Karyotypic fissioning and canid phylogeny.
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Animals↗
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Sequential cytogenetic and molecular cytogenetic characterization of an SV40T-immortalized nasopharyngeal cell line transformed by Epstein-Barr virus latent membrane protein-1 gene.
Cytogenetic and molecular cytogenetic analyses were performed on four sublines derived from a newly established, SV40T-immortalized nasopharyngeal (NP) cell line, NP69, with two of the sublines expressing LMP1, an Epstein-Barr virus-encoded gene. A total of seven cytogenetically related subclones were identified, all having highly complex karyotypes with massive numerical and structural rearrangements. Centromeric rearrangements in the form of isochromosomes and whole-arm translocations were prevalent. A cytogenetic sign of gene amplification [i.e., homogeneously staining region (HSR)] was detected at 1q25 in all metaphase cells analyzed. Multicolor combined binary ratio labeling fluorescence in situ hybridization (COBRA-FISH) was used to confirm the karyotypic interpretations. Furthermore, multicolor COBRA-FISH also showed that part of the HSR contained chromosome 20 material. Extensive clonal evolution could be observed by the assessment of karyotypic variation among different subclones and individual metaphase cells. The evaluation of clonal evolution enabled the identification of the temporal order of chromosome aberrations during cell immortalization and malignant transformation. A striking karyotypic similarity was found between sublines expressing LMP1 and an NP carcinoma cell line, with loss of genetic material from chromosome arm 3p being an important recurrent observation. More interestingly, the karyotypic features of NP69 were also similar to those of many epithelial malignancies. Our observations suggest that serial transformation of NP cell lines might provide a useful in vitro model for the study of the multistep neoplastic transformation of NP cells.
Cell Culture Techniques↗
Chromosomal evolution in the lizard genus Varanus (reptilia).
The karyotypes have been determined of 16 of the 32 species of the genus Varanus, including animals from Africa, Israel, Malaya and Australia. A constant chromosome number of 2n = 40 was observed. The karyotype is divided into eight pairs of large chromosomes and 12 paris of microchromosomes. A series of chromosomal rearrangements have become established in both size groups of the karyotype and are restricted to centromers shifts, probably caused by pericentric inversion. Species could be placed in one of six distinct karyotype groups which are differentiated by these rearrangements and whose grouping does not always correspond with the current taxonomy. An unusual sex chromosome system of the ZZ/ZW type was present in a number of the species examined. The evolutionary significance of these chromosomal rearrangements, their origin and their mode of establishment are discussed and related to the current taxonomic groupings. The most likely phylogenetic model based on chromosome morphology, fossil evidence and the current distribution of the genus Varanus is presented.
Animals↗
Telomeric fusion and chromosome instability in multiple tissues of a patient with mosaic Ullrich-Turner syndrome.
We describe the cytogenetic evolution of multiple cell lines in the gonadal tissue of a 10-year-old girl with mosaic Ullrich-Turner syndrome (UTS) involving clonal telomeric associations (tas) of the Y chromosome. G-band analysis of all tissues showed at least 2 cell lines; 45, X and 46,X,tas(Y;21)(q12;p13). However, analysis of left gonadal tissue of this patient showed the evolution of 2 additional cell lines, one designated 45,X,tas(Y;21)(q12;p13),-22 and the other 46,X,tas(Y;21)(q12;p13),+tas(Y;14)(q12;p13), -22. Fluorescence in situ hybridization (FISH) analysis of interphase nuclei from uncultured gonadal tissue confirmed the findings of aneuploidy in the left gonadal tissue and extended the findings of aneuploidy to the tissue of the right gonad. The chromosome findings in the gonadal tissue of this patient suggest a preneoplastic karyotype relating to several distinct tumor associations. The clonal evolution of telomeric fusions indicates chromosomes instability and suggests the extra copy of the Y chromosome may have resulted from a fusion-related malsegregation. In addition, the extra Y suggests low-level amplification of a putative gonadoblastoma gene, while the loss of chromosome 22 suggests the loss of heterozygosity for genes on chromosome 22. This case demonstrates the utility of the study of gonadal tissue in 45,X/46XY UTS patients, and provides evidence that clonal telomeric fusions may, in rare cases, be associated with chromosome malsegregation and with the subsequent evolution of unstable karyotypes.
Child↗
Statistical analyses of karyotypic complexity in head and neck squamous cell carcinoma.
