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Results for “Chromosomal Instability”

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PubMed1987

[Spontaneous and induced chromosome instability in patients with fragile X syndrome].

Spontaneous and degranol- and dimatiph-induced chromosomal instability in the lymphocyte culture of patients with fra-X syndrome was investigated. The cultures contained TC 199 and 5% FC serum. It was found that the frequency of spontaneous chromosomal aberrations (CA) was 7.3% in cells from patients with fra(X), 3.9% in patients with MR of unknown origin, and 1.3% in normal individuals. Spontaneous break-points in the patients with fra(X) were localized in 1p, 2q, 3p, 6q, 7q, 16 q more often than in normal individuals. No significant difference was found in SCEs. The cells of patients with fra(X) were not sensitive to the induction of CA by degranol. It was found that chromosomal telomeric changes (CTC) were mutagen-independent, remaining at the spontaneous level: in the patients with fra(X) CTC were 10.5% (9.5% fra-Xq27, and 1% autosomal telomeric changes); in normal individuals CTC were 0.1%.

Cells, Cultured↗
PubMed2002

Chromosome instability in human lung cancers: possible underlying mechanisms and potential consequences in the pathogenesis.

Chromosomal abnormality is one of the hallmarks of neoplastic cells, and the persistent presence of chromosome instability (CIN) has been demonstrated in human cancers, including lung cancer. Recent progress in molecular and cellular biology as well as cytogenetics has shed light on the underlying mechanisms and the biological and clinical significance of chromosome abnormalities and the CIN phenotype. Chromosome abnormalities can be classified broadly into numerical (i.e., aneuploidy) and structural alterations (e.g., deletion, translocation, homogenously staining region (HSR), double minutes (DMs)). However, both alterations usually occur in the same cells, suggesting some overlap in their underlying mechanisms. Missegregation of chromosomes may result from various causes, including defects of mitotic spindle checkpoint, abnormal centrosome formation and failure of cytokinesis, while structural alterations of chromosomes may be caused especially by failure in the repair of DNA double-strand breaks (DSBs) due to the impairment of DNA damage checkpoints and/or DSB repair systems. Recent studies also suggest that telomere erosion may be involved. The consequential acquisition of the CIN phenotype would give lung cancer cells an excellent opportunity to efficiently alter their characteristics so as to be more malignant and suitable to their microenvironment, thereby gaining a selective growth advantage.

Animals↗
PubMed2006

The CpG island methylator phenotype and chromosomal instability are inversely correlated in sporadic colorectal cancer.

BACKGROUND & AIMS: The CpG island methylator phenotype (CIMP) is one of the mechanisms involved in colorectal carcinogenesis (CRC). Although CIMP is probably the cause of high-frequency microsatellite instability (MSI-H) sporadic CRCs, its role in microsatellite stable (MSS) tumors is debated. The majority of MSS CRCs demonstrate chromosomal instability (CIN) with frequent loss of heterozygosity (LOH) at key tumor suppressor genes. We hypothesized that the majority of sporadic CRCs without CIN would be associated with CIMP. METHODS: We tested 126 sporadic CRCs for MSI and LOH and categorized tumors into MSI, LOH, or MSI-/LOH- subgroups. Methylation status was evaluated using 6 CIMP-related markers (MINT1, MINT2, MINT31, p16(INK4alpha), p14(ARF), and hMLH1) and 6 tumor suppressor genes (PTEN, TIMP3, RUNX3, HIC1, APC, and RARbeta2). BRAF V600E mutation analysis was performed using allele-specific polymerase chain reaction and DNA sequencing. RESULTS: We observed frequent methylation at all 12 loci in all CRCs. BRAF V600E mutations correlated with the MSI (P < .0001) and MSI-/LOH- (P = .03) subgroups. MSI and MSI-/LOH- tumors exhibited more promoter methylation than CRCs with LOH (P < .0001). We also found an inverse correlation between the frequencies of methylation and LOH (rho = -0.36; P < .0001). CONCLUSIONS: The associations between methylation frequencies at CIMP-related markers and MSI or MSI-/LOH- sporadic CRCs suggest that the majority of these tumors evolve through CIMP. These findings suggest that CIN and CIMP represent 2 independent and inversely related mechanisms of genetic and epigenetic instability in sporadic CRCs and confirm that MSI cancers arise as a consequence of CIMP.

Adult↗
PubMed1988

[Immunodeficiency and chromosome instability].

In this paper, a survey is given of the immunological disturbances in some chromosome instability disorders (e.g. Bloom syndrome, ataxia teleangiectasia and Nijmegen Breakage syndrome). Further, the clinical symptoms and the diagnostic approach will be discussed.

