Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanisms of phorbol ester- and thrombin-mediated pulmonary artery endothelial barrier dysfunction were compared. Phorbol ester dibutyrate (PDBU) mediated slow force velocity and less force than thrombin. Taxol did not attenuate PDBU-mediated tension, while it reversed nocodazole-mediated tension. PDBU-mediated tension was not affected by acrylamide; PDBU increased cell stiffness and produced greater declines in transendothelial resistance (TER) than acrylamide. Thus PDBU caused a net increase in tension and did not unload microtubule or intermediate filaments. Microfilament remodeling, determined on the basis of immunocytochemistry and actin solubility, lacked the sensitivity and specificity to predict actin-dependent mechanical properties. Thrombin increased myosin light chain (MLC) kinase site-specific MLC phosphorylation, according to peptide map analysis, whereas PDBU did not increase PKC-specific MLC phosphorylation. The initial PDBU-mediated tension development temporally correlated with PDBU-mediated decline in TER and increased low-molecular-weight caldesmon (l-CaD) phosphorylation. PDBU-mediated tension development and decreases in TER were associated with a temporal loss of endothelial cell-matrix adhesion, based on a numerical model of TER. Although, on the basis of immunocytochemistry, thrombin-mediated tension was associated with actin insolubility, actin reorganization, and gap formation, these changes did not predict thrombin-mediated gap formation, based on TER and time-lapse differential interference contrast microscopy. These data suggest that PDBU may disrupt endothelial barrier function through loss of cell-matrix adhesion through l-CaD-dependent actin contraction.
Am J Physiol Lung Cell Mol Physiol 2004 Jul
PMID:Phorbol ester-mediated pulmonary artery endothelial barrier dysfunction through regulation of actin cytoskeletal mechanics. 1500 26

Overexpression of the anti-apoptotic protein Bcl-2 has been associated with several malignancies, including small cell lung cancer (SCLC). In the present study, we have investigated if Bcl-2 contributes to the emergence of cisplatin resistance in SCLC H69 cells. The ability of cisplatin to induce apoptosis was decreased in H69 cells that acquired resistance to cisplatin (H69/CP). The level of Bcl-2 was, however, substantially reduced in H69/CP cells compared to parental H69 cells. There was little change in Bcl-2 content in H69 cells that were resistant to etoposide (VP-16) or Taxol. Bcl-2 was constitutively phosphorylated at serine 70 in H69 cells but not in H69/CP cells and cisplatin had little effect on Bcl-2 phosphorylation. The level of procaspase-3 was elevated in H69/CP cells but the ability of cisplatin to induce mitochondrial depolarization, caspase-9 activation, and poly(ADP-ribose) polymerase (PARP) cleavage was compromised in H69/CP cells. The level of the anti-apoptotic protein Bcl-x(L) and the pro-apoptotic protein Bax was slightly reduced in H69/CP cells but the ratio of pro-apoptotic and anti-apoptotic Bcl-2 family proteins was not sufficient to explain cellular resistance to cisplatin. These results suggest that the acquisition of cisplatin resistance by H69 cells was not due to an increase in the level/phosphorylation status of the anti-apoptotic protein Bcl-2.
Mol Cancer Ther 2004 Mar
PMID:Down-regulation of Bcl-2 is associated with cisplatin resistance in human small cell lung cancer H69 cells. 1502 53

