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PubMed1987

Chromosome instability in cell lineages of amniocyte clones morphologically transformed by Simian virus 40.

Seven clonally derived human amniocyte cell lines from independent Simian virus-40 transformation events were analyzed for chromosomal aberrations in the precrisis stage. The distribution of chromosomal aberrations over the haploid complement was nonrandom. With increasing passage number the number of involved chromosomes increased, but the type of aberrations were the same: dicentric chromosomes and translocations due, respectively, to fusion of telomeres and breakage in the centromere regions. Interruptions to telomeres were also evident from extrachromosomal material terminally on the p arms, especially, of chromosomes #7 and #11. The cytogenetic similarities between the present results and those in transfection experiments are mentioned. All seven clones became highly heterogeneous over 10 to 20 passages (i.e., 30-60 population doublings) when, in general, transformed amniocytes enter crisis. The chromosomes which were nonrandomly involved in aberrations exhibited great diversity in types of rearrangements. Thus, for each clone multiple different rearrangements for specific chromosomes were observed in different cells. Most of these aberrations had a single step origin, which implies that breakage occurred repeatedly for the same chromosome in different cells, suggesting that the specific chromosome had become unstable in an earlier cell generation. Thus, we observed development of clonal chromosome instability, a phenomenon not reported for viral transformed cells.

Amniotic Fluid↗
PubMed1990

An increased risk for malignant neoplasms in heterozygotes for a syndrome of microcephaly, normal intelligence, growth retardation, remarkable facies, immunodeficiency and chromosomal instability.

We have collected and studied the genealogical data of 8 patients with the autosomal recessive syndrome of microcephaly, normal intelligence, immunodeficiency, risk of malignancy and chromosomal instability resembling ataxia telangiectasia (AT), but different in complementation group. 50% of our probands died from lymphoreticular malignancies in early childhood. We have found a significantly increased incidence of malignant tumors in 142 blood relatives as compared with a control group of 87 spouses. All patients belonged to the same complementation group differing from the 5 known AT complementation groups, which seems to be in general more malignant than all other groups of AT. From this standpoint our material is homogeneous in contrast to other similar studies in AT families. We think this syndrome represents another model to examine the relationship between genetic background, chromosomal abnormalities, immunodeficiency and cancer development.

Adult↗
PubMed1987

[Chromosome instability observed in cells from monospermic, homozygous moles].

The present study was undertaken to disclose the mechanism which concerned to the propensity to malignancy of complete moles. For this purpose, the incidence of chromosomal aberrations and sister chromatid exchanges(SCE) after the administration of 0-30 ng/ml mitomycin C(MMC) were compared among cells cultured from molar and normal villi, and peripheral blood. Abnormally high induction of chromosomal aberrations and SCE was observed in molar cells without MMC treatment when compared with those of the remaining two cells. Then, higher susceptible responses to the low concentration of MMC were also noticeable in molar cells rather than two kinds of cells. As a result, it was assumed that chromosome instability possibly played an important role for choriocarcinogenesis of molar cells. Homozygosity of paternally derived genes may be responsible for this chromosome fragility. Six chromosomal bands (1q 21, 2p 24, 2p 13, 7q 31, 8q 22, 13q 33) were preferentially involved in the formation of chromosomal aberrations occurred spontaneously in molar cells. Four of these six bands were identical with the break points necessary for the production of the marker chromosomes in various tumors described previously, though one band was consistent with the N-myc oncogene locus. Thus, the possible association between chromosome rearrangements occurred in those six bands and the choriocarcinogenesis was assumed, though further accumulation of cytogenetic and molecular data was absolutely necessary.

Chromosome Aberrations↗
PubMed1999

Chromosomal instability of fanconi anemia cells is not the consequence of a defective repair activity of the ribosomal protein S3.

Fanconi anemia (FA) is an autosomal recessive chromosomal breakage disorder characterized by developmental defects, hypersensitivity toward oxygen and DNA crosslinking agents, and susceptibility to cancer. An increased level of reactive oxygen intermediates and an increased level of 8-oxoguanine in FA cells point to a defective oxygen metabolism. Recent investigations showed that FA cells from several complementation groups have a reduced capacity to repair oxidatively damaged DNA. One major enzyme involved in the repair of oxidative DNA lesions is the ribosomal protein S3. Previous reports implied a role for the ribosomal protein S3 in DNA repair in FA cells. However, a more detailed analysis of the ribosomal protein S3 in FA cells from complementation groups A-E could not confirm this. DNA analysis and Western blot analysis did not show significant differences in ribosomal protein S3 between FA cells and cells from healthy individuals. Furthermore, even the overexpression of the ribosomal protein S3 did not reduce the chromosomal instability of FA cells.

