Loss of heterozygosity and K-ras gene mutations in gastric cancer

In order to identify relevant genetic lesions in gastric carcinoma, we searched for tumor suppressor gene inactivation and K-ras gene mutations by analyzing tumor and control DNAs from 34 patients. These were from an epidemiologically defined area of Italy characterized by one of the world's highest incidences of stomach cancer. Allele losses were investigated by the Southern blotting procedure at 16 polymorphic loci on 11 different chromosomes. Our data demonstrate that chromosomal regions 5q, 11p, 17p and 18q are frequently deleted, and that 7q and 13q chromosome arms are also involved, although at a lower frequency. Loss of heterozygosity (LOH) at region 11p was not found during other surveys carried out on patients of different geographic origins. No specific combination of allelic losses could be recognized in the samples analyzed, the only exception being that tumors with 17p allelic loss also showed LOH on the 18q region. When matching frequent LOH events and the stage of progression of the tumors, we observed a trend of association between advanced stages and allelic losses on 17p and 18q chromosome arms. The analysis of K-ras, carried out by the polymerase chain reaction and denaturing gradient gel electrophoresis, demonstrated transforming mutations in only 3 out of 32 cases. Colorectal tumorigenesis proceeds by the accumulation of genetic alterations, including K-ras mutations and inactivation of tumor suppressor genes on the 5q, 17p and 18q regions. Our data indicate that, although gastric and colorectal neoplasias share common genetic alterations, they probably progress through different pathways.     

Non-random jumping translocations as a result of SV40 large T-antigen expression in benign human tumor cells.

In an attempt to analyse the cytogenetic effects caused by SV40 large T-antigen expression in cells of human benign tumors we transfected cells of an uterine leiomyoma characterized by a primary reciprocal translocation t(12;14)(q15;q24) and a pleomorphic adenoma of the salivary gland with an inversion inv(12) (q15q24.1) using a construct coding for SV40 large and small T-antigen. The most interesting finding was not a generally destabilized karyotype, but the strictly non-random involvement of two chromosomal breakpoints, i.e. 5p13 and 10q11 in jumping translocations, never described before as a result of SV40 transformation. In addition we were able to show by non-radioactive in situ hybridization that there was no direct relationship between the integration site of the construct and the pre-disposition of 5p13 and 10q11 to somatic recombination. The jumping translocations with consistent breakpoints observed closely resemble the cytogenetic situation seen in a variety of human tumors with specific translocations. Based on the findings described here it is tempting to assume that the expression of SV40 large T-antigen can induce specific karyotypic alterations following an unknown trans-acting mechanism.     

Painting of defined chromosomal regions by in situ suppression hybridization of libraries from laser-microdissected chromosomes

"Painting" of defined chromosomal regions provides a powerful tool for cytogenetic analyses. Here, we demonstrate that chromosomal in situ suppression (CISS)-hybridization of DNA libraries derived by microcloning laser-microdissected chromosomal regions can be applied to achieve this goal. As an example, we used unbanded metaphase spreads from a female patient carrying a balanced translocation. t(1;7)(1qter----1p36::7q11----7qter). Fragments from the long arms of 130 translocation chromosomes were microdissected. After microcloning, human inserts with an average size of about 3 kb were pooled from 400 recombinant bacteriophage DNA clones and used as a complex probe set in CISS-hybridization experiments. This resulted in painting of the translocation chromosome along the region 7q35 to 1p31. Painted chromosomal subregions in normal chromosomes 1 and 7 were consistent with this finding. This approach may be used to perform painting of any chromosome regions for which microlibraries can be established. Possible applications include the definition of marker chromosomes in clinical and tumor cytogenetics and studies of chromosomal evolution, as well as studies of nuclear chromosome topography in animal and plant species.     

SV40LT highly mutates and immortalizes two fibroblast strains from patients with Wilms' tumor.

