Modulation of endothelial cell proliferation, adhesion, and motility by recombinant heparin‐binding domain and synthetic peptides from the type I repeats of thrombospondin

Abstract

Thrombospondin is an inhibitor of angiogenesis that modulates endothelial cell adhesion, proliferation, and motility. Synthetic peptides from the second type I repeat of human thrombospondin containing the consensus sequence-Trp-Ser-Pro-Trp- and a recombinant heparin binding fragment from the amino-terminus of thrombospondin mimic several of the activities of the intact protein. The peptides and heparin-binding domain promote endothelial cell adhesion, inhibit endothelial cell chemotaxis to basic fibroblast growth factor (bFGF), and inhibit mitogenesis and proliferation of aortic and corneal endothelial cells. The peptides also inhibit heparin-dependent binding of bFGF to corneal endothelial cells. The antiproliferative activities of the peptides correlate with their ability to bind to heparin and to inhibit bFGF binding to heparin. Peptides containing amino acid substitutions that eliminate heparin-binding do not alter chemotaxis or proliferation of endothelial cells. Inhibition of proliferation by the peptide is time-dependent and reversible. Thus, the antiproliferative activities of the thrombospondin peptide and recombinant heparin-binding domain result at least in part from competition with heparin-dependent growth factors for binding to endothelial cell proteoglycans. These results suggest that both the Trp-Ser-Xaa-Trp sequences in the type I repeats and the amino-terminal domain play roles in the antiproliferative activity of thrombospondin.

Thrombospondin-1 inhibits endothelial cell responses to nitric oxide in a cGMP-dependent manner

“…TSP1 Inhibits NO-Stimulated Proliferation. TSP1 inhibits proliferation of endothelial cells, with reported IC 50 values of 5-70 nM, depending on the growth medium (36)(37)(38). Consistent with those studies, 22 nM TSP1 was required to significantly inhibit BAEC proliferation stimulated by serum in the absence of NO donor, but proliferation stimulated by 10 M DETA͞NO was inhibited by 50% at Ͻ22 pM TSP1 (Fig.…”

“…A comparable potency was reported for TSP1 to inhibit endothelial cell chemotaxis stimulated by fibroblast growth factor 2 (FGF2) (IC 50 ϭ 22 pM) (36), but others obtained a much higher IC 50 of 700 pM (43). In contrast, 50% inhibition of endothelial cell proliferation stimulated by FGF2 typically requires 5-70 nM TSP1 (36)(37)(38). TSP1 inhibits endothelial cell adhesion, as assessed by focal adhesion disruption, with a reported IC 50 of 2-4 nM (44).…”

Melanoma Cell Invasive and Metastatic Potential Correlates with Endothelial Cell Reorganization and Tenascin Expression

“…Previous studies have revealed that treatment of endothelial cells with TN or other related proteins such as SPARC and thrombospondin (TSP) result in a diminished number of focal adhesions (MurphyUllrich and Hook, 1989;Vrucinic-Filipi andChiquet-Ehrismann, 1993, Murphy-Ullrich et al, 1991). Furthermore, these interactions might also result in modulation of adhesive contacts and cellular receptivity to motility factors leading to reorganization of the actin cytoskeleton (Goldblum et al, 1994, Vogel et al, 1993, Rosen et al, 1990. The profound reorganization of HUVECs on A375SM matrix expressing TN and the role of TN in endothelium adhesion supports the hypothesis that TN might mediate tumor cell-endothelial cell interactions.…”

Cooperation between Thrombospondin-1 Type 1 Repeat Peptides and αvβ3 Integrin Ligands to Promote Melanoma Cell Spreading and Focal Adhesion Kinase Phosphorylation

“…Recombinant fragments and GST or T7 fusion proteins expressing fragments of TSP1 were prepared as described (15,19,20). Synthetic peptides containing TSP1 sequences were prepared as described previously (2,14,(21)(22)(23)(24).…”

“…Peptides from the type 1 repeats and procollagen domains that bind to CD36 inhibit endothelial cell motility (12,13). Heparin-binding peptides from the type I repeats promote cell adhesion and chemotaxis (14) but also inhibit growth, motility, and survival of endothelial cells (8,15). The RFK sequence in the second type 1 repeat activates latent transforming growth factor-␤1 (16).…”