Cell Line↗
PubMedDate not supplied

Loss of mitotic spindle checkpoint activity predisposes to chromosomal instability at early stages of fibrosarcoma development.

Mice carrying the bovine papillomavirus type I genome develop dermal fibrosarcomas in a multiple step process characterized by distinctive proliferative stages. Chromosomal aberrations are identified early in this tumorigenic pathway, however, the mechanism that originates them is unknown. Using a functional assay, we investigated the status of the mitotic spindle cell cycle checkpoint (MSCCC) that regulates the metaphase to anaphase transition, in cells representing different stages of fibrosarcoma progression. Loss of MSCCC activity was apparent in mild fibromatosis and completely abolished in aggressive fibromatosis and fibrosarcoma lesions. This altered MSCCC status was confirmed biochemically by deregulated expression of Cks1 protein and unscheduled cyclin B metabolism. Immunoprecipitation and sequencing analyses indicated that mutation of p53 was not required for the abrogation of the MSCCC. These results demonstrate that loss of mitotic spindle checkpoint activity predisposes to chromosomal instability at early stages of fibrosarcoma development. To our knowledge, these studies constitute the first report of a transition in MSCCC activity in a tumorigenesis model.

Adaptor Proteins, Signal Transducing↗
PubMed2005

Genotype-dependent induction of transmissible chromosomal instability by gamma-radiation and the benzene metabolite hydroquinone.

Although it is well established that ionizing radiation and benzene are epidemiologically linked to acute myeloid leukemia (AML), the underlying mechanisms are not understood. We have shown that gamma-radiation can induce a persisting genomic instability in the clonal descendants of hemopoietic stem cells manifested as a high frequency of nonclonal chromosome and chromatid aberrations. A strikingly similar instability is shown after exposure to the benzene metabolite hydroquinone. The CBA/Ca but not the C57BL/6 genotype is susceptible to the induction of instability by both ionizing radiation and hydroquinone and exposure of CBA/Ca, but not C57BL/6, mice to either agent is known to be associated with the development of AML. The results are consistent with the proposal that chromosomal instability induced by either agent may contribute to AML development by increasing the number of genetic lesions in hemopoietic cells. Genotype-dependent chromosomal instability can be induced by hydroquinone doses that are not acutely stem cell toxic and this may have important implications for current assessment of safe levels of exposure to benzene as well as for mechanistic understanding of the hemotoxic and leukemogenic effects.

Acute Disease↗
PubMed1993

Chromosome instability and the FAMMM syndrome.

Our study involved two extended familial atypical multiple mole melanoma (FAMMM) kindreds wherein a sufficient number of informative, high genetic risk, and affected patients enabled collection of pertinent tissue samples (normal skin/fibroblasts and atypical nevi/melanocytes) for cytogenetic analysis, and peripheral blood lymphocytes for DNA usage for linkage studies. We observed marked chromosome instability, as evidence by increased frequencies of cells with chromosomal rearrangements (translocations, deletions, and inversions) in cell cultures from atypical nevi and normal skin. There was no evidence of linkage of the FAMMM disease locus to any of the markers for the short arm of chromosome 1p in these two families. Well-characterized FAMMM kindreds provide an opportunity for biomarker investigations for elucidating heterogeneity and, ultimately, improving cancer control.

Adolescent↗
PubMed1988

A new chromosomal instability disorder confirmed by complementation studies.

Two sisters with a complex clinical pattern, including microcephaly, microgenia, defects of skin pigmentation, anal stenosis/atresia, and combined immunodeficiency together with spontaneous chromosomal instability and cellular hypersensitivity to X-rays and bleomycin are described. Complementation studies on heterokaryons proved that the underlying genetic defect is non-allelic with that of patients with ataxia telangiectasia (complementation groups AB-E) and the Nijmegen breakage syndrome, but identical with the case described by Conley et al. (1986).

Ataxia Telangiectasia↗
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↗
PubMed2000

Chromosomal instability syndrome of total premature chromatid separation with mosaic variegated aneuploidy is defective in mitotic-spindle checkpoint.

Skin fibroblast cells from two unrelated male infants with a chromosome-instability disorder were analyzed for their response to colcemid-induced mitotic-spindle checkpoint. The infants both had severe growth and developmental retardation, microcephaly, and Dandy-Walker anomaly; developed Wilms tumor; and one died at age 5 mo, the other at age 3 years. Their metaphases had total premature chromatid separation (total PCS) and mosaic variegated aneuploidy. Mitotic-index analysis of their cells showed the absence of mitotic block after the treatment with colcemid, a mitotic-spindle inhibitor. Bromodeoxyuridine-incorporation measurement and microscopic analysis indicated that cells treated with colcemid entered G1 and S phases without sister-chromatid segregation and cytokinesis. Preparations of short-term colcemid-treated cells contained those cells with chromosomes in total PCS and all or clusters of them encapsulated by nuclear membranes. Cell-cycle studies demonstrated the accumulation of cells with a DNA content of 8C. These findings indicate that the infants' cells were insensitive to the colcemid-induced mitotic-spindle checkpoint.

