Studies on the role of protein kinases in the TNF‐mediated enhancement of murine tumor cell‐endothelial cell interactions

Abstract

We have previously demonstrated that the exposure of mouse microvascular endothelium (MME) to tumor necrosis factor-alpha (TNF) led to the increased binding of mouse mastocytoma cells (P815) to endothelial monolayers (Bereta et al., in press). In the current study we examined the possible involvement of protein kinases in TNF signal transduction in the endothelial cells. PKA does not appear to play a role in the potentiation of binding by TNF. We found that the TNF-generated signal is inhibited by H-7 and sangivamycin, but not by staurosporine. TNF did not cause translocation of PKC to the cell membrane and its effect could not be completely mimicked by PMA nor by PMA in the presence of calcium-raising agents. Thus, we concluded that the "classical" PKC pathway is not completely responsible for TNF signalling in this system. We also found that staurosporine itself strongly enhanced adhesion of tumor cells to endothelium, utilizing a mechanism distinct from that of TNF. Although the data provide evidence for the role of kinases in the effect of TNF on binding of tumor cells to MME, this role appears to be a complex one.

Mechanism of the cardioprotective effect of transforming growth factor beta 1 in feline myocardial ischemia and reperfusion.

“…Moreover, TGF-f1-treated cats exhibited a markedly lower number of PMNs adhering to the reperfused LAD coronary vascular endothelium. This highly significant antiadherent effect of TGF-,81 is consistent with earlier in vitro anti-leukocyte adherence reports of TGF-,B by Gamble and Vadas (31) and confirmed by Bereta et al (32) with tumor cell adherence to endothelial cells. This anti-adherence property of TGF-(31 appears to be a key mechanism of its amelioration of reperfusion injury.…”

Effect of Proinflammatory Cytokines on the Interplay between Roxithromycin, HMR 3647, or HMR 3004 and Human Polymorphonuclear Neutrophils

“…The molecular mechanisms by which cytokines alter PMN functions is still a matter of debate. However, serine or threonine phosphorylation and/or tyrosine phosphorylation are recognized as key pathways in the priming actions of TNF-␣ and GM-CSF (2,6,13,15,27,29,35). We therefore assessed the effect of the following drugs, which interfere with protein phosphorylation, on the inhibition of macrolide uptake induced by cytokines: PMA, a protein kinase C (PKC) activator; H89, a protein kinase A (PKA) inhibitor; tyrphostin A23, a tyrosine kinase (TK) inhibitor; staurosporin, a not fully specific PKC inhibitor; H7, a nonspecific protein kinase inhibitor; and two inhibitors of the mitogen-activated protein (MAP) kinase pathways, PD 098059 and SB 203580.…”