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Biomedical subjects

B Dutrillaux

Publications and source records attributed to B Dutrillaux.

At least 145 records · Page 8Linked to original sources
PubMed1994

Gene dosage and expression, and enzyme activity of thymidine kinase and thymidylate synthase in xenografted colorectal adenocarcinomas.

Cytogenetic studies performed on human colorectal tumors have revealed 2 specific patterns of chromosomal anomalies. The major pattern, known as the monosomic type (MT), is characterized by the loss or deletion of chromosomes 18, 17 (short arm 17p) and, less frequently, 1p, 4, 15, 5 (long arm 5q) and 21. The other one, known as the trisomic type (TT), is characterized by the gain of several chromosomes: 7, 12, X, 5 and 8. Losses of chromosome 18 and of the 17p arm never coexist in TT tumors. It was observed that many chromosome losses or deletions involved genes encoding for enzymes of the de novo pathways of nucleotide synthesis. In contrast, gains involved genes encoding for enzymes of the salvage pathways of the same metabolism. This led to the hypothesis that chromosome imbalances corresponded to those of nucleotide synthesis in tumor cells. Such an interrelation was confirmed by the dosage of thymidylate synthase (TS) and thymidine kinase (TK) activities in a series of colorectal grafted tumors. This study has been expanded to a larger series of xenografted tumors (23 cases) in which both TS and TK activities were studied, in parallel with an analysis of mRNA, by Northern blotting. The amount of mRNA was found to correlate with the number of gene copies calculated from cytogenetic data, indicating a direct gene-dosage effect. It also correlated with enzyme activities, but less strongly. This suggests the existence of an efficient post-transcriptional regulation, in particular for TS, whose level of expression varies over a wide range. Such variations may explain the diversity of responses to chemotherapy.

Adenocarcinoma↗
PubMed1994

Organization and chromosomal assignment of two human PAG gene loci: PAGA encoding a functional gene and PAGB a processed pseudogene.

A cDNA, designated PAG, was recently isolated by differential cloning between an untransformed and a ras-transformed human mammary cell line. Higher levels of expression were found to be associated with cell proliferation. The absence in the pag protein of known consensus sequence, as well as its close relationship with a gene product involved in the differentiation of a mouse erythroleukemia cell line, has suggested that the PAG gene belongs to a family of genes associated with cell proliferation and differentiation. To further characterize this gene, a physical map has been established from a human genomic cosmid library. The PAG gene spans 13 kb of DNA and contains six exons. The promoter region is GC-rich and contains a TFIID motif located 25 nucleotides upstream of the potential site for initiation of transcription and potential recognition sites for a variety of trans-acting factors. Using fluorescence in situ hybridization, the PAG gene was mapped to human chromosome band 1p34.1. A pseudogene was also isolated, sequenced, and mapped to human chromosome band 9p22.

Base Sequence↗
PubMed1994

Detection of DNA amplification in 17 primary breast carcinomas with homogeneously staining regions by a modified comparative genomic hybridization technique.

A modified comparative genomic hybridization (mCGH) technique was applied to a series of 17 primary breast carcinomas in which cytogenetic study (CG) demonstrated the presence of homogeneously staining region(s), suggesting the occurrence of DNA amplification. mCGH demonstrated recurrent amplifications of the whole chromosome arms 8q (9 times) and 1q (7 times) and of DNA loci in the following bands: 11q13 (6 times), 9p13 and 17q21.1 (4 times), 1q21.1 and 16p11.2 (3 times), and 8q22, 8q24.1, 10q22, 15q26, 17q23, and 20q13.3 (twice). Amplification of whole chromosome arms is likely to have resulted from unbalanced translocations or isochromosomes, whereas amplifications of smaller chromosomal segments probably arose through real DNA amplification processes. In all tumors but one, more than one amplified locus was detected. The fact that many chromosomal sites were involved suggests that the process of amplification is complex and that many genes are potential targets.

Breast Neoplasms↗
PubMed1994

New sites of methylcytosine-rich DNA detected on metaphase chromosomes.