Abnormalities, Multiple↗
PubMedDate not supplied

DNA repair defects and chromosome instability disorders.

Xeroderma pigmentosum (XP), Fanconi anaemia (FA), ataxia telangiectasia (AT) and Bloom disease (BS) are four rare autosomal recessive disorders in which there is defective DNA repair and/or chromosome instability and proneness to malignancy. Between 80 and 90% of patients with XP have a defect, demonstrable at cell level, of excision of DNA lesions induced by ultraviolet rays, while the remainder have a cellular error of post-replication repair. XP cells are also deficient in repairing DNA damage caused by a variety of chemical mutagens. There are at least five different complementation groups of the first, or classical, type of XP (A to D, etc.) Apparently group C patients, as well as those with defective post-replication repair, do not show the progressive neurological illness found in a proportion of the other patients. AT is heterogeneous clinically and genetically. Clinically it presents with a progressive neurological illness, progressive telangiectases and a developmental disorder of the thymus. AT is characterized by sensitivity to X-rays and AT cells are unable to repair gamma-ray-induced damage to bases in the DNA. It appears that in many cases of the disorder a chromosomally marked cellular clone is found. In BS the main defect, which results in growth retardation, sun-induced lesions of the face and susceptibility to infection, appears to be a slow DNA chain maturation during DNA synthesis. An increase of sister chromatid exchanges is characteristically seen in the chromosomes of cultured BS cells. In FA, in which there is progressive pancytopenia with eventual bone marrow exhaustion and a tendency to haemorrhage and infection, the cellular defect seems to consist of faulty removal of repair of cross-links in the DNA. In this condition, as in BS and AT, various structural chromosome changes are detected in cultured cells. Patients with XP develop skin cancers in early life and often maligant melanomas. In the other three disorders, in which an immune deficiency is often present, leukaemia and related proliferative disorders are a frequent cause of death while other malignancies also occur. There is some evidence that points to an increased risk of malignancy in heterozygotes who carry the FA and AT genes.

Abnormalities, Multiple↗
PubMed1991

Chromosome instability and X-ray hypersensitivity in a microcephalic and growth-retarded child.

We report on a microcephalic, growth-retarded newborn girl without major anomalies who has chromosome instability in lymphocytes and fibroblasts. Frequent involvement of bands 7p13, 7q34, 14q11, and 14q32 suggested the diagnosis of ataxia telangiectasia (AT) or a related disorder. Supportive evidence was radioresistant DNA synthesis in fibroblasts and radiation hypersensitivity of short-term lymphocyte cultures. Follow-up for nearly 4 years showed largely normal development, and no signs of telangiectasia, ataxia, or immunodeficiency. Serum AFP levels turned from elevated at age 5 months to normal at age 2 years. We propose that our patient belongs to the expanding category of "AT-related" genetic disorders, probably to the Nijmegen breakage syndrome.

Cell Cycle↗
PubMed1995

Seckel syndrome in a family with three affected children and hematological manifestations associated with chromosome instability.

In the present communication we report on a family with three children affected by Seckel-syndrome with mental deficiency, microcephaly, micrognathia and severe growth deficiency. All patients had chromosome instability, which was employed for the prenatal diagnosis of a fourth fetus suspected as a potential Seckel syndrome patient, and one of them had additional hematological disorders. As this condition has been previously characterized as a Seckel syndrome subgroup we report our data concerning this distinct entity.

Abnormalities, Multiple↗
PubMed2005

Chromosomal instability induced by Pim-1 is passage-dependent and associated with dysregulation of cyclin B1.

Overexpression of the oncogenic serine/threonine kinase Pim-1 has been shown to induce chromosomal missegregation and polyploidy in prostate epithelial cell lines (1). Here we demonstrated that Pim-1-induced polyploidy develops in a passage-dependent manner in culture consistent with a stochastic mode of progression. Induction of chromosomal instability by Pim-1 was not restricted to prostate cells as it was also observed in telomerase-immortalized normal human mammary epithelial cells. Elevated levels of cyclin B1 protein, but not its messenger RNA, were evident in early passage Pim-1 overexpressing cells, suggesting that increased cyclin B1 levels contribute to the development of polyploidy. Furthermore, regulation of cyclin B1 protein and cyclin B1/CDK1 activity after treatment with anti-microtubule agents was impaired. Small interfering RNA targeting cyclin B1 reversed the cytokinesis delay but not the mitotic checkpoint defect in Pim-1 overexpressing cells. These results indicated that chronic Pim-1 overexpression dysregulates cyclin B1 protein expression, which contributes to the development of polyploidy by delaying cytokinesis.