Antibody Formation↗
PubMed2006

Frequent rearrangements and amplification of the CDX2 homeobox gene in human sporadic colorectal cancers with chromosomal instability.

The expression of the CDX2 gene, a crucial regulator of gut homeostasis, is altered in human colorectal cancers in parallel with de-differentiation. Here, we have investigated the chromosomal status of CDX2 in human sporadic colorectal cancers with the phenotype of chromosomal instability. Allelic imbalance determination showed frequent rearrangements at the CDX2 locus. The rearrangements correlated with CDX2 gene amplification, as assessed by quantitative PCR analysis. However, they were not predictive of the Cdx2 protein pattern. These data suggest that mechanisms other than structural alterations at the CDX2 locus account for the change of expression in colorectal cancers.

Base Sequence↗
PubMed2003

Chromosomal instability and human hepatocarcinogenesis.

Recently, many studies have identified losses and gains of several chromosomal loci in human hepatocellular carcinoma (HCC) with fine microsatellite analysis and comparative genomic hybridization. Although distribution of aberrant chromosomal arms differs among HCCs, loss of 1p, 4q, 6q, 8p, 9p, 10q, 13q, 16q and 17p, and gain of 1q, 6p, 8q, 17q and 20q have been recurrently reported, and loss of 4q and 16q seems to occur preferentially in hepatitis B virus-related HCCs. Accumulation of these aberrant chromosomal regions is associated with tumor progression, and some chromosomal aberrations, such as loss of 1p, are frequently identified in well-differentiated HCCs and also detected even in dysplastic nodule and cirrhotic nodule. This evidence suggests that chromosomal instability (CIN) emerges at an early stage during hepatocarcinogenesis and is successively inherent to tumor cells, resulting in acquisition of malignant phenotype. The molecular basis of CIN is beginning to be explored; however, several mechanisms may be involved for CIN of HCC.

Allelic Imbalance↗
PubMed2001

Chromosomal instability detected by fluorescence in situ hybridization in Japanese breast cancer patients.

The relationship between chromosomal instability (CIN) and prognostic factors was investigated in 31 breast cancers and 5 benign breast lesions (three fibroadenomas and two papillomas). Using fluorescence in situ hybridization (FISH) with chromosome-specific DNA probes of chromosomes 1, 2, 6, 7, 10, 11, 17 and 18, CIN for each case was determined. CIN varied from 8.1% to 59.3% among the breast cancer patients tested, and was significantly higher than that observed in the benign breast lesions (p<0.01). Moreover, CIN showed a significant correlation with lymph node metastases (p<0.05) and estrogen receptor negativity (p<0.01). These findings suggest that CIN might be useful in the prediction of the biological aggressiveness of breast cancers.

Asian People↗
PubMed2000

Acceleration of chromosomal instability by loss of BRCA1 expression and p53 abnormality in sporadic breast cancers.

Correlation of chromosomal instability (CIN) with BRCA1 expression and p53 abnormality was studied in sporadic breast cancers since these genes are implicated in the double strand DNA repair and mitotic checkpoint, and loss of their function is speculated to result in the accumulation of CIN. CIN values (percentage of cells with non-modal chromosomes) were determined by fluorescence in situ hybridization of chromosomes 1, 11, and 17. BRCA1 expression was studied by immunostaining, and p53 abnormality was studied by immunostaining and polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP). CIN values of BRCA1 negative/p53 normal tumors (28.9+/-13.8, n=23) and those of BRCA1 positive/p53 abnormal tumors (27.0+/-2.3, n=3) were not significantly different from those of BRCA1 positive/p53 normal tumors (23.8+/-11.5, n=10). On the other hand, BRCA1 negative/p53 abnormal tumors (41.2+/-12.7, n=23) showed a significant (P<0.01) increase in CIN values than BRCA1 positive/p53 normal tumors. There was no significant association between CIN values and menopausal status, tumor size, histological grade, lymph node status, or estrogen receptor status. These results suggest that BRCA1 down-regulation and p53 abnormality work synergistically to induce CIN in breast cancers, and that clinico-pathological characteristics of breast cancers with high CIN still remain to be established.

Adult↗
PubMed2000

[Chromosomal instability in offspring of voles in unfavorable radiation zones].

A high frequency of cells having chromosomal aberrations was shown to be preserved in the first generation of laboratory offspring of common voles, whose ancestors were captured near the East Ural radioactive track (EURT). In F2 and F3, a decrease in frequency was observed. Most likely, the cytogenetic effects observed were caused by environmental contamination with plutonium in the locality of capture. An increased chromosomal instability observed in the first laboratory generation of nonirradiated common voles was caused by reversible modifications in the expression of mutator genes inherited from parents exposed to alpha-irradiation rather than by classic mutations occurred in specific loci.

