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S Mateos

Publications and source records attributed to S Mateos.

At least 19 recordsLinked to original sources
PubMed2006

Stable expression of intracellular Notch suppresses v-Src-induced transformation in avian neural cells.

Understanding how disruption of differentiation contributes to the cancer cell phenotype is required to identify alterations essential for malignant transformation and provide experimental basis for their correction. We investigated whether primary quail neuroretina cells, transformed by a conditional v-Src mutant (QNR/v-src(ts)), could revert to a normal phenotype, in response to the stable expression of constitutively active Notch1 intracellular domain (ICN). This model system was chosen because Notch signaling plays an instructive role in cell fate determination during NR development, and because the intrinsic capacity of QNR cultures to differentiate is blocked by v-Src. We report that stable ICN expression results in suppression of QNR/v-src(ts) cell transformation in the presence of an active oncoprotein. This phenotypic reversion coincides with a major switch in cell identity, as these undifferentiated cells acquire glial differentiation traits. Both changes appear to be mediated by CBF, a transcription factor that binds to ICN and activates target genes. Cells restored to a normal and differentiated phenotype have undergone changes in the functioning of signaling effectors, essentially regulating cell morphology and cytoskeleton organization. This dominant interference may be partially mediated by an autocrine/paracrine mechanism, as revertant cells secrete a factor(s), which inhibits transformation properties of QNR/v-src(ts) cells.

Animals↗
PubMed2006

Topoisomerase II inhibition and high yield of endoreduplication induced by the flavonoids luteolin and quercetin.

Luteolin and quercetin are widely distributed plant flavonoids that possess a variety of chemical and biological activities, including free-radical scavenging and antioxidant activity. Recently, both flavonoids have been reported to inhibit DNA topoisomerases I and II (topo I and topo II), a property that, together with their ability to induce DNA and chromosome damage, has made them candidate anticancer compounds. In the present study, we confirmed that both compounds are topo II inhibitors by conducting a comparative study of their effect on topo II activity from Chinese hamster ovary AA8 cells. Because interference with the function of topo II to resolve DNA entanglement at the end of replication results in chromosome malsegregation at mitosis, we investigated whether luteolin and quercetin are effective in inducing endoreduplication in AA8 cells. Concentrations of luteolin and quercetin that inhibited topo II catalytic activity resulted in extraordinarily high yields of metaphases showing diplochromosomes. Given the established relationship of polyploidy with tumor development via aneuploidy and genetic instability, these results question the usefulness of luteolin and quercetin in cancer therapy.

Animals↗
PubMed2005

Induction of genotoxic and cytotoxic damage by aclarubicin, a dual topoisomerase inhibitor.

The anthracycline aclarubicin (ACLA) is an intercalative antibiotic and antineoplastic agent that efficiently binds to DNA, leading to a secondary inhibition of the catalytic activity of topoisomerase II (topo II) on DNA. Besides this activity, ACLA has been reported to exert a concomitant poisoning effect on topo I, in a fashion similar to that of the antitumor drug camptothecin and its derivatives. As a consequence of this dual (topo II catalytic inhibiting/topo I poisoning) activity of ACLA, the picture is somewhat confusing with regards to DNA damage and cytotoxicity. We studied the capacity of ACLA to induce catalytic inhibition of topo II as well as cytotoxic effects and DNA damage in cultured Chinese hamster V79 cells and their radiosensitive counterparts irs-2. The ultimate purpose was to find out whether differences could be observed between the two cell lines in their response to ACLA, as has been widely reported for radiosensitive cells treated with topo poisons. Our results seem to agree with the view that the radiosensitive irs-2 cells appear as hypersensitive ACLA as compared with radiation repair-proficient V79 cells. The recovery after ACLA treatment was also followed-up, and the irs-2 mutant was found to be less proficient than V79 to repair DNA strand breaks induced by ACLA.

