Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: CAS:13243-65-7 (Staurosporine)
 1,173 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Staurosporine, a potent inhibitor of C-kinase, enhances accumulation of vincristine (VCR) in multidrug-resistant cells. We investigated this enhancement by two methods: (I) ATP-dependent VCR binding system; (II) azidopine photolabeling system. The ATP-dependent VCR binding to the resistant cell membrane was inhibited more efficiently by staurosporine than by verapamil. Staurosporine also inhibited the azidopine photolabeling of P-glycoprotein. These results indicate that staurosporine, an inhibitor of C-kinase, might directly bind to P-glycoprotein as well as antitumor agents and Ca2+ channel blockers. These findings also indicate that C-kinase might be involved in the function of P-glycoprotein.
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PMID:Staurosporine, a potent inhibitor of C-kinase, enhances drug accumulation in multidrug-resistant cells. 198 66

Multidrug resistance (MDR) is the phenomenon in which cells become resistant to several classes of structurally and functionally diverse drugs after exposure to a single cytotoxic agent. One form of MDR is associated with the overexpression of a large plasma membrane phosphoglycoprotein, P-glycoprotein, which acts as an energy-requiring drug transport pump. Protein kinase C may participate in MDR through posttranslational modification of P-glycoprotein. The purpose of this study is to critically evaluate P-glycoprotein as a substrate for protein kinase C and to determine whether phosphorylation leads to changes in drug transport. Protein kinase C from rat brain phosphorylated immunoprecipitated P-glycoprotein in a manner dependent on the activation of the exogenous kinase. Phorbol 12-myristate 13-acetate (PMA) increased the phosphorylation of P-glycoprotein 6-fold and selectively decreased the accumulation of vinblastine in resistant MCF-7/AdrR cells. PMA selectively decreased the cellular association of vinblastine with MDR cells after brief periods of incubation, but only after critical concentrations of drug were achieved. The actions of PMA did not require new synthesis of P-glycoprotein. PMA had similar effects in MCF-7/BC-19, a cell line transfected with a cDNA for P-glycoprotein. Staurosporine inhibited the effects of PMA on the phosphorylation of P-glycoprotein and on the accumulation of vinblastine. These data demonstrated that immunoprecipitated P-glycoprotein can be a substrate for protein kinase C, and that phosphorylation of the transporter is associated with significant changes in drug transport.
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PMID:Functional role of phosphorylation of the multidrug transporter (P-glycoprotein) by protein kinase C in multidrug-resistant MCF-7 cells. 794 66

Inhibition by staurosporine derivatives of cyclic AMP-dependent protein kinase (A-kinase) and protein kinase C (C-kinase), and drug resistance has been investigated. The substitution of an acetyl or an ethoxycarbonyl group for the amine N-ethoxycarbonyl-7-oxostaurosporine moiety on the tetrahydropyran ring of staurosporine decreased inhibition of both protein kinases, but increased selectivity for C-kinase by further modification of the lactam moiety to the imide (NA-382). The activities of SF-2370 on protein kinases were decreased by decarboxylation and hydroxyalkylation. These staurosporine derivatives enhanced accumulation of vinblastine in adriamycin-resistant P388 (P388/ADR) cells in a dose-dependent manner. The potency for the drug accumulation of these compounds was correlated with their inhibitory activity on the drug efflux, but was not correlated with their activity on protein kinases. Staurosporine and NA-382, with high potency for vinblastine accumulation, inhibited the photolabelling of [3H]azidopine on 140 kDa P-glycoprotein in the plasma membrane. The tetrahydrofuran compounds and NA-357, which had low potency for the drug accumulation, hardly interacted with azidopine on P-glycoprotein. Most of these compounds were highly cytotoxic by themselves, and only NA-382 was less cytotoxic among them and completely reversed the vinblastine-resistance of P388/ADR cells at a non-cytotoxic concentration. These results suggest that staurosporine derivatives can enhance drug accumulation and inhibit drug resistance through their direct action on the P-glycoprotein.
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PMID:Effect of staurosporine derivatives on protein kinase activity and vinblastine accumulation in mouse leukaemia P388/ADR cells. 809 45