Animals↗
PubMed2000

Chromosomal instability and cytoskeletal defects in oral cancer cells.

Oral squamous cell carcinomas are characterized by complex, often near-triploid karyotypes with structural and numerical variations superimposed on the initial clonal chromosomal alterations. We used immunohistochemistry combined with classical cytogenetic analysis and spectral karyotyping to investigate the chromosomal segregation defects in cultured oral squamous cell carcinoma cells. During division, these cells frequently exhibit lagging chromosomes at both metaphase and anaphase, suggesting defects in the mitotic apparatus or kinetochore. Dicentric anaphase chromatin bridges and structurally altered chromosomes with consistent long arms and variable short arms, as well as the presence of gene amplification, suggested the occurrence of breakage-fusion-bridge cycles. Some anaphase bridges were observed to persist into telophase, resulting in chromosomal exclusion from the reforming nucleus and micronucleus formation. Multipolar spindles were found to various degrees in the oral squamous cell carcinoma lines. In the multipolar spindles, the poles demonstrated different levels of chromosomal capture and alignment, indicating functional differences between the poles. Some spindle poles showed premature splitting of centrosomal material, a precursor to full separation of the microtubule organizing centers. These results indicate that some of the chromosomal instability observed within these cancer cells might be the result of cytoskeletal defects and breakage-fusion-bridge cycles.

Antigens, Nuclear↗
PubMed1989

Chromosome instability in lymphocytes from a patient with Werner's syndrome is not associated with DNA repair defects.

Different cellular parameters used to detect genetic instability were analyzed in lymphocytes from a patient affected by Werner's syndrome (WS). Cytogenetic studies indicated the presence of structural and numerical chromosomal abnormalities and the occurrence of variegated translocation mosaicism. The baseline mutation frequency was similar to that observed in normal donor samples. DNA repair investigations showing a normal capability to perform UV-induced DNA repair synthesis and a normal sensitivity to various mutagens (UVC light, mono- and bi-functional alkylating agents) indicate that different DNA repair mechanisms act normally in WS. In this feature, WS appears to differ from the other genetically determined syndromes in which chromosomal instability is associated with a marked hypersensitivity to specific DNA-damaging agents.

Cells, Cultured↗
PubMed1983

Analysis of spontaneous, carcinogen-induced and promoter-induced chromosomal instability in patients with hereditary retinoblastoma.

Skin fibroblasts from patients with hereditary retinoblastoma (RB cells) were examined since predisposition to the tumour might be expected to involve some degree of chromosomal instability, as has been noted for several cancer-prone conditions. Spontaneous and N-Methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced aberration frequencies were measured, the cytogenetic effects of long-term treatment with 12-O-tetradecanoyl-phorbol-13acetate (TPA) were examined and also the spontaneous and TPA-induced sister chromatid exchange (SCE) frequencies. In all the studies the RB cells behaved in a similar fashion to normal human skin fibroblasts.

Cells, Cultured↗
PubMed2001

Persistent increase in chromosome instability in lung cancer: possible indirect involvement of p53 inactivation.

Karyotype and fluorescence in situ hybridization analyses have demonstrated the frequent presence of an altered static state of the number of chromosomes (ie, aneuploidy) in lung cancer, but it has not been directly established whether aneuploidy is in fact associated with a persistent increase in the rate of chromosomal losses and gains (ie, chromosome instability, or CIN). The study presented here used a panel of 10 lung cancer cell lines to provide for the first time direct evidence that CIN is a common feature in lung cancer cell lines in association with the presence of significant aneuploidy. In addition, we found that the CIN phenotype correlates well with the presence of p53 mutations. However, human papilloma virus 16-E6-directed inactivation of p53 in a representative non-CIN lung cancer cell line did not result in the induction of CIN, at least up to the 25th generation, suggesting that inactivation of p53 itself is unlikely to directly induce CIN in lung cancer cells. Interestingly, however, significant CIN could be induced in conjunction with the generation of aneuploid populations when the mitotic spindle formation was transiently abrogated in p53-inactivated cells. These results suggest that inactivation of p53 may allow lung cancer cells to go through an inappropriate second division cycle under certain forms of mitotic stresses, which would result in the induction of the CIN phenotype in conjunction with the generation of aneuploidy.

Aneuploidy↗