In order to analyze in detail the process of immortalization of human cells, SV40LT was introduced into two chromosome 11p- fibroblast strains from Wilms' tumor patients. Both fibroblasts, hereafter referred to as CM1 and CM2, displayed the mutant phenotype in the crisis stage of cellular aging. In comparison to a control fibroblast, the density of the CM1 strain was abnormally high while the crisis period of the CM2 strain was abnormally long. The CM1 immortalization was 7 times greater than the control and the CM2 strain had the highest frequency of immortalization, 7 times greater than the CM1. These findings indicate that genes associated with chromosome 11p- may be involved in the immortalization of human cells. During their abnormal crisis periods, the cells derived from the patients with Wilms' tumor showed an extremely high frequency of chromosomal aberrations and mutations (6TGs --> 6TGr). These results indicate that when the growth-arrested cells from Wilms' patients are induced to grow with the introduction of SV40LT at the crisis stage they are highly mutable, resulting in their immortalization in vitro.     

Complex Patterns of Chromosome 11 Aberrations in Myeloid Malignancies Target CBL,MLL, DDB1 and LMO2

Exome sequencing of primary tumors identifies complex somatic mutation patterns. Assignment of relevance of individual somatic mutations is difficult and poses the next challenge for interpretation of next generation sequencing data. Here we present an approach how exome sequencing in combination with SNP microarray data may identify targets of chromosomal aberrations in myeloid malignancies. The rationale of this approach is that hotspots of chromosomal aberrations might also harbor point mutations in the target genes of deletions, gains or uniparental disomies (UPDs). Chromosome 11 is a frequent target of lesions in myeloid malignancies. Therefore, we studied chromosome 11 in a total of 813 samples from 773 individual patients with different myeloid malignancies by SNP microarrays and complemented the data with exome sequencing in selected cases exhibiting chromosome 11 defects. We found gains, losses and UPDs of chromosome 11 in 52 of the 813 samples (6.4%). Chromosome 11q UPDs frequently associated with mutations of CBL. In one patient the 11qUPD amplified somatic mutations in both CBL and the DNA repair gene DDB1. A duplication within MLL exon 3 was detected in another patient with 11qUPD. We identified several common deleted regions (CDR) on chromosome 11. One of the CDRs associated with de novo acute myeloid leukemia (P=0.013). One patient with a deletion at the LMO2 locus harbored an additional point mutation on the other allele indicating that LMO2 might be a tumor suppressor frequently targeted by 11p deletions. Our chromosome-centered analysis indicates that chromosome 11 contains a number of tumor suppressor genes and that the role of this chromosome in myeloid malignancies is more complex than previously recognized.     

Association between genetic subgroups of pancreatic ductal adenocarcinoma defined by high density 500 K SNP-arrays and tumor histopathology

The specific genes and genetic pathways associated with pancreatic ductal adenocarcinoma are still largely unknown partially due to the low resolution of the techniques applied so far to their study. Here we used high-density 500 K single nucleotide polymorphism (SNP)-arrays to define those chromosomal regions which most commonly harbour copy number (CN) alterations and loss of heterozygozity (LOH) in a series of 20 PDAC tumors and we correlated the corresponding genetic profiles with the most relevant clinical and histopathological features of the disease. Overall our results showed that primary PDAC frequently display (>70%) extensive gains of chromosomes 1q, 7q, 8q and 20q, together with losses of chromosomes 1p, 9p, 12q, 17p and 18q, such chromosomal regions harboring multiple cancer- and PDAC-associated genes. Interestingly, these alterations clustered into two distinct genetic profiles characterized by gains of the 2q14.2, 3q22.1, 5q32, 10q26.13, 10q26.3, 11q13.1, 11q13.3, 11q13.4, 16q24.1, 16q24.3, 22q13.1, 22q13.31 and 22q13.32 chromosomal regions (group 1; n = 9) versus gains at 1q21.1 and losses of the 1p36.11, 6q25.2, 9p22.1, 9p24.3, 17p13.3 and Xp22.33 chromosomal regions (group 2; n = 11). From the clinical and histopathological point of view, group 1 cases were associated with smaller and well/moderately-differentiated grade I/II PDAC tumors, whereas and group 2 PDAC displayed a larger size and they mainly consisted of poorly-differentiated grade III carcinomas. These findings confirm the cytogenetic complexity and heterogenity of PDAC and provide evidence for the association between tumor cytogenetics and its histopathological features. In addition, we also show that the altered regions identified harbor multiple cancer associate genes that deserve further investigation to determine their relevance in the pathogenesis of PDAC.     

