UMLS:C0027819 - FACTA Search

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

Query: UMLS:C0027819 (neuroblastoma)
27,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The presence of volume-activated chloride channels has been examined in neuroblastoma C1300 cells using the whole-cell configuration of the patch-clamp technique. Chloride channels could not be detected under isotonic conditions. However, hypotonic challenge induced slowly developed inward and outward anionic currents that exhibited outward rectification and inactivation at the most depolarizing potentials, features that were similar to the currents described in other cell preparations where volume-activated Cl- channels have been associated with the expression of P-glycoprotein. This hypotonicity-activated Cl- currents could be reversibly blocked by extracellular exposure to toremifene, a novel synthetic antioestrogen. The fact that toremifene and its analog tamoxifen, have been shown to block P-glycoprotein-associated chloride channels and to reverse P-glycoprotein associated multidrug resistance in a number of cell lines suggest that P-glycoprotein could be involved in the generation of hypotonic-induced chloride conductance in neuroblastoma cells.
...
PMID:Volume-activated chloride channels in neuroblastoma cells are blocked by the antiestrogen toremifene. 881 5

Among the differentiation-related changes in neuroblastoma are expressions of mdr-1 and bcl-2, which may be potentially related to the resistance to anticancer chemotherapy. In the present study, the authors performed an immunohistochemical analysis of mdr-1 and bcl-2 expressions in 30 neuroblastomas using monoclonal anti-P-glycoprotein(mdr-1 product) antibody and monoclonal anti-bcl-2 antibody to investigate the significance of their expression. The overall incidence of mdr-1 and bcl-2 expressions were 53.3% (16/30) and 93.3% (28/30), respectively. The expressions of mdr-1 and bcl-2 didn't seem to be related to the status of preoperative chemotherapy or stage of disease. The expression of mdr-1 was closely related to the differentiation of tumor cells (p < 0.01), especially to the neuronal differentiation. The bcl-2 expression was so common that it seemed to be indigenous to this neoplasm. The overall findings suggested that the expression of mdr-1 is one of the differentiation markers, while bcl-2 expression may partly explain the reasons for the relatively poor prognosis of neuroblastoma by the resistance to anticancer chemotherapy, which is a major therapeutic tool for this peculiar neoplasm.
...
PMID:An immunohistochemical analysis of mdr-1 and bcl-2 expressions in neuroblastoma. 883 69

Multifactorial resistance is the main mechanism of chemotherapy failure in cancers. Multidrug resistance (MDR) is related to the expression of a 170 kDa membrane glycoprotein, the so-called P-glycoprotein (P-gp). This protein is able to extrude drugs of various structures and mechanisms out of the cytoplasm. P-gp is a pronostic value in hemopathy as well as in child sarcoma, osteosarcoma and neuroblastoma. Modulator agents of different generations are capable of inhibiting P-gp. MDR modulation is obtained in hemopathies and is associated with an eradication of the P-gp (+) cell clones. In solid tumors, clinical trials using verapamil or cyclosporin are not so convincing. It is likely that other mechanisms of resistance are responsible for tumor progression, such as the MRP system, glutathion and topoisomerases. A better knowledge of multifactorial resistance and drug synthesis counteracting these resistance mechanisms will allow to elaborate new therapeutic basis for cancer therapy.
...
PMID:[MDR (Multiple Drug Resistant) type of resistance to chemotherapy in clinical practice]. 886 40

Cancer survival among children and adolescents has improved markedly due to evolution of multimodal treatment that incorporates combination chemotherapy, radiation therapy and/or surgery. However, 20-30% of children with malignancies will succumb to their disease or complications associated with their disease or treatment. A major limiting factor to improvement in survival among these patients is the occurrence of intrinsic and/or acquired resistance to our treatment interventions, chemotherapy and radiotherapy. Among these mechanisms, multidrug resistance, the focus of this review, is a well-documented phenomenon whose biochemistry, pharmacology and molecular biology has been extensively studied. A role for multidrug resistance in chemoresistance and therapeutic failure in childhood malignancies is suggested by the observation of clinical resistance to treatment regimes containing agents that are known substrates of multidrug resistance mechanisms. With the current results from studies in rhabdomyosarcoma, neuroblastoma, osteosarcoma, Ewing's sarcoma, leukemia and retinoblastoma, the role of multidrug resistance is still unclear. Earlier studies attempted to define a role for P-glycoprotein-mediated multidrug resistance; however, a limited number of reports suggest that the multidrug-associated resistance protein may play an active role in neuroblastoma. Further studies will be necessary using standardized and uniform approaches for the analyses of these mechanisms. Clinical trials directed toward reversal of multidrug resistance are premature since the exact role of P-glycoprotein is controversial in pediatric malignancies, the role of other mechanisms of multidrug resistance must be assessed and selective inhibitors of multidrug resistance have yet to be developed.
...
PMID:Multidrug resistance in pediatric oncology. 888 Mar 94

