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T Ried

Publications and source records attributed to T Ried.

At least 37 records · Page 2Linked to original sources
PubMed2000

Response to RAG-mediated VDJ cleavage by NBS1 and gamma-H2AX.

Genetic disorders affecting cellular responses to DNA damage are characterized by high rates of translocations involving antigen receptor loci and increased susceptibility to lymphoid malignancies. We report that the Nijmegen breakage syndrome protein (NBS1) and histone gamma-H2AX, which associate with irradiation-induced DNA double-strand breaks (DSBs), are also found at sites of VDJ (variable, diversity, joining) recombination-induced DSBs. In developing thymocytes, NBS1 and gamma-H2AX form nuclear foci that colocalize with the T cell receptor alpha locus in response to recombination activating gene (RAG) protein-mediated VDJ cleavage. Our results suggest that surveillance of T cell receptor recombination intermediates by NBS1 and gamma-H2AX may be important for preventing oncogenic translocations.

Amino Acid Sequence↗
PubMed2000

Novel molecular cytogenetic techniques for identifying complex chromosomal rearrangements: technology and applications in molecular medicine.

Molecular cytogenetic techniques that are based on fluorescence in situ hybridisation (FISH) have become invaluable tools for the diagnosis and identification of the numerous chromosomal aberrations that are associated with neoplastic disease, including both haematological malignancies and solid tumours. FISH can be used to identify chromosomal rearrangements, by detecting specific DNA sequences with fluorescently labelled DNA probes. The technique of comparative genomic hybridisation (CGH) involves two-colour FISH. It can be used to establish ratios of fluorescence intensity values between tumour DNA and control DNA along normal reference metaphase chromosomes, and thereby to detect DNA copy-number changes such as gains and losses of specific chromosomal regions and gene amplifications. Spectral karyotyping (SKY) is a novel molecular cytogenetic method for characterising numerical and structural chromosomal aberrations. SKY involves the simultaneous hybridisation of 24 differentially labelled chromosome-painting probes, followed by spectral imaging and chromosome classification, and produces a colour karyotype of the entire genome. The use of SKY has contributed significantly to the identification of chromosomal anomalies that are associated with constitutional and cancer cytogenetics, and has revealed many aberrations that go undetected by traditional banding techniques. In this article, we have reviewed these new molecular cytogenetic techniques and described their various applications in molecular medicine.

Journal Article↗
PubMed2000

Abnormal rearrangement within the alpha/delta T-cell receptor locus in lymphomas from Atm-deficient mice.

Atm-deficient mice (Atm(-/-)) recapitulate many aspects of the ataxia telangiectasia (AT) syndrome, including the susceptibility to tumors of lymphoid origin. To investigate the mechanism of tumorigenesis, we have examined a panel of 8 thymic lymphomas from Atm(-/-) mice. All Atm(-/-) tumors are of thymic lymphoblastoid origin, display an immature CD3(-) and CD4(+)/CD8(+) phenotype, and arise coincident with V(D)J recombination. Cytogenetically, all tumors are diploid or near diploid but exhibit multiple chromosome aberrations with an average of 4 abnormal chromosomes per tumor. All the tumors revealed chromosome 14 rearrangements precisely at the T-cell receptoralpha/delta (Tcralpha/delta) locus, suggesting the involvement of V(D)J recombination in these translocations. In addition, 11.5% of Atm(-/-) peripheral T cells showed chromosome 14 translocations, suggesting that rearrangements at the Tcralpha/delta locus occur early during tumor development in the absence of ATM. However, additional genetic aberrations are required for tumorigenesis. For example, translocations involving chromosome 12, often with chromosome 14 (more than 60%), and partial or complete trisomy of chromosome 15, with copy number increases of the c-myc oncogene were frequently observed. These observations suggest that ATM is required for normal rearrangement of the Tcralpha/delta locus but not for V(D)J recombination at other loci. The mechanisms that lead to tumorigenesis may be due to the involvement of ATM in monitoring double-stranded DNA breaks. (Blood. 2000;96:1940-1946)

Animals↗
PubMed2000

Recombinase-activating gene (RAG) 2-mediated V(D)J recombination is not essential for tumorigenesis in Atm-deficient mice.

