O-sulfated bacterial polysaccharides with low anticoagulant activity inhibit metastasis.

Heparin-like polysaccharides possess the capacity to inhibit cancer cell proliferation, angiogenesis, heparanase-mediated cancer cell invasion, and cancer cell adhesion to vascular endothelia via adhesion receptors, such as selectins. The clinical applicability of the antitumor effect of such polysaccharides, however, is compromised by their anticoagulant activity. We have compared the potential of chemically O-sulfated and N,O-sulfated bacterial polysaccharide (capsular polysaccharide from E. COLI K5 [K5PS]) species to inhibit metastasis of mouse B16-BL6 melanoma cells and human MDA-MB-231 breast cancer cells in two in vivo models. We demonstrate that in both settings, O-sulfated K5PS was a potent inhibitor of metastasis. Reducing the molecular weight of the polysaccharide, however, resulted in lower antimetastatic capacity. Furthermore, we show that O-sulfated K5PS efficiently inhibited the invasion of B16-BL6 cells through Matrigel and also inhibited the in vitro activity of heparanase. Moreover, treatment with O-sulfated K5PS lowered the ability of B16-BL6 cells to adhere to endothelial cells, intercellular adhesion molecule-1, and P-selectin, but not to E-selectin. Importantly, O-sulfated K5PSs were largely devoid of anticoagulant activity. These findings indicate that O-sulfated K5PS polysaccharide should be considered as a potential antimetastatic agent.

Safety of blocking vascular adhesion protein-1 in patients with contact dermatitis.

Vascular adhesion protein-1 mediates leukocyte binding to vascular endothelia and migration to tissues. It is upregulated in inflammatory conditions. We studied the safety of vascular adhesion protein-1 blockade by a single dose of the mouse monoclonal antibody vepalimomab in patients with nickel-induced allergic contact dermatitis lesions. Vepalimomab, 0.05-0.50 mg kg(-1) was safe and well tolerated. Four of nine patients reported adverse events of mild to moderate intensity. Human antimouse antibodies were detected after infusion in all the patients and they remained above the basal level for at least one month. Vepalimomab dose-dependently labelled vascular adhesion protein-1 in the inflamed skin. Luminal upregulation of vascular adhesion protein-1 on the endothelium upon inflammation was demonstrated for the first time in patients in vivo. Vepalimomab was found on the endothelium up to 24 hr after dosing whilst it was cleared from the circulation with an apparent half-life of 25-50 min. The results provide in vivo support for the concept of blocking vascular adhesion protein-1 in human disease states and support previous proposals that vascular adhesion protein-1 is a potential target molecule for inhibition of inflammatory reactions.

Generation of "neoheparin" from E. coli K5 capsular polysaccharide.

Heparin remains a major drug in prevention of thromboembolic disease. Concerns related to its animal source have prompted search for heparin analogues. The anticoagulant activity of heparin depends on a specific pentasaccharide sequence that binds antithrombin. We report the generation of a product with antithrombin-binding, anticoagulant, and antithrombotic properties similar to those of heparin, through combined chemical and enzymatic modification of a bacterial (E. coli K5) polysaccharide. The process is readily applicable to large-scale production.

Crystallization and preliminary X-ray analysis of the human vascular adhesion protein-1.

Human vascular adhesion protein-1 (VAP-1) is a membrane-bound multifunctional glycoprotein with both adhesive and enzymatic properties. The protein belongs to the copper-containing amine oxidase (CAO) family, which use 2,4,5-trihydroxyphenylalanine quinone as a cofactor. Here, the crystallization and preliminary X-ray analysis of a mammalian CAO, human VAP-1, is reported. The protein was expressed in Chinese hamster ovary cells as a full-length form with an N-terminal transmembrane region and multiple glycosylation sites. Hexagonal crystals with unit-cell parameters a = b = 225.9, c = 218.7 A, alpha = beta = 90, gamma = 120 degrees were obtained using the vapour-diffusion method. Data from three different crystals were collected at 100 K using synchrotron radiation and were processed to 3.2 A resolution with 95.9% completeness and an R(merge) of 19.6%.