Heparin Impairs Angiogenesis through Inhibition of MicroRNA-10b

Abstract

Heparin, which has been used as an anticoagulant drug for decades, inhibits angiogenesis, whereas thrombin promotes tumor-associated angiogenesis. However, the mechanisms underlying the regulation of angiogenesis by heparin and thrombin are not well understood. Here, we show that microRNA-10b (miR-10b) is down-regulated by heparin and up-regulated by thrombin in human microvascular endothelial cells (HMEC-1). Overexpression of miR-10b induces HMEC-1 cell migration, tube formation, and angiogenesis, and downregulates homeobox D10 (HoxD10) expression via direct binding of miR-10b to the putative 3 UTR of HoxD10. In addition, HMEC-1 cell migration and tube formation are induced by HoxD10 knockdown, whereas angiogenesis is arrested when HoxD10 expression is increased after anti-miR-10b or heparin treatments. Furthermore, expression of miR-10b and its transcription factor Twist are up-regulated by thrombin, whereas HoxD10 expression is impaired by thrombin. Using quartz crystal microbalance analysis, we show that heparin binds to thrombin, thereby inhibiting thrombin-induced expression of Twist and miR-10b. However, the expression of miR-10b is not attenuated by heparin any more after thrombin expression is silenced by its siRNA. Interestingly, we find that heparin attenuates miR10b expression and induces HoxD10 expression in vivo to inhibit angiogenesis and impair the growth of MDA-MB-231 tumor xenografts. These results provide insight into the molecular mechanism by which heparin and thrombin regulate angiogenesis.Thrombosis is considered an early clinical indication and frequent complication of cancer (1, 2). Malignant tumors often exhibit increased expression of tissue factor and cancer procoagulant, which can be followed by activation of cell surface protease receptors and fibrin generation (3). In addition, tumor cells can interact with blood cells, particularly monocytes, macrophages, and platelets, leading to the generation of thrombin and thrombosis through the clotting cascade or platelet activation (4). Moreover, aggressive antitumor therapies such as chemotherapy, radiation, and surgery also increase the risk of thrombosis.Positive feedback signaling loops exist between tumor tissue and the coagulation system (5, 6). For instance, it is widely accepted that elements of the coagulation and fibrinolytic system may aid in cancer cell survival, proliferation, invasion, and metastasis, as well as tumor angiogenesis (7). Therefore, inhibition of the activation of coagulation could be a useful antitumor strategy. A number of studies have shown that anticoagulant drugs can extend survival in patients with certain types of cancer (8), and studies are currently ongoing to confirm the effects of anticoagulant therapy in a range of tumor types. However, the molecular mechanisms involved in the action of anticoagulants in this process are not well understood.Heparins, in particular those of low molecular weight, are effective in the prevention and treatment of thromboembolic events in cancer patients (9, 10). As early...

MicroRNAs Regulate Tumor Angiogenesis Modulated by Endothelial Progenitor Cells

“…In fact, suppression of miR-10b and miR-196b led to significant defects in tube number, length, and mobilization in human and murine endothelial cells (Fig. 5) in agreement with a recent observation showing that miR-10b regulates HOXD10 in microvessels (35). HOXD10 has been showed to suppress angiogenesis (37).…”

miR‐10a restores human mesenchymal stem cell differentiation by repressing KLF4

“…Contrary to being increased in human pancreatic adenocarcinomas and glioblastoma multiforme (Ciafre et al, 2005; Bloomston et al, 2007), miR-10b has been found to be decreased in breast cancer tissues (Ma et al, 2007). MiR-10b levels have been reported to be repressed by heparin; however, they are increased by thrombin in human microvascular endothelial cells (Shen et al, 2011). In future studies, the function of miR-10a in angiogenesis should be investigated.…”

AngiomiR-126 expression and secretion from circulating CD34+ and CD14+ PBMCs: role for proangiogenic effects and alterations in type 2 diabetics

“…MiR-10b has recently been suggested to regulate angiogenesis in human microvascular endothelial cells, where miR-10b overexpression promoted endothelial cell migration and tube formation. 35 These findings raise the possibility that this microRNA may also regulate proangiogenic effects in CD34 ϩ mononuclear cells; this needs to be further evaluated in future studies. However, miR-10b was substantially higher expressed in CD34 ϩ CD14 ϩ compared with CD34 ϩ CD14 Ϫ mononuclear cells that had a rather similar proangiogenic capacity in the present study, which would suggest that miR-10b is not a major regulator of proangiogenic effects of CD34 ϩ mononuclear cells.…”