The majority of Atm-deficient mice die of malignant thymic lymphoma by 4-5 mo of age. Cytogenetic abnormalities in these tumors are consistently identified within the Tcr alpha/delta locus, suggesting that tumorigenesis is secondary to aberrant responses to double-stranded DNA breaks that occur during V(D)J recombination. Since V(D)J recombination is a recombinase-activating gene (RAG)-dependent process, we generated Rag2(-/-)Atm(-/-) mice to assess the requirement for RAG-dependent recombination in thymic lymphomagenesis. In contrast to expectation, the data presented here indicate that development of malignant thymic lymphoma in Atm(-/-) mice is not prevented by loss of RAG-2 and thus is not dependent on V(D)J recombination. Malignant thymic lymphomas in Rag2(-/-)Atm(-/-) mice occurred at a lower frequency and with a longer latency as compared with Atm(-/-) mice. Importantly, cytogenetic analysis of these tumors indicated that multiple chromosomal abnormalities occurred in each tumor, but that none of these involved the Tcr alpha/delta locus. Nonmalignant peripheral T cells from TCR-transgenic Rag2(-/-)Atm(-/-) mice also revealed a substantial increase in translocation frequency, suggesting that these translocations are early events in the process of tumorigenesis. These data are consistent with the hypothesis that the major mechanism of tumorigenesis in Atm(-/-) mice is via chromosomal translocations and other abnormalities that are secondary to aberrant responses to double-stranded DNA breaks. Furthermore, these data suggest that V(D)J recombination is a critical, but not essential, event during which Atm-deficient thymocytes are susceptible to developing chromosome aberrations that predispose to malignant transformation.

Animals↗
PubMed2000

DNA repair protein Ku80 suppresses chromosomal aberrations and malignant transformation.

Cancer susceptibility genes have been classified into two groups: gatekeepers and caretakers. Gatekeepers are genes that control cell proliferation and death, whereas caretakers are DNA repair genes whose inactivation leads to genetic instability. Abrogation of both caretaker and gatekeeper function markedly increases cancer susceptibility. Although the importance of Ku80 in DNA double-strand break repair is well established, neither Ku80 nor other components of the non-homologous end-joining pathway are known to have a caretaker role in maintaining genomic stability. Here we show that mouse cells deficient for Ku80 display a marked increase in chromosomal aberrations, including breakage, translocations and aneuploidy. Despite the observed chromosome instabilities, Ku80-/- mice have only a slightly earlier onset of cancer. Loss of p53 synergizes with Ku80 to promote tumorigenesis such that all Ku80-/- p53-/- mice succumb to disseminated pro-B-cell lymphoma before three months of age. Tumours result from a specific set of chromosomal translocations and gene amplifications involving IgH and c-Myc, reminiscent of Burkitt's lymphoma. We conclude that Ku80 is a caretaker gene that maintains the integrity of the genome by a mechanism involving the suppression of chromosomal rearrangements.

Animals↗
PubMed2000

Identification of novel regions of allelic loss from a genomewide scan of esophageal squamous-cell carcinoma in a high-risk Chinese population.

Esophageal cancer is one of the most common fatal cancers worldwide. Deletions of genomic regions are thought to be important in esophageal carcinogenesis. We conducted a genomewide scan for regions of allelic loss using microdissected DNA from 11 esophageal squamous-cell carcinoma patients with a family history of upper gastrointestinal tract cancer from a high-risk region in north central China. Allelic patterns of 366 fluorescently labeled microsatellite markers distributed at 10-cM intervals over the 22 autosomal chromosomes were examined. We identified 14 regions with very high frequency (>/= 75%) loss of heterozygosity (LOH), including broad regions encompassing whole chromosome arms (on 3p, 5q, 9p, 9q, and 13q), regions of intermediate size (on 2q, 4p, 11p, and 15q), and more discrete regions identified by very high frequency LOH for a single marker (on 4q, 6q, 8p, 14q, and 17p). Among these 14 regions were 7 not previously described in esophageal squamous-cell carcinoma as having very high frequency LOH (on 2q, 4p, 4q, 6q, 8p, 14q, and 15q). The very high frequency LOH regions identified here may point to major susceptibility genes, including potential tumor suppressor genes and inherited gene loci, which will assist in understanding the molecular events involved in esophageal carcinogenesis and may help in the development of markers for genetic susceptibility testing and screening for the early detection of this cancer. Genes Chromosomes Cancer 27:217-228, 2000. Published 2000 Wiley-Liss, Inc.