The microtubule-depolymerizing agents colchicine, vinblastine (VB), vincristine, nocodazole, and podophyllotoxin were found to increase dramatically the transfection of cationic phospholipid-DNA (CMV-beta-gal) complexes on cultured vascular smooth muscle cells (VSMCs). Pretreatment of cells with free colchicine before addition of lipoplexes increased transgene expression both in the presence and in the absence of serum. Free vinblastine had similar effects; however, vinblastine was more effective (approximately 30-fold maximal stimulation) when incorporated into the lipoplexes. Under optimal conditions, vincristine, nocodazole, and podophyllotoxin produced 25- and 39-, 31- and 14-, and 26- and 14-fold increases in the absence and presence of serum, respectively. Taxol, which stabilizes microtubules, had no effect on transfection, but it blocked the positive effect of colchicine. Cytochalasin B, which inhibits microfilament polymerization, had no effect on transgene expression. By fluorescence microscopy, normal lipoplexes colocalized with lysosomes. In contrast, there was little, if any, colocalization of VB lipoplexes with lysosomes. Because depolymerization of microtubules induces NF-kappaB-dependent gene expression, the effects of pyrrolidinedithiocarbamate and Nalpha-p-tosyl-L-lysine chloromethyl ketone, inhibitors of NF-kappaB activation, were tested; inhibition of vinblastine stimulation of transfection was 85 and 66%, respectively. Also, immunofluorescence microscopy showed that vinblastine induced the translocation of NF-kappaB from the cytoplasm to the nucleus. It is concluded that microtubule-depolymerizing agents, especially when incorporated into lipoplexes, dramatically increase transfection of VSMCs, probably by two mechanisms: (i) inhibition of transport of lipoplexes to lysosomes and (ii) activation of transcription (via NF-kappaB). There have been some reports on the use of pharmaceutical agents to enhance gene expression, but generally these have involved separate applications of drug and gene. The ability to deliver a drug and a gene in a single therapeutic formulation could have significant clinical implications.
Mol Ther 2004 May
PMID:Effects of microtubule-depolymerizing agents on the transfection of cultured vascular smooth muscle cells: enhanced expression with free drug and especially with drug-gene lipoplexes. 1512 Mar 34

Taxol is a microtubule-stabilizing agent that has recently been shown effective in the treatment of experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis. As astrocytes could modulate central nervous system (CNS) autoimmunity through inducible nitric oxide synthase (iNOS)-mediated production of immunoregulatory free radical nitric oxide (NO), we investigated the effect of taxol on NO synthesis in rat astrocytes. Taxol, either alone or in combination with interferon-gamma, induced NO generation in primary astrocytes and astrocytoma C6 cells in a dose- and time-dependent manner. Accordingly, the drug markedly up-regulated the expression of both iNOS mRNA and protein in astrocytes. The observed effect of taxol was mediated through induction of iNOS transcription factors NF-kappaB and IRF-1, and required the activation of p38 MAP kinase and JNK. Finally, NO release by taxol-stimulated astrocytes was blocked with the microtubule-depolymerizing agent colchicine, suggesting the involvement of a microtubule-stabilizing activity of taxol in the observed effect.
Cell Mol Life Sci 2004 May
PMID:Taxol activates inducible nitric oxide synthase in rat astrocytes: the role of MAP kinases and NF-kappaB. 1514 2

Drugs that disrupt microtubule dynamics include some of the most important of cancer chemotherapies. While these drugs, which include paclitaxel (Taxol), are known to invoke the mitotic checkpoint, the factors that determine cancer cell killing remain incompletely characterized. Cells that are relatively resistant to killing by these drugs block robustly in mitosis, whereas cells sensitive to killing block only transiently in mitosis before undergoing nuclear fragmentation and death. Passage through mitosis was an absolute requirement of drug-induced death, because death was markedly reduced in cells blocked at both G(1)-S and G(2). Cell killing was at least in part linked to the absence or inactivation of BubR1, a kinetochore-associated phosphoprotein that mediates the mitotic checkpoint. Sensitivity to paclitaxel correlated with decreased BubR1 protein expression in human cancer cell lines, including those derived from breast and ovarian cancers. Silencing of BubR1 via RNA interference inactivated the mitotic checkpoint in drug-resistant cells, and reversed resistance to paclitaxel and nocodazole. Together, these results suggest that the mitotic checkpoint is an important determinant of the efficacy of microtubule-targeting drugs in killing cancer cells, potentially providing novel targets for increasing treatment efficacy.
Mol Cancer Ther 2004 Jun
PMID:Inactivation of the mitotic checkpoint as a determinant of the efficacy of microtubule-targeted drugs in killing human cancer cells. 1521 Aug 51