Animals↗
PubMed1988

Spontaneous and induced chromosomal instability in Werner syndrome.

In extension of a previous study, spontaneous and clastogen-induced chromosome damage was analyzed in cultures of peripheral blood lymphocytes from six further patients with Werner syndrome (WS) and six healthy controls. In addition, sister chromatid exchange (SCE) was estimated in four of these cases. Lymphocytes of patients with various other diseases were used for another series of control experiments. Diepoxybutane (DEB), 4-nitroquinoline-1-oxide (NQO), and bleomycin (BLM) were the standard clastogens throughout the study. While the spontaneous frequency of chromosomal breakage was significantly higher in lymphocytes from all the patients than in the control cells, the basis SCE rate was unaffected in WS cells. Sensitivity of WS cells to the chromosome-damaging action of BLM did not differ from that of control cells, and their sensitivity to DEB was slightly greater than that of control lymphocytes. However, NQO induced a more distinct increase of both break and interchange aberrations in the WS cells than in control cells or cells from patients with other diseases. This effect was not found for the SCE rate. Our data demonstrate the exceptional cytogenetic features of this syndrome: Although the spontaneous and the DEB- and NQO-induced chromosomal breakage rate would suggest that WS is like a classic chromosomal instability syndromes, the lack of sensitivity of WS cells to bleomycin and their stable SCE frequency compared with that of control cells clearly delimitate this syndrome from other entities.

4-Nitroquinoline-1-oxide↗
PubMed2005

Establishment of an immortalised human ovarian surface epithelial cell line without chromosomal instability.

Epithelial ovarian carcinoma is thought to derive from ovarian surface epithelium (OSE). The black box of the early molecular changes in ovarian carcinogenesis is being interpreted by the development of experimental systems employing immortalised human OSE cells. However, the existing cell lines of the OSE cells have limited utility due to chromosomal instability. Our goal was to establish new immortalised human OSE cells that retain the original characteristics of the primary cells without chromosomal alterations. Using primary human OSE cells obtained from a postmenopausal patient with endometrial cancer, five cell lines ('HOSE1' lines) were newly established by infection with retroviral expression vectors containing type 16 human papillomavirus (HPV-16) E6, E7, a variant E6 (E6delta151), and Bmi1 polycomb gene, in combination with telomerase reverse transcriptase (hTERT). Consequently, five HOSE1s cell lines, HOSE1s-E6/hTERT, -E7/hTERT, -E6/E7/hTERT, -E6delta151/E7/hTERT, and -E6delta151/Bmi1/hTERT, grew beyond the population doubling number of 200. These cell lines, except for HOSE1-E6/hTERT, essentially showed the original features of the primary human OSE cells. Of them, HOSE1-E7/hTERT preserved diploidy in a kariotype analysis, and did not show transformed phenotypes in anchorage-independent growth and tumour formation. Thus, HOSE1-E7/hTERT may provide a novel model system with which to investigate the mechanisms of early molecular changes.

Animals↗
PubMed1983

Chromosome instability in lymphocytes, fibroblasts, and colon epithelial-like cells from patients with familial polyposis coli.

Detailed chromosome studies on early-passage skin fibroblast cultures from 17 patients with familial polyposis coli (FPC) showed an increase in all classes of chromosome aberrations compared with controls. The most striking difference was in the number of cytogenetically abnormal clones, some of which reached 80-100% in early cultures, suggesting either presence in vivo or considerable proliferative advantage. The occasional occurrence of very high levels of tetraploidy in these cultures was thought to be a manifestation of clone formation. The same type of chromosome instability was found to extend to colon fibroblasts and lymphocytes but without evidence of clone formation, apart from high tetraploidy in the former. Chromosomes in colon epithelial-like cultures were remarkably stable initially, despite the time span of several months required to establish them. However, from the outset one of these cultures was composed of three abnormal clones. After approximately 18 months in culture, stable and unstable chromosome rearrangements clearly increased in all tested cultures, although the cells were not senescent, suggesting a possible shift toward malignancy.

Adolescent↗
PubMed2004

Radiation-induced chromosomal instability and gene expression profiling: searching for clues to initiation and perpetuation.

