Evidence of involvement of CD44 in endothelial cell proliferation, migration and angiogenesisin vitro

Abstract

Angiogenesis is essential for tumor growth and metastasis. In the process of angiogenesis, the interaction between adhesive proteins of endothelial cells and extracellular matrix components plays an important role by mediating cell attachment, which is indispensable for their motility, and by transmitting the regulatory signals for cell locomotion and proliferation. In this study, we examined the hypothesis that CD44 expressed on the endothelial cell surface is involved in the angiogenesis process. The experiments using calf pulmonary artery endothelial cells (CPAE) and a human microvascular endothelial cell line (HMEC-I) show that a monoclonal antibody against CD44 (clone J 173) inhibits endothelial cell proliferation by about 30% and migration by 25-50%, and abolishes the stimulating effect of hyaluronan polysaccharides on endothelial cell migration and proliferation. This antibody also suppresses the capillary formation of CPAE in an in vitro model of angiogenesis using fibrin matrix. These results provide evidence of the involvement of endothelial-cell-associated CD44 in angiogenesis.o 1996 Wiley-Liss, Inc.Angiogenesis plays a fundamental role in many physiological and pathological processes including wound healing, tissue repair and tumor growth (Folkman, 1995). For the formation of a new vessel, migration of stimulated endothelial cells and subsequent tube formation virtually depend on the occurrence of timely and locally coordinated extracellular proteolysis, cell adhesion and activation during the cell migration. Therefore, the interaction of adhesive proteins expressed on the endothelial cell surface with the components of extracellular matrix is one of the factors determining the occurrence of angiogenesis. Perturbation of these interactions may abolish an ongoing angiogenesis process. For example, blocking the binding of the integrin molecule to matrix-associated vitronectin led to endothelial cell apoptosis and abolished tumor-induced angiogenesis in vivo (Brooks et al., 1994). Furthermore, the interaction of adhesive proteins with their endothelial cell-surface receptors may also activate the process of angiogenesis. For instance, endothelial cells could be stimulated by the surrounding fibrin I1 matrix to form capillary tubes in vitro (Chalupowicz et al., 1995). However, due to the complexity of the mechanisms involved in cell adhesion, the functions of many adhesive molecules on the endothelial cell surface still remain to be determined.One of the examples is CD44, discovered through its role in mediating leukocyte adhesion and lymphocyte homing (Haynes et al., 1989). Although several studies reported the presence of CD44 on endothelial cells such as human microvascular endothelial cells (HMEC-1) (Xu et al., 1994), bovine microvascular endothelial cells (BME) (Bourguignon et al., 1992) and human umbilical endothelial cells (HUVEC) (Liesveld et al., 1994), the role of CD44 expressed on the endothelial cell surface still remains to be clarified. CD44 is a transmembrane molecule with multiple isofo...

Testicular hyaluronidase induces tubular structures of endothelial cells grown in three‐dimensional colagen gel through a CD44‐mediated mechanism

“…The involvement of CD44 in tube formation of endothelial cells is also supported by data obtained by Trochon et al 20 The mechanism whereby CD44 isoforms exert their different biologic activities involves interactions with the cytoskeletal proteins ankyrin and the ERM family, as well as binding to signaling molecules such as Rho GTPase. 17,41 Interestingly, Stern and Csóka 10 have suggested that one of the multiple-splice forms of CD44 can interact with hyaluronidase.…”

“…16,17 Although several studies have reported the expression of CD44 on endothelial cells, 18,19 little is known about the physiologic significance of CD44 expression on these cells. 18,20 Hyaluronan turnover in humans is very rapid (in the blood stream its half-life is about 5 min and in skin about 1 day); the enzymes responsible for hyaluronan degradation, hyaluronidases, exist in several isoforms 21 and are broadly distributed. Overexpression of hyaluronidases have been reported in several tumors of aggressive character.…”

Early-response gene signalling is induced by angiogenic oligosaccharides of hyaluronan in endothelial cells. Inhibition by non-angiogenic, high-molecular-weight hyaluronan

“…Trochon et al (1996) found that antibodies to CD44 inhibit both endothelial-cell migration and proliferation, the suggestion being that endothelial-cell-associated CD44 is important in angiogenesis. It has been reported that cells from malignant human tumours, but not from normal tissues, express hyaluronidase (HAase) (Liu et al, 1995).…”

Angiogenesis induced in muscle by a recombinant adenovirus expressing functional isoforms of basic fibroblast growth factor

“…34,35 This matrix has been used as an in vitro model to mimic closely the angiogenesis phenomenon since endothelial cells invade blood clots in the process of wound repair. 20,36 In this gel aggregates of endothelial cells organize themselves to form characteristic tubes that resemble blood capillaries. Pepper et al 20 have shown that bFGF induces capillary lumen formation in this model, demonstrating the direct effect of this factor in angiogenesis.…”