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B Dutrillaux

Publications and source records attributed to B Dutrillaux.

At least 19 recordsLinked to original sources
PubMed1999

Amplification and over-expression of OZF, a gene encoding a zinc finger protein, in human pancreatic carcinomas.

The OZF gene encodes a protein consisting of 10 zinc finger motifs and is located on chromosome 19q3.1. We report here the amplification and over-expression of the OZF gene in pancreatic carcinomas. Increased gene copy number was detected in 3 of 12 tumour cell lines and 2 of 12 primary pancreatic carcinomas. Expression was detected in all cell lines, and the gene was over-expressed in cell lines with OZF gene amplification. Five of 8 tumours, including 2 primary tumours with OZF gene amplification, displayed high levels of OZF protein, whereas normal pancreas expressed low levels. Immuno-histochemical analysis showed that expression was restricted to tumour cells. Thus, high-level expression of OZF is frequent in pancreatic carcinomas and may contribute to the development or progression of this tumour.

Blotting, Western↗
PubMed1999

Distinct chromosomal alterations associated with TP53 status of LoVo cells under PALA selective pressure: a parallel with cytogenetic pathways of colorectal cancers.

This study investigates the chromosomal alterations involved in the acquisition of PALA resistance of LoVo colorectal cancer cells homozygous for wild-type TP53 before and after transfection with a 143Ala-mutated TP53 gene. PALA resistance was always associated with an increased number of CAD gene copies, but gene amplification sensu stricto was rarely observed. Interestingly, distinct chromosome patterns were found in relation to the TP53 status of the cells. In parental LoVo cells, the CAD copy number was increased through gains of normal chromosome 2 whereas in transfectant clones, resistance mostly occurred through chromosome rearrangements. The relationship with the two different cytogenetic patterns described in colorectal tumors is discussed.

Aspartic Acid↗
PubMed1998

Light-induced photoactivation of hypericin affects the energy metabolism of human glioma cells by inhibiting hexokinase bound to mitochondria.

Glucose-dependent energy required for glioma metabolism depends on hexokinase, which is mainly bound to mitochondria. A decrease in intracellular pH leads to a release of hexokinase-binding, which in turn decreases glucose phosphorylation, ATP content, and cell proliferation. Thus, intracellular pH might be a target for therapy of gliomas, and a search for agents able to modulate intracellular pH was initiated. Hypericin, a natural photosensitizer, displays numerous biological activities when exposed to light. Its mechanism and site of action at the cellular level remain unclear, but it probably acts by a type II oxygen-dependent photosensitization mechanism producing singlet oxygen. Hypericin is also able to induce a photogenerated intracellular pH drop, which could constitute an alternative mechanism of hypericin action. In human glioma cells treated for 1 h with 2.5 microg/ml hypericin, light exposure induced a fall in intracellular pH. In these conditions, mitochondria-bound hexokinase was inhibited in a light- and dose-dependent manner, associated with a decreased ATP content, a decrease of mitochondrial transmembrane potential, and a depletion of intracellular glutathione. Hexokinase protein was effectively released from mitochondria, as measured by an ELISA using a specific anti-hexokinase antibody. In addition to decreased glutathione, a response to oxidative stress was confirmed by the concomitant increase in mRNA expression of gamma-glutamyl cysteine synthetase, which catalyzes the rate-limiting step in overall glutathione biosynthesis, and is subject to feedback regulation by glutathione. Hypericin also induced a dose- and light-dependent inhibition of [3H]thymidine uptake and induced apoptosis, as demonstrated by annexin V-FITC binding and cell morphology. This study confirmed the mitochondria as a primary target of photodynamic action. The multifaceted action of hypericin involves the alteration of mitochondria-bound hexokinase, initiating a cascade of events that converge to alter the energy metabolism of glioma cells and their survival. In view of the complex mechanism of action of hypericin, further exploration is warranted in a perspective of its clinical application as a potential phototoxic agent in the treatment of glioma tumors.

Anthracenes↗
PubMed1998

Fluorescence-based analysis of DNA ploidy and cell proliferation within fine-needle samplings of breast tumors: a new approach using automated image cytometry.