Adult↗
PubMed2000

Chromosomes 1 and 5 harbor plasmacytoma progressor genes in mice.

Mouse spectral karyotyping (SKY) was employed to analyze 29 primary BALB/c plasmacytomas (PCTs) for the presence of chromosomal aberrations that took place subsequent to the Myc-activating T(12F1;15D2) or T(6C1;15D2) translocations, the initiating oncogenic mutations in plasmacytomagenesis. Recurrent amplifications of chromosome (Chr) 1 (48% prevalence) and promiscuous non-reciprocal translocations of Chr 5 (52% prevalence) suggested the existence of important PCT progressor genes on bands 1B/C and 5F. The additional occurrence of sporadic aberrations (93% prevalence) most likely reflected the general instability of the PCT genome. This instability, however, was not consistent, as two PCTs lacked secondary cytogenetic changes detectable by SKY. Our findings led us to conclude that BALB/c PCTs show a remarkably similar degree of cytogenetic heterogeneity to human multiple myeloma, despite being genetically defined (inbred mouse strain) and uniformly initiated (deregulation of Myc). Published 2000 Wiley-Liss, Inc.

Aneuploidy↗
PubMed2000

Integration of cytogenetic data with genome maps and available probes: present status and future promise.

The National Cancer Institute has established an initiative, called the Cancer Chromosome Aberration Project (Ccap), in order to link and integrate the physical and genetic maps of the human genome with cytogenetic data and the location of chromosomal rearrangements in human diseases. This goal will be achieved by high-resolution fluorescence in situ hybridization (FISH) mapping of colony-purified bacterial artificial chromosome (BAC) clones spaced at 1-to 2-Mb intervals across the entire genome. All BAC clones will be anchored on the physical map by the presence of a mapped sequence tagged site (STS). The generation of a publicly accessible clone repository will allow convenient distribution of these BACs. Ccap data can be correlated with other cancer-associated and genomic databases, such as the catalog of chromosomal aberrations in cancer and the emerging full genomic sequence. We anticipate that the use of Ccap clones will expedite and refine the mapping of chromosomal breakpoints. The eventual set of approximately 3,000 Ccap BACs should facilitate the production of BAC-containing DNA chips for assessing copy number of genomic segments by matrix comparative genomic hybridization. In addition, the repository will provide genome-wide tools for defining chromosomal aberrations in cytological specimens by interphase cytogenetics. The Ccap Web site illustrates goals and progress of this initiative (http://www.ncbi.nlm.nih.gov/CCAP/).

Chromosome Mapping↗
PubMed2000

Amplification of 4q21-q22 and the MXR gene in independently derived mitoxantrone-resistant cell lines.

Molecular cytogenetic studies were conducted on three multidrug-resistant cancer sublines which are highly resistant to the chemotherapeutic agent mitoxantrone, an anthracenedione. The three independently selected sublines were derived by exposure to mitoxantrone or Adriamycin and do not overexpress MDR1 or MRP. Two sublines, MCF-7 AdVp3000 and MCF-7 MX, showed an amplification peak at 4q21-q22, as demonstrated by comparative genomic hybridization (CGH), while the third, S1-M1-80, did not. FISH using a whole chromosome 4 paint demonstrated multiple rearrangements involving chromosome 4 in MCF-7 AdVp3000 and MCF-7 MX, while S1-M1-80 contained only a simple reciprocal translocation. The parental cell lines had no chromosome 4 rearrangements and no copy number gain or amplification of chromosome 4. Spectral karyotyping (SKY) analysis revealed a balanced translocation, t(4;17)(q21-q22;p13) in S1-M1-80 and multiple clonal translocations involving chromosome 4 in MCF-7 AdVp3000 and MCF-7 MX. A novel cDNA, designated MXR, which encodes an ABC half-transporter and is highly overexpressed in the three sublines, was localized to chromosome 4 by somatic cell hybrid analysis. Southern blot analysis demonstrated amplification of the MXR gene in MCF-7 AdVp3000 and MCF-7 MX, but not in S1-M1-80. FISH studies with a BAC probe for MXR localized the gene to 4q21-22 in the normal chromosome 4 and revealed in both MCF-7 AdVp3000 and MCF-7 MX amplification of MXR at one translocation juncture, shown by SKY to be t(4;5)(4qter-->4cen-->4q21-22::5q13-->5qter++ +) in MCF-7 AdVp3000 and t(6;4;6;3)(6pter-->6q15::4q21-q22::hsr::6q?::3q?27-->+ ++3qter) in MCF MX; neither of the breakpoints in the partner chromosomes showed amplification by CGH. The data are consistent with the hypothesis of a transporter, presumably that encoded by the MXR gene, mediating mitoxantrone resistance. The MXR gene encodes a half-transporter and the absence of cytogenetic evidence of coamplification of other regions suggests that a partner may not be overexpressed, and instead the MXR half-transporter homodimerizes to mediate drug transport. Genes Chromosomes Cancer 27:110-116, 2000. Published 2000 Wiley-Liss, Inc.