In situ immunofluorescence detection of antibodies against 5-methylcytosine on metaphase chromosomes prepared by a new procedure allows the display of new 5-methylcytosine-rich sites as compared to previously published methods. In short-term culture lymphocytes, the immunofluorescent signals give a recurrent pattern in which four types of binding sites can be distinguished. Type I sites are the secondary constrictions and a few juxtacentromeric regions, type II sites correspond to T-bands. Both types I and II sites emit a strong fluorescence. Type III sites form an R-band pattern and emit a weaker fluorescence. Type IV sites are the short arms of acrocentrics, they emit strong but polymorphic signals. The results obtained from control experiments suggest that the pattern observed is rather the expression of an uneven distribution of 5-methylcytosine-rich sites than a consequence of the various treatments used. In a lymphoblastoid cell line known to have a reduced 5-methylcytosine content, it was possible to demonstrate a heterogeneous hypomethylation among chromosome structures, principally involving type I sites. The method opens the possibility of studying in situ on chromosomes, regional variations of methylation in pathological conditions.

5-Methylcytosine↗
PubMed1994

Cytogenetic study of 30 colorectal adenomas.

The cytogenetic analysis of 30 colorectal adenomas obtained from 24 patients is reported. Only normal karyotypes were observed in eight cases. Among the 22 adenomas with abnormal karyotypes, 15 showed clonal anomalies. Chromosome gains involving chromosomes 13, 20, 7, 9, and 12 were recurrently observed. Chromosome 18 was frequently lost or involved in translocations at bands q21-q22. More chromosome alterations were observed in the cases in which histologic examination revealed severe dysplasia or a carcinomatous component. These anomalies are discussed in relation to those described in colorectal adenocarcinoma.

Adenocarcinoma↗
PubMed1994

Detection of methylcytosine-rich heterochromatin on banded chromosomes. Application to cells with various status of DNA methylation.

A procedure including incorporation of 5-bromodeoxyuridine (BrdU) in DNA and a thermal denaturation step was developed to obtain both R-banding and efficient binding of anti-5-methylcytosine antibodies on metaphase chromosomes. BrdU incorporation improved the efficiency of antibody binding disclosed by immunofluorescence staining. This method allowed semiquantitative analysis of the antibody binding sites on straightforward characterized metaphase chromosomes and was applied to normal human lymphocytes and lymphoblastoid cell lines for which DNA methylation status had been previously analyzed. A correlation was established between level of DNA methylation and the semiquantitative estimate of antibody fixation. This procedure can be used to study DNA methylation on metaphase chromosomes in transformed and cancerous cell lines.

Chromosome Banding↗
PubMed1994

Chromosome instability in lymphocytes from patients affected by or genetically predisposed to colorectal cancer.

To determine whether there are chromosomal clues to inherited forms of colorectal cancer, we studied chromosome instability in lymphocytes cultured from persons with sporadic colorectal cancer before treatment and from persons with a genetic predisposition to colorectal cancer due to adenomatous polyposis coli, Peutz-Jeghers syndrome, or juvenile polyposis. Spontaneous aberrations of chromosome number and structure were scored and compared to control studies by the same methods. Sex chromosome aneuploidy was found increased in patients. Autosomal aneuploidy was not increased. Chromosome breakage was elevated in young persons genetically predisposed to colorectal cancer compared to young patients with sporadic colorectal cancer. Chromosome rearrangements, other than those of chromosomes 7 and/or 14, rose with age, particularly in patients. Despite considerable interindividual variations, it would seem that increased chromosome breakage and rearrangement in addition to sex chromosome aneuploidy may be signs of chromosome instability in the predisposition to colorectal cancer.

Adenomatous Polyposis Coli↗
PubMed1994

A cytogenetic study of 19 recurrent gliomas.

A cytogenetic analysis was performed on 19 recurrent gliomas all of which had been treated by radiotherapy. All cases exhibited clonal chromosomal anomalies, the tumors were classified into four categories in relation to their mono- or polyclonality and to the presence or absence of a clonal evolution. Polyclonal tumors without clonal evolution had a delay of recurrence significantly longer than monoclonal or polyclonal tumors with clonal evolution. This difference could be related to the presence of clones with different malignant potential, which could be differentiated by their pattern of chromosomal aberrations. The malignant potential of "highly malignant" clones resulted from the juxtaposition of imbalances, such as monosomy 10, as in high-grade primary gliomas, and presumably radiation-induced structural rearrangements. That of clones of low malignancy was almost limited to the presence of multiple balanced structural rearrangements, probably induced by radiation.

Adolescent↗
PubMed1994

The frequency of micronuclei with X chromosome increases with age in human females.

