Placenta growth factor (PlGF), a member of the vascular endothelial growth factor family, plays an important role in adult pathological angiogenesis. To further investigate PlGF functions in tumor growth and metastasis formation, we used transgenic mice overexpressing PlGF in the skin under the control of the keratin 14 promoter. These animals showed a hypervascularized phenotype of the skin and increased levels of circulating PlGF with respect to their wild-type littermates. Transgenic mice and controls were inoculated intradermally with B16-BL6 melanoma cells. The tumor growth rate was fivefold increased in transgenic animals compared to wild-type mice, in the presence of a similar percentage of tumor necrotic tissue. Tumor vessel area was increased in transgenic mice as compared to controls. Augmented mobilization of endothelial and hematopoietic stem cells from the bone marrow was observed in transgenic animals, possibly contributing to tumor vascularization. The number and size of pulmonary metastases were significantly higher in transgenic mice compared to wild-type littermates. Finally, PlGF promoted tumor cell invasion of the extracellular matrix and increased the activity of selected matrix metalloproteinases. These findings indicate that PlGF, in addition to enhancing tumor angiogenesis and favoring tumor growth, may directly influence melanoma dissemination.

We studied the anticancer activity of a series of new combretastatin derivatives with B-ring modifications. The structure-activity relationship (SAR) information confirmed the importance of cis-stereochemistry and of a phenolic moiety in B-ring. We selected the benzo[b]thiophene and benzofuran combretastatin analogues 11 (ST2151) and 13 (ST2179) and their phosphate prodrugs (29 and 30) for their high antitumor activity in in vitro and in vivo models. Cell exposure to IC50 of 11, 13, and CA-4 led to the arrest of various cell types in the G2/M phase of the cell cycle and induction of apoptosis. Mainly, 11 and 13 induced the formation of multinucleated cells with abnormal chromatin distribution, with only a minimal effect on the microtubule organization, with respect to CA-4. Interestingly, both the pharmacokinetic profile of 29 and its in vivo antitumor effect and those of 30, active even after oral administration, suggest additional pharmacological differences between these compounds and CA-4P.

Placenta growth factor (PlGF) belongs to the vascular endothelial growth factor (VEGF) family and represents a key regulator of angiogenic events in pathological conditions. PlGF exerts its biological function through the binding and activation of the seven immunoglobulinlike domain receptor Flt-1, also known as VEGFR-1. Here, we report the first detailed mutagenesis studies that provide a basis for understanding molecular recognition between PlGF-1 and Flt-1, highlighting some of the residues that are critical for receptor recognition. Mutagenesis analysis, performed on the basis of a structural model of interaction between PlGF and the minimal binding domain of Flt-1, has led to the identification of several PlGF-1 residues involved in Flt-1 recognition. The two negatively charged residues, Asp-72 and Glu-73, located in the ␤3-␤4 loop, are critical for Flt-1 binding.

Objective-The beneficial effect of the natural compound propionyl-L-carnitine (PLC) on intermittent claudication in patients with peripheral arterial disease is attributed to its anaplerotic function in ischemic tissues, but inadequate information is available concerning action on the vasculature. Methods and Results-We investigated the effects of PLC in rabbit hind limb collateral vessels after femoral artery excision, mouse dorsal air pouch, chicken chorioallantoic membrane, and vascular cells by angiographic, Doppler flow, and histomorphometrical and biomolecular analyses. PLC injection accelerated hind limb blood flow recovery after 4 days (PϽ0.05) and increased angiographic quadriceps collateral vascularization after 7 days (PϽ0.001) Histomorphometry confirmed the increased vascular area (PϽ0.05), with unchanged intramuscular capillary density. PLCinduced dilatative adaptation, and growth was found associated with increased inducible nitric oxide synthase and reduced arterial vascular endothelial growth factor and intracellular adhesion molecule-1 expression. PLC also increased vascularization in air pouch and chorioallantoic membrane (PϽ0.05), particularly in large vessels. PLC increased endothelial and human umbilical vascular endothelial cell proliferation and rapidly reduced inducible nitric oxide synthase and NADPH-oxidase 4 -mediated reactive oxygen species production in human umbilical vascular endothelial cells; NADPH-oxidase 4 also regulated NF-B-independent intracellular adhesion molecule-1 expression. Conclusion-Our results provided strong evidence that PLC improves postischemic flow recovery and revascularization and reduces endothelial NADPH-oxidase-related superoxide production. We recommend that PLC should be included among therapeutic interventions that target endothelial function. Key Words: arteriogenesis Ⅲ endothelial function Ⅲ oxidative stress Ⅲ vascular function P eripheral arterial disease (PAD) is the most common clinical consequence of atherosclerosis, affecting Ϸ20% of adults older than age 55 years. 1 Atherosclerotic occlusion of leg arteries induces clinical manifestations, most frequently intermittent claudication. 1,2 Among the functional vascular changes observed with atherosclerosis, endothelial dysfunction plays a major role. 3,4 L-carnitine is a natural amino acid that plays a crucial role in the shuttle mechanism of long-chain fatty acids and in fueling ␤ oxidation. 5 The endogenous L-carnitine pool includes a series of short-chain, medium-chain, and long-chain esters in homeostatic equilibrium. 5,6 Propionyl-L-carnitine (PLC) is a short-chain L-carnitine ester that has been introduced among emerging noninterventional medical regiments that aim to counteract PAD-related adverse effects. 1,2,7 PLC activity is classically related to the anaplerotic function of providing substrates for energy expenditure in ischemic tissues. 1,8 Although some data showed beneficial remodeling after injury, 9 the mechanisms through which PLC influences arterial function remain largely hypot...

Angiogenesis is one of the crucial events for cancer development and growth.

The aim of the present study was to identify specific A v B 3 /A v B 5 integrin antagonists active on tumor-induced angiogenesis. To this purpose, in vitro integrin-binding assays were used to screen a library of conformationally constrained bicyclic lactam Arg-Gly-Asp -containing pseudopeptides. The results identified ST1646 as a high-affinity specific ligand for A v B 3 and A v B 5 integrins with negligible interacting with A 5

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With the aim of understanding the influence of fluorine on the double bond of the cis-stilbene moiety of combretastatin derivatives and encouraged by a preliminary molecular modeling study showing a different biological environment on the interaction site with tubulin, we prepared, through various synthetic approaches, a small library of compounds in which one or both of the olefinic hydrogens were replaced with fluorine. X-ray analysis on the difluoro-CA-4 analogue demonstrated that the spatial arrangement of the molecule was not modified, compared to its nonfluorinated counterpart. SAR analysis confirmed the importance of the cis-stereochemistry of the stilbene scaffold. Nevertheless, some unpredicted results were observed on a few trans-fluorinated derivatives. The position of a fluorine atom on the double bond may affect the inhibition of tubulin polymerization and cytotoxic activity of these compounds.