In tumor development, the degradation of heparan sulfate (HS) by heparanase (HPSE) is associated with cell-surface and extracellular matrix remodeling as well as the release of HS-bound signaling molecules, allowing cancer cell migration, invasion and angiogenesis. Because of their structural similarity with HS, sulfated polysaccharides are considered a promising source of molecules to control these activities. In this study, we used a depolymerisation method for producing λ-carrageenan oligosaccharides (λ-CO), with progressive desulfation over time. These were then used to investigate the influence of polymeric chain length and degree of sulfation (DS) on their anti-HPSE activity. The effects of these two features on λ-CO anticoagulant properties were also investigated to eliminate a potential limitation on the use of a candidate λ-CO as a chemotherapeutic agent. HPSE inhibition was mainly related to the DS of λ-CO, however this correlation was not complete. On the other hand, both chain length and DS modulated λ-CO activity for factor Xa and thrombin IIa inhibition, two enzymes that are involved in the coagulation cascade, and different mechanisms of inhibition were observed. A λ-carrageenan oligosaccharide of 5.9 KDa was identified as a suitable anticancer candidate because it displayed one of the lowest anticoagulant properties among the λ-CO produced, while showing a remarkable inhibitory effect on MDA-MB-231 breast cancer cell migration.

Sugar-based molecules such as heparins or natural heparan sulfate polysaccharides have been developed and widely studied for controlling heparanase (HPSE) enzymatic activity, a key player in extracellular matrix remodelling during cancer pathogenesis. However, non-enzymatic functions of HPSE have also been described in tumour mechanisms. Given their versatile properties, we hypothesized that sugar-based inhibitors may interfere with enzymatic but also non-enzymatic HPSE activities. In this work, we assessed the effects of an original marine λ-carrageenan derived oligosaccharide (λ-CO) we previously described, along with those of its native counterpart and heparins, on cell viability, proliferation, migration, and invasion of MDA-MB-231 breast cancer cells but also of sh-MDA-MB-231 cells, in which the expression of HPSE was selectively downregulated. We observed no cytotoxic and no anti-proliferative effects of our compounds but surprisingly λ-CO was the most efficient to reduce cell migration and invasion compared with heparins, and in a HPSE-dependent manner. We provided evidence that λ-CO tightly controlled a HPSE/MMP-14/MMP-2 axis, leading to reduced MMP-2 activity. Altogether, this study highlights λ-CO as a potent HPSE “modulator” capable of reducing not only the enzymatic activity of HPSE but also the functions controlled by the HPSE levels.

Des molécules à base de sucre telles que les héparines ou les polysaccharides d'héparane sulfate naturels ont été développées et largement étudiées pour contrôler l'activité enzymatique de l'héparanase (HPSE), acteur clé du remodelage de la matrice extracellulaire au cours de la pathogenèse du cancer. Cependant, des fonctions non enzymatiques de l'HPSE ont également été décrites dans les mécanismes tumoraux. Compte tenu de leurs propriétés polyvalentes, nous avons émis l'hypothèse que les inhibiteurs à base de sucre peuvent interférer avec les activités enzymatiques mais aussi non enzymatiques de l’HPSE. Dans ce travail, nous avons évalué les effets d'un oligosaccharide marin original dérivé du carraghénane-λ (CO-λ) que nous avons décrit précédemment, ainsi que ceux de son homologue natif et des héparines, sur la viabilité cellulaire, la prolifération, la migration et l'invasion des cellules cancéreuses du sein, MDA-MB- 231, mais aussi des cellules sh-MDA-MB231, dans lesquelles l'expression de l’HPSE a été sélectivement régulée à la baisse en utilisant la stratégie shRNA. Nous n'avons montré aucun effet cytotoxique ni prolifératif de nos candidats inhibiteurs, mais le CO-λ était le plus efficace pour réduire la migration et l'invasion cellulaire par rapport aux héparines et ce, de manière HPSE dépendante. Nous avons mis en évidence que le CO-λ contrôlait étroitement un axe HPSE/MMP-14/MMP-2 conduisant à une activité MMP-2 réduite. Au final, cette étude met en évidence que le CO-λ est un puissant « modulateur » de l'HPSE capable de réduire non seulement l'activité enzymatique de l'HPSE mais également les fonctions contrôlées par les niveaux d'HPSE.