RESUMO
Sulfated polysaccharides from Laminaria saccharina (new name: Saccharina latissima) brown seaweed show promising activity for the treatment of inflammation, thrombosis, and cancer; yet the molecular mechanisms underlying these properties remain poorly understood. The aim of this work was to characterize, using in vitro and in vivo strategies, the anti-inflammatory, anti-coagulant, anti-angiogenic, and anti-tumor activities of two main sulfated polysaccharide fractions obtained from L. saccharina: a) L.s.-1.0 fraction mainly consisting of O-sulfated mannoglucuronofucans and b) L.s.-1.25 fraction mainly composed of sulfated fucans. Both fractions inhibited leukocyte recruitment in a model of inflammation in rats, although L.s.-1.25 appeared to be more active than L.s.-1.0. Also, these fractions inhibited neutrophil adhesion to platelets under flow. Only fraction L.s.-1.25, but not L.s.-1.0, displayed anticoagulant activity as measured by the activated partial thromboplastin time. Investigation of these fractions in angiogenesis settings revealed that only L.s.-1.25 strongly inhibited fetal bovine serum (FBS) induced in vitro tubulogenesis. This effect correlated with a reduction in plasminogen activator inhibitor-1 (PAI-1) levels in L.s.-1.25-treated endothelial cells. Furthermore, only parent sulfated polysaccharides from L. saccharina (L.s.-P) and its fraction L.s.-1.25 were powerful inhibitors of basic fibroblast growth factor (bFGF) induced pathways. Consistently, the L.s.-1.25 fraction as well as L.s.-P successfully interfered with fibroblast binding to human bFGF. The incorporation of L.s.-P or L.s.-1.25, but not L.s.-1.0 into Matrigel plugs containing melanoma cells induced a significant reduction in hemoglobin content as well in the frequency of tumor-associated blood vessels. Moreover, i.p. administrations of L.s.-1.25, as well as L.s.-P, but not L.s.-1.0, resulted in a significant reduction of tumor growth when inoculated into syngeneic mice. Finally, L.s.-1.25 markedly inhibited breast cancer cell adhesion to human platelet-coated surfaces. Thus, sulfated fucans are mainly responsible for the anti-inflammatory, anticoagulant, antiangiogenic, and antitumor activities of sulfated polysaccharides from L. saccharina brown seaweed.
Assuntos
Produtos Biológicos/farmacologia , Laminaria/química , Polissacarídeos/fisiologia , Inibidores da Angiogênese/metabolismo , Inibidores da Angiogênese/farmacologia , Animais , Anti-Inflamatórios/metabolismo , Anti-Inflamatórios/farmacologia , Anticoagulantes/metabolismo , Anticoagulantes/farmacologia , Produtos Biológicos/química , Produtos Biológicos/metabolismo , Células Cultivadas , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/fisiologia , Feminino , Fucose/química , Fucose/fisiologia , Humanos , Inflamação/patologia , Inflamação/prevenção & controle , Laminaria/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Neovascularização Fisiológica/efeitos dos fármacos , Phaeophyceae/química , Phaeophyceae/metabolismo , Polissacarídeos/química , Polissacarídeos/metabolismo , Polissacarídeos/farmacologia , Ratos , Ratos Wistar , Alga Marinha/química , Alga Marinha/metabolismoRESUMO
The anti-inflammatory, antiangiogenic, anticoagulant, and antiadhesive properties of fucoidans obtained from nine species of brown algae were studied in order to examine the influence of fucoidan origin and composition on their biological activities. All fucoidans inhibited leucocyte recruitment in an inflammation model in rats, and neither the content of fucose and sulfate nor other structural features of their polysaccharide backbones significantly affected the efficacy of fucoidans in this model. In vitro evaluation of P-selectin-mediated neutrophil adhesion to platelets under flow conditions revealed that only polysaccharides from Laminaria saccharina, L. digitata, Fucus evanescens, F. serratus, F. distichus, F. spiralis, and Ascophyllum nodosum could serve as P-selectin inhibitors. All fucoidans, except that from Cladosiphon okamuranus carrying substantial levels of 2-O-alpha-D-glucuronopyranosyl branches in the linear (1-->3)-linked poly-alpha-fucopyranoside chain, exhibited anticoagulant activity as measured by activated partial thromboplastin time whereas only fucoidans from L. saccharina, L. digitata, F. serratus, F. distichus, and F. evanescens displayed strong antithrombin activity in a platelet aggregation test. The last fucoidans potently inhibited human umbilical vein endothelial cell (HUVEC) tubulogenesis in vitro and this property correlated with decreased levels of plasminogen-activator inhibitor-1 in HUVEC supernatants, suggesting a possible mechanism of fucoidan-induced inhibition of tubulogenesis. Finally, fucoidans from L. saccharina, L. digitata, F. serratus, F. distichus, and F. vesiculosus strongly blocked MDA-MB-231 breast carcinoma cell adhesion to platelets, an effect which might have critical implications in tumor metastasis. The data presented herein provide a new rationale for the development of potential drugs for thrombosis, inflammation, and tumor progression.
Assuntos
Inibidores da Angiogênese/farmacologia , Anti-Inflamatórios não Esteroides/farmacologia , Células Endoteliais/metabolismo , Phaeophyceae , Polissacarídeos/farmacologia , Alga Marinha , Veias Umbilicais/metabolismo , Inibidores da Angiogênese/isolamento & purificação , Anti-Inflamatórios não Esteroides/isolamento & purificação , Plaquetas/citologia , Plaquetas/metabolismo , Adesão Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Células Endoteliais/citologia , Humanos , Inflamação/tratamento farmacológico , Inflamação/metabolismo , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Phaeophyceae/química , Inibidor 1 de Ativador de Plasminogênio/metabolismo , Polissacarídeos/isolamento & purificação , Alga Marinha/química , Trombose/tratamento farmacológico , Trombose/metabolismo , Veias Umbilicais/citologiaRESUMO
Galectins, a family of structurally related carbohydrate-binding proteins, contribute to different events associated with cancer biology, including apoptosis, homotypic cell aggregation, angiogenesis and tumor-immune escape. To interfere with galectin-carbohydrate interactions during tumor progression, a current challenge is the design of specific galectin inhibitors for therapeutic purposes. Here, we report the synthesis of three novel low molecular weight synthetic lactulose amines (SLA): (1) N-lactulose-octamethylenediamine (LDO), (2) N,N'-dilactulose-octamethylenediamine (D-LDO), and (3) N,N'-dilactulose-dodecamethylenediamine (D-LDD). These compounds showed a differential ability to inhibit binding of galectin-1 and/or galectin-3 to the highly glycosylated protein 90K in solid-phase assays. In addition, each compound demonstrated selective regulatory effects in different events linked to tumor progression including tumor-cell apoptosis, homotypic cell aggregation, and endothelial cell morphogenesis. Our results suggest that galectin inhibitors with subtle differences in their carbohydrate structures may be potentially used to specifically block different steps of tumor growth and metastasis.