Aclarubicin↗
PubMed2005

Genotyping of Uruguayan Human adenovirus isolates collected between 1994 and 1998.

Adenoviruses are one of the most frequent causative agents of acute lower respiratory infections in infants and young children. Twenty-three adenovirus isolates from nasopharyngeal aspirates of children hospitalized for acute lower respiratory infections in Uruguay between 1994 and 1998 were studied by restriction enzyme analysis. The genomic analysis showed that 60.9% (n = 14) of isolates belonged to the species Human adenovirus C (HAdV-C) and 31.9% (n = 9) to the species Human adenovirus B (HAdV-B). Whereas some isolates could be classified according to the published profiles into genotype or genomic variant, others displayed migration patterns not allowing classification. Eight isolates (89%) of HAdV-B corresponded to the Ad7h genotype that has been associated with severe and fatal pneumonia and necrotizing bronchiolitis in children in South America. The isolates of HAdV-C showed a great variability in accordance with the data published earlier.

Adenovirus Infections, Human↗
PubMed2003

DNA strand breaks induced by the anti-topoisomerase II bis-dioxopiperazine ICRF-193.

The bis-dioxopiperazine ICRF-193 has long time been considered as a pure topoisomerase II catalytic inhibitor able to exert its inhibitory effect on the enzyme without stabilization of the so-called cleavable complex formed by DNA covalently bound to topoisomerase II. In recent years, however, this concept has been challenged, as a number of reports have shown that ICRF-193 really "poisons" the enzyme, most likely through a different mechanism from that shown by the classical topoisomerase II poisons used in cancer chemotherapy. In the present investigation, we have carried out a study of the capacity of ICRF-193 to induce DNA strand breaks, as classical poisons do, in cultured V79 and irs-2 Chinese hamster lung fibroblasts using the comet assay and pulsed-field gel electrophoresis (PFGE). Our results clearly show that ICRF-193 readily induces breakage in DNA through a mechanism as yet poorly understood.

Animals↗
PubMed2003

The contribution of the CEA marker to CA 15.3 in the follow-up of breast cancer.

PURPOSE OF INVESTIGATION: The clinical use of tumor markers during breast cancer follow-up is still surrounded by controversy. The objective of this study consisted of determining the contribution of the CEA marker to CA 15.3 in the follow-up of breast cancer patients as applied to clinical practice. METHODS: Three hundred and eighteen cases of women with breast cancer were analyzed retrospectively as far as the sensitivity, the specificity and the positive and negative predictable values of the CA 15.3 and CEA markers. RESULTS: Of the 318 patients, 59 suffered a relapse during the study. After evaluation of both markers the sensitivity was 56.8% (CA 15.3: 47.4%), the specificity 85.3% (CA 15.3: 88.4%), the positive predictable value was 46.4% (CA 15.3: 48.2%) and the negative predictable value was 89.41% (CA 15.3: 88%). CONCLUSIONS: The low sensitivity of studied tumor markers proved of limited use on a clinical scale.

Adult↗
PubMed2001

Testing the SCE mechanism with non-poisoning topoisomerase II inhibitors.

There are controversial theoretical models about a possible involvement of DNA topoisomerase II (topo II) in the molecular mechanism of sister chromatid exchanges (SCEs). In order to clarify the role of this enzyme, if any, in such recombinational event, CHO parental AA8 and mutant EM9 cells, which shows and extremely high baseline frequency of SCE, have been treated with different doses of the non-poisoning topoisomerase inhibitors, ICRF-193 and bufalin. The frequencies of SCEs after the treatments have been determined and the inhibitory effect of these compounds has been assessed using a topo II activity assay. The results indicate that ICRF-193 and bufalin effectively inhibit topo II activity in AA8 and EM9 cell lines. ICRF-193 induced a moderate increase in the frequency of SCEs in both types of cells, while bufalin did not modify the level of SCEs in any of them. The results are discussed taking into account the apparently unlike mechanisms of inhibition of topo II by ICRF-193 and bufalin.

