Evaluation of Original Dual Thromboxane A₂ Modulators as Antiangiogenic Agents

Abstract

Angiogenesis is a promising target for the therapy of several diseases including cancer. This study was undertaken to characterize the antiangiogenic properties of a series of original dual thromboxane A 2 (TXA 2 ) inhibitors derived from torasemide, a marketed loop diuretic with TXA 2 antagonistic properties, by evaluating their effects on human endothelial cell migration, adhesion, and viability in vitro, as well as in the ex vivo rat aortic ring assay. All drugs tested exhibited a marked affinity toward human platelet TXA 2 receptor, significantly prevented platelet aggregation induced by U-46,619, a stable TXA 2 receptor agonist, and inhibited platelet TXA 2 synthase without affecting cyclooxygenase (COX)-1 or COX-2 enzymatic activities. These dual TXA 2 inhibitors dose dependently inhibited endothelial cell migration in chemotaxis assays using vascular endothelial growth factor (VEGF) as a chemoattractant but failed to affect cell adhesion and viability. The highest rates of cell migration inhibition were obtained with original compounds BM-567 and BM-573 (50.3 and 59.4% inhibition, respectively) when used at the final concentration of 10 M. In addition, pretreatment of endothelial cells with these two drugs significantly prevented U-46,619-induced intracellular Ca 2ϩ pool mobilization, thus suggesting a mechanistic link between inhibition of the TXA 2 pathway and reduced endothelial cell migration. Treatment of rat aortic explants with U-46,619 (9,11-dideoxy-9,11-methanoepoxy-prostaglandin F 2 ) significantly enhanced vessel sprouting whereas aortic rings treated with some of the compounds, including BM-567 (N-n-pentyl-NЈ-[2-(cyclohexylamino)-5-nitrobenzenesulfonyl]urea) and BM-573 (N-tert-butyl-NЈ-[5-nitro-2-p-toluylaminobenzenesulfonyl]urea), showed a significant decrease in vessel sprouting, which was not reversed by the addition of VEGF. These data suggest that our original dual TXA 2 inhibitors bear antiangiogenic properties, mainly by inhibiting endothelial cell migration. Angiogenesis, a process by which new blood vessels are formed from preexisting vascular networks, occurs both in physiologic conditions, including wound healing, organ regeneration, ovulation, menstruation, and placenta formation, and in pathologic situations, such as rheumatoid arthritis, osteoarthritis, psoriatic skin disease, endometriosis, preeclampsia, diabetic retinopathy, and tumor growth. At the cellular level, angiogenesis is characterized by the transition of endothelial cells from a quiescent state into a metabolically active, proliferative and migrative state. This activation coincides with important changes in the metabolism of endothelial cells and their expression of numerous enzymes. Among these, cyclooxygenase

Eicosanoid signalling pathways in the development and progression of colorectal cancer: novel approaches for prevention/intervention

“…The eicosanoids are derived from 20-carbon (termed 'eicosa') essential fatty acids containing three, four or five double bonds [34]. The omega-6 family of eicosanoids consists of the well-known prostanoids, leukotrienes and epoxygenases [35], while the newer, omega-3 family of eicosanoids includes the eicosapentaenoic acid (EPA)-and docosahexaenoic acid (DHA)-derived resolvins and protectins [36].…”

4-Methylnitrosamino-1-3-pyridyl-1-butanone (NNK) promotes lung cancer cell survival by stimulating thromboxane A2 and its receptor

“…The PI3K-specific inhibitor, wortmannin, was purchased from Sigma Chemical Co. (St Louis, MO, USA). The concentrations of all chemicals used were based on the product datasheets and previous publications (Daniel et al, 1999;de Leval et al, 2006;Aronov et al, 2007;Li et al, 2007;Wei et al, 2007;Cailleteau et al, 2008;Moussa et al, 2008a, b), and they were proven to be optimal in the present study. Dimethylsulfoxide, an organic solvent, was used in the treatment with different drugs.…”

The role of prostacyclin synthase and thromboxane synthase signaling in the development and progression of cancer

“…Dual TXS/TP inhibitors have been shown to dose-dependantly inhibit endothelial cell migration in chemotaxis assays. In addition, pretreatment of endothelial cells with these original dual inhibitors significantly attenuated TP agonist-induced intracellular Ca 2+ pool mobilization, suggesting a mechanistic link between TXS/TP inhibition and reduced endothelial cell migration [158].…”

“…Ozagrel is therefore an interesting pharmacological tool to evaluate the role of thromboxane synthase and TXA 2 production in both physiologic and pathologic states [175,179]. A recent report has demonstrated that dual TXA 2 inhibitors (which display dual inhibitory activity of both TXS and TP) exhibit anti-angiogenic properties in human endothelial cells, suggesting that this pathway may be an attractive target for anti-angiogenic/anti-cancer therapies [158]. In addition to this, TP antagonists have been shown to sensitize non-small cell lung cancer cells to cisplatin in several studies.…”