Tissue Factor Pathway Inhibitor Inhibits Endothelial Cell Proliferation via Association with the Very Low Density Lipoprotein Receptor

Abstract

Tissue factor pathway inhibitor (TFPI) contains three Kunitz-type proteinase inhibitor domains and is a potent inhibitor of tissue factor-mediated coagulation. Here, we report that TFPI inhibits the proliferation of basic fibroblast growth factor-stimulated endothelial cells. A truncated form of TFPI, containing only the first two Kunitz-type proteinase inhibitor domains, has very little antiproliferative activity, suggesting that the carboxyl-terminal region of TFPI is responsible for this activity. Binding studies revealed that full-length TFPI, but not the truncated TFPI molecule, is recognized by the very low density lipoprotein receptor (VLDL receptor) indicating that this receptor is a novel high affinity endothelial cell receptor for TFPI. The antiproliferative activity of TFPI on endothelial cells is inhibited by the receptor-associated protein, a known antagonist of ligand binding by the VLDL receptor, and by anti-VLDL receptor antibodies. These results confirm that the antiproliferative activity of TFPI is mediated by the VLDL receptor and suggest that this receptor-ligand system may be a useful target for the development of new antiangiogenic and antitumor agents.The extrinsic pathway of blood coagulation is initiated when factor VII (fVII) 1 binds to its cellular receptor, tissue factor (TF). The fVIIa⅐TF complex then functions as a potent enzyme, activating factor X which leads to thrombin generation. In addition to initiating coagulation, recent research suggests that fVIIa⅐TF complexes play an important role in angiogenesis (1-3). Zhang et al. (1) correlated TF expression in tumor cells with the ability of the tumors to secrete vascular endothelial growth factor (VEGF) and, in turn, to induce an angiogenic response when implanted in immunodeficient mice. Although TF is not normally expressed on the surface of vascular endothelial cells, in situ hybridization studies have detected TF mRNA in tumor-associated endothelial cells from patients with invasive breast cancer (2). Finally, in a TF-dependent metastasis model, the binding and proteolytic activity of VIIa was shown to be necessary for the initial steps of tumor metastasis (3).The tissue factor pathway is regulated by a potent inhibitor termed tissue factor pathway inhibitor (TFPI). TFPI forms a tight complex with both fXa and fVIIa leading to their inhibition. The TFPI molecule contains three Kunitz-type domains and a basic carboxyl-terminal region. By employing site-directed mutagenesis, Girard et al. (4) demonstrated that the second Kunitz domain is required for efficient binding and inhibition of fXa, and both Kunitz domains 1 and 2 are required for the inhibition of fVIIa/TF activity. Mutation of the predicted inhibitory residues of the third Kunitz domain had no significant effect on either function of TFPI. Rather, this portion of the molecule binds to the cell surfaces by interacting with cell-surface glycosaminoglycans (5). TFPI can also bind to the low density lipoprotein receptor-related protein (LRP) (6) and, in doing so, mediates ...

Increased bone marrow microvascular density in haematological malignancies is associated with differential regulation of angiogenic factors

“…11 The antiangiogenic molecule TFPI-1 inhibits endothelial cell proliferation. 7 We found increased free TFPI-1 antigen and TFPI-1 activity before cancer therapy, and increased TFPI-1 activity after cancer therapy. Despite a shift in the balance between TF and its inhibitor TFPI-1 towards an antiangiogenic phenotype, we found increased angiogenesis in bone marrows.…”

“…7 Despite advances in treatment, chronic lymphatic leukaemia (CLL), MM and indolent subtypes of NHL are still regarded to be incurable diseases, and only half of the patients with acute myeloid leukaemia (AML) and aggressive subtypes of NHL are alive after 5 years. 8 Given the role of angiogenesis in haematological neoplasias, several angiogenesis-inhibitors have been tested in clinical trials, but many have not lived up to expectations.…”

A novel function of tissue factor pathway inhibitor-2 (TFPI-2) in human glioma invasion

“…Our recent studies demonstrated the a ect of TFPI-2 in vitro in other cancers like prostate cancer cell line (LNCaP) and amelanotic melanomas (C-32) and lung cancer cell line (A549) . Recently it was reported that antiproliferative activity of TFPI is mediated by the VLDL receptor and suggest that this receptor-ligand system may be a useful target for the development of new antiangiogenic and antitumor agents (Hembrough et al, 2001). In the present study, transfecting SNB19 cells with a sense-TFPI-2 cDNA construct inhibited cell migration and invasiveness in vitro and reduced tumor formation in vivo, but transfecting low-grade Hs683 cells with antisense-TFPI-2 enhanced migration and invasiveness in vitro and very small tumor formation in vivo (Figures 3, 4 and 5).…”

Genomic loss and epigenetic silencing of very-low-density lipoprotein receptor involved in gastric carcinogenesis

“…VLDLR may serve as an energy source for the rapid growth of cancer cells or may contribute to tumor formation through ligands such as urokinase-plasminogen activator (uPA) and uPA-plasminogen activator inhibitor-1 complex (Webb et al, 1999). On the other hand, a recent report revealed that the antiproliferative activity of tissue factor pathway inhibitor, which is a potent inhibitor of endothelial proliferation, is mediated through interaction with VLDLR (Hembrough et al, 2001), and so the effects of VLDLR protein expression on the neoplastic process in various tissues seem to be controversial.…”