The rate of micronuclei counted on lymphocyte cultures from five healthy female donors, 27-80 years old, increased with age. Using pXBR1 probe, specific for the alphoid DNA of the X chromosome, the presence of this chromosome was investigated by FISH (fluorescence in situ hybridization) in both micronuclei and metaphases. Both X aneuploidy and frequency of X chromosome per micronuclei increased with age. However, this overinvolvement of X chromosome was not sufficient to explain the overall increase of micronuclei with age, suggesting that autosomes are also involved. Thus, the higher increase of X than autosome aneuploidy in lymphocytes may result from both an excess of X chromosome losses and a better survival of cells with a monosomy X.

Adult↗
PubMed1994

Purine and pyrimidine metabolism in human gliomas: relation to chromosomal aberrations.

Chromosomal aberrations in human gliomas are principally numerical. In tumours of low malignancy, karyotypes are frequently normal, but occasionally an excess of chromosome 7 and a loss of sex chromosome are observed. In highly malignant tumours, the most frequent aberrations are gain of chromosome 7, loss of chromosome 10 and less frequently losses or deletions of chromosomes 9, 22, 6, 13 and 14 or gains of chromosomes 19 and 20. To understand the meaning of these chromosome imbalances, the relationships between chromosome abnormalities and metabolic disturbances were studied. The losses or deletions observed affected principally chromosomes carrying genes encoding enzymes involved in purine metabolism. The activities of ten enzymes were measured: adenosine kinase, adenine phosphoribosyltransferase, adenylate kinase, methylthioadenosine phosphorylase, hypoxanthine phosphoribosyltransferase, adenylosuccinate lyase, inosine monophosphate dehydrogenase, adenosine deaminase, nucleoside phosphorylase and adenosine monophosphate deaminase. In parallel, two enzymes involved in pyrimidine metabolism, thymidine kinase and thymidylate synthase (TS), were studied. The activities of all these enzymes were measured on samples from 30 human primary glial tumours with low or high malignancy, six xenografted tumours at different passages, four portions of normal brain tissue and four non-glial brain neoplasms. As suggested by cytogenetic data, the enzymatic results showed a relatively low activity of purine metabolism in glial tumours when compared with normal brain and non-glial brain neoplasms. Considering the two enzymes involved in pyrimidine metabolism, only TS had higher activity in glial tumours of high malignancy than in normal brain. In comparison with normal brain, the balance between salvage and de novo pathways changes in gliomas, and even more in grafted tumours, in favour of de novo synthesis. The relation between chromosomes and metabolic imbalances does not correspond to a simple gene dosage effect in these tumours. These data suggest that the decrease of adenosine metabolism occurs before chromosomal aberrations appear, since it is observed in tumours of low malignancy when most karyotypes are still normal, and that the de novo pathway increases with tumour progression.

Adolescent↗
PubMed1994

Possible role of inner-shell ionization phenomena in cell inactivation by heavy ions.

The existence of a correlation between experimental probabilities of cell inactivation by charged particles and calculated probabilities for K-vacancy production in heavy atoms (C, N, O, P) of the DNA of cell nuclei is established. Both phenomena display a similar dependence upon the linear energy transfer (LET) of incident particles. In particular for low LET values, K cross sections for various incident ions have nearly the same functional dependence on ion-LET and for higher LET-values, K cross sections display maxima which look like those of inactivation cross sections. These characteristics are well-understood features of the K-ionization phenomenon, in particular the maxima of probability occur for projectile velocities near orbital velocities of the ejected electrons. The meaning of the observed correlation is discussed in terms of deposited energy and in the light of existing experimental results on cell inactivation by X-ray absorption at K-threshold. We consider a mechanism which has already been evoked to explain these photo-absorption experiments and which assumes that a K ionization triggers a double-strand break by Coulomb explosion and energy dissipation of Auger electrons. However, it is seen that K cross sections are important for C, N and O atoms but negligible for P atoms. Thus, the lesion considered here affects other atoms than those involved in the K-photoabsorption experiments. The lesion efficiency with respect to subsequent double-strand breakage and repair processes is not yet known, however one may suspect a direct link between DNA blunt ends possibly induced by such K ionizations and cell inactivation.

Animals↗
PubMed1994

Chromosomal instability and alterations of telomeric repeats in irradiated human fibroblasts.