DNA amplifications and aneuploidy, high proliferative activity and impaired cell cycle control characterize breast carcinomas with poor prognosis.

In order to explore whether specific cytogenetic abnormalities can be used to stratify tumors with a distinctly different clinical course, we performed comparative genomic hybridization (CGH) of tumors from patients who were diagnosed with metastatic disease after an interval of less than 2 years or who remained free from distant metastases for more than 10 years. All patients presented with distant metastases after mastectomy indicating that none of the patients in this study was cured and free of remaining tumor cells. Tumors in the group of short-term survivors showed a higher average number of chromosomal copy alterations compared to the long-term survivors. Of note, the number of sub-chromosomal high-level copy number increases (amplifications) was significantly increased in the group of short-term survivors. In both short- and long-term survivors recurrent chromosomal gains were mapped to chromosomes 1q, 4q, 8q, and 5p. Copy number changes that were more frequent in the group of short-term survivors included gains of chromosome 3q, 9p, 11p and 11q and loss of 17p. Our results indicate that low- and high grade malignant breast adenocarcinomas are characterized by a specific pattern of chromosomal copy number changes. Furthermore, immunohistochemical evaluation of the expression levels of Ki-67, p27KIP1, p21WAF1, p53, cyclin A and cyclin E revealed a correlation between increased proliferative activity and poor outcome.     

Chromosomal imbalances are associated with metastasis-free survival in breast cancer patients.

Multiple chromosomal imbalances have been identified in breast cancer using comparative genomic hybridization (CGH). Their association with the primary tumors' potential for building distant metastases is unknown. In this study we have investigated 39 invasive breast carcinomas with a mean follow-up period of 99 months (max. 193 months) by CGH to determine the prognostic value of chromosomal gains and losses.The mean number of chromosomal imbalances per tumor was 6.5+/-0.7 (range 2 to 18). The most frequent alterations identified in more than 1/3 of cases were gains on chromosomes 11q13, 12q24, 16, 17, and 20q, and losses on 2q and 13q. A significantly different frequency of chromosomal aberrations (p相似文献   

Combined cytogenetic and molecular analyses for the diagnosis of Prader-Willi/Angelman syndromes

Prader-Willi (PWS) and Angelman (AS) are syndromes of developmental impairment that result from the loss of expression of imprinted genes in the paternal (PWS) or maternal (AS) 15q11-q13 chromosome. Diagnosis on a clinical basis is difficult in newborns and young infants; thus, a suitable molecular test capable of revealing chromosomal abnormalities is required. We used a variety of cytogenetic and molecular approaches, such as, chromosome G banding, fluorescent in situ hybridization, a DNA methylation test, and a set of chromosome 15 DNA polymorphisms to characterize a cohort of 27 PWS patients and 24 suspected AS patients. Molecular analysis enabled the reliable diagnosis of 14 PWS and 7 AS patients, and their classification into four groups: (A) 6 of these 14 PWS subjects (44 %) had deletions of paternal 15q11-q13; (B) 4 of the 7 AS patients had deletions of maternal 15q11-q13; (C) one PWS patient (8 %) had a maternal uniparental disomy (UPD) of chromosome 15; (D) the remaining reliably diagnoses of 7 PWS and 3 AS cases showed abnormal methylation patterns of 15q11-q13 chromosome, but none of the alterations shown by the above groups, although they may have harbored deletions undetected by the markers used. This study highlights the importance of using a combination of cytogenetic and molecular tests for a reliable diagnosis of PWS or AS, and for the identification of genetic alterations.     

