FGF2-mediated upregulation of urokinase-type plasminogen activator expression requires a MAP-kinase dependent activation of poly(ADP-ribose) polymerase

Modulation of urokinase plasminogen activator system by poly(ADP-ribose)polymerase-1 inhibition

The urokinase plasminogen activator (uPA) system is a complex regulator of extracellular proteolysis which is involved in various physiological and pathological processes. The major components of this system are the serine protease uPA, two inhibitors PAI-1 and PAI-2, and the receptor uPAR. It has been previously shown by several groups that the uPA system has an important role in cancer progression and therefore its possible prognostic and therapeutic value has been evaluated. The aim of this study is to tackle the role of poly(ADP-ribosyl)ation in the induction of uPA activity in a glioblastoma cell line, A1235. This cell line is sensitive to alkylation damage and is a model for drug treatment. The components of the uPA system and the level of DNA damage were analyzed after alkylation agent treatment in combination with poly(ADP-ribose)polymerase-1 (PARP-1) inhibition. Here we show that the increase in uPA activity results from the net balance change between uPA and its inhibitor at mRNA level. Further, PARP-1 inhibition exerts its influence on uPA activity through DNA damage increase. Involvement of several signaling pathways, as well as cell specific regulation influencing the uPA system are discussed.

Low doses of 3-aminobenzamide, a poly(ADP-ribose) polymerase inhibitor, stimulate angiogenesis by regulating expression of urokinase type plasminogen activator and matrix metalloprotease 2

Background

Poly(ADP-Ribose) polymerase (PARP) activity has been demonstrated fundamental in many cellular processes, including DNA repair, cell proliferation and differentiation. In particular, PARP activity has been recently found to affect proliferation, migration, and tube formation of human umbilical vein endothelial cells. In recent times, PARP inhibitors have entered in clinical trials to potentiate cancer treatments by preventing DNA repair, but little is known about the effects performed by different drug concentrations on neoangiogenesis, an essential step in tumor growth.

Methods

Human umbilical vein endothelial cells were treated with 3 aminobenzamide (3ABA), a PARP inhibitor, and tested for several different cellular parameters.

Results

Here we present in vitro evidence that a low concentration of 3ABA (50 μM), stimulates angiogenesis by decreasing fibrinolytic activity, carried out by urokinase-type plasminogen activator (uPA), and by enhancing matrix metalloprotease-2 (MMP-2) gelatinolytic activity, in fibroblast growth factor-2-stimulated endothelial cells. These unbalanced pathways modify in vitro angiogenic steps, inhibiting chemoinvasion and stimulating tubulogenic activity.

Conclusions

Our results suggest that the proangiogenic effect of low concentrations of 3ABA alerts on the efficacy of PARP inhibitors to potentiate anticancer therapy. Moreover, they indicate that endothelial chemoinvasion and tubulogenesis depend on distinct proteolytic pathways.

Anti-angiogenic active immunotherapy: a new approach to cancer treatment

Tumor angiogenesis plays an important role in tumor growth, aggression and metastasis. Many molecules have been demonstrated as positive regulators of angiogenesis, including vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), epidermal growth factor (EGF), and others. In recent years, significant progress has been made in the research on anti-angiogenic strategies for tumor therapies. In this review, anti-angiogenic active immunotherapies for tumors based on vaccination with xenogeneic homologous molecules and non-xenogeneic homologous molecules are discussed.

p38 and c-Jun N-terminal kinase mitogen-activated protein kinase signaling pathways play distinct roles in the response of organogenesis-stage embryos to a teratogen

Mitogen-activated protein kinase (MAPK) signaling plays an important role during embryo development. We hypothesize that MAPK activation is a determinant of the fate of organogenesis-stage embryos exposed to insult. To test this hypothesis, CD1 mice were exposed to a model teratogen, hydroxyurea, on gestational day 9. Hydroxyurea exposure triggered a dramatic, transient increase in the activation of p38 MAPKs and c-Jun N-terminal kinases (JNKs) in embryos, without activating extracellular signal-regulated kinases 1 and 2. Selectively blocking p38 MAPKs with 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole (SB203580) enhanced hydroxyurea-induced fetal mortality without affecting growth retardation or the incidence of deformities among surviving fetuses. In contrast, selectively blocking JNKs with JNK peptide inhibitor 1, L-stereoisomer did not affect hydroxyurea-induced fetal death but increased the incidence of the hindlimb defects observed. Thus, p38 MAPKs and JNKs play distinct roles in protecting the conceptus against insult. Pharmacological inhibition of teratogen exposure induced MAPK activation has adverse consequences on the embryo.