The potent kinase inhibitor staurosporine and its protein kinase C (PKC)-selective analogue CGP 41251 are known to sensitise cells with the multidrug resistance (MDR) phenotype mediated by P-glycoprotein (P-gp) to cytotoxic agents. Here four PKC-selective staurosporine cogeners, CGP 41251, UCN-01, RO 31 8220 and GF 109203X, were compared with staurosporine in terms of their MDR-reversing properties and their susceptibility towards P-gp-mediated drug efflux from MCF-7/Adr cells. Staurosporine was the most potent and the bisindolylmaleimides RO 31 8220 and GF 109203X the least potent cytostatic agents. When compared with MCF-7 wild-type cells, MCF-7/Adr cells were resistant towards the growth-arresting properties of RO 31 8220 and UCN-01, with resistance ratios of 12.6 and 7.0 respectively. This resistance could be substantially reduced by inclusion of the P-gp inhibitor reserpine. The ratios for GF 109203X, staurosporine and CGP 41251 were 1.2, 2.0 and 2.9 respectively, and they were hardly affected by reserpine. These results suggest that RO 31 8220 and UCN-01 are avidly transported by P-gp but that the other compounds are not. Staurosporine and CGP 41251 at 10 and 20 nM, respectively, decreased efflux of the P-gp probe rhodamine 123 (R123) from MCF-7/Adr cells, whereas RO 31 8220 and GF 109203X at 640 nM were inactive. CGP 41251 was the most effective and GF 109203X the least effective inhibitor of equilibrium binding of [3H]vinblastine to its specific binding sites, probably P-gp, in MCF-7/Adr cells. Overall, the results imply that for this class of compound the structural properties that determine susceptibility towards P-gp-mediated substrate transport are complex. Comparison with ability to inhibit PKC suggests that the kinase inhibitors affect P-gp directly and not via inhibition of PKC. Among these compounds CGP 41251 was a very potent MDR-reversing agent with high affinity for P-gp and least affected by P-gp-mediated resistance, rendering it an attractive drug candidate for clinical development.
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PMID:Comparison of staurosporine and four analogues: their effects on growth, rhodamine 123 retention and binding to P-glycoprotein in multidrug-resistant MCF-7/Adr cells. 862 64

Protein kinase C (PKC) is an enzyme family with serine/threonine kinase function which is involved in the transduction of signals for cell proliferation and differentiation. The important role played in processes relevant to neoplastic transformation, carcinogenesis and tumor cell invasion renders PKC a potentially suitable target for anticancer therapy. Bryostatin 1, a macrocyclic lactone isolated from Bugula nerutina, is a partial PKC agonist, and has shown potent antineoplastic properties in vitro and in vivo. Staurosporine, an alkaloid isolated from microbial sources, is ine of the most potent PKC inhibitors and has shown high antiproliferative activity in vitro, but poor selectivity. Staurosporine analogs have thus been synthesize with the aim of obtaining more selective PKC inhibition; among these, CGP 41251 has shown reduced PKC inhibitory activity, but a higher degree of selectivity when assayed for inhibition of different kinases. Several studies indicate a role for PKC in the regulation of the multidrug resistance (MDR) phenotype, since several PKC inhibitors are able to partially reverse MDR and inhibit P-glycoprotein (Pgp) phosphorylation. The MDR phenotype is also associated with variation in PKC isoenzyme content, in particular with PKC-alpha overexpression. While adequate PKC modulation might offer an attractive concept to modulate MDR, other potential mechanisms of PKC interaction with anticancer drugs exist and have been documented, such as the enhancement of chemotherapy-induced apoptosis by safingol, a specific PKC inhibitor. Three phase I clinical trials with bryostatin have been completed so far and have shown that myalgia is the dose-limiting toxicity, while some antitumor activity is evident. Safingol is presently undergoing a phase I clinical trial in combination with doxorubicin. While no definitive data are presently available, it appears that safingol plasma levels approach those associated with chemopotentiation in animals and no pharmacokinetic interaction between the two drugs exists. Drugs targeting PKC are well work considering for clinical trials, particularly for their potential as modulators of currently available cytotoxic agents.
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PMID:Protein kinase C: a worthwhile target for anticancer drugs? 914 7

