Inhibitory effects of chemically modified heparin on the P-selectin-mediated adhesion of breast cancer cells in vitro

P-selectin plays a crucial role during hematogenous metastasis, and the blockade of P-selectin binding to its ligand can attenuate metastasis in various tumor models. Heparin or chemically modified heparins with decreased anticoagulant activities exhibit marked inhibitory effects on P-selectin-mediated adhesion. Here, we prepared chemically modified heparins with reduced anticoagulant activities and investigated whether they effectively inhibited P-selectin binding to breast cancer cells under static and flow conditions. The results indicated that P-selectin binding to ZR-75-30 cells was attenuated by chemically modified heparins in a sulfation-dependent manner under static and flow conditions. Flow cytometric analysis with heparan sulfate-specific monoclonal antibody revealed that heparan sulfate-like proteoglycans on the tumor cell surface were not implicated in this process. Instead, other glycoproteins were found to serve as P-selectin ligands. These findings suggest that further detailed research involving chemically modified heparins with low or no anticoagulant activities is warranted, and that chemically modified heparins should be considered in the treatment of metastatic breast cancer disease, with P-selectin potentially being a good target.