Animals↗
PubMed2001

The use of DNA double-strand break quantification in radiotherapy.

DNA double-strand breaks (DSB) are an important direct consequence of treating cells with ionizingradiation. A variety of evidence points toward DSBs being the key damage type linked to radiation-induced lethality. In particular, the link between DSB and chromosome breakage, which in turn closely correlates with cell death in some cell types, is strongly supportive of this concept. There has been much interest in the possibility of using measures of strand breaks as a pretreatment test of radiation response. This has largely been in the context of assessing inherent cellular sensitivity through damage induction or repair parameters. A number of studies have produced hopeful results, but overall there has been no parameter that can reliably predict radiosensitivity. This may be due to the inadequacies of the assays, but it is more likely to reflect the fact that the radiosensitivity of cells is dictated by a whole series of events; alterations in many of these can alter the overall response. In addition, it is now recognized that cell-signalling pathways form an essential part of the cellular response to damage, and these can be triggered by damage other than DSB. It is therefore possible that while DSBs are clearly important--and they may be the single most important lesion in some types--other damage types may be significant triggers of cell death pathways after ionizing radiation treatment.

Cell Cycle↗
PubMed2000

Yield of SCEs and translocations produced by 3 aminobenzamide in cultured Chinese hamster cells.

Different concentrations of 3-aminobenzamide (3AB), a strong inhibitor of poly(ADP-ribose) polymerase (PARP), were used to study their effect on the BrdU-substituted DNA of the Chinese hamster AA8 cell line. The frequencies of sister chromatid exchanges (SCEs) and translocations were determined using the fluorescence plus Giemsa (FPG) and fluorescence in situ hybridization (FISH) techniques, respectively. The results indicate that 3AB effectively induced a dose-dependent increase in the frequency of SCEs, but this enhancement in the yield of SCEs was not paralleled by an increase in translocations. These results are discussed in terms of the as yet poorly understood molecular mechanisms of action of the enzyme PARP.

Animals↗
PubMed2000

Variation in sensitizing effect of caffeine in human tumour cell lines after gamma-irradiation.

BACKGROUND AND PURPOSE: We have investigated whether the protective role of the G2 checkpoint has increasing importance when the p53-dependent G1 checkpoint is inactivated. MATERIALS AND METHODS: We have studied the differential effect of caffeine by clonogenic assays and flow cytometry in three human tumour cell lines with different functionality of p53 protein. RESULTS: The radiosensitizing effect of caffeine (2 mM) expressed itself as a significant decrease in surviving fraction at 2 Gy and a significant increase in alpha-values in RT112 and TE671, both with non-functional p53. However, no radiosensitizing effect was seen in cells with a normal p53 function (MCF-7 BUS). Two millimoles of caffeine also caused important changes in the cell cycle progression after irradiation. MCF-7 BUS showed a G1 arrest after irradiation and an early G2 arrest but those cells that reached the second G2 did not arrest significantly. In contrast, TE671 exhibited radiosensitization by caffeine, no G1 arrest, a G2 arrest in those cells irradiated in G2, no significant accumulation in the second G2 but an overall delay in release from the first cell cycle, which could be abrogated by caffeine. RT112 was similar to TE671 except that the emphasis in a G2 arrest was shifted from the block in cells irradiated in G2 to those irradiated at other cell cycle phases. CONCLUSION: The data presented confirm that p53 status can be a significant determinant of the efficacy of caffeine as radiosensitizer in these tumour cell lines, and document the importance of the G2 checkpoint in this effect.

Breast Neoplasms↗
PubMed2000

Spatiotemporal expression of noncatalytic TrkC NC2 isoform during early and late CNS neurogenesis: a comparative study with TrkC catalytic and p75NTR receptors.