P-glycoprotein (P-gp) is an ATP-dependent drug pump that confers multidrug resistance. In addition to its ability to efflux toxins P-gp can also inhibit apoptosis induced by a wide array of cell death stimuli that rely on activation of intracellular caspases for full function. We have previously demonstrated that stimuli including drugs such as hexamethylene bisacetamide (HMBA), the cytotoxic lymphocyte granule protein granzyme B, and pore-forming proteins such as perforin, kill P-gp positive cells in a caspase-independent manner. We therefore hypothesised that drugs that are not effluxed by P-gp and which induce cell death in the absence of caspase activation could induce death of P-gp expressing cells. Staurosporine has been previously shown to kill cells in the absence of caspase activation. Consistent with our hypothesis, we demonstrate here that staurosporine can equivalently kill P-gp(+ve) and P-gp(-ve) tumor cell lines in a caspase-independent manner.
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PMID:Equivalent death of P-glycoprotein expressing and nonexpressing cells induced by the protein kinase C inhibitor staurosporine. 1100 11

The effects of cell cycle inhibition on the expression of the multidrug resistance transporter P-glycoprotein (P-gp) as well as of the cyclin-dependent kinase (CDK) inhibitors p27(Kip1) and p21(WAF-1) were investigated in DU-145 prostate tumor spheroids. With increasing spheroid size the number of cells in the G0/G1 phase augmented, whereas the number of cells in the G2/M phase and the S phase of the cell cycle declined. The number of G0/G1 cells was elevated after incubation with either mimosine, staurosporine or serum-free medium. Mitomycin C and roscovitine increased the number of S phase cells. Roscovitine additionally increased cells in the G2/M phase. Incubation in serum-free medium upregulated p21(WAF-1), p27(Kip1) and P-gp. Mimosine treatment resulted in upregulation of p27(Kip1) and P-gp, whereas p21(WAF-1) remained unchanged. Upon roscovitine treatment p27(Kip1) and p21(WAF-1) were downregulated, whereas P-gp was unaltered. Mitomycin C treatment resulted in downregulation of p27(Kip1) and p21(WAF-1); no significant change in P-gp levels was observed. Staurosporine induced upregulation of p21(WAF-1) whereas p27(Kip1) remained unaltered. P-gp was downregulated upon staurosporine treatment, which was owing to an elevation of intracellular reactive oxygen species by this compound. It is concluded that upregulation of P-gp in G0/G1 phase cells requires coexpression of the CDK inhibitor p27(Kip1) but not the CDK inhibitor p21(WAF-1).
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PMID:Modulation of intrinsic P-glycoprotein expression in multicellular prostate tumor spheroids by cell cycle inhibitors. 1190 40

Gemcitabine, a deoxycytidine analog, active against non-small cell lung cancer, is phosphorylated by deoxycytidine kinase (dCK) to active nucleotides. Earlier, we found increased sensitivity to gemcitabine in P-glycoprotein (SW-2R160) and multidrug resistance-associated protein (SW-2R120), overexpressing variants of the human SW1573 non-small cell lung cancer cells. This was related to increased dCK activity. As protein kinase C (PKC) is higher in 2R120 and 2R160 cells and may control the dCK activity, we investigated whether gemcitabine sensitivity was affected by the protein kinase C inhibitor, staurosporine, which also modulates the cell cycle. Ten nmol/l staurosporine enhanced the sensitivity of SW1573, 2R120 and 2R160 cells 10-fold, 50-fold and 270-fold, respectively. Staurosporine increased dCK activity about two-fold and the activity of thymidine kinase 2, which may also activate gemcitabine. Staurosporine also directly increased dCK in cell free extracts. Staurosporine decreased expression of the free transcription factor E2F and of ribonucleotide reductase (RNR), a target for gemcitabine inhibition. In conclusion, staurosporine may potentiate gemcitabine by increasing dCK and decreasing E2F and RNR, which will lead to a more pronounced RNR inhibition.
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PMID:Staurosporine increases toxicity of gemcitabine in non-small cell lung cancer cells: role of protein kinase C, deoxycytidine kinase and ribonucleotide reductase. 2043 41