Familial Wiedemann-Beckwith syndrome and a second Wilms tumor locus both map to 11p15.5.

Wilms tumor of the kidney occurs with increased frequency in association with two clinically and cytogenetically distinct congenital syndromes, the Wiedemann-Beckwith syndrome (WBS) and the triad of aniridia, genitourinary anomalies, and mental retardation (WAGR). Constitutional deletions in the latter situation and similar alterations in sporadic Wilms tumors have implicated the chromosomal 11p13 region in neoplastic development. In contrast, some sporadic cases of WBS have been reported to have a constitutional duplication of chromosome 11p15. In order to resolve this seeming paradox, we have analyzed a family segregating WBS for linkage to DNA markers mapped to chromosome 11p. Consonant with the cytogenetic alterations in sporadic WBS cases, we obtained evidence for tight linkage of the mutation causing the syndrome to markers located at 11p15.5. Also consistent with this localization, we identified a subset of Wilms tumors, not associated with WBS, which have attained somatic homozygosity through mitotic recombination, with the smallest shared region of overlap being distal to the beta-globin complex at 11p15.5. These data provide evidence that familial WBS likely results from a defect at the same genetic locus as does its sporadic counterpart. Further, the data suggest there is another locus, distinct from that involved in the WAGR syndrome, which plays a role in the association of Wilms tumor with WBS.     

Characteristics of the spontaneously transformed human endothelial cell line ECV304. I. Multiple chromosomal rearrangements in endothelial cells ECV304

Karyotype of endothelial line ECV304 cells obtained from human umbilicus vein endothelial cells was studied using G-banding chromosome staining. It has been revealed that the cells have a polyploidy karyotype with 96-112 chromosomes and multiple numerical and structural clonal rearrangements. Almost all the chromosomes of the karyotype are involved in structural rearrangements. There are several double chromosome rearrangements revealed including del(9)(p21) as well as two derivatives of chromosome 3 with the breakpoint in the locus p25 - der(3)t(3;12)(3p25;12q11- 12q24.?1) and der(3)t(3;?)(3p25). The role of these rearrangements in the immortalization of endothelial cells and sighs of transformation are discussed. In connection with the information received about the fact that the cells of ECV304 line are not endothelial cells but T24, urinary bladder cancer cells (which karyotype was studied by Hurst et al., 2000), the comparative analysis of the karyotypes of these two lines was carried out. It has been revealed that these two lines differ by all cytogenetic characteristics. Neither identical structural chromosomal rearrangements nor cell characteristic of urinary bladder cancer cells were detected. Our line ECV304 is not identical to the line T24.     

A nine-year cytogenetic follow-up of a patient injected with thorotrast

Summary Chromosomal abnormalities in the peripheral lymphocytes of a Thorotrast case were followed up for almost nine years during which four direct bone marrow observations were made. Chromosomal abnormalities, both Cu type (dicentrics, rings, and acentric fragments) and Cs type (reciprocal translocations, inversions, deletions, duplications, and others), were observed with an average frequency of about 7.5% and 8%, respectively. The frequency of chromosomal abnormalities showed no significant changes during the nine years. Formation of clones of cells with identical chromosomal abnormalities was observed both in bone marrow and peripheral lymphocytes. There were clones common to myeloid and lymphoid cell series, which may be regarded as evidence for the presence of pluripotent stem cells in man. One such common clone had a translocation involving chromosomes 2 and 22. Banding analysis revealed a break in chromosome 22 at the q12 or q12/13 band interface. The frequency of the clone remained fairly constant within 5% for several years and the patient showed no indication of leukemia or any other blood disease. The finding seems to suggest a genetic factor relating to the development of chronic myelocytic leukemia (CML), which generally shows the Ph¹ chromosome resulting from a translocation of chromosome 22 with the break at the q11 or q11/12 band interface. The increase in the number of cells lacking the Y chromosome was observed in our final bone marrow sample, but the phenomenon may be attributed to the age of the patient rather than to the direct effect of radiation. Results of the cytogenetic follow-up study seem to indicate the importance of studies in this direction for a better understanding of radiation effects on human beings.     

