Interferon-alpha-mediated down-regulation of angiogenesis-related genes and therapy of bladder cancer are dependent on optimization of biological dose and schedule.
(9/4006)
The purpose of this study was to identify and optimize the antiangiogenic activity of IFN-alpha against human bladder cancer cells growing in the bladder of nude mice. 253J B-V IFN(R) cells (resistant to antiproliferative effects of IFN-alpha or IFN-beta) were implanted into the bladder wall of nude mice. Three days later, the mice were treated with s.c. injections of IFN-alpha (70,000 units/week) at different dosing schedules (1, 2, 3, or 7 times/week). Daily therapy with IFN-alpha produced the most significant inhibition of tumor growth, tumor vascularization, and down-regulation of basic fibroblast growth factor and matrix metalloprotease-9 mRNA and protein expression. Changing dose and schedule of IFN-alpha administration had minimal effects on the expression of vascular endothelial growth factor or interleukin 8. The daily s.c. administrations of 5,000 or 10,000 units IFN-alpha-2a produced maximal inhibition of bFGF and MMP-9 expression (mRNA and protein), maximal reduction in tumor vessel density, and maximal reduction in serum levels of bFGF. Daily administration of higher doses of IFN-alpha failed to produce significant antiangiogenic effects. These data suggest that the antiangiogenic activity of IFN-alpha is dependent on frequent administration of optimal biological dose and not maximal tolerated dose. (+info)
Inhibition of angiogenesis by blocking activation of the vascular endothelial growth factor receptor 2 leads to decreased growth of neurogenic sarcomas.
(10/4006)
Neurogenic sarcomas are incurable, common malignant human peripheral nerve tumors subject to local recurrence and systemic metastasis. In this study, the vascularity, vascular endothelial growth factor (VEGF) expression, and effects of inhibiting VEGF receptor on growth of neurogenic sarcomas were examined. Vascularization and VEGF expression were 6.4- and 15-fold higher in tumors than in normal nerves. The small molecule inhibitor (SU5416) of VEGF receptor 2 had no effect on neurogenic sarcoma cell lines in vitro, but the growth of a human tumor explant xenograft model was reduced by 54.8% compared to vehicle. Reduction in tumor growth was due to decreased tumor angiogenesis, leading to reduction of tumor cell proliferation and increased apoptosis. Inhibiting VEGF function may therefore be a useful adjuvant therapy for neurogenic sarcomas. (+info)
Multi-institutional study of the angiogenesis inhibitor TNP-470 in metastatic renal carcinoma.
(11/4006)
PURPOSE: Renal cell carcinoma is resistant to most chemotherapy, and only a minority of patients respond to immunotherapy. Its highly vascular nature suggests that antiangiogenesis therapy might be useful. We thus performed a phase II study of the fumigillin analog TNP-470 in previously treated patients with metastatic renal cell carcinoma. PATIENTS AND METHODS: Metastatic renal cell carcinoma patients with good organ function were entered onto the study through five separate institutions. There were no exclusion criteria for prior therapy. All patients were treated at a dose of 60 mg/m(2) of TNP-470 infused over 1 hour three times per week. RESULTS: Thirty-three patients were enrolled. Therapy was generally well tolerated, but asthenia, fatigue, vertigo, dizziness, sense of imbalance, and loss of concentration were common and severe enough to lead to therapy discontinuation in five patients. There was only one partial response of short duration (response rate, 3%, 95% confidence interval, 0% to 16%), but six patients (18%) remained on study for 6 or more months without toxicity or disease progression. CONCLUSION: Long-term therapy with TNP-470 has manageable toxicities and is feasible in patients with metastatic renal cell carcinoma but does not lead to any significant objective responses. Further studies in this population using TNP-470 schedules that produce more prolonged drug levels and clinical trial end points other than objective tumor regression may be indicated. (+info)
Structural basis and potential role of heparin/heparan sulfate binding to the angiogenesis inhibitor endostatin.
(12/4006)
Recombinant mouse endostatin produced by mammalian cells was shown to bind to heparin with a K(d) of 0.3 microM, suggesting that this interaction may play a role in its anti-angiogenic activity. Alanine mutagenesis demonstrated that a major site of four clustered arginines (positions 155, 158, 184 and 270) and a second site (R193, R194) are essential for binding. The same epitopes also participate in endostatin binding to heparan sulfate and sulfatides but not in its binding to the extracellular protein ligands fibulin-1 and fibulin-2. Analyses with various heparin fragments demonstrated a minimum size (12mer) for efficient binding to endostatin and a crucial role of 2-O- and 6-O-sulfation. Furthermore, a substantial proportion (10-50%) of heparan sulfate chains obtained from various tissues showed a distinct binding to endostatin, indicating its potential to interact with extracellular and/or membrane-bound proteoglycans. Angiogenesis induced by basic fibroblast growth factor-2 (FGF-2), but not by vascular endothelial growth factor (VEGF), in a chick chorioallantoic membrane assay could be inhibited by endostatin in a dose-dependent manner. The mutational block of heparin binding decreased endostatin inhibition to low levels but elimination of zinc binding had no effect. (+info)
Antitumor activity of thalidomide in refractory multiple myeloma.