More than 250 head and neck squamous cell carcinomas (HNSCCs) with clonal chromosomal abnormalities have been reported. Even though the pattern of aberrations is nonrandom, no specific primary or secondary karyotypic abnormalities have been identified. One explanation for the still-rudimentary understanding of the cytogenetic evolution in HNSCC could be the pronounced karyotypic complexity seen in these tumors. In an attempt to overcome this difficulty, we have applied several statistical methods such as hierarchical cluster analysis, multidimensional scaling, and k-means clustering, which allow the identification and interpretation of karyotypic pathways, as well as establishing a temporal order of chromosomal imbalances on 241 published and 70 previously unpublished HNSCC karyotypes. From the analysis of the distribution of the number of imbalances per tumor we suggest that the carcinomas evolve through three phases representing different stages of chromosomal instability. Two major cytogenetic pathways, one dominated by gains and another by losses, were identified by means of principal component analysis. These were initiated by +7 and by any of the aberrations 1p-, 3p-, or 7q-, respectively.
Allelic Imbalance↗
Chromosomal evolution in African megachiroptera: G- and C-band assessment of the magnitude of change in similar standard karyotypes.
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Africa↗
Understanding the recent evolution of the human genome: insights from human-chimpanzee genome comparisons.
The sequencing of the chimpanzee genome and the comparison with its human counterpart have begun to reveal the spectrum of genetic changes that has accompanied human evolution. In addition to gross karyotypic rearrangements such as the fusion that formed human chromosome 2 and the human-specific pericentric inversions of chromosomes 1 and 18, there is considerable submicroscopic structural variation involving deletions, duplications, and inversions. Lineage-specific segmental duplications, detected by array comparative genomic hybridization and direct sequence comparison, have made a very significant contribution to this structural divergence, which is at least three-fold greater than that due to nucleotide substitutions. Since structural genomic changes may have given rise to irreversible functional differences between the diverging species, their detailed analysis could help to identify the biological processes that have accompanied speciation. To this end, interspecies comparisons have revealed numerous human-specific gains and losses of genes as well as changes in gene expression. The very considerable structural diversity (polymorphism) evident within both lineages has, however, hampered the analysis of the structural divergence between the human and chimpanzee genomes. The concomitant evaluation of genetic divergence and diversity at the nucleotide level has nevertheless served to identify many genes that have evolved under positive selection and may thus have been involved in the development of human lineage-specific traits. Genes that display signs of weak negative selection have also been identified and could represent candidate loci for complex genomic disorders. Here, we review recent progress in comparing the human and chimpanzee genomes and discuss how the differences detected have improved our understanding of the evolution of the human genome.
Animals↗
The specific organisation of satellite DNA sequences on the X-chromosome of Mus musculus: partial independence of chromosome evolution.
DNA was isolated from a chinese hamster/mouse hybrid cell line containing a single mouse chromosome, the X-chromosome, and digested with a variety of restriction endonucleases known to cut mouse satellite DNA. After agarose gel electrophoresis and transfer to nitrocellulose, hybridisation was carried out to a radioactive mouse satellite DNA probe. In this manner the organisation of satellite sequences at an individual chromosome was determined. We have found that the organisation of centromeric satellite DNA sequences on the mouse X-chromosome differs from that of other chromosomes in the complement. The nature of the differences suggests features of evolution of highly repeated sequences within a karyotype.
Animals↗
Rapid speciation and chromosomal evolution in mammals.
To test the hypothesis that population subdivision into small demes promotes both rapid speciation and evolutionary changes in gene arrangement by inbreeding and drift, we estimated rates of speciation and rates of chromosomal evolution in 225 genera of vertebrates. Rates of speciation were estimated by considering the number of living species in each genus and the fossil record of each genus as well as information about extinction rates. Speciation rate was strongly correlated with rate of chromosomal evolution and average rates of speciation in lower vertebrate genera were one-fifth those in mammalian genera. Genera with high karyotypic diversity and rapid speciation rates may generally have small effective population size (Ne), whereas large Ne values may be associated with karyotypically uniform genera and slow rates of speciation. Speciation and chromosomal evolution seem fastest in those genera with species organized into clans or harems (e.g., some primates and horses) or with limited adult vagility and juvenile dispersal, patchy distribution, and strong individual territoriality (e.g., some rodents). This is consistent with the above hypothesis regarding the evolutionary importance of demes.
Animals↗
Cytogenetic intratumor heterogeneity in soft tissue tumors.
