Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.6.3.44 (P-glycoprotein)
13,344 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

N-(5,5-Diacetoxypent-1-yl)doxorubicin (DAPDOX) (3), a new, water-soluble analogue of doxorubicin, has been synthesized by coupling doxorubicin with 5-oxopentane-1,1-diacetate in the presence of NaBH3CN. This analogue was designed to be converted to the corresponding aldehyde, N-(5-oxopent-1-yl)doxorubicin, in the presence of carboxylate hydrolases, enzymes that are ubiquitous in tissue. DAPDOX had a half-life of several days in 0.05 M phosphate or 0.05 M acetate buffer solution at pH 4.0. However, in 0.05 M phosphate buffer at pH 7.4 in the presence of 20 unit equiv of porcine liver carboxylate esterase, the half-life of DAPDOX was less than 1 min. N-(5-acetoxypent-1-yl)doxorubicin (4), which should give rise to N-(5-hydroxypent-1-yl)doxorubicin on esterase-mediated hydrolysis, and N-(pent-1-yl)doxorubicin (5), were also prepared for comparative biological studies. DAPDOX was 150 times more potent than doxorubicin at inhibiting the growth of Chinese hamster ovary (CHO) cells in culture. The compound retained the same degree of potency against a CHO subline 100-fold resistant to doxorubicin (CHO/DOX) that expressed elevated levels of P-glycoprotein. Compounds 4 and 5, on the other hand, were no more effective than doxorubicin at inhibiting the growth of CHO cells and were 4-7-fold less potent against the CHO/DOX subline. DAPDOX is representative of a new structural class of doxorubicin analogues with unique chemical and biological properties.
...
PMID:N-(5,5-diacetoxypent-1-yl)doxorubicin: a new intensely potent doxorubicin analogue. 135 50

Calpain inhibitor I, N-acetyl-leucyl-leucyl-norleucinal (ALLN), a cell-permeable synthetic tripeptide with an aldehyde at its C terminus specifically inhibits the activity of cysteine proteases. Since the regulated degradation of 3-hydroxy-3-methylglutaryl-CoA reductase in Chinese hamster ovary (CHO) cells is blocked by ALLN and ALLN has a cytotoxic effect on cells, we attempted to isolate ALLN-resistant cells that overproduce an ALLN-sensitive protease(s). However, we obtained an ALLN-resistant cell line that overproduced P-glycoprotein (Sharma, R. C., Inoue, S., Roitelman, J., Schimke, R. T., and Simoni, R. D. (1992) J. Biol. Chem. 267, 5731-5734). To circumvent the multidrug resistance (MDR) phenotype during selection, we have stepwise selected an ALLN-resistant cell line of CHO cells in the presence of verapamil, a competitive inhibitor of P-glycoprotein. These non-MDR ALLN-resistant cells overexpress a 35-kDa protein and have increased aldo-keto reductase activity. Partial amino acid sequences of the 35-kDa protein are highly homologous to members of the aldo-keto reductase superfamily. The aldo-keto reductases are NADPH-dependent oxidoreductases and catalyze reduction of a wide range of carbonyl compounds such as aldehydes, sugars, and ketones. Our findings support the concept that a physiological function for aldo-keto reductases may be detoxification.
...
PMID:Cellular detoxification of tripeptidyl aldehydes by an aldo-keto reductase. 844 54

