Inhibitors ofPARP-1(Poly(ADP-ribose)polymerase-1)act by competing with NAD+, the enzyme physiological substrate, which play a protective role in many pathological conditions characterized by PARP-1 overactivation. It has been shown thatPARP-1 also promotes tumor growth and progression through its DNA repair activity. Since angiogenesis is an essential requirement for these activities, we sought to determine whether PARP inhibition might affect rat brain microvascular endothelialcells(GP8.3) migration,stimulated by C6-glioma conditioned medium(CM).Through wound-healing experiments and MTT analysis, we demonstrated thatPARP-1 inhibitorPJ-34[N-(6-Oxo-5,6-dihydro-phenanthridin-2-yl)-N,N-dimethylacetamide]abolishes the migratory response of GP8.3cells and reduces their viability.PARP-1 also acts in a DNA independent way with in the Extracellular-Regulated-Kinase(ERK)signaling cascade, which regulates cell proliferation and differentiation.By western analysis and confocal laser scanning microscopy(LSM),we analyzed the effects of PJ-34 on PARP-1expression, phospho-ERK and phospho-Elk-1 activation.The effect of MEK(mitogen-activated-protein-kinase-kinase)inhibitor PD98059(2-(2-Amino-3-methoxyphenyl)-4H-1benzopyran-4-one)on PARP1 expression in unstimulated and in CM-stimulated GP8.3 cells was analyzed byRT-PCR.PARP-1 expression and phospho-ERK activation were significantly reduced by treatment of GP8.3 cells withPJ-34 orPD98059. By LSM, we further demonstrated that PARP1 and phospho-ERK are coexpressed and share the same subcellular localization in GP8.3 cells, in the cytoplasmas well as in nucleoplasm. Based on these data,wep roposet hatPARP-1 andp hospho-ERK interact in the cytosol and then translocate to the nucleus, where they trigger a proliferative response. We also propose that PARP-1 inhibition blocks CM-induced endothelial migration by interfering with ERKsignal-transduction pathway.
|Titolo:||PJ-34 inhibits PARP-1 expression and ERK phosphorylation in glioma-conditioned brain microvascular endothelial cells.|
|Data di pubblicazione:||2015|
|Appare nelle tipologie:||1.1 Articolo in rivista|