The occurrence of multidrug resistance (MDR) is one of the main obstacles in the successful chemotherapeutic treatment of cancer. MDR cell lines are resistant to the so-called naturally occurring anti-cancer drugs, such as anthracyclines, Vinca alkaloids and epipodophyllotoxins, but are not cross-resistant to alkylating agents, antimetabolites and cisplatin. So far, three separate forms of MDR have been characterized in more detail: classical MDR, non-Pgp MDR and atypical MDR. Although all three MDR phenotypes have much in common with respect to cross-resistance patterns, the underlying mechanisms certainly differ. Atypical MDR is associated with quantitative and qualitative alterations in topoisomerase II alpha, a nuclear enzyme that actively participates in the lethal action of cytotoxic drugs. Atypical MDR cells do not overexpress P-glycoprotein, and are unaltered in their ability to accumulate drugs. In this review we will focus on classical and non-Pgp MDR. The molecular mechanism of classical and non-Pgp MDR is transcriptional activation of membrane-bound transport proteins. These transport proteins belong to the ATP-binding cassette (ABC) superfamily of transport systems. The classical MDR phenotype is characterized by a reduced ability to accumulate drugs, due to activity of an energy-dependent uni-directional, membrane-bound, drug-efflux pump with broad substrate specificity. The classical MDR drug pump is composed of a transmembrane glycoprotein (P-glyco-protein-Pgp) with a molecular weight of 170 kD, and is, in man, encoded by the so-called multidrug resistance (MDR1) gene. Typically, non-Pgp MDR has no P-gly-coprotein expression, yet has about the same cross-resistance pattern as classical MDR. This non-Pgp MDR phenotype is caused by overexpression of the multidrug resistance-associated protein (MRP) gene, which encodes a 190 kD membrane-bound glycoprotein (MRP). MRP probably works by direct extrusion of cytotoxic drugs from the cell and/or by mediating sequestration of the drugs into intracellular compartments, both leading to a reduction in effective intracellular drug concentrations. For the classical MDR phenotype, evidence is accumulating that it plays a role indeed, in clinical drug resistance, especially in some hematological malignancies (acute myeloid leukemia, multiple myeloma and non-Hodgkin's lymphoma) and solid tumors (soft tissue sarcomas and neuroblastoma). The association of MRP with clinical drug resistance has not been elaborated, yet, and studies on MRP expression in human cancer have just begun. We found that overexpression of MRP, as determined by RNase protection assay as well as by immunohistochemistry, occurs in several human cancers, among which are cancer of the lung, esophagus, breast and ovary, and leukemias. Further studies are indicated to establish whether elevated MRP expression at diagnosis is an unfavorable prognostic factor for clinical outcome of chemotherapy.
...
PMID:Molecular mechanisms of multidrug resistance in cancer chemotherapy. 888 Aug 78

Expression of P-glycoprotein was studied in formalin-fixed tissue sections from 75 materials with an immunoperoxidase (ABC) method using the monoclonal antibody MRK-16. Specimens examined were from three monkey fetuses, eight autopsy cases, and 64 neuroblastoma patients, 25 of whom were underwent mass screening for diagnosis. P-glycoprotein test results were positive in fetal lung alveolar tissue and in the adrenal medulla of three of seven adult autopsy cases. Expression of P-glycoprotein was demonstrated in 22 of 35 cases (63%) in a group of neuroblastoma patients younger than 12 months of age, as compared with 9 of 20 (31%) who were older than 12 months of age at diagnosis. P-glycoprotein positivity was higher in patients who were alive (25 of 40, 63%) than in those who had died (6 of 24, 25%). Previous studies on P-glycoprotein expression in neuroblastoma were carried out using specimens mainly from older children, and the results were not analyzed with reference to the findings in normal tissues. The present study has clearly shown that positive P-glycoprotein expression in neuroblastoma patients should be evaluated carefully in infant cases because it stains frequently in normal adrenal glands.
...
PMID:Expression of multidrug resistance-related P-glycoprotein shows good prognosis in neuroblastoma. 909 7

