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The angiogenic potential of solid tumors, or the ability to initiate neovasculature development from pre-existing host vessels, is facilitated by soluble factors secreted by tumor cells and involves breaching of extracellular matrix barriers, endothelial cell (EC) proliferation, migration and reassembly. We evaluated the angiogenic potential of human melanoma cell lines differing in their degree of aggressiveness, based on their ability to regulate directionally persistent EC migration. We observed that conditioned-medium (CM) of the aggressive melanoma cell line BLM induced a high effective migratory response in ECs, while CMs of Mel57 and 1F6 had an inhibitory effect. Further, the melanoma cell lines exhibited a varied expression profile of tissue inhibitor of metalloproteinase-3 (TIMP3), detectable in the CM. TIMP3 expression inversely correlated with aggressiveness of the melanoma cell line, and ability of the respective CMs to induce directed EC migration. Interestingly, TIMP3 expression was found to be silenced in the BLM cell line, concurrent with its role as a tumor suppressor. Treatment with recombinant human TIMP3 and CM of modified, TIMP3 expressing, BLM cells mitigated directional EC migration, while CM of TIMP3 silenced 1F6 cells induced directed EC migration. The functional implication of TIMP3 expression on tumor growth and angiogenic potential in melanoma was evaluated in vivo. We observed that TIMP3 expression reduced tumor growth, angiogenesis and macrophage infiltration of BLM tumors while silencing TIMP3 increased tumor growth and angiogenesis of 1F6 tumors. Taken together, our results demonstrate that TIMP3 expression correlates with inhibition of directionally persistent EC migration and adversely affects the angiogenic potential and growth of melanomas.

Background: Nonresectable primary and metastatic liver tumors remain an important clinical problem. Melphalan-based isolated hepatic perfusion (M-IHP) leads to more than 70% objective responses in selective groups of patients with nonresectable metastases confined to the liver. Complete responses are rare and progression-free survival is limited. Tumor necrosis factor (TNF), a very active agent in isolated limb perfusion, is linked to serious hepatotoxicity, restricting its use in IHP. Because of its vasoactive properties, histamine (Hi) is an alternative to TNF. In this article we evaluate its potential synergistic effect in M-IHP, improving response rates., Methods: Our experimental rat IHP model is used for the treatment of soft tissue sarcoma liver metastases. Blood samples are collected for monitoring liver enzymes. Livers are excised 72 h and 7 days after treatment for histologic evaluation., Results: After sham-IHP and Hi-IHP, tumor progression was observed in 100% of treated animals, while after M-IHP this number fell to 62% and after Hi + M-IHP it fell to only 22% (P = 0.006). Overall response rates were of 55% for Hi + M-IHP vs. 25% for M-IHP, and, more importantly, complete responses (CR) were observed only after Hi + M-IHP (22%) (P = 0.009). Hepatotoxicity peaked within 24 h after IHP, independent of the treatment administered, recovered in 48 h, and was related mainly to the elevation of transaminases (grade 3 ASAT and grade 1 ALAT for control group and grades 3 and 4, respectively, for all other treatments). No serious systemic toxicity was observed. Histology of the liver showed no serious damage., Conclusion: Hi + M-IHP has synergistic antitumor effects without any increase in regional or systemic toxicity.

Endothelial monocyte-activating polypeptide-II (EMAP-II), a proinflammatory cytokine with antiangiogenic properties, renders tumours sensitive to tumour necrosis factor-alpha (TNF) treatment. The exact mechanisms for this effect remain unclear. Here we show that human endothelial cells (EC) are insensitive to TNF-induced apoptosis but after a short pre-treatment with EMAP-II, EC quickly undergo TNF-induced apoptosis. We further analysed this EMAP-II pre-treatment effect and found no increase of TNF-R1 protein expression but rather an induction of TNF-R1 redistribution from Golgi storage pools to cell membranes. In addition, we observed EMAP-II induced mobilization and membrane expression of the TNF-R1-Associated Death Domain (TRADD) protein. Immunofluorescence co-staining experiments revealed that these two effects occurred at the same time in the same cell but TNF-R1 and TRADD were localized in different vesicles. These findings suggest that EMAP-II sensitises EC to apoptosis by facilitating TNF-R1 apoptotic signalling via TRADD mobilization and introduce a molecular and antiangiogenic explanation for the TNF sensitising properties of EMAP-II in tumours.