Cryptophycin 52 (LY355703) is a potent antiproliferative analogue of the marine natural product cryptophycin 1. It has been shown to have a broad range of antitumor activity against human tumor xenografts and murine tumors including tumors resistant to Taxol and Adriamycin. Its mechanism of action involves arresting cells in the G2-M phase of the cell cycle by binding to microtubules and suppressing their dynamics. This 16-membered depsipeptide can be divided into four major subunits or fragments (A-D). We reported previously on our synthetic efforts around fragment A and discovered that this region of the molecule was amenable to a structure-activity relationship study that resulted in highly active antiproliferative agents when evaluated in the CEM leukemia cell line. The synthetic analogues were designed to help improve the efficacy and aqueous solubility of the parent compound; therefore, many in this series contained ionizable functional groups such as an amino group, a hydroxy group, or a carboxylic acid. Although several of these analogues showed improvements in potency over cryptophycin 52 in drug-sensitive tumor xenograft models, many lost their activity against Adriamycin-resistant tumor lines. It was discovered on additional in vitro evaluation that these analogues became good substrates of the multidrug resistance transporter P-glycoprotein.
Mol Cancer Ther 2004 Sep
PMID:Biological evaluation of cryptophycin 52 fragment A analogues: effect of the multidrug resistance ATP binding cassette transporters on antitumor activity. 1536

Angiogenesis is a critical event in tumor growth and metastasis, which can be inhibited by conventional anticancer drugs such as the microtubule-damaging agent paclitaxel (Taxol). In this study, we investigate the mechanism of action of paclitaxel on human endothelial cells. We characterize two distinct effects of paclitaxel on human umbilical vein endothelial cell and human microvascular endothelial cell-1 proliferation according to drug concentration: a cytostatic effect at low concentrations and a cytotoxic effect at concentrations > or =10 nmol/L. The cytotoxic effect involves signaling pathways similar to those described in tumor cells (i.e., microtubule network disturbance, G(2)-M arrest, increase in Bax/Bcl-2 ratio, and mitochondria permeabilization) that result in apoptosis. In sharp contrast, the cytostatic effect involves an inhibition of endothelial cell proliferation without apoptosis induction and without any structural modification of the microtubule network. This cytostatic effect is due to a slowing of the cell cycle rather than to an arrest in a specific phase of the cell cycle. In addition, paclitaxel, at cytostatic concentrations, early initiates an apoptotic signaling pathway associated with increases in the mitochondrial reducing potential, mitochondrial membrane potential, p53 expression, and Bax/Bcl-2 ratio. However, this apoptotic pathway is stopped upstream of mitochondria permeabilization and it does not lead to endothelial cell death. Finally, we found that paclitaxel inhibits endothelial cell morphogenesis on Matrigel at all tested concentrations. In conclusion, we describe the mechanism of action of low concentrations of paclitaxel related to the antiangiogenic properties of this drug.
Mol Cancer Ther 2004 Oct
PMID:Antiangiogenic activity of paclitaxel is associated with its cytostatic effect, mediated by the initiation but not completion of a mitochondrial apoptotic signaling pathway. 1548 97

Progesterone receptors (PRs) are prognostic markers in breast cancers irrespective of the patient's progestational status. However, there are two PR isoforms, PR-A and PR-B, that are equimolar in the normal breast but dysregulated in advanced disease. Postmenopausal, tamoxifen-treated patients with estrogen receptor (ER)-positive, PR-A-rich tumors have much faster disease recurrence than patients with PR-B-rich tumors. To study the mechanisms we engineered ER+ breast cancer cells that express each PR isoform under control of an inducible promoter. We identified 79 genes regulated by progesterone (P), mainly by PR-B, and 51 genes regulated without progesterone, mainly by PR-A. Only nine genes were regulated with and without ligand, leading to definition of three classes: I) genes regulated only by liganded PR; II) genes regulated only by unliganded PR; III) genes regulated by both. Unliganded PR-A and PR-B differentially regulate genes that coordinate extracellular signaling pathways and influence tumor cell biology. Indeed, in the absence of P, compared with ER+/PR-B+ or PR- cells, ER+, PR-A+ cells exhibit an aggressive phenotype, are more adhesive to an extracellular matrix, and are more migratory. Additionally, unliganded PR-A and PR-B both inhibit cell growth and provoke resistance to Taxol-induced apoptosis. We propose that PR-A:PR-B ratios, even in the absence of P, influence the biology and treatment response of ER+ tumors, that PR-A isoforms are functionally dominant in P-deficient states, and that PR-A rich tumors are especially aggressive.
Mol Endocrinol 2005 Mar
PMID:Progesterone-independent effects of human progesterone receptors (PRs) in estrogen receptor-positive breast cancer: PR isoform-specific gene regulation and tumor biology. 1556 44