In recent years, evidence has been presented suggesting that genomic instability can appear several generations after cellular exposure to radiations. Kadhim et al. (1992) have shown that irradiation by alpha-particles of Pu238 (LET = 120 keV/microns) induce a transmissible instability in mouse haematopoietic cells. Working with human dermis fibroblasts irradiated by heavy ions in a large range of LETs (386-13,600 keV/microns), we demonstrated that an instability could also be acquired by human cells and that particular chromosomes (13, 16, 1) were recurrently involved in telomeric associations (Sabatier et al. 1992). This instability resulted in specific chromosome imbalances and in a particular monosomy 13 (Martins et al. 1993). In this study, we wanted to determine whether telomeres are shortened with the appearance of the chromosomal instability. Our results show no drastic shortening of the mean length of telomeres by Southern blot. By in situ hybridization we are looking to see if chromosomes specifically involved in instability have alterations of the telomeres. We have observed large variations of the hybridization signal of individual telomeres with no telomeric sequences detectable at the junction of end to end associations.

Cell Transformation, Neoplastic↗
PubMed1994

Liver cells can spontaneously resume proliferation in long-term quiescent primary cultures.

We report here data on the spontaneous resumption of proliferation in long-term primary cultures and we show that the proliferating areas are neoplastic. Normal rat hepatocytes were explanted in serum-supplemented Ham F12 medium and maintained over 8 months without transfer. The cells remained quiescent for the first 10 weeks and they were not tumorigenic when injected into nude mice. Later, without any modification of the culture conditions or transfer, progressive changes spontaneously occurred. Foci of dividing cells were detected, some displaying gamma-glutamyl-transpeptidase (gamma-GT) activity and F-actin fragmentation. These proliferating foci overcame the quiescent population. When injected into nude mice, the 15-week-old primary cultures were highly tumorigenic, with a 3-6 week latency for tumour formation. Furthermore, a cell line was derived from a primary culture started with a liver carcinogen promoter (biliverdin-enriched medium). This cell line proliferated rapidly and differed from a liver epithelial line, also established from our primary cultures, in its 1 karyotype (hyperploidy and translocation on chromosome 3), 2 requirement for arginine to proliferate, 3 gamma-GT positive reaction correlated to changes in actin fibre pattern, 4 sensitivity to protease inhibitors (i.e. alpha2 macroglobulin, PMSF) and 5 tumorigenicity. Long-term primary cultures and the karyotypically defined cell line are useful tools for further studies on in vitro genetic deviations.

Animals↗
PubMed1994

Mapping of 18 probes on human chromosome 18 using single- and double-color FISH.

Fluorescence in situ hybridization (FISH) techniques were applied to the mapping of 18 probes from chromosome 18, permitting seven new assignments: D18S16 (18p11.31), D18S12 (18p11.1), D18S1 (18q12.2), D18S13 (18q21.31), D18S18 (18q21.31), D18S14 (18q21.33), and D18S17 (18q23). In addition, the localization of D18S3 in 18p11.3 was confirmed and that of D18S6, previously mapped in 18p11, was changed to 18q21.13. Finally, a more accurate mapping for nine probes was proposed: D18S7 (18q12.2), D18S10 (18q12.2), D18S24 (18q21.13), D18S8 (18q21.13), GRP (18q21.31), BCL2 (18q21.33), D18S5 (18q22.1), D18S19 (18q22.1), and D18S11 (18q22.3). The ordering of probes located in close proximity was made possible by combined use of single-color FISH with direct assignment on banded chromosomes, chromosomal length measurements, and double-color FISH.

Chromosome Mapping↗
PubMed1994

Increased FISH efficiency using APC probes generated by direct incorporation of labeled nucleotides by PCR.

Probes of various sizes from the adenomatous polyposis coli gene (APC) were directly biotinylated by polymerase chain reaction (PCR) from genomic DNA. PCR labeling gave high efficiency in detection of fluorescence in situ hybridization (FISH) signals. Probes as small as 250 base pairs could be visualized through a fluorescence microscope without any image processing.

Adenomatous Polyposis Coli↗
PubMed1994

In situ hybridization approach at infragenic level on metaphase chromosomes.

Analysis of the retinoblastoma locus (RB1) by in situ hybridization at the infragenic level was done using human chromosomes. A high level of resolution was attained with nonisotopic in situ hybridization on banded chromosomes in both fluorescence and electron microscopy. DNA sequences less than 100 kb apart could be positioned on band 13q14 in the order expected from molecular mapping. These observations suggest that the DNA target of hybridized probes on metaphase chromosomes may correspond to nucleoprotein loops giving a resolution comparable to that obtained in interphase nuclei.

Genes, Retinoblastoma↗