Abstract 259: Study of a low anticoagulant bovine heparin as a drug capable of disrupting tumor cell-platelet interaction and preventing hematogenous metastasis
Authors: Motta Juliana Maria , Roberto-Fernandes Carlos , Micheli Kayene Vitória , Tovar Ana Maria , Mourão Paulo Antônio , Pereira Mariana Sá 
Published: June 2022

Abstract
Metastasis is the leading cause of death in cancer patients. During metastatic dissemination, circulating tumor cells need to survive in the bloodstream and their interaction with platelets through P-selectin-ligand seems to be crucial. It has been demonstrated that heparin (from porcine mucosa, porcine UFH), a glycosaminoglycan composed by repetitive disaccharides of uronic acid and glucosamine, may interfere with P-selectin interaction. Recently our research group purified by ion exchange chromatography a fraction of bovine heparin displaying very low anticoagulant potential, named LABH (~20 IU/mg LABH x ~200 IU/mg porcine UFH x ~100 IU/mg bovine UFH). The advantage of bovine UFH and, especially of LABH, is their reduced risk of bleeding side effect. Our aim in this work was to investigate the potential use of LABH as an antimetastatic agent in vitro and in vivo, evaluating its ability to interfere with tumor cell-platelet interaction, tumor cell binding to P-selectin and preventing induced metastasis in mice. For this, we challenged 8-12 weeks C57Bl/6 mice with 4 or 8 mg/kg of porcine UFH, bovine UFH or LABH followed by intravenous injection of B16F10 cells (murine melanoma cell line). After 21 days, lungs were analyzed and metastatic foci were counted. The number of metastatic foci was significantly reduced when animals were pretreated with heparins (50-70 foci in control mice and 10-15 in treated mice). In other attempt, isolated platelets from healthy volunteers were incubated for 1h with MV3 cells (human melanoma cell line) in vitro in the presence or absence of heparin. All three heparins tested were efficient in blocking MV3-platelet interaction in a dose-response manner, but LABH required higher doses than porcine and bovine UFH. When analyzing the direct binding of U937 cell (human lymphoma cell line) to immobilized P-selectin, we could observe that porcine and bovine UFH inhibited at the same level (~ 60% of inhibition with 100 μg/mL), while LABH was less effective (~ 45% of inhibition with 100 μg/mL). Collectively our results demonstrate that despite presenting distinct patterns of sulfation and anticoagulant potential, all heparins significantly reduced lung metastasis, platelet-tumor cell adhesion and P-selectin binding. On the other hand, we hypothesize that LABH may act suppressing metastasis also by other mechanisms since its effect on in vitro experiments was less pronounced in comparison to porcine and bovine UFH.
Citation Format: Juliana Maria Motta, Carlos Roberto-Fernandes, Kayene Vitória Micheli, Ana Maria Tovar, Paulo Antônio Mourão, Mariana Sá Pereira. Study of a low anticoagulant bovine heparin as a drug capable of disrupting tumor cell-platelet interaction and preventing hematogenous metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 259.