BACKGROUND: Automated image cytometry can allow concurrent quantification of several parameters in each individual cell within a population, opening new possibilities for diagnosis and prognosis. In this study, the authors investigated the capacity of this method for performing a bivariate analysis of DNA ploidy and synthesis in fine-needle samplings obtained without aspiration from breast tumors. METHODS: Samplings from 25 unselected cases of ductal infiltrative breast adenocarcinoma and 2 cases of fibroadenoma were analyzed. For each case, 3-5 slides (containing approximately 1000 cells each) were quantified to assess experimental precision. Ploidy was determined by fluorescent staining of DNA using 4,6-diamidino-2-phenylindole (DAPI). Contaminating lymphocytes were taken as internal controls to calculate DNA indices. DNA synthesis was analyzed by immunofluorescent detection of 5-bromodeoxyuridine (BrdU) incorporation. Measurements were compared with flow cytometric data obtained from the same patients. RESULTS: Relative error in determination of DNA indices was generally below 5%. Determination of proliferation indices were more variable, with a mean relative error of 25%. Two different populations of BrdU positive cells were detected systematically, one in the diploid and another in the aneuploid fraction. For both cytometric methods, DNA indices were similar in all 27 cases, whereas BrdU labeling indices showed no significant correlation in 13 cases. The remaining cases were not comparable due to lack of flow cytometric data. Labeling indices obtained by image cytometry did not reveal any significant correlation with Scarff-Bloom-Richardson grading or clinical staging. CONCLUSIONS: Automated image cytometry allows concurrent measurement of ploidy and cell proliferation within individual breast carcinoma cells. Statistical reliability can be reached with a relative small number of cells (1000), which is crucial for samples in which the cell number is too low for flow cytometry analysis. Visual control for artifact elimination and better characterization of cell populations makes this a powerful tool for tumor cell investigation. Automated image cytometry allows the obtainment of valuable prognostic parameters of traditional flow cytometry with the relatively small number of cells obtained in aspiration procedures.

Adult↗
PubMed1998

Amplification of DNA sequences from chromosome 19q13.1 in human pancreatic cell lines.

Conventional cytogenetics and comparative genomic hybridization (CGH) were utilized to identify recurrent chromosomal imbalances in 12 pancreatic adenocarcinoma cell lines. Multiple deletions and gains were observed in all cell lines. Losses affecting chromosomes or chromosome arms 9p, 13, 18q, 8p, 4, and 10p and gains involving chromosome arms or bands 19q13.1, 20q, 5p, 7p, 11q, 3q25-qter, 8q24, and 10q were commonly observed. Interestingly, 19 distinct sites of high-level amplification were found by CGH. Recurrent sites involved 19q13.1 (6 cases), 5p (3 cases), and 12p and 16p (2 cases). Amplification of KRAS2 was demonstrated in 2 cell lines and that of ERBB2 in another. To define the occurrence of chromosome 19 amplification further, two-dimensional analysis of NotI genomic restriction digests and fluorescence in situ hybridization using probes from band 19q13.1 were utilized. High-level amplification of overlapping sets of chromosome 19 NotI fragments was exhibited in 3 cell lines of which 2 showed amplification of both OZF and AKT2 genes and 1 that of AKT2 alone. In these 3 cell lines, amplification of chromosome 19 sequences was associated with the presence of a homogeneously staining region. Our results provide evidence of heterogeneity in the extent of chromosome 19 amplification and suggest the existence of yet unknown amplified genes that may play a role in pancreatic carcinogenesis.

Chromosome Aberrations↗
PubMed1998

Potentiation of lonidamine and diazepam, two agents acting on mitochondria, in human glioblastoma treatment.

BACKGROUND: Cellular metabolism in glioblastoma multiforme, the most common primary brain tumor in humans, is characterized by a high rate of aerobic glycolysis that is dependent on mitochondria-bound hexokinase. Moreover, high levels of glucose utilization and tumor aggressiveness in glioblastoma are associated with a high density of mitochondrial benzodiazepine receptors. We sought to inhibit glioblastoma metabolism by simultaneously inhibiting hexokinase with lonidamine and binding benzodiazepine receptors with diazepam. METHODS: Cellular glioblastoma metabolism in five glioblastoma cell lines was assessed in vitro by measuring cell proliferation (by use of a tetrazolium-based colorimetric assay, measurement of DNA synthesis, and assessment of cell cycle distribution), by measuring membrane fluidity (by fluorescence polarization measurement of cells stained with a fluorescent probe), and by measuring changes in intracellular pH. Immunodeficient nude mice bearing subcutaneous xenografts of human glioblastoma cells were used to assess the antitumor activities of lonidamine and diazepam; the mice were treated twice daily with lonidamine (total daily dose of 160 mg/kg body weight) and/or diazepam (total daily dose of 1 mg/kg body weight) for 10 consecutive days. RESULTS: When used in combination, the two drugs had a stronger effect on glioblastoma cell proliferation and metabolism in vitro than did either agent used alone. In vivo, the combination of lonidamine and diazepam was significantly more effective in reducing glioblastoma tumor growth than either drug alone (two-sided P<.01, Mann-Whitney U test, comparing growth of treated tumors with that of untreated tumors); this tumor growth retardation was maintained as long as treatment was given. CONCLUSION: The combination of lonidamine and diazepam--drugs that target two distinct mitochondrial sites involved in cellular energy metabolism--potentiates the effects of the individual drugs and may prove useful in the treatment of human glioblastomas.