Antineoplastic Agents↗
PubMed2000

Centrosome amplification and instability occurs exclusively in aneuploid, but not in diploid colorectal cancer cell lines, and correlates with numerical chromosomal aberrations.

Measurement of the nuclear DNA content allows classification of human cancers as either diploid or aneuploid. To gain further insight into mechanisms of aneuploidy, we compared the cytogenetic profile of mismatch-repair-deficient diploid versus mismatch-repair-proficient aneuploid colorectal carcinoma cell lines using comparative genomic hybridization and spectral karyotyping. Aneuploid carcinomas revealed an average of 19 chromosomal imbalances per cell line. Such numerical aberrations were exceedingly scarce in the diploid tumors. This pattern of chromosomal aberrations is consistent with a mechanism involving the impairment of chromosome segregation fidelity during mitotic cell division. In support of this idea, we demonstrate the exclusive occurrence of centrosome amplification and instability in all of the aneuploid tumor cell lines analyzed. All diploid tumors contained centrosomes that were functionally and structurally indistinguishable from those in normal human fibroblasts. Due to the observed differences in centrosomes between these two classes of tumors, we incubated the cells with the microtubule depolymerizing drugs nocodazole and griseofulvin. Our results indicate that the aneuploid tumor cell lines have an increased sensitivity to these reagents and a delay in aster formation and microtubule regrowth. However, microtubule nucleation was initiated from one or two centers in both the diploid and aneuploid cells. These observations support the notion that the integrity of the centrosome plays a central role in the development of aneuploidy. Genes Chromosomes Cancer 27:183-190, 2000. Published 2000 Wiley-Liss, Inc.

Aneuploidy↗
PubMed1999

Chromosomal aberrations in PARP(-/-) mice: genome stabilization in immortalized cells by reintroduction of poly(ADP-ribose) polymerase cDNA.

Depletion of poly(ADP-ribose) polymerase (PARP) increases the frequency of recombination, gene amplification, sister chromatid exchanges, and micronuclei formation in cells exposed to genotoxic agents, implicating PARP in the maintenance of genomic stability. Flow cytometric analysis now has revealed an unstable tetraploid population in immortalized fibroblasts derived from PARP(-/-) mice. Comparative genomic hybridization detected partial chromosomal gains in 4C5-ter, 5F-ter, and 14A1-C1 in PARP(-/-)mice and immortalized PARP(-/-)fibroblasts. Neither the chromosomal gains nor the tetraploid population were apparent in PARP(-/-) cells stably transfected with PARP cDNA [PARP(-/-)(+PARP)], indicating negative selection of cells with these genetic aberrations after reintroduction of PARP cDNA. Although the tumor suppressor p53 was not detectable in PARP(-/-) cells, p53 expression was partially restored in PARP(-/-) (+PARP) cells. Loss of 14D3-ter that encompasses the tumor suppressor gene Rb-1 in PARP(-/-) mice was associated with a reduction in retinoblastoma(Rb) expression; increased expression of the oncogene Jun was correlated with a gain in 4C5-ter that harbors this oncogene. These results further implicate PARP in the maintenance of genomic stability and suggest that altered expression of p53, Rb, and Jun, as well as undoubtedly many other proteins may be a result of genomic instability associated with PARP deficiency.