Determining and interpreting new predictive rules for breast cancer familial inheritance

DNA copy number alterations have been discovered to be key genetic events in development and progression of cancer. No clear data of familial and sporadic breast cancer are available. We focused on looking for an independent platform as a tool to identify the chromosomal profile in familial versus sporadic breast cancer patients. A total of 124 breast cancer patients were studied utilizing aCGH. The dataset was analyzed using Gaussian Mixture Models to determine the thresholds in order to assess gene copy number changes and to minimize the impact of noise on further data analyses. The identification of regions of consistent aberration across samples was carried out with statistical approaches and machine learning tools to draw profiles for familial and sporadic groups. Familial and sporadic cases resulted with a chromosome imbalance of 15% [false discovery rate (FDR): q=718E-5] and 18% (FDR: q=632E-13), respectively. The differential map evidenced two cytogenetic bands (8p23 and 11q13-11q14) significantly altered in familial versus sporadic cases (FDR: q=7E-4). The application of a new bioinformatics tool that discovers fuzzy classification rules (IFRAIS) let to individualize association of genes alterations that identify familial or sporadic cases. These results are comparable to those of the other systems used and are consistent from the biological point of view.     

A Yeast Artificial Chromosome Contig That Spans the RB1-D13S31 Interval on Human Chromosome 13 and Encompasses the Frequently Deleted Region in B-cell Chronic Lymphocytic Leukemia

Abnormalities involving chromosome 13 have been reported as the only cytogenetic change in B-cell chronic lymphocytic leukemia (BCLL). Deletions are the most common cytogenetic abnormality and always involve 13q14, but when translocations are seen, the consistent breakpoint is always in 13q14. It is now established that deletions, distal to the RB1 gene in 13q14, are invariably associated with these translocations. We have recently described the smallest such deletion from a series of rearrangements from these tumors isolated in somatic cell hybrids, which spans approximately 1 Mb. In this report, we present the results of a series of a chromosome walking experiments using YACs and have been able to span this small deletion, which must contain the gene that is frequently deleted in BCLL. Four probes from 13q14 (RBI-mgg15-D13S25-D13S31) were used to isolate corresponding YACs for each of the markers. The chromosomal location of these YACs was verified using FISH, which also demonstrated their nonchimeric nature. Vectorette end rescue was then used to demonstrate the overlap of the YACs and to isolate new clones to complete the contig. The extremes of the contig were shown to cross the chromosome 13 translocation breakpoints isolated in somatic cell hybrids that carry the derivatives of chromosome 13 involved in the smallest BCLL deletion. This YAC contig covers the entire deletion and will prove a valuable resource to begin isolating genes from this region. In addition, we have isolated YACs corresponding to the RB1 locus, which extends the contig over a 3.8-cM distance on the chromosome.     

Human T-cell tumours containing chromosome 14 inversion or translocation with breakpoints proximal to immunoglobulin joining regions at 14q32.

T-cell tumours are frequently found to carry an inversion of chromosome 14 (inv(14)) (q11;q32) or more rarely a chromosome 14 translocation t(14;14) with the same cytogenetic breakpoints (q11;q32). We have examined the molecular junctions of an inv(14) and a translocation t(14;14) using T-cell receptor (TCR) alpha joining (J) region probes. Both of these chromosomal abnormalities have breakpoints within the TCR J alpha locus at 14q11 and both have breakpoints which are proximal (i.e. on the centromeric side) to the immunoglobulin heavy chain JH region at 14q32. The cloned segments corresponding to the junctions at 14q32 are not associated with obvious immunoglobulin-like sequences. This contrasts to the previously described inv(14) in the cell line SUP-T1 and places a potential cluster of chromosome 14 breakpoints downstream of the Ig JH locus. The possible role of the varying breakpoints in the development of these tumours is discussed.     