Radiation-induced genomic instability (RIGI) manifests in the progeny of cells surviving ionizing radiation (IR), and can be measured using such endpoints as delayed mutation, micronuclei formation, and chromosomal instability. The frequency of RIGI is relatively high, exceeding the gene mutation rate of IR by orders of magnitude, leading to conjecture that a gene mutation is not the cause of the phenotype. We have started to explore whether differential gene expression patterns are associated with the instability phenotype, in order to shed light on its initiation and perpetuation. Using GM10115 human-hamster hybrid-derived chromosomally stable and radiation-induced unstable clones, gene expression patterns were analyzed using microarray analysis. Two methods were used to find differentially expressed genes, and all candidate genes identified by these methods were under-expressed relative to the chromosomally stable reference sample. Among this set differentially expressed genes identified were two candidates with a relationship to the ubiquitin/proteasome pathway. While follow-up gene expression analyses have confirmed the under-expression of these two genes in some of our chromosomally unstable clones, preliminary functional studies have been unable to demonstrate a link to instability. It is anticipated that as we apply this technology to the study of radiation-induced genomic instability, clues to its onset will be revealed, ultimately contributing to a greater understanding of the mechanisms of radiation carcinogenesis.

Animals↗
PubMed1997

Cytogenetic and interphase cytogenetic analyses reveal chromosome instability but no clonal trisomy 8 in Dupuytren contracture.

The results of cytogenetic and FISH analysis performed in 26 cases of Dupuytren contracture are reported. Clonal or sporadic chromosome changes were found in 18 cases (69%). Clonal changes consisted of: +2, +16, -10, -Y, add(1)(p23), del(2)(q21), t(3;16)(p21;q24), add (3)(p24), del(18)(q21), t(Y;14)(p12;q24), +mar. The results differ from those obtained in normal palmar fascia used as control, in which -Y and +Y were the only clonal changes found in 2 of 11 analyzed cases (18%). No clonal trisomy 8 was found. FISH analysis performed in 11 cases (centromeric probe specific for chromosome 8) failed to show the presence of a cell population with +8. Clonal and sporadic structural changes were different from case to case and no clustering breakpoint was observed. The significance of the chromosome instability leading to clonal and sporadic chromosome changes not specific to Dupuytren contracture are discussed.

Aged↗
PubMed2004

Detection of chromosomal instability in alpha-irradiated and bystander human fibroblasts.

There is increasing evidence biological responses to ionizing radiation are not confined to those cells that are directly hit, but may be seen in the progeny at subsequent generations (genomic instability) and in non-irradiated neighbors of irradiated cells (bystander effects). These so called non-targeted phenomena would have significant contributions to radiation-induced carcinogenesis, especially at low doses where only a limited number of cells in a population are directed hit. Here we present data using a co-culturing protocol examining chromosomal instability in alpha-irradiated and bystander human fibroblasts BJ1-htert. At the first cell division following exposure to 0.1 and 1Gy alpha-particles, irradiated populations demonstrated a dose dependent increase in chromosome-type aberrations. At this time bystander BJ1-htert populations demonstrated elevated chromatid-type aberrations when compared to controls. Irradiated and bystander populations were also analyzed for chromosomal aberrations as a function of time post-irradiation. When considered over 25 doublings, all irradiated and bystander populations had significantly higher frequencies of chromatid aberrations when compared to controls (2-3-fold over controls) and were not dependent on dose. The results presented here support the link between the radiation-induced phenomena of genomic instability and the bystander effect.

Alpha Particles↗
PubMed2005

YB-1 provokes breast cancer through the induction of chromosomal instability that emerges from mitotic failure and centrosome amplification.

YB-1 protein levels are elevated in most human breast cancers, and high YB-1 levels have been correlated with drug resistance and poor clinical outcome. YB-1 is a stress-responsive, cell cycle-regulated transcription factor with additional functions in RNA metabolism and translation. In this study, we show in a novel transgenic mouse model that human hemagglutinin-tagged YB-1 provokes remarkably diverse breast carcinomas through the induction of genetic instability that emerges from mitotic failure and centrosome amplification. The increase of centrosome numbers proceeds during breast cancer development and explanted tumor cell cultures show the phenotype of ongoing numerical chromosomal instability. These data illustrate a mechanism that might contribute to human breast cancer development.

Animals↗
PubMed2005

Mutant KRAS, chromosomal instability and prognosis in colorectal cancer.

The RAS gene family provides a global effect on gene expression by encoding small GTP-binding proteins which act as molecular switches connecting extracellular signals with nuclear transcription factors. While wild type RAS proteins are switched off shortly after activation, mutant RAS proteins remain constitutively activated leading to complex interactions among their downstream effectors. For some human tumor types, these interactions were shown to contribute to cancer genesis and progression by inducing changes in cell survival, apoptosis, angiogenesis, invasion and metastasis. This review addresses the controversial link of KRAS mutations in colorectal cancer with chromosomal instability and patient prognosis.

Chromosomal Instability↗