N-(5,5-Diacetoxypent-1-yl)doxorubicin (1b) is an intensely cytotoxic doxorubicin analogue that retains full potency against tumor cells that express elevated levels of P-glycoprotein and are resistant to doxorubicin. 1b was designed to be hydrolyzed in the presence of carboxylate esterases to N-(5-oxypent-1-yl)doxorubicin, an aldehyde capable of existing in equilibrium with a cyclic carbinolamine. To investigate the structural determinants of potency for 1b, we have prepared a series of chemically related compounds in which various omega-[bis(acetoxy)]alkyl or omega-[bis(acetoxy)]alkoxyalkyl groups are substituted at the 3'-amino position of the daunosamine sugar. These groups were selected to assess the effect of chain length, oxygen substitution, and carbinolamine ring size on analogue potency. The compounds were evaluated for their ability to inhibit the in vitro growth of the following cell lines: (a) Chinese hamster ovary (CHO) cells, (b) a CHO cell mutant 100-fold resistant to doxorubicin that expresses elevated levels of P-glycoprotein, (c) a murine ductal cell pancreatic adenocarcinoma (Panc 02), and (d) a murine mammary carcinoma (CA 755). The most potent members of the series were those that could form a straight chain aldehyde intermediate after esterase-mediated hydrolysis of the omega-bis(acetoxy) groups and give rise to 5- or 6-membered ring carbinolamines. Analogues capable of forming 7-, 8-, or 9-membered carbinolamines were markedly less active. The N-methyl derivative of 1b, which cannot give rise to a cyclic carbinolamine, was 2 orders of magnitude less potent than 1b. A branched chain analogue, 1f, which contained a tertiary carbon atom adjacent to the omega-bis(acetoxy) groups, was also substantially less active than its nonbranched counterpart, 1a. These findings suggest that the chain length of the 3'-amino substituents and the ability of the derived aldehydes to form 5- or 6-membered carbinolamines are critical determinants of biologic potency.
...
PMID:Intensely potent doxorubicin analogues: structure-activity relationship. 952 70

Differentiation therapy provides an alternative treatment of cancer that overcomes the undesirable effects of classical chemotherapy, i.e. cytotoxicity and resistance to drugs. This new approach to cancer therapy focuses on the development of specific agents designed to selectively engage the process of terminal differentiation, leading to the elimination of tumorigenic cells and recovery of normal cell homeostasis. A series of new anti-cancer pyrimidine acyclonucleoside-like compounds were designed and synthesized by structural modifications of 5-fluorouracil, a drug which causes considerable cell toxicity and morbidity, and we evaluated their applicability for differentiation therapy in human rhabdomyosarcoma cells. We tested the pyrimidine derivative GR-891, (RS)-1-[[3-(2-hydroxyethoxy)-1-isopropoxy]propyl]-5-fluorouracil, an active drug which shows low toxicity in vivo and releases acrolein which is an aldehyde with anti-tumour activity. Both GR-891 and 5-fluorouracil caused time- and dose-dependent growth inhibition in vitro; however, GR-891 showed no cytotoxicity at low doses (22.5 micromol l(-1) and 45 micromol l(-1)) and induced terminal myogenic differentiation in RD cells (a rhabdomyosarcoma cell line) treated for 6 days. Changes in morphological features and in protein organization indicated re-entry in the pathway of muscular maturation. Moreover, GR-891 increased adhesion capability mediated by the expression of fibronectin, and did not induce overexpression of P-glycoprotein, the mdr1 gene product, implicated in multidrug resistance. New acyclonucleoside-like compounds such as GR-891 have important potential advantages over 5-fluorouracil because of their lower toxicity and their ability to induce myogenic differentiation in rhabdomyosarcoma cells. Our results suggest that this drug may be useful for differentiation therapy in this type of tumour.
...
PMID:GR-891: a novel 5-fluorouracil acyclonucleoside prodrug for differentiation therapy in rhabdomyosarcoma cells. 1007 Aug 73

Multidrug resistance is a major obstacle for the successful use of chemotherapy. The multidrug resistance phenotype is often attributed to overexpression of P-glycoprotein, which is an energy-dependent drug efflux pump. We investigated a new strategy to overcome multidrug resistance, using purified bovine serum amine oxidase, which generates two major toxic products from the polyamine spermine. The cytotoxicity of the aldehyde(s) and H2O2, produced by the enzymatic oxidation of micromolar concentrations of spermine, was evaluated in multidrug resistant Chinese hamster ovary cells CHRC5 with overexpression of P-glycoprotein, using a clonogenic cell survival assay. We examined the ability of hyperthermia (42 degrees C), and inhibition of cellular detoxification systems, to sensitize multidrug resistant cells to spermine oxidation products. Severe depletion of intracellular glutathione was achieved using L-buthionine sulfoximine and inhibition of glutathione S-transferase by ethacrynic acid. CH(R)C5 cells showed no resistance to the toxic oxidation products of spermine, relative to drug-sensitive AuxB1 cells. Exogenous catalase protected cells against cytotoxicity of H2O2, but spermine-derived aldehyde(s) still caused some cytotoxicity. Hyperthermia (42 degrees C) enhanced cytotoxicity of spermine oxidation products. Cytotoxic responses in CH(R)C5 cells were compared to the drug-sensitive cells, to determine whether there are differential responses. CH(R)C5 cells were more sensitive to the cytotoxic effect of spermine oxidation products under more extreme conditions (higher temperature, higher spermine concentration, and longer exposure time). Glutathione depletion or glutathione S-transferase inhibition also led to enhanced cytotoxicity of spermine oxidation products in CH(R)C5 and AuxB1 cells. Our findings suggest that hyperthermia, combined with toxic oxidation products generated from spermine and amine oxidase, could be useful for eliminating drug-sensitive and multidrug resistant cells.
...
PMID:Amine oxidase, spermine, and hyperthermia induce cytotoxicity in P-glycoprotein overexpressing multidrug resistant Chinese hamster ovary cells. 1131 May 64