Losses at chromosome 4q are associated with poor survival in operable ductal pancreatic adenocarcinoma

Here we tested the prognostic impact of genomic alterations in operable localized pancreatic ductal adenocarcinoma (PDAC). Fifty-two formalin-fixed and paraffin-embedded primary PDAC were laser micro-dissected and were investigated by comparative genomic hybridization after whole genome amplification using an adapter-linker PCR. Chromosomal gains and losses were correlated to clinico-pathological parameters and clinical follow-up data. The most frequent aberration was loss on chromosome 17p (65%) while the most frequent gains were detected at 2q (41%) and 8q (41%), respectively. The concomitant occurrence of losses at 9p and 17p was found to be statistically significant. Higher rates of chromosomal losses were associated with a more advanced primary tumor stage and losses at 9p and 18q were significantly associated with presence of lymphatic metastasis (chi-square: p = 0.03, p = 0.05, respectively). Deletions on chromosome 4 were of prognostic significance for overall survival and tumor recurrence (Cox-multivariate analysis: p = 0.026 and p = 0.021, respectively). In conclusion our data suggest the common alterations at chromosome 8q, 9p, 17p and 18q as well as the prognostic relevant deletions on chromosome 4q as relevant for PDAC progression. Our comprehensive data from 52 PDAC should provide a basis for future studies with a higher resolution to discover the relevant genes located within the chromosomal aberrations identified.     

Cytogenetic findings in a prospective series of patients with DiGeorge anomaly.

High-resolution cytogenetics analysis of peripheral blood lymphocytes was done prospectively on 27 of 28 patients with features of DiGeorge anomaly. Twenty-two patients (81%) had normal chromosome studies with no detectable deletion in chromosome 22. Five patients (18%) had demonstrable chromosome abnormalities. Three patients had monosomy 22q11, one due to a 4q;22q translocation, one due to a 20q;22q translocation, and one due to an interstitial deletion of 22q11. One patient had monosomy 10p13, and one patient had monosomy 18q21.33, although the latter had subsequent resolution of T-cell defects. These findings are consistent with the heterogeneity of DiGeorge anomaly but confirm the association with monosomy 22q11 in some cases. However, monosomy 10p13 may also lead to this phenotype. Because of these associated chromosome findings, cytogenetic analyses should be done on patients with suspected DiGeorge anomaly. This is particularly important since many of the abnormalities involving chromosome 22 are translocations that can be familial with a higher recurrence risk. Since only one subtle, interstitial deletion of chromosome 22 was observed, it is not clear whether high-resolution cytogenetic analysis is cost beneficial for all such patients.     