Multiple (two to seven) samples, obtained from the same surgical specimen or at different occasions, were analyzed in 54 benign and malignant soft tissue tumors, to investigate cytogenetic clonal evolution. In 28 tumors only normal karyotypes were found. Ten tumors had abnormal karyotypes, but were noninformative, most often due to a high level of karyotypic complexity or great cell-to-cell variation. Sixteen tumors were informative: four (leiomyosarcoma, liposarcoma, malignant Schwannoma, and a benign mesenchymal tumor, probably leiomyoma) had identical karyotypes in different samples, whereas the remaining 12 tumors (seven malignant fibrous histiocytomas [MFH], two leiomyosarcomas, two liposarcomas, and one synovial sarcoma) displayed intersample heterogeneity. Also, intrasample heterogeneity was detected; more than one clone was found in 21 of 73 samples with aberrations from 26 tumors. The different clones were related in all cases except two. In seven cases, samples from different occasions were studied, and clonal evolution could be evidenced in five of them, whereas in two cases the karyotypes remained unchanged. The results indicate that the acquisition of ring chromosomes is an early event in the development of MFH and possibly also pleomorphic liposarcoma. The findings, together with previous data, also indicate that rearrangements of 19p13 are late events in the progression of pleomorphic sarcomas. The overall conclusion from this study is that cytogenetic heterogeneity is common in soft tissue tumors, and that this might influence the evaluation of cytogenetic and molecular genetic findings.
Adult↗
The seven-chromosome karyotype of the African frog Arthroleptis, a probable derivative of the thirteen-chromosome karyotype of Rana (Ranidae, Anura).
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Animals↗
Determination of the primitive karyotype for Peromyscus.
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Animals↗
Cytohematologic and cytogenetic prognostic factors at diagnosis and in the evolution in 46 primary myelodysplastic syndromes.
The myelodysplastic syndromes (MDS) are a heterogeneous group of diseases with different prognosis and evolution. Most of the studies on prognostic factors performed previously have independently evaluated the clinico-hematologic or cytogenetic data at diagnosis. In the present paper, 46 primary MDS were clinically, hematologically, and cytogenetically investigated at diagnosis, in order to determine the principal factors affecting the survival probability between a great number of characteristics. A univariate regression analysis of all the data allows one to recognize that the main factors are: the complexity of karyotype (p = 0.00001), the percentage of type I and total marrow blast cells (p = 0.001), and the abnormal localized immature myeloid precursors' (ALIP) presence (p = 0.001). Twenty-five patients underwent consecutive studies during their evolution. The karyotype instability gives information both on the likely evolution to acute leukemia and on poor survival.
Adult↗
Mixed myelodysplastic syndrome and myeloproliferative disorder with bone marrow and pulmonary fibrosis: the role of megakaryocytes.
The case of an 80-year-old woman displaying myelodysplastic syndrome evolving into a myeloproliferative disorder with myelofibrosis and pulmonary fibrosis, is reported. This case is characterized by an initial presentation of a myelodysplastic syndrome with normal karyotype and moderate fibrosis, its evolution towards a myeloproliferative disorder with myelofibrosis and the worsening of pulmonary fibrosis in parallel to the acceleration of the myeloproliferative disorder and myelofibrosis. These features and the high concentration of plasma platelet factor-4 suggest a role of megakaryocyte/platelet degranulation in the development of fibrosis.
Aged↗
Mature B-cell leukemias with more than 55% prolymphocytes. A heterogeneous group that includes an unusual variant of mantle cell lymphoma.
We studied 20 cases of mature B-cell leukemia with more than 55% prolymphocytes in peripheral blood or bone marrow, fulfilling the French-American-British criteria for B-cell prolymphocytic leukemia (PLL). Cases segregated into 3 groups: de novo PLL, 6; PLL occurring in patients with a previous well-established diagnosis of chronic lymphocytic leukemia (PLL-HxCLL), 10; and t(11;14)(q13;q32)-positive neoplasms, 4. All cases expressed monotypic immunoglobulin light chain, and most were positive for CD5. All t(11;14)-positive neoplasms were CD23- and uniquely positive for cyclin D1. Cytogenetic abnormalities were present in 19; in all 19, the karyotype was complex, indicating clonal evolution and genomic instability. The most frequent cytogenetic abnormality in de novo PLL involved chromosome 7 in 4 cases. Trisomy 12 or add(12p) was present in 4 cases of PLL-HxCLL. We conclude that mature B-cell leukemias with more than 55% prolymphocytes are a heterogeneous group that includes t(11;14)-positive neoplasms, which we suggest are best classified as mantle cell lymphoma. We also suggest that prolymphocytic morphologic features are a common end-stage of transformation for several B-cell neoplasms.
