have been extensively investigated; more evidence exists for C-reactive protein (CRP). Using high sensitivity (hs) assays, epidemiologic data demonstrate an association between hs-CRP and risk for future cardiovascular morbidity and mortality among those at high risk or with documented CAD. Moreover, a series of prospective studies provide consistent data documenting that mild elevation of baseline levels of hs-CRP among apparently healthy individuals is associated with higher long-term risk for cardiovascular events. Yet, the predictive value of hs-CRP is found to be independent of traditional cardiovascular risk factors. Recent studies suggest that, besides CRP, other inflammatory biomarkers such as cytokines [interleukin (IL)-1, IL-6, IL-8, monocyte chemoattractant protein-1 (MCP-1)], soluble CD40 ligand, serum amyloid A (SAA), selectins (E-selectin, P-selectin), myeloperoxidase (MPO), matrix metalloproteinases (MMPs), cellular adhesion molecules [intercellular adhesion molecule 1 (ICAM-1), vascular adhesion molecule 1 (VCAM-1)], placental growth factor (PlGF) and A(2) phospholipases may have a potential role for the prediction of risk for developing CAD and may correlate with severity of CAD. Finally, indications suggest that the increased risk associated with inflammation may be modified with certain preventive therapies and biomarkers may help to identify the individuals who would benefit most from these interventions.

Fabry disease, an X-linked systemic vasculopathy, is caused by a deficiency of alpha-galactosidase A resulting in globotriaosylceramide (Gb(3)) storage in cells. The pathogenic role of Gb(3) in the disease is not known. Based on previous work, we tested the hypothesis that accumulation of Gb(3) in the vascular endothelium of Fabry disease is associated with increased production of reactive oxygen species (ROS) and increased expression of cell adhesion molecules. Gb(3)-loading resulted in increased intracellular ROS production in cultured vascular endothelial cells in a dose-dependent manner. Increased Gb(3) also induced expression of intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin. Reduction of endogenous Gb(3) by treatment of the cells with an inhibitor of glycosphingolipid synthase or alpha-galactosidase A led to decreased expression of adhesion molecules. Plasma from Fabry patients significantly increased ROS generation in endothelial cells when compared with plasma from non-Fabry controls. This effect was not influenced by reduction of intracellular Gb(3). This study provided direct evidence that excess intracellular Gb(3) induces oxidative stress and up-regulates the expression of cellular adhesion molecules in vascular endothelial cells. In addition, other factors in patient's plasma may also contribute to oxidative stress in Fabry vascular endothelial cells.