Animals↗
PubMed1999

Comprehensive and definitive molecular cytogenetic characterization of HeLa cells by spectral karyotyping.

We revisited the cytogenetic alterations of the cervical adenocarcinoma cell line HeLa through the use of spectral karyotyping (SKY), comparative genomic hybridization (CGH), and fluorescence in situ hybridization (FISH). SKY analysis unequivocally characterized all abnormal chromosomes. Chromosomal breakpoints were primarily assigned by simultaneous assessment of SKY painted chromosomes and inverted 4,6-diamidino2-phenylindole banding from the same cell. Twenty clonally abnormal chromosomes were found. Comparison with previously reported HeLa G-banding karyotypes revealed a remarkably stable cytogenetic constitution because 18 of 20 markers that were found were present before. The classification of 12 markers was refined in this study. Our assignment of the remaining six markers was consistent with those described in the literature. The CGH map of chromosomal copy number gains and losses strikingly matched the SKY results and was, in a few instances, decisive for assigning breakpoints. The combined use of molecular cytogenetic methods SKY, CGH, and FISH with site-specific probes, in addition to inverted 4,6-diamidino-2-phenylindole or conventional G-banding analysis, provides the means to fully assess the genomic abnormalities in cancer cells. Human papillomaviruses (HPVs) are frequently integrated into the cellular DNA in cervical cancers. We mapped by FISH five HPV18 integration sites: three on normal chromosomes 8 at 8q24 and two on derivative chromosomes, der(5)t(5;22;8)(qll;q11q13;q24) and der(22)t(8; 22)(q24;q13), which have chromosome 8q24 material. An 8q24 copy number increase was detected by CGH. Dual-color FISH with a c-MYC probe mapping to 8q24 revealed colocalization with HPV18 at all integration sites, indicating that dispersion and amplification of the c-MYC gene sequences occurred after and was most likely triggered by the viral insertion at a single integration site. Numerical and structural chromosomal aberrations identified by SKY, genomic imbalances detected by CGH, as well as FISH localization of HPV18 integration at the c-MYC locus in HeLa cells are common and representative for advanced stage cervical cell carcinomas. The HeLa genome has been remarkably stable after years of continuous cultivation; therefore, the genetic alterations detected may have been present in the primary tumor and reflect events that are relevant to the development of cervical cancer.

Chromosome Aberrations↗
PubMed1999

Molecular cytogenetic analysis of the bladder carcinoma cell line BK-10 by spectral karyotyping.

The bladder cancer cell line BK-10 was established from a grade III-IV transitional cell carcinoma (TCC). BK-10 is near-tetraploid (+/-4n) and consists of two subclones with 20-25 structural aberrations. Here we report the cytogenetic analysis of BK-10 by G-banding, spectral karyotyping (SKY), and FISH. SKY refers to the hybridization of 24 differentially labeled chromosome painting probes and the simultaneous visualization of all human chromosomes using spectral imaging. SKY enabled us to confirm 12 markers in BK-10 previously described by G-banding, redefine 11 aberrations, and detect 4 hidden chromosomal rearrangements, 2 of which had been identified as normal or deleted copies of chromosome 20 and 1 as a normal chromosome 3. Twenty out of 21 translocations identified were unbalanced. FISH analysis of BK-10 using chromosome arm-specific paints, centromere probes, and oncogene/tumor suppressor gene-specific probes revealed a deletion of CDKN2A (p16) in all copies of chromosome 9, a low-level amplification of MYC (five copies), and loss of one copy of TP53; detected the presence of the Y chromosome in a hidden translocation; and detected four copies of ERBB-2. A probe set for BCR and ABL verified breakpoints for all translocations involving chromosomes 9 and 22. A new karyotype presentation, "SKY-gram," is introduced by combining data from G-banding, SKY, and FISH analysis. This study demonstrates the approach of combining molecular cytogenetic techniques to characterize fully the multiple complex chromosomal rearrangements found in the bladder cancer cell line BK-10, and to refine the chromosomal breakpoints for all translocations.