Iron (Fe) chelators of the pyridoxal isonicotinoyl hydrazone (PIH) class may be useful agents to treat Fe overload disease and also cancer. These ligands possess high activity at mobilizing 59Fe from neoplastic cells, and the present study has been designed to examine whether their marked activity may be related to an energy-dependent transport process across the cell membrane. Initial experiments examined the release of 59Fe from SK-N-MC neuroblastoma (NB) cells prelabelled for 3 h at 37 degrees C with 59Fe-transferrin (1.25 microM) and then reincubated in the presence and absence of the chelators for 3 h at 4 degrees C or 37 degrees C. Prelabelled cells released 4-5% of total cellular 59Fe when reincubated in minimum essential medium at 4 degrees C or 37 degrees C. When the chelators desferrioxamine (DFO; 0.1 mM) or PIH (0.1 mM) were reincubated with labelled cells at 4 degrees C, they mobilized only 4-5% of cellular 59Fe, whereas as 37 degrees C, these ligands mobilized 21% and 48% of cell 59Fe, respectively. The lipophilic PIH analogue, 311 (2-hydroxy-1-naphthylaldehyde isonicotinoyl hydrazone; 0.1 mM), which exhibits high anti-proliferative activity, released 10% and 53% of cellular 59Fe when reincubated with prelabelled cells at 4 degrees C and 37 degrees C, respectively. Almost identical results were obtained using the SK-Mel-28 melanoma cell line. These data suggest that perhaps temperature-dependent mechanisms are essential for 59Fe mobilization from these cells. Interestingly, the metabolic inhibitors, 2,4-dinitrophenol, oligomycin, rotenone, and sodium azide, markedly decreased 59Fe mobilization mediated by PIH, but had either no effect or much less effect on 59Fe release by 311. Considering that an ATP-dependent process was involved in 59Fe release by PIH, further studies examined 4 widely used inhibitors of the multi-drug efflux pump P-glycoprotein (P-gp). All of these inhibitors, namely, verapamil (Ver), cyclosporin A (CsA), reserpine (Res) and quinine (Qui), decreased 59Fe mobilization by PIH but had little or no effect on 59Fe release mediated by analogue 311. Further, both CsA and Ver increased the proportion of ethanol-soluble 59Fe within cells in the presence of PIH, suggesting inhibited transport of the 59Fe complex from the cell. However, when PIH-mediated 59Fe release was compared between a well characterized Chinese hamster ovary cell line (CHRB30) expressing high levels of P-gp and the relevant control cell line (AuxB1), no appreciable difference in the kinetics of 59Fe release were found. In contrast, it was intriguing that the CHRB30 cells released more 59Fe into control medium (i.e., without PIH) than the AuxB1 control line (16.7% compared to 5.9%, respectively). In summary, the results suggest that a temperature- and energy-dependent process was involved in the efflux of the PIH-59Fe complex from the cells. In contrast, 59Fe release mediated by 311 was temperature-dependent but not energy-dependent, and could occur by simple diffusion or passive transport. Further studies investigating the membrane transport of Fe chelators may be useful in designing regimes that potentiate their anti-neoplastic effects.
...
PMID:Mobilization of iron from neoplastic cells by some iron chelators is an energy-dependent process. 918 79

