Cobalt hematoporphyrin inhibits CLEC-2–podoplanin interaction, tumor metastasis, and arterial/venous thrombosis in mice

Abstract

The platelet activation receptor C-type lectin-like receptor 2 (CLEC-2) interacts with podoplanin on the surface of certain types of tumor cells, and this interaction facilitates tumor metastasis. CLEC-2 is also involved in thrombus formation and its stabilization. Because CLEC-2-depleted mice are protected from experimental lung metastasis and thrombus formation and do not show increased bleeding time, CLEC-2 may serve as a good target for antimetastatic or antithrombotic drugs. We screened 6770 compounds for their capability to inhibit CLEC-2-podoplanin binding using an enzyme-linked immunosorbent assay. In the first screening round, 63 compounds were identified and further evaluated by flow cytometry using CLEC-2-expressing cells. We identified protoporphyrin IX (H2-PP) as the most potent inhibitor and modified its hematoporphyrin moiety to be complexed with cobalt (cobalt hematoporphyrin [Co-HP]), which resulted in an inhibitory potency much stronger than that of H2-PP. Surface plasmon resonance analysis and molecular docking study showed that Co-HP binds directly to CLEC-2 at N120, N210, and K211, previously unknown podoplanin-binding sites; this binding was confirmed by analysis of CLEC-2 mutants with alterations in N120 and/or K211. Co-HP at a concentration of 1.53 μM inhibited platelet aggregation mediated through CLEC-2, but not that mediated through other receptors. IV administration of Co-HP to mice significantly inhibited hematogenous metastasis of podoplanin-expressing B16F10 cells to the lung as well as in vivo arterial and venous thrombosis, without a significant increase in tail-bleeding time. Thus, Co-HP may be a promising molecule for antimetastatic and antiplatelet treatment that does not cause bleeding tendency.

Co-SLD suppressed the growth of oral squamous cell carcinoma via disrupting mitochondrial function

“…Currently, the development of metal complexes with nonplatinum central atoms including ruthenium [11], gold [12], silver [13], copper [14], zinc [15], Manganese [16], nickel [17], iridium [18] and cobalt [19] has been one of the hottest emerging areas of anticancer drug research. Among these, carbonyl cobalt complex has strong properties of cancer prevention including tumour growth/metastasis suppression [20], antiproliferative [21], DNA cleavage [22], apoptotic induction [23] and autophagy [8], which was more active than cisplatin on the human breast tumour cell lines (MCF-7 and MDA-MB-231) [24,25] and ovarian cancer cells (SKOV3/ DDP) [26]. With the concept of carbonyl metal CO-releasing molecules (CORMs) appearing, the anti-inflammatory effects were found through liberating CO to inhibit nitrite content [27].…”

Role of Platelet C-Type Lectin-Like Receptor 2 in Promoting Lung Metastasis in Osteosarcoma

“…( 35 ) We recently reported that cobalt hematoporphyrin could selectively inhibit the CLEC‐2–podoplanin interaction without affecting the responsiveness to other platelet agonists and bleeding time whereas cobalt hematoporphyrin could reduce arterial and deep vein thrombosis. ( 36 ) Consequently, platelet CLEC‐2 may be a more promising and safer treatment target than podoplanin for patients with osteosarcoma.…”

C‐type lectin receptors of the Dectin‐1 cluster: Physiological roles and involvement in disease

“…In fact, CLEC‐2 plays a critical role in embryonic development, facilitating blood‐lymphatic separation, cerebrovascular patterning and integrity, lymph node and lung development, as well as platelet formation and the maintenance of hematopoietic stem cells in the bone marrow . In cancer, the interaction of CLEC‐2 with podoplanin‐expressing tumour cells promotes angiogenesis, tumour growth and metastasis, and may represent a target for therapy, if the side‐effects on the haemostatic functions of the receptor can be overcome . In contrast, expression of CLEC‐2 on some cancer cells, such as gastric cancer cells, may be protective .…”