Geranylgeranyl diphosphate synthase (GGPPS, EC: 2.5.1.29) catalyzes the biosynthesis of geranylgeranyl diphosphate (GGPP), which is a key precursor for diterpenes including Taxol, one of the most potent antitumor drugs. In order to investigate the role of GGPP synthase in taxol biosynthesis, we cloned, characterized and functionally expressed the GGPP synthase gene from Taxus media. A 3743-bp genomic sequence of T. media was isolated by genome walking strategy which contained an 1182-bp open reading frame (ORF) encoding a 393-amino acid polypeptide that showed high similarity to other plant GGPPSs. Subsequently the full-length cDNA of the GGPPS gene of T. media (designated TmGGPPS) was amplified by RACE. Bioinformatic analysis showed that TmGGPPS was an intron-free gene and its deduced polypeptide contained all the five conserved domains and functional aspartate-rich motifs of the prenyltransferases. By constructing the phylogenetic tree of plant GGPPSs, it was found that plant-derived GGPPSs could be divided into two classes, angiosperm and gymnosperm classes, which might have evolved in parallel from the same ancestor. To our knowledge this was the first report that the geranylgeranyl diphosphate synthase genes were free of intron and evolved in parallel between angiosperms and gymnosperms. The coding sequence of TmGGPPS was expressed in yeast mutant (SFNY368) lacking of GGPP synthase activity through functional complementation, and the transgenic yeast showed to have activity of GGPP synthase. This was also the first time to use SFNY368 to identify the function of plant-derived GGPPSs. Furthermore, investigation of the impact of methyl jasmonate (MeJA) on the expression of TmGGPPS revealed that MeJA-treated T. media cultured cells had much higher expression of TmGGPPS than untreated cells.
Mol Biol (Mosk)
PMID:[An intron-free methyl jasmonate inducible geranylgeranyl diphosphate synthase gene from Taxus media and its functional identification in yeast]. 1577 43

A 95-fold epothilone B (EpoB)-resistant, but not dependent, A549 human lung carcinoma cell line, A549.EpoB40 (EpoB40), has a Gln to Glu mutation at residue 292 that is situated near the M-loop of betaI-tubulin. Further selection of this cell line with higher concentrations of EpoB produced A549.EpoB480 (EpoB480), which is approximately 900-fold resistant to EpoB. This cell line, like EpoB40, exhibits cross-resistance to Taxol and extreme sensitivity to vinblastine, but in contrast to EpoB40 it is unusually dependent on EpoB, requiring a minimum of 125 nmol/L EpoB to maintain normal growth. Sequence analysis of the beta-tubulin and Kalpha1-tubulin genes in EpoB480 showed that, in addition to the beta292 mutation, beta60 was mutated from Val to Phe and alpha195 was mutated from Leu to Met. Mass spectrometry indicated that both the Val(60)Phe and Leu(195)Met mutations in betaI- and Kalpha1-tubulin, respectively, were expressed at the protein level. Molecular modeling indicated that beta60 is located at the end of the H1-S2 loop that has been implicated as a principal partner of the M-loop for contacts between protofilaments. A mutation at beta60 could inhibit the lateral contacts between protofilaments, thereby destabilizing microtubules. alpha195 is located at the external surface of the microtubule that has been proposed as the domain that interacts with a variety of endogenous proteins, such as stathmin and microtubule-associated protein 4. A mutation at alpha195 could modulate the interactions between tubulin and regulatory proteins. We propose that the betaVal(60)Phe mutation plays a critical role in the drug-dependent phenotype of EpoB480 cells.
Mol Cancer Ther 2005 Jun
PMID:A highly epothilone B-resistant A549 cell line with mutations in tubulin that confer drug dependence. 1595 56


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