(13/4006)
BACKGROUND: Patients with myeloma who relapse after high-dose chemotherapy have few therapeutic options. Since increased bone marrow vascularity imparts a poor prognosis in myeloma, we evaluated the efficacy of thalidomide, which has antiangiogenic properties, in patients with refractory disease. METHODS: Eighty-four previously treated patients with refractory myeloma (76 with a relapse after high-dose chemotherapy) received oral thalidomide as a single agent for a median of 80 days (range, 2 to 465). The starting dose was 200 mg daily, and the dose was increased by 200 mg every two weeks until it reached 800 mg per day. Response was assessed on the basis of a reduction of the myeloma protein in serum or Bence Jones protein in urine that lasted for at least six weeks. RESULTS: The serum or urine levels of paraprotein were reduced by at least 90 percent in eight patients (two had a complete remission), at least 75 percent in six patients, at least 50 percent in seven patients, and at least 25 percent in six patients, for a total rate of response of 32 percent. Reductions in the paraprotein levels were apparent within two months in 78 percent of the patients with a response and were associated with decreased numbers of plasma cells in bone marrow and increased hemoglobin levels. The microvascular density of bone marrow did not change significantly in patients with a response. At least one third of the patients had mild or moderate constipation, weakness or fatigue, or somnolence. More severe adverse effects were infrequent (occurring in less than 10 percent of patients), and hematologic effects were rare. As of the most recent follow-up, 36 patients had died (30 with no response and 6 with a response). After 12 months of follow-up, Kaplan-Meier estimates of the mean (+/-SE) rates of event-free survival and overall survival for all patients were 22+/-5 percent and 58+/-5 percent, respectively. CONCLUSIONS: Thalidomide is active against advanced myeloma. It can induce marked and durable responses in some patients with multiple myeloma, including those who relapse after high-dose chemotherapy. (+info)
Selective inhibition of amino-terminal methionine processing by TNP-470 and ovalicin in endothelial cells.
(14/4006)
BACKGROUND: The angiogenesis inhibitors TNP-470 and ovalicin potently suppress endothelial cell growth. Both drugs also specifically inhibit methionine aminopeptidase 2 (MetAP2) in vitro. Inhibition of MetAP2 and changes in initiator methionine removal in drug-treated endothelial cells have not been demonstrated, however. RESULTS: Concentrations of TNP-470 sufficient to inactivate MetAP2 in intact endothelial cells were comparable to those that inhibited cell proliferation, suggesting that MetAP2 inhibition by TNP-470 underlies the ability of the drug to inhibit cell growth. Both drug-sensitive and drug-insensitive cell lines express MetAP1 and MetAP2, indicating that drug sensitivity in mammalian cells is not simply due to the absence of compensating MetAP activity. With a single exception, detectable protein N-myristoylation is unaffected in sensitive endothelial cells treated with TNP-470, so MetAP1 activity can generally compensate when MetAP2 is inactive. Analysis of total protein extracts from cells pulse-labeled with [(35)S]-methionine following TNP-470 treatment revealed changes in the migration of several newly synthesized proteins. Two of these proteins were identified as glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and cyclophilin A. Purification and amino-terminal sequencing of GAPDH from TNP-470-treated cells revealed partial retention of its initiator methionine, indicating that methionine removal from some, but not all, proteins is affected by MetAP2 inactivation. CONCLUSIONS: Amino-terminal processing defects occur in cells treated with TNP-470, indicating that inhibition of MetAP2 by the drug occurs in intact cells. This work renders plausible a mechanism for growth inhibition by TNP-470 as a consequence of initiator methionine retention, leading to the inactivation of as yet unidentified proteins essential for endothelial cell growth. (+info)
Different patterns of angiogenesis in sarcomas and carcinomas.
(15/4006)
Solid tumors depend on angiogenesis for growth and metastasis. It has been shown that blood vessel density, as determined by counting the number of capillaries in clustered bursts, is a significant prognostic factor in carcinomas. It is unclear, however, whether vessel density is a prognostic factor in sarcomas. In this study, we examined angiogenesis in sarcomas of various grades and compared their vascular patterns to those of carcinomas. Microvessels were identified by von Willebrand factor staining. The matrix of multiple sarcoma and breast carcinoma specimens were extracted and subjected to Western analysis of various angiogenic factors and inhibitors. Metalloproteinase inhibitor presence was also determined by in situ hybridization. In breast carcinomas, capillaries were clustered in bursts within the stroma of the tumor, whereas the sarcoma capillaries were homogeneously distributed in the tumor stroma. Random blood vessel density per high power field in sarcomas did not correlate with patient prognosis. The matrix of sarcomas and carcinomas contained both angiogenic stimulators and inhibitors. Tissue inhibitor of metalloproteinase-1 was found predominantly in fibroblasts and myofibroblasts in the matrix of carcinoma specimens. The difference in the pattern of angiogenesis in sarcomas and carcinomas may be attributable to the presence of fibroblasts and myofibroblasts in carcinomas, resulting in the compartmentalization of bursts of angiogenic factors. The homogeneous appearance of vessel density in sarcomas observed in the present study would be the consequence of the influence of a single compartment. (+info)
BAY 12-9566, a novel inhibitor of matrix metalloproteinases with antiangiogenic activity.
(16/4006)
Matrix metalloproteinases (MMPs) have been implicated in tumor cell invasion, metastasis, and angiogenesis. BAY 12-9566, a novel, non-peptidic biphenyl MMP inhibitor, has shown preclinical activity on a broad range of tumor models and is currently in clinical development. The purpose of this study was to investigate the antiangiogenic activity of BAY 12-9566. In vitro, BAY 12-9566 prevented matrix invasion by endothelial cells in a concentration-dependent manner (IC50 = 8.4x10(-7) M), without affecting cell proliferation. In vivo, oral daily administration of BAY 12-9566 (50-200 mg/kg) inhibited angiogenesis induced by basic fibroblast growth factor in the Matrigel plug assay, reducing the hemoglobin content of the pellets. Histological analysis showed a reduction in the amount of functional vessels within the Matrigel. We conclude that the MMP inhibitor BAY 12-9566 inhibits angiogenesis, a property that further supports its clinical development as an antimetastatic agent. (+info)