A derivative of staurosporine (CGP 41 251) shows selectivity for protein kinase C inhibition and In vitro anti‐proliferative as well as In vivo anti‐tumor activity

Abstract

Analogues of staurosporine were synthesized and their ability to inhibit protein kinases was examined. Staurosporine is a potent but non-selective inhibitor of in vitro protein kinase C(PKC) activity (IC50 6.0 nM). The derivative CGP 41 251 had reduced PKC activity with an IC50 of 50 nM but showed a high degree of selectivity when assayed for inhibition of cyclic AMP-dependent protein kinase (IC50 2.4 microM), S6 kinase (IC50 5.0 microM) and tyrosine-kinase-specific activity of epidermal growth factor receptor (IC50 3.0 microM). Staurosporine and CGP 41 251 exerted growth inhibition in the human bladder carcinoma line T-24, human promyelocytic leukemia line HL-60 and bovine corneal endothelial cells at concentrations which correlated well with in vitro PKC inhibition. In addition, both compounds inhibited the release of H2O2 from human monocytes pre-treated with 12-O-tetradecanoyl-phorbol-13-acetate at non-toxic concentrations. In vivo anti-tumor activity was examined in T-24 human bladder carcinoma xenografts in athymic nude mice. Tumor growth inhibition tests revealed significant anti-tumor activity (2p less than 0.001) at 1/10 of the maximum tolerated doses for both compounds. By contrast, a closely related derivative of staurosporine (CGP 42 700) was inactive at concentrations of over 100 microM in all in vitro enzyme and anti-proliferative assays as well as in animal tumor models. Our data suggest an association between PKC inhibition and anti-proliferative and anti-tumor activity.

Hypoxia-induced accumulation of erythropoietin mRNA in isolated hepatocytes is inhibited by protein kinase C

“…The concentration of staurosporine that inhibits EPO mRNA expression is in the same range as that required to inhibit PKC-mediated reactions, but both RO 317549 and RO 318220 were 50-fold less potent than staurosporine in inhibiting EPO mRNA accumulation. Second, CGP 41251 was reported to be 3-9 times less potent than staurosporine in inhibiting the PKC-mediated H202 release from human monocytes, and in inhibiting proliferation of different cell lines [35]. At doses required for these inhibitory effects, CGP 41252 did, however, only marginally affect EPO gene expression, and considering half-maximal inhibition of EPO mRNA accumulation CGP 41252 was approximately 200-fold less efficient than staurosporine.…”

“…Thus staurosporine is known to inhibit not only PKC but also, for example, cyclic-nucleotide dependent kinases, tyrosine kinase, Ca2+-calmodulin-dependent kinase [1,40] and p34Cdc2-1ike kinases [20]. The three structurally different derivatives of staur0sporine, RO 317549, RO 318220 [9,12] and CGP 41251 [35] exhibit increased selectivity for PKC, but were also shown previously to inhibit cyclicnucleotide-dependent kinases [9,26,35] or tyrosine kinase [7,35]. In fact, a comparison of the concentrations of the various inhibitors required to suppress EPO gene induction with those concentrations required to suppress PKC-mediated reactions in other systems suggests that the inhibitory effect on EPO gene expression is not mediated by inhibition of PKC.…”

“…In an attempt to investigate hypoxia-induced EPO mRNA accumulation in the presence of reduced activity of PKC, cells exposed to 3% oxygen for 2.5 h were treated with staurosporine [40], the staurosporine derivatives CGP 41251 [35], RO 318220, RO 317549 [9,12] and the isoquinolinesulphonamides H7, H8 and H9 [26]. In order to assess unspecific alterations of RNA synthesis, [3H]uridine incorporation was measured in parallel.…”

Essential role of calcium in the regulation of MAP kinase phosphatase-1 expression

“…CGP41251 is a compound which inhibits Ca 2+ -dependent and independent isoforms of PKC (Meyer et al, 1989;Marte et al, 1994), while Go6976 is more selective for the classical Ca 2+ -dependent PKC isoforms (Martiny-Baron et al, 1993). As shown in Figure 2a, the two PKC inhibitors, and the biologically inactive analog CGP42700, had no e ect on the phosphatase expression level.…”

Staurosporine‐induced apoptosis in human cornea epithelial cells in vitro

“…The SV-40 -transformed HCE cell line is well characterized and has been used as an in vitro model for ocular irritation (10). For the induction of apoptosis we use staurosporine (STS), which is a nonspecific serine-threonine kinase inhibitor, working effectively in several cell types including corneal epithelium (11). We quantify: (i) the mitochondrial viability, (ii) the proteolytic activity of caspase-3, (iii) the translocation of phosphatidylserine (PS) from the inner to the outer membrane layer, (iv) the chromatin degradation in high and low molecular weight DNA, and (v) alterations in the chromatin structures of the cellular nuclei.…”