Multidrug resistance (MDR) has been studied extensively because it is one of major problems in cancer chemotherapy. The MDR phenotype is often due to overexpression of P-glycoprotein (P-gp), that acting as an energy-dependent drug efflux pump exports various anticancer drugs out of cells. The major goal of our investigation is to establish whether bovine serum amine oxidase (BSAO), which generates the products H(2)O(2) and aldehyde(s), from the polyamine spermine, is able to overcome MDR of human cancer cells. The cytotoxicity of the products was evaluated in both drug-sensitive (LoVo WT) and drug-resistant (LoVo DX) colon adenocarcinoma cells. A clonogenic cell survival assay demonstrated that LoVo DX cells were more sensitive than LoVo WT cells. Exogenous catalase protected cells against cytotoxicity mainly due to the formation of H(2)O(2). However, spermine-derived aldehyde(s) still induced some cytotoxicity. The cytotoxic effect was totally inhibited in the presence of both enzymes, catalase and NAD-dependent aldehyde dehydrogenase (ALDH). Transmission electron microscopy investigations showed that BSAO and spermine induced evident mitochondria alterations, more pronounced in MDR than in LoVo WT cells. The mitochondrial activity was checked by flow cytometry studies, labelling cells with the probe JC1, that displayed a basal hyperpolarized status of the mitochondria in multidrug-resistant cells. After treatment with amine oxidase in the presence of polyamine-spermine, the cells showed a marked increase in mitochondrial membrane depolarization higher in LoVo DX than in LoVo WT cells. Our findings suggest that toxic oxidation products formed from spermine and BSAO could be a powerful tool in the development of new anticancer treatments, mainly against MDR tumor cells.
...
PMID:Mitochondrial alterations induced by serum amine oxidase and spermine on human multidrug resistant tumor cells. 1522 8

Pluronic block copolymers (PBCs) have been shown to reverse multidrug resistance (MDR) by inhibiting the P-glycoprotein (P-gp) pump in cancer cells. One of the problems encountered with the use of PBCs is that the micelles disassociate at low concentrations. The study focused on the stabilization of PBC L121 micelles by the formation of crosslinks within their outer shells. To form crosslinks, the two terminal alcohols on L121 were first chemically converted into aldehydes (L121-CHO) using the Dess-Martin periodinane. Diamine compounds were then used to bridge the converted aldehyde termini on L121-CHO via conjugated Schiff bases. After crosslinking, the morphology of the L121 micelles remained spherical in shape and the mean particle sizes of the micelles before and after crosslinking were comparable (100nm). After exposure of MDR KBv cells to free rhodamine-123 (R123), the accumulation of R123 in cells was limited due to the function of P-gp. In contrast, crosslinking of L121 micelles within their outer shells significantly reduced their critical micelle concentration and greatly enhanced their stability, while maintaining their ability to inhibit P-gp function in resistant cells. The results indicated that the L121 micelles with shell crosslinks may be useful as a drug delivery vehicle for cancer chemotherapy.
...
PMID:Shell-crosslinked Pluronic L121 micelles as a drug delivery vehicle. 1705 46