The TrkC subfamily of primary high-affinity neurotrophin-3 receptors is composed of catalytic (kinase-containing; TrkC K) and noncatalytic (TrkC NC) isoforms generated by alternative splicing. We previously reported the presence of the mouse noncatalytic TrkC NC2 isoform in regions of neuronal differentiation [Menn, B., Timsit, S., Calothy, G. & Lamballe, F. (1998) J. Comp. Neurol., 401, 47-64]. In order to gain insight into specific roles for TrkC NC2 receptors during CNS neurogenesis, we compared its distribution with that of its catalytic counterparts and the p75NTR receptor in in vivo and in vitro model systems of early and late neuronal differentiation. We found that TrkC NC2 expression coincided with the exit of neuronal progenitors from the cell cycle and was maintained in differentiated cerebellar neurons. We also showed that, whilst TrkC K receptors were expressed both in mitotic and postmitotic cells, TrkC NC2 was present only in differentiating neural stem cell progeny, suggesting its involvement in neuronal and glial cell differentiation. During neuritogenesis of primary neocortical neurons, both TrkC isoforms as well as p75NTR were located in axonal and dendritic processes. However, whilst these various receptors were present in the same neuronal compartments, TrkC NC2 distribution was specifically restricted to distinct areas of extending neurites. Taken together, these findings suggest that spatiotemporal localization of the noncatalytic receptor could account for specific local effects of neurotrophin-3.

Animals↗
PubMed1999

Increased levels of DNA topoisomerases in cultured CHO cells treated with the antitumour drug 5-azacytidine.

Cultured Chinese hamster ovary (CHO) cells were treated with the cytidine analogue 5-azacytidine (5-azaC) which, in good agreement with results previously described from studies carried out in other primary or established mammalian cell lines, resulted in extensive chromosome decondensation and a shift in the time of replication of normally late-replicating heterochromatin to earlier replication. DNA topoisomerases (mainly topo I) have been involved in transcription, and the hypomethylating effect of 5-azaC reportedly results in the expression of silenced genes. Whether such an increase in transcription is paralleled by increased levels of both topo I and topo II, as well as by an enhancement in the topoisomerase activities, has been investigated in this work. The results seem to suggest that both the relative amount of topoisomerases and their activities are enhanced after a protracted treatment with the cytidine analogue over those observed in untreated controls. These observations could be significant for antitumour therapy.

Animals↗
PubMed1998

Differences between a human bladder carcinoma cell line and its radiosensitive clone in the formation of radiation-induced DNA double-strand breaks in different chromatin substrates.

It is well established that DNA-associated proteins, as well as soluble free-radical scavengers, can significantly influence the amount of damage inflicted in DNA by ionising radiation. It is not known, however, to what degree there is variation between cell lines in the effectiveness of these cellular components to protect DNA. In this study we have examined the level of strand break induction in a human bladder carcinoma cell line, MGH-U1, and its radiosensitive mutant, U1-S40b, when soluble scavengers and DNA-associated proteins were progressively removed. DNA double-strand breaks were measured using pulsed-field gel electrophoresis when cells were irradiated after lysis in solutions containing various salt concentrations. The two cell lines showed only a small, non-significant difference in damage induced in intact cells but isolated nuclei and chromatin devoid of non-histone proteins showed significantly more damage in the U1-S40b cells. Once the histone H1 was removed again there was no difference between the cell lines in the damage induced. We conclude that the different components of the cellular defences against free radical attack can have different influences in different cells. It is not clear whether this has an influence on the cellular sensitivity to the killing effects of radiation but it does suggest that artificial manipulation of the different components of the system may not affect overall damage induction to the same degree in all cells.

Chromatin↗
PubMed1998

Enhanced sensitivity to topoisomerase inhibitors in synchronous CHO cells pre-treated with 5-azacytidine.