Aged↗
PubMed1999

Genomic changes defining the genesis, progression, and malignancy potential in solid human tumors: a phenotype/genotype correlation.

The transition of normal epithelium to invasive carcinoma occurs sequentially. In colorectal and cervical carcinogenesis, this transition is reflected by histomorphologically defined grades of increasing dysplasia that untreated may progress to invasive disease. In an attempt to understand the role of chromosomal aberrations during tumorigenesis we have applied comparative genomic hybridization using DNA extracted from defined stages of colorectal and cervical tumors, from low- and high-grade astrocytic tumors and from diploid and aneuploid breast carcinomas. Genetic instability, as measured by the number of chromosomal copy alterations per case, increases significantly at the transition from precursor lesions to invasive carcinomas and continues to increase with tumor stage. Aggressive tumors have a higher number of copy alterations per case. High-level copy number changes (amplifications) become more prevalent in advanced-stage disease. Subtractive karyograms of chromosomal gains and losses were used to map tumor stage-specific chromosomal aberrations and clearly showed that nonrandom chromosomal aberrations occur during disease progression. In colorectal and cervical tumors, chromosomal copy number changes were correlated with nuclear DNA content, proliferative activity, expression levels of the tumor suppressor gene TP53, and the cyclin-dependent kinase inhibitor p21/WAF1, as well as the presence of viral genomes. Here we summarize and review the results of this comprehensive phenotype/genotype correlation and discuss the relevance of stage-specific chromosomal aberrations with respect to diagnostic applications.

Disease Progression↗
PubMed1999

Analysis of B-cell neoplasias by spectral karyotyping (SKY).

B-cell neoplasias represent a heterogeneous group of diseases, including acute lymphocytic leukemia (ALL) and the broad spectrum of non-Hodgkin's lymphomas (NHL). Conventional cytogenetic analysis has revealed specific chromosomal aberrations in ALL as well as in NHL. Spectral karyotyping (SKY) is a novel molecular cytogenetic technique which allows the visualization of all human chromosomes in different colors, therefore greatly facilitating the recognition of chromosomal aberrations. The potential of SKY is exemplified by the fact that in our experience, 70% of the cases analyzed resulted in karyotypes where the majority of aberrations were either refined or new aberrations were detected when compared to their G-banding karyotypes. This also applies to the analysis of B-cell neoplasias. In hematologic malignancies, especially acute leukemias, specific chromosomal aberrations are of etiologic as well as diagnostic and prognostic importance. The identification of new recurrent chromosomal aberrations could therefore lead to a better characterization of disease entities or subgroups in ALL and NHL and further improve diagnosis, treatment stratification and ultimately prognosis. Interestingly, the comparison of the pattern of chromosomal aberrations in hematological neoplasias and carcinomas revealed striking differences. While about 50% of the aberrations in hematological malignancies are balanced translocations, such aberrations are exceedingly rare in epithelial cancers in which unbalanced structural and numerical aberrations prevail.

Burkitt Lymphoma↗
PubMed1999

Recurrent non-reciprocal translocations of chromosome 5 in primary T(12;15)-positive BALB/c plasmacytomas.

The majority of inflammation-induced peritoneal BALB/c plasmacytomas (approximately 90%) harbor a balanced T(12;15) chromosomal translocation that deregulates the expression of the proto-oncogene c-myc. Recent evidence suggests that the T(12;15) is an initiating tumorigenic mutation that occurs in early plasmacytoma precursor cells. However, plasmacytomas take a long time to develop (average tumor latency approximately 220 days), which suggests that additional tumor progression events may be required to complete oncogenesis. We hypothesized that such tumor progression events may take the form of secondary chromosomal aberrations that can be detected by spectral karyotyping (SKY). We screened the entire chromosome complement of 18 primary BALB/c plasmacytomas carrying the T(12;15) and found in nine tumors (50% recurrence) secondary cytogenetic aberrations that involved bands D, E and F chromosome (Chr) 5. The Chr 5D-F rearrangements were manifested predominantly as unbalanced translocations with various partner chromosomes. This finding led us to propose the existence of an important plasmacytoma progression locus in the central region of Chr 5, which presumably becomes involved in peritoneal plasmacytoma development by promiscuous chromosomal translocations.

Animals↗