Animals↗
PubMed1998

Analysis of distribution in the human, pig, and rat genomes points toward a general subtelomeric origin of minisatellite structures.

We have developed approaches for the cloning of minisatellites from total genomic libraries and applied these approaches to the human, rat, and pig genomes. The chromosomal distribution of minisatellites in the three genomes is strikingly different, with clustering at chromosome ends in human, a seemingly almost even distribution in rat, and an intermediate situation in pig. A closer analysis, however, reveals that interstitial sites in pig and rat often correspond to terminal cytogenetic bands in human. This observation suggests that minisatellites are created toward chromosome ends and their internalization represents secondary events resulting from rearrangements involving chromosome ends.

Animals↗
PubMed1998

Increased radiation-induced chromosome breakage after progesterone addition at the G1/S-phase transition.

Pregnant females appear to have an increased chromosomal sensitivity to gamma-irradiation. This hypersensitivity was found to parallel the increase of gestation hormone amounts [M. Ricoul, L. Sabatier, B. Dutrillaux, Increased chromosome radiosensitivity during pregnancy, Mutat. Res. 374(1997) 73-78]. An in vitro experiment was developed to study the effect of progesterone. We performed irradiations of whole blood from normal human donors and chromosome were analysed in first generation metaphases. By comparison to untreated controls, all cultures in which progesterone was added around the 24th h of culture exhibited an increased frequency of chromosome rearrangements, principally dicentrics and rings, which confirms the role of progesterone in the results of in vivo studies. BrdU incorporation studies suggested that progesterone was particularly efficient just before the entry into S-phase, which corresponds to the G1/S transition period. Cultures with an increased frequency of chromosome breakage had a slightly higher mitotic index than controls. It is suggested that progesterone may stimulate DNA repair in cells which reached the end of G1-phase with unrepaired breaks. This would allow the cells to enter the S-phase and survive, although some illegitimate repair leads to chromosome rearrangements, visible at the following metaphase.

Blood Cells↗
PubMed1998

GAC1, a new member of the leucine-rich repeat superfamily on chromosome band 1q32.1, is amplified and overexpressed in malignant gliomas.

We have used two-dimensional electrophoresis of enzyme-digested genomic DNA to identify a novel gene GAC1, which maps at 1q32.1 and which is overexpressed in malignant gliomas in which it is amplified. GAC1 encodes a protein which belongs to the leucine-rich repeat superfamily. Amplification and overexpression of GAC1 was demonstrated in two of eight tumors where amplifications were previously evidenced by comparative genomic hybridization (one glioblastoma multiforme and one anaplastic astrocytoma), and in one of eight unselected glioblastomas multiforme. GAC1 exhibits sequence homology with other proteins which function as cell-adhesion molecules or as signal transduction receptor and is a likely candidate for the target gene in the 1q32.1 amplicon in malignant gliomas.

Amino Acid Sequence↗
PubMed1998

Mutations in OGG1, a gene involved in the repair of oxidative DNA damage, are found in human lung and kidney tumours.

The human OGG1 gene encodes a DNA glycosylase activity catalysing the excision of the mutagenic lesion 7,8-dihydro-8-oxoguanine from oxidatively damaged DNA. The OGG1 gene was localized to chromosome 3p25, a region showing frequent loss of heterozygosity (LOH) in lung and kidney tumours. In this study, we have analysed by RT-PCR the expression of OGG1 in 25 small cell lung cancers, in 15 kidney carcinomas and the 15 normal kidney counterparts. The results show that OGG1 messenger RNA can be detected in all tumours tested and that no significant difference was observed in the level of expression between normal and tumoral kidney tissues. Denaturing gradient gel electrophoresis (DGGE) was used to screen this series of human tumours for alterations in the OGG1 cDNA. The study revealed homozygous mutations in three tumours, two from lung and one from kidney. Sequencing analysis of the mutants identified a single base substitution in each of the three cases: two transversions (GC to TA and TA to AT) and one transition (GC to AT). All three substitutions cause an amino acid change in the hOgg1 protein. For the mutant kidney tumour, the normal tissue counterpart shows a wild-type profile. These results suggest a role for OGG1 mutations in the course of the multistage process of carcinogenesis in lung or kidney.