Multidrug combination has been shown to be very useful to improve antitumor activity as well as to reduce the toxicity of different anti-cancer drugs. We have evaluated the interaction between the hypomethylating agent 5-azacytidine and the topoisomerase I and topoisomerase II inhibitors Camptothecin (CPT) and 4'-(9-acridinylamino) methanesulfon-m-anisidide (m-AMSA) respectively, based on the hypothesis that through the alteration of chromosome replication timing following DNA hypomethylation, the number of replication forks in early S phase might increase, so enhancing the probability of a collision between a blocked cleavable complex (DNA-topo I-CPT or DNA-topo II-m-AMSA) and a replication fork. We have tested the capacity of CPT and m-AMSA to induce chromosomal aberrations as well as reproductive cell death in synchronous cultured Chinese hamster ovary cells after a pretreatment with 5-azacytidine with positive results.

Amsacrine↗
PubMed1996

Cell-cycle variation in DNA migration in pulsed-field gel electrophoresis.

Pulsed-field electrophoresis is being used extensively in the gene mapping studies and in the analysis of DNA strand breakage by ionizing radiation. We have evaluated the relationship between the fraction of S phase DNA in a cell population and its ability to modify the migration of DNA in pulsed-field gel electrophoresis. We have shown that increasing the proportion of S phase DNA reduced the effective rate of migration of MGH-U1 cellular DNA. This effect was observed after treatment with ionizing radiation or the restriction enzyme Not I. However, when radiation-induced damage was studied using intact cells, only the DNA with 70 percent S phase showed apparent differences in damage induction. These studies therefore provide data to indicate the percentage of S phase cells at which overall DNA migration might be affected significantly.

Cell Cycle↗
PubMed1994

DNA double-strand break rejoining in xrs5 cells is more rapid in the G2 than in the G1 phase of the cell cycle.

The radiosensitive xrs5 mutant cell line of CHO K1 shows an overall deficiency in DNA double-strand break (dsb) rejoining. However, xrs5 paradoxically shows an apparently normal rate of disappearance of chromatid breaks with time, the kinetics of which is thought to reflect the underlying rejoining of dsb. Nevertheless the yield of chromatid breaks is elevated by four-fold in xrs5. A possible explanation of the paradox might be that xrs5 is proficient in rejoining dsb in the G2 phase of the cell cycle but converts a higher number of dsb into chromatid breaks. In order to test this we have measured the rejoining of dsb in partially synchronised G2 xrs5 cells and compared the kinetics with those of cells synchronised in the G1 phase. Synchronisation of cells was achieved in G2 by release of cells from an aphidicolin block, and in G1 by staurosporine block. Cell synchrony was monitored by cytofluorometry and showed typically a 67% synchronisation of G2 cells and a 91% synchronisation of G1 cells. Rejoining of dsb was measured using neutral filter elution at pH 9.6. G2 cells showed a two-component kinetic with t1/2 values of 9 min and 3.6 h for dsb rejoining. Corresponding t1/2 values for G1 cells were 15 min and approximately 8.8 h. The t1/2 value of 3.6 h found for dsb rejoining in G2 cells is similar to a previously published value for asynchronous parental CHO K1 cells of approximately 4 h. The kinetics of chromatid break rejoining was measured in both xrs5 and CHO K1 following a dose of 0.75 Gy. The kinetics were found to be similar (t1/2 = 2.4 h) in the two cell lines, as previously reported using an equiclastogenic dose.

Animals↗
PubMed1993

Poly-D-lysine enhances the genotoxicity of bleomycin in cultured CHO cells.

Cultured CHO cells were treated with the radiomimetic antitumor agent bleomycin (BLM) and post-treated with the polycationic compound poly-D-lysine (PDL), recently reported by us as able to potentiate chromosome damage induced by X-rays and chemical mutagens in both plant and mammalian cells. Our results seem to indicate that PDL enhances the genotoxic action of BLM measured as induced chromosomal aberrations, colony-forming ability and DNA strand breakage. Taking into account the reported low efficiency of BLM treatment due to problems with cellular uptake, enzymatic degradation and efficient repair, the possibility of optimizing the dose-effectiveness for cancer therapy is discussed.

Animals↗