Aged↗
The SKM-1 leukemic cell line established from a patient with progression to myelomonocytic leukemia in myelodysplastic syndrome (MDS)-contribution to better understanding of MDS.
Although molecular and cytogenetic studies strongly point to the role of oncogenes, the mechanisms underlying the development of MDS and their progressive evolution to AML are still largely unknown. It has been postulated that AML has a preleukemic stage and a multi step pathogenesis, with the preleukemic stem cell able to undergo clonal evolution, with the acquisition of karyotypic abnormalities, leading to the development of acute leukemic subclones. The activations of the ras oncogenes or inactivation of the p53 anti-oncogene by point mutations have been described recently in several cases of MDS as well as AML, suggesting a critical role for these alterations in the development of these myelogenous leukemias. We reported previously establishment of a leukemic cell line, SKM-1, from the patient who initially possessed multiple point mutations of ras genes but lost these mutations during disease progression to myelomonocytic leukemia with acquisition of chromosomal abnormalities involving the p53 anti-oncogene. This process is characterized by genetic instabilities probably due to the failure of their DNA repairment leading to abnormal control of cell proliferation and differentiation. Studying this cell line, SKM-1, is a promising approach to understand the mechanisms of the initiation, disease progression, alterations of DNA repairment, and genetic instability in MDS and myelogenous malignancies.
Disease Progression↗
[Update in radiation-induced neoplasms: genetic studies].
Radiation induced tumors are a possible (very) late complications of radiotherapy. The evaluation of the risks of radiation-induced tumors has been presented in different epidemiological studies, with the evaluation of the relative risk for different tissues. But, the genetic studies are rare, and no global theory exists. Two cytogenetic profiles are described, one with translocations and one with genetic material losses, evoking two different genetic evolutions. Two questions are stated. What are the radiation-induced genetic mechanisms? Is it possible to differentiate the radiation-induced and spontaneous tumors with genetic approaches? With 37 cytogenetic cases, 12 analyzed in our laboratory, the radiation-induced tumors were characterized by genetic material losses. An anti-oncogenic evolution is probable. A new molecularly study confirm these results. Only thyroid tumors do not have this evolution. For tumors with simple karyotype, like meningioma, radiation-induced tumors seem to be more complex than spontaneous tumors. But for the others, the differentiation is impossible to be done with cytogenetic. The mechanism of the chromosomic material losses in unknown, but some hypothesis are discussed.
Age Factors↗
Suppression of cytogenetic clonal evolution with interferon alfa therapy in patients with Philadelphia chromosome-positive chronic myelogenous leukemia.
PURPOSE: To investigate whether cytogenetic clonal evolution can be suppressed with interferon alfa (IFN-alpha) therapy in patients with chronic myelogenous leukemia (CML). PATIENTS AND METHODS: Ninety patients with CML and cytogenetic clonal evolution who received IFN-alpha-based regimens were analyzed. Clonal evolution was defined as the presence of karyotypic abnormalities in addition to the Philadelphia (Ph) chromosome. Patients were evaluated for the suppression of cytogenetic clonal evolution after therapy, the cytogenetic response, and survival. RESULTS: The median age of the population was 39 years (range, 15 to 70 years), median time from diagnosis to clonal evolution 14 months (range, 0 to 145 months), and median percentage of abnormal metaphases 18% (range, 4% to 100%). Fifty six patients (62%) achieved some suppression of cytogenetic clonal evolution; in 41 patients (46%), the suppression was complete. The overall median survival was 51 months, with 43% alive at 5 years. Patients who achieved a complete suppression of cytogenetic clonal evolution had a median survival of 66 months, with 51% alive at 5 years. Characteristics associated with a better response include a lower percentage of abnormal metaphases, time to cytogenetic clonal evolution of 24 months or less, and absence of other features of accelerated disease. A prognostic classification for cytogenetic clonal evolution defined three groups with complete response (CR) rates of 85%, 34%, and 0% (P < .0001) and median survival times of 58, 31, and 30 months, respectively (P=.02). CONCLUSION: Patients with cytogenetic clonal evolution can respond to IFN-alpha therapy, and this response is associated with longer survival. A previously described prognostic model separates patients into subsets with different probabilities of response to IFN-alpha and survival.
Adolescent↗