Carcinoma, Small Cell↗
PubMed1998

Near haploidy in breast cancer: a particular pathway of chromosome evolution.

In a series of 260 cytologically abnormal breast cancers studied in our laboratory, we observed a single case of near-haploid karyotype: 27,X, +der(1;16)(q10;p10), +7, +14, +15. A review of published cases of near-haploid malignancies suggests that near haploidy belongs to a process of chromosome evolution distinct from that of most epithelial cancers in which hypodiploidy is strongly associated with the occurrence of unbalanced structural rearrangements. In near-haploid tumors, chromosome loss is independent from chromosome rearrangements and may not be associated with an adverse prognosis.

Aneuploidy↗
PubMed1998

Low catalase activity in xeroderma pigmentosum fibroblasts and SV40-transformed human cell lines is directly related to decreased intracellular levels of the cofactor, NADPH.

We have previously shown that fibroblasts from ultra-violet (UV) hypersensitive xeroderma pigmentosum patients (XP) are markedly deficient in catalase activity resulting in high intracellular levels of hydrogen peroxide (H2O2) following UV irradiation. No direct correlation between catalase activity and repair ability was found since XP variant cells which are proficient in nucleotide excision repair (NER) showed activities as low as those found in NER deficient classical XP groups A and D. However, in contrast to the skin cancer prone XP patients, another NER deficient syndrome, trichothiodystrophy (TTD), which does not exhibit any cancer predisposition, was found to present normal catalase activity. Moreover, it was found that a variety of SV40 transformed human cell lines also showed decreased catalase activities. Our previous data showed that a molecular analysis of the normal, XP, TTD or transformed human fibroblast cell lines did not reveal any differences in levels of catalase transcription or amount of catalase protein subunits. These results incited us to examine the structure/function relationship of the tetrameric active enzyme form of catalase (which is the only one able to carry out H2O2 dismutation) with its cofactor NADPH. In the present study, we have measured the effects on catalase activity after adding NADPH either to acellular extracts or during cell culture of the different cell types. The NADPH levels were also quantified directly in intact cells using flow cytometry. Our results show a clear relationship between low catalase activity and striking decrease in intracellular NADPH levels.

Catalase↗
PubMed1998

Characterization of recurrent homogeneously staining regions in 72 breast carcinomas.

Cytogenetic analyses were performed on 223 breast carcinomas, of which 60% contained homogeneously staining regions (hsr), an intrachromosomal cytogenetic feature of gene amplification. The precise hsr localization could be determined for 123 hsr from 72 cases. The juxtacentromeric region of chromosome 8, band 11q13, and the whole of chromosome 17 were frequently involved. For 28 cases, the origin of the DNA sequences forming HSR could be investigated by chromosome painting, comparative genomic hybridization, and/or Southern blotting. Sequences from chromosomes 11 and 17 were mostly found within hsr located on chromosomes 11 and 17, respectively. In contrast, sequences from chromosome 8 were rarely found within hsr localized on chromosome 8. These observations suggest that different mechanisms lead to hsr formation in breast cancer. Band 11 q13 and the 17p chromosome arm may correspond to sites of in situ amplification driven by deletions distal to the amplification target genes. hsr in the region 17q2, which is also a frequent site of in situ amplification, takes place without the occurrence of a distal deletion. The short arm of chromosome 8 is often deleted, but frequently becomes the site of hsr formed elsewhere in the genome.

Adolescent↗
PubMed1998

Origin of human chromosome 21 and its consequences: a 50-million-year-old story.

Great apes (Pongidae) possess a chromosome similar to human chromosome 21 (HSA21), whose trisomy was described in both chimpanzee and orangutan. Having studied more than 200 mammalian species by chromosome banding techniques and reconstructed Primates phylogeny, we reinvestigated, using fluorescence in situ hybridization, primate and non-primate mammals that we considered to possess a karyotype representative of their taxonomic group. DNA sequences from HSA21 and human chromosome 3 (HSA3) are synthenic and form a large and similar chromosome in species from distinct orders, such as Primates, Carnivora, Artiodactyla and Scandentia. In Primates, this syntheny was maintained in lemurs and was disrupted by a fission in Old World monkeys (catarrhines). Another fission occurred in New World monkeys (platyrrhines), conserving a syntheny between HSA21 and a very short segment of HSA3 DNA sequences. Thus, the ancestral HSA21 was formed after the divergence between platyrrhines and catarrhines and before the emergence of Cercopithecidae. This exposed the human and Pongidae ancestry to trisomy 21 for a period of 30-50 million years, while, in other catarrhines, the equivalent of HSA21 was further involved in various translocations forming large chromosomes whose aneuploidy, very probably incompatible with life, protected them against trisomy 21.

