Evidence that inhibition of phorbol ester-induced superoxide anion formation by cyclosporin a in phagocytes is not mediated by direct inhibition of protein kinase C

Abstract

Abstraet--Cyclosporin A (CsA) has been reported to inhibit phorbol myristate acetate (PMA)-induced superoxide anion (02) formation in human neutrophils and murine macrophages. We found that CsA inhibited 02 formation in HL-60 cells induced by PMA (30 nM) and phorbol dibutyrate (200 nM) with a half-maximal effect at 1 and 0.75 pM, respectively. One possible target of CsA action is protein kinase C (PKC) [EC 2.7.1.37] since phorbol esters activate this kinase. However, CsA did not inhibit PMAmediated reduction of histamine-induced rises in cytosolic Ca 2+ concentration in, and PMA-induced differentiation of, HL-60 cells and platelet aggregation. CsA did not reduce the activity of various recombinant c-PKC isoenzymes (o~,/31 and 7), n-PKC isoenzymes (6 and e), an a-PKC isoenzyme (~) nor of PKC purified from rat brain in vitro. These data show that CsA inhibits phorbol ester-induced O2 formation in HL-60 cells but not other phorbol ester-mediated events and that inhibition by CsA of O2 formation cannot readily be attributed to direct PKC inhibition. We also show that CsA does not change the activity of nucleoside diphosphate kinase ]EC 2.7.4.6] in HL-60 membranes nor the latter's physical properties.

Mechanism of antitumor action of PKC activator, gnidimacrin

“…PKC is a family of c-, n-and a-PKC isozymes (Wenzel-Seifert et al, 1994). It is known that c-PKC isozymes (␣, ␤I, ␤II and ␥) and n-PKC isozymes (␦, ⑀, and ) but not a-PKC ( and ) respond to phorbol esters.…”

“…PKC is a family comprising c-, n-and a-PKC isozymes (Wenzel-Seifert et al, 1994). c-PKC isozymes (␣, ␤I, ␤II and ␥) and n-PKC isozymes (␦, ⑀, and ) are activated by phorbol esters and are Ca 2ϩ -dependent and -independent, respectively.…”

N-Formyl-Methionyl-Leucyl-Phenylalanine (fMLP) Promotes Osteoblast Differentiation via the N-Formyl Peptide Receptor 1-mediated Signaling Pathway in Human Mesenchymal Stem Cells from Bone Marrow

“…In differentiated cells, both basal and fMLP-stimulated PLC or PLD activity showed a significant increase, compared with undifferentiated cells. In addition, fMLP-induced PLC or PLD activation was significantly attenuated by pretreatment with CysH, a potent and selective FPR1 antagonist (25,26). Taken together, these data indicate that expression of functional FPR, particularly FPR1, is significantly increased during osteogenic differentiation of MSCs.…”

Therapeutic Effects and Mechanisms of Action of Cyclosporine A Ophthalmic Solution in the Treatment of Vernal Keratoconjunctivitis

“…Cyclosporine A (100-1000ng/ml) was reported to suppress IL-8-mediated chemotactic migration, N-formyl-methionyl-leucyl-phenylalanine (fMLP)-stimulated superoxide generation, and chemokine production (IL-8 and MIP-1 from lipopolysaccharide (LPS)-stimulated neutrophils) in neutrophils from healthy donors [50]. Wenzel-Seifert et al reported that O 2 formation induced by fMLP in human neutrophils treated with 1 μM cyclosporine A was 53.1% lower compared with untreated cells [51]. Cyclosporine H, which has an extremely low affinity for cyclophilin coupled with potent binding affinity to calmoduline, showed more powerful inhibition than cyclosporine A.…”

“…Other reports support the anti-proliferative effects of cyclosporine on human subconjunctival fibroblasts. Damji et al showed that cyclosporine blocked cell growth at an Human neutrophils 83 nM(100ng/mL) O2production fMLP [50] Human neutrophils 83 nM(100ng/mL) IL-8 and MIP1 production LPS [50] Human neutrophils 1 μM O2production fMLP [51] Human neutrophils 830 nM Migration (no effect) IL-8, LTB4, C5a, fMLP [52] IC50 of 0.9 g/ml and that concentrations exceeding 100 g/ml were lethal [57]. Taken together, these data indicate that cyclosporine A may be capable of fibroblast growth inhibition in conjunctiva, but has the opposite effect in gingival tissues ( Table 5).…”