A population of NG108-15 neuroblastoma cells resistant to doxorubicin (NG/DOXR) was established. The cells exhibited a multidrug resistance phenotype with cross-resistance to vinblastin and colchicine, overexpression of a 170 kDa membrane protein identified as P-glycoprotein and reversal of resistance by verapamil and quinine. Compared with NG108-15 cells, NG/DOXR cells showed an increase in Na+ current density and a decrease in cyclic-AMP-activated Cl- current density with no change in K+- and volume-sensitive Cl- current densities. As previously observed in NG108-15 cells, the vacuolar-type H+-ATPase inhibitors bafilomycin A1 and nitrate induced membrane depolarizations in NG/DOXR cells. The resting potentials of sensitive and resistant cells were not significantly different, but the depolarizations evoked by these agents were significantly larger in NG/DOXR than in NG108-15 cells. The resting membrane potential of NG/DOXR cells, but not that of NG108-15 cells, was depolarized by verapamil, and this effect was abolished by bafilomycin. The volume-sensitive Cl- currents of drug-sensitive and drug-resistant cells were inhibited by a decrease in intracellular pH from 7.3 to 6.8. Whereas bafilomycin prevents activation of Cl- currents in both drug-sensitive and drug-resistant cells, verapamil inhibited the Cl- current only in NG/DOXR cells. The results are discussed in terms of the roles of cytoplasmic pH and membrane potential in multidrug resistance.
...
PMID:Alterations of ionic membrane permeabilities in multidrug-resistant neuroblastoma x glioma hybrid cells. 939 Sep 33

Neuroblastoma (NB) tumour cells have a remarkable tendency to differentiate spontaneously or under the influence of certain drugs. It is not clear whether metaiodobenzylguanidine (MIBG) uptake correlates with differentiation of NB cells. In 28 tumours of 26 patients, iodine-123 MIBG uptake in primary NBs was studied in relation to tumour differentiation, tumour size, cell density and degree of necrosis in subsequently resected specimens. Genetic features such as the presence of chromosomal aberrations (1p-deletion and MYCN amplification) and/or P-glycoprotein (mdr-1 gene product) were also evaluated in relation to MIBG uptake. A highly variable and unpredictable intensity of MIBG uptake was observed in primary as well as secondary resected tumours. This intensity did not relate to any of the above-mentioned factors except that there was a trend towards more intense uptake with increasing size of the tumour. We conclude from our observations that, in contrast to commonly held opinion, well-differentiated tumours do not a priori show a lower MIBG uptake in vivo, even when there are a low number of viable cells and a high degree of necrosis. The degree of differentiation or tumour viability and necrosis following longstanding chemotherapeutic treatment cannot be predicted by the MIBG scan findings. The observed MIBG uptake may be importantly influenced by factors other than those associated with cellular differentiation.
...
PMID:Activity of iodine-123 metaiodobenzylguanidine in childhood neuroblastoma: lack of relation to tumour differentiation in vivo. 947 62

Four rhabdomyosarcoma and three neuroblastoma cell lines were characterised for the presence of P-glycoprotein and MDR-1 expression using immunohistochemistry, northern analysis, RT-PCR and in situ mRNA hybridisation. None of the rhabdomyosarcoma lines were unequivocally positive in contrast to all three neuroblastoma lines. Chemosensitivity to cytotoxic agents was determined using the MTT assay and chemosensitisation by cyclosporin and verapamil was evaluated. In a single rhabdomyosarcoma line (HX 170) there was sensitisation to etoposide using verapamil but not to other drugs or using cyclosporin A. In contrast, in all three neuroblastoma lines both cyclosporin and verapamil sensitised to vincristine and doxorubicin. No evidence of sensitisation to etoposide was apparent. The sensitisation was most marked for vincristine, using either modulator and therefore the influence of modulator scheduling was evaluated with this drug in the neuroblastoma line SK N BE. Prolonged pre-exposure to modulator did not appear necessary and maximum sensitisation was apparent where either cyclosporin or verapamil was added 1-3 h prior to and post vincristine. Continuity of exposure was important and even a break of 30 min appeared to reduce sensitisation. These data confirm the potential for chemosensitisation in MDR-1 positive neuroblastoma cell lines and provide some basis for rational schedule design in clinical practice. Because of the probability that vincristine resistance is predominantly related to MDR-1 and less multifactorial than for other drugs such as doxorubicin or etoposide, this agent should be considered for inclusion in any clinical evaluation of MDR reversal strategies.
...
PMID:Multidrug resistance modulation in rhabdomyosarcoma and neuroblastoma cell lines. 953 41

<< Previous 1 2 3 4 5 6 7 Next >>