Aneuploidy↗
PubMed1998

DNA methylation of the extraembryonic tissues: an in situ study on human metaphase chromosomes.

DNA methylation level and pattern of human metaphase chromosomes from extraembryonic tissues (chorionic villi and placental fibroblasts) were analysed in situ. The DNA methylation global level of these tissues was studied by comparing them with the one observed in fetal fibroblasts and adult lymphocytes. In order to assess the tissue specificity and significance of the observed differences, chromosomal preparations were then treated in parallel. They were first stained with distamycin A/DAPI and pictured, then treated with immunofluorescent staining using monoclonal antibodies raised against 5-methylcytosine. Compared with metaphases from lymphocytes or placental and fetal fibroblasts, distamycin-A/DAPI stained metaphases and constitutive heterochromatic regions with very similar intensities. In contrast, in chorionic villi, the immunofluorescent intensities revealing the presence of 5-methylcytosine was much duller than in the other tissues. In addition, in both chorionic villi and placental fibroblasts, large differences were observed between various chromosome structures within individual metaphases. In particular, the secondary constriction of chromosome 9, the distal segment of chromosome Y and the short arms of acrocentric chromosomes exhibited a much lower staining than the one observed for the secondary constrictions of chromosome 1 and 16 of the same metaphases. Because all these structures are known to be deeply methylated in other somatic tissues, this suggests that in extraembryonic tissues DNA methylation level remained hypomethylated and the pattern is under precise control.

Adult↗
PubMed1998

Homogeneously staining regions in 223 breast carcinomas: cytogenetic and clinicopathological correlations.

A correlation analysis was performed on 223 breast carcinomas to assess the relationships between gene amplification, karyotypic and clinicopathological features. Homogeneously staining region (HSR) is the most frequent form of amplification found in breast cancer. HSR-containing tumours accounted for 60% of the cases. Although up to 40% of tumours with slightly altered karyotype contained HSRs, an excess of HSRs was found within the tumours whose karyotype showed the highest rates of rearranged chromosomes. HSRs were also found to be particularly frequent in small tumours of high histological grade and with a low expression of progesterone receptors. An excess of HSRs seems to be observed in younger patients, however, significant correlation could be demonstrated only for patients below 55 years and below 60 years, compared with older ones. With a 120-month follow-up for 152 patients, a significant association between the presence of HSRs and a shortened overall survival was observed. Altogether, the presence of HSRs appears to be a good indicator of poor prognosis. Further studies are needed to determine whether amplification of specific genes or cell ability to amplify is the most important parameter for tumour progression.

Adolescent↗
PubMed1998

Emergence of a brain-expressed variant melanin-concentrating hormone gene during higher primate evolution: a gene "in search of a function".

Two related but distinct melanin-concentrating hormone (MCH) gene systems, i.e., the authentic and variant genes, have been characterized in the human, while only a single MCH gene has been found in the rat. We previously established that the variant gene corresponds to exon-I-deleted copies of the authentic gene mapped on chromosomes 5 and 12, respectively. In this report, we examined the expression of the authentic and variant MCH genes in the human brain. Mature mRNAs of the authentic MCH gene appeared to be predominantly expressed in the hypothalamus, whereas putative unprocessed transcripts of the variant MCH gene were found in other brain areas but not in the hypothalamus. Several products of the variant MCH gene were identified by RACE-PCR in the fetal human brain. One of these transcripts encoded a putative protein of 72 amino acids, while another transcript may potentially generate a protein of 35 amino acids. Thereafter, we explored the question of MCH gene transposition during Primate evolution. Southern blotting, PCR analyses using several genomic DNAs of Primates, and in situ hybridization on metaphase chromosomes led us to define at least three types of genetic events associated with the emergence of the variant MCH gene: (1) translocation of an exon II-exon III copy of the authentic MCH gene onto the equivalent of the human chromosome 5p arm of Anthropoidea ancestors (between 25 and 55 MYA); (2) exon II truncation and mutations before divergence of the Hylobatidae (about 15 MYA); and (3) duplication of the variant gene on the equivalent of the human chromosome 5p and 5q arms in the Hominidae, i.e., 5-10 MYA. Taken together, these results support the hypothesis that transposition/gene rearrangement processes could underlie the evolutionary emergence of new MCH-related genes expressed differentially in the brains of higher Primates, illustrating the concept of genes "in search of function" instead of true "pseudogenes."

Animals↗