Genetic features of B-cell chronic lymphocytic leukemia

The genetic features of B-cell chronic lymphocytic leukemia (CLL) are currently being reassessed by molecular cytogenetic techniques such as fluorescence in situ hybridization (FISH). Conventional cytogenetic studies by chromosome banding are difficult in CLL mainly because of the low in vitro mitotic activity of the tumor cells, which leads to poor quantity and quality of metaphase spreads. Molecular genetic analyses are limited because candidate genes are known for only a few chromosomal aberrations that are observed in CLL. FISH was found to be a powerful tool for the genetic analysis of CLL as it overcomes both the low mitotic activity of the CLL cells and the lack of suitable candidate genes for analysis. Using FISH, the detection of chromosomal aberrations can be performed at the single cell level in both dividing and non-dividing cells, thus circumventing the need of metaphase preparations from tumor cells. Probes for the detection of trisomies, deletions and translocation breakpoints can be applied to the regions of interest with the growing number of clones available from genome-wide libraries. Using the interphase cytogenetic FISH approach with a disease specific set of probes, chromosome aberrations can be found in more than 80% of CLL cases. The most frequently observed abnormalities are losses of chromosomal material, with deletions in band 13q14 being the most common, followed by deletions in 11q22-q23, deletions in 17p13 and deletions in 6q21. The most common gains of chromosomal material are trisomies 12q, 8q and 3q. Translocation breakpoints, in particular involving the immunoglobulin heavy chain locus at 14q32, which are frequently observed in other types of non-Hodgkin's lymphoma, are rare events in CLL. Genes affected by common chromosome aberrations in CLL appear to be p53 in cases with 17p deletion and ataxia telangiectasia mutated (ATM), which is mutated in a subset of cases with 11q22-q23 aberrations. However, for the other frequently affected genomic regions, the search for candidate genes is ongoing. In parallel, the accurate evaluation of the incidence of chromosome aberrations in CLL by FISH allows the correlation of genetic abnormalities with clinical disease manifestations and outcome. In particular, 17p abnormalities and deletions in 11q22-q23 have already been shown to be among the most important independent prognostic factors identifying subgroups of patients with rapid disease progression and short survival. In addition, deletion 17p has been associated with resistance to treatment with purine analogs. Therefore, genetic abnormalities may allow a risk assessment for individual patients at the time of diagnosis, thus giving the opportunity for a risk-adapted management.     

Tissue specificity of chromosomal rearrangements in ataxia-telangiectasia

Summary Cytogenetic studies of lymphocytes and fibroblasts from individuals with ataxia-telangiectasia (AT) demonstrate spontaneous chromosomal breakage. In the AT lymphocytes, this damage results in a high frequency of balanced rearrangements involving chromosome bands 7p14, 7q35, 14q12, and 14q32. The T-cell receptor , , and chain gene complexes and the immunoglobulin heavy chain gene complex, all of which may be functional in lymphocytes, have been localized to these bands. To assess the relationship between genes at these breakpoints and the entirety of the AT phenotype, we undertook a detailed cytogenetic analysis of fibroblasts and lymphocytes from seven AT homozygotes. Our findings indicate that the rearrangements present in the lymphocytes are not commonly observed in the fibroblasts, despite the increased instability of chromosomes from these cells relative to lymphocytes. Furthermore, the changes in the fibroblasts are neither consistent within nor between patients, suggesting that chromosome rearrangement occurs more randomly in this tissue. Therefore, differential site-specific damage in separate tissues may generate the distinct features of the disease in those tissues and may account for the pleiotrophic effects of the AT gene.     

Characterization of the spontaneously transformed human endothelial cell line ECV304: 1. Multiple chromosomal rearrangements in ECV304 cells

Using differential G-staining of chromosomes, the karyotype of the endothelial cell line ECV304 obtained from endotheliocytes of the human umbilical vein was studied. The cells have been shown to have a polyploid karyotype with a number of chromosomes ranging from 96 to 112, as well as multiple numerical and structural clonal chromosome abnormalities. The structural rearrangements involve almost all chromosomes of the karyotype. Several paired chromosomal rearrangements have been revealed and include del(9)(p21), as well as two derivates of chromosome 3 with a breakpoint at the p25 locus, i.e., der(3)t(3;12)(3p25;12q11～12;12q21～24.?1) and der(3)t(3;?)(3p25). The role of these rearrangements in the immortalization of endotheliocytes and in angiogenesis is discussed. A comparison of the karyotypes of the cell line ECV304 and of the bladder carcinoma T24 cell line has shown that these karyotypes differ in all of the main cytogenetic characteristics. No identical structural chromosomal rearrangements, nor rearrangements characteristic of bladder carcinoma cells have been revealed. The studied endothelial cell line ECV304 is not identical to the T24 cell line.