Proteasome inhibitors display potent anti-neoplastic and anti-angiogenic properties both in vitro and in vivo. The mechanisms, however, by which proteasome inhibitors kill tumor cells are still fairly elusive as is the molecular basis of resistance to treatment. To address these questions, we employed a high-throughput Western blotting procedure to analyze changes in a subproteome of approximately 800 proteins in the promyelocytic leukemia cell line HL-60 upon treatment with the proteasome inhibitor PSI (Z-Ile-Glu(OtBu)-Ala-Leu-aldehyde) and correlated the changes of selected target proteins with the changes in two multidrug-resistant HL-60 variants. In total, 105 proteins were upregulated more than 1.5-fold after PSI treatment, while 79 proteins were downregulated. Activation of caspases-3 and -8, modulation of members of the Bcl-2 family as well as stimulation of stress signaling pathways was prominent during HL-60 apoptosis. We also identified changes in the abundance of proteins previously not known to be affected by proteasome inhibitors. In contrast, two multidrug-resistant HL-60 cell lines, overexpressing either MRP1 or P-glycoprotein were largely resistant to PSI-induced apoptosis and could not be resensitized by the pharmacological inhibitors of the drug efflux pumps MK571 or PSC833. Drug resistance was also independent of the upregulation of Bad. Overexpression of multidrug resistance proteins, P-glycoprotein and MRP-1 is thus not sufficient to explain resistance of HL-60 cells to treatment with proteasome inhibitor PSI, which remains more closely related to a low level of Bax expression and to the inability to activate JNK. Alternative routes to the acquisition of resistance to PSI have therefore to be considered.
...
PMID:Analysis of changes in the proteome of HL-60 promyeloid leukemia cells induced by the proteasome inhibitor PSI. 1846 79

By exploiting a Still-Gennari HWE coupling with a common C11-C26 aldehyde, a series of C2-C6 modified analogues of the microtubule-stabilising marine natural product dictyostatin were synthesised and evaluated in vitro for growth inhibition against a range of human cancer cell lines, including the (P-glycoprotein efflux-mediated) Taxol-resistant NCI/ADR cell line. Removal of the C6 methyl substituent in dictyostatin was found to be well tolerated and led to the retention of antiproliferative activity in the low nanomolar range (IC(50)=43 nM in the NCI/ADR cell line), while partial and full saturation of the (2Z,4E)-dienoate region led to a progressive reduction in biological potency. The lactone ring size was found to be critical, as C21 to C19 translactonisation to afford 20-membered isodictyostatin analogues led to a significant loss of cytotoxicity. In a series of incubatory experiments performed on the PANC-1 cell line, all three of the 22-membered macrolide analogues acted in an analogous fashion to dictyostatin, through a mechanism of microtubule stabilization, causing both an accumulation of cells at the G2/M phase and formation of characteristic dense intracellular microtubule bundles.
...
PMID:Total synthesis and biological evaluation of novel C2-C6 region analogues of dictyostatin. 1902 79

Alcohol consumption leads to the production of the highly reactive ethanol metabolite, acetaldehyde, which may affect intestinal tight junctions and increase paracellular permeability. We examined the effects of elevated acetaldehyde within the gastrointestinal tract on the permeability and bioavailability of hydrophilic markers and drug molecules of variable molecular weight and geometry. In vitro permeability was measured unidirectionally in Caco-2 and MDCKII cell models in the presence of acetaldehyde, ethanol, or disulfiram, an aldehyde dehydrogenase inhibitor, which causes acetaldehyde formation when coadministered with ethanol in vivo. Acetaldehyde significantly lowered transepithelial resistance in cell monolayers and increased permeability of the low-molecular-weight markers, mannitol and sucrose; however, permeability of high-molecular-weight markers, polyethylene glycol and inulin, was not affected. In vivo permeability was assessed in male Sprague-Dawley rats treated for 6 days with ethanol, disulfiram, or saline alone or in combination. Bioavailability of naproxen was not affected by any treatment, whereas that of paclitaxel was increased upon acetaldehyde exposure. Although disulfiram has been shown to inhibit multidrug resistance-1 P-glycoprotein (P-gp) in vitro, our data demonstrate that the known P-gp substrate paclitaxel is not affected by coadministration of disulfiram. In conclusion, we demonstrate that acetaldehyde significantly modulates tight junctions and paracellular permeability in vitro as well as the oral bioavailability of low-molecular-weight hydrophilic probes and therapeutic molecules in vivo even when these molecules are substrates for efflux transporters. These studies emphasize the significance of ethanol metabolism and drug interactions outside of the liver.
...
PMID:The ethanol metabolite acetaldehyde increases paracellular drug permeability in vitro and oral bioavailability in vivo. 1982 Feb 8


1 2 Next >>

---