The objective of this study was to evaluate the potential of dynamic contrast-enhanced MRI for quantitative characterization of tumor microvessels and to assess the microvascular changes in response to isolated limb perfusion with TNF-alpha and melphalan. Dynamic contrast-enhanced MRI was performed in an experimental cancer model, using a macromolecular contrast medium, albumin-(Gd-DTPA)45. Small fragments of BN 175, a soft-tissue sarcoma, were implanted in 11 brown Norway (BN) rats. Animals were assigned randomly to a control (Haemaccel) or drug-treated group (TNF-alpha/melphalan). MRI was performed at baseline and 24 h after ILP. The transendothelial permeability (K(PS)) and the fractional plasma volume (fPV) were estimated from the kinetic analysis of MR data using a two-compartment bi-directional model. K(PS) and fPV decreased significantly in the drug-treated group compared to baseline (p<0.05). In addition, K(PS) post therapy was significantly lower (p<0.05) in the drug-treated group than in the control group. There was no significant difference in fPV between the drug-treated and the control group after therapy. Tumor microvascular changes in response to isolated limb perfusion can be determined after 24 h by dynamic contrast-enhanced MRI. The data obtained in this experimental model suggest possible applications in the clinical setting, using the appropriate MR contrast agents.

Background: Experiments with tumor necrosis factor alpha (TNF) in rodents have shown that a high dose can lead to hemorrhagic necrosis in tumors. Endothelial monocyte-activating polypeptide II (EMAP-II) is a novel tumor-derived cytokine, and its expression increases the TNF-1 receptor on tumor endothelium, enhances the induction of tissue factor on tumor endothelial cells, and has an antiangiogenic effect. It has recently been shown that in vivo sensitivity of tumor vasculature to TNF is determined by tumor production of EMAP-II., Methods: We measured the level of EMAP-II in a TNF-resistant soft tissue sarcoma. We subsequently stabile-transfected this cell line with a retroviral construct containing the EMAP gene. In an extremity perfusion model in tumor-bearing rats, we measured response rates to TNF therapy., Results: Functional EMAP-II production was increased after this transfection. Immunostaining of paraffin-embedded tumor tissue sections in rats showed an overexpression of human EMAP-II. Results of the TNF perfusions in rats suggest that this tumor is more sensitive to TNF therapy., Conclusions: EMAP-II is produced in various levels. One can increase the sensitivity of tumor for TNF therapy in vivo by upregulating the EMAP-II production. This result leaves an opportunity for enhanced TNF response of tumors in future settings.

Background: Since the introduction of high-dose tumor necrosis factor-alpha (TNFalpha) in the setting of isolated limb perfusion (ILP) in the clinic, prevention of leakage to the body of the patient is monitored with great precision for fear of TNF-mediated toxicity. That we observed remarkably little toxicity in patients with and without leakage prompted us to determine patterns of cytokines and acute phase proteins in patients with high leakage and in patients without any leakage., Methods: TNFalpha, interleukin (IL)-6, IL-8, C-reactive protein, and secretory (s)-phospholipase A2 were measured at several time points during and after (until 7 days) ILP in 10 patients with a leakage to the systemic circulation varying in percentage from 12% to 65%. As a control, the same measurements, both in peripheral blood and in perfusate, were performed in nine patients without systemic leakage., Results: In patients with systemic leakage, levels of TNFalpha increased during ILP, reaching values to 277 ng/ml. IL-6 and IL-8 peaked 3 hours after ILP with values significantly higher compared with patients without systemic leakage. C-reactive protein and s-phospholipase A2 peaked at day 1 in both patient groups, s-phospholipase A2 with significant higher levels and C-reactive protein, in contrast, with lower levels in the leakage patients., Conclusions: High leakage of TNFalpha to the systemic circulation, caused by a complicated ILP, led to 10-fold to more than 100-fold increased levels of TNFalpha, IL-6, and IL-8 in comparison with patients without leakage. The increase of the acute phase proteins was limited. Even when high leakage occurs, this procedure should not lead to fatal complications. The most prominent clinical toxicity was hypotension (grade III in four patients), which was easily corrected. No pulmonary or renal toxicity was observed in any patient. It is our experience that, even in the rare event of significant leakage during a TNFa-based ILP, postoperative toxicity is usually mild and can be easily managed by the use of fluid and, in some cases, vasopressors.

Research on the potential application of liposomes in the prevention and treatment of infectious diseases has focussed on improvement of the therapeutic index of antimicrobial drugs and immunomodulators and on stimulation of the immune response to otherwise weak antigens in vaccines composed of purified micro-organism subunits. In this review current approaches in this field are outlined. The improved therapeutic index of antimicrobial drugs after encapsulation in liposomes is a result of enhanced drug delivery to infected tissue or infected cells and/or a reduction of drug toxicity of potentially toxic antibiotics. Liposomal encapsulation of immunomodulators that activate macrophages aims at reducing the toxicity of these agents and targeting them to the cells of the mononuclear phagocyte system in order to increase the nonspecific resistance of the host against infections. Studies on the immunogenicity of liposomal antigens have demonstrated that liposomes can potentiate the humoral and cell mediated immunity to a variety of antigens.