Telomeric association of chromosomes in B-cell lymphoid leukemia

Giant cell tumor of soft tissue is genetically distinct from its bone counterpart

Giant cell tumors of bone are locally aggressive bone neoplasms with a predilection for young adults. Histologically, they are composed of histiocytoid to spindled mononuclear cells, admixed with numerous large osteoclastic giant cells. Giant cell tumors of soft tissue are rare tumors that bear striking histological resemblance to giant cell tumors of bone and might be regarded as a soft tissue analog thereof. Point mutations of the H3F3A gene (coding for a histone H3.3 protein) at the Gly34 codon, mostly G34W resulting from a GGG>TGG nucleotide change, have recently been identified in a vast majority of giant cell tumors of bone. To delineate the possible pathogenic linkage between both tumor types, we analyzed the H3F3A genotypes in a series of 15 giant cell tumors of soft tissue by Sanger sequencing and found no mutation in any case. We then sequenced cognate histone H3 genes with an identical nucleotide sequence ('GGG') at the codon Gly34, including the H3F3B, H3F3C, HIST2H3A, HIST2H3C, and HIST2H3D genes, and no somatic mutation was detected. These results reveal that giant cell tumors of soft tissue are probably genetically distinct from their bone counterparts and suggest that they might be pathogenically unrelated. Given the prominence of non-neoplastic cells in these tumors and the limitations of the current study, however, analyses using more sensitive techniques might be required to solve the issue.

Jumping translocation of chromosome 1q associated with good clinical outcome in a case of Burkitt leukemia

Acquired jumping translocations (JTs) are rare secondary aberrations occurring in various hematological malignancies. In Burkitt lymphoma/leukemia (BL) chromosome 1q abnormalities such as partial or whole arm duplications/translocations are frequently associated with the disease-specific t(8;14)(q24;q32). JTs of 1q are considered to have a bad prognostic impact in BL. We report clinical, conventional and molecular cytogenetic findings of a 12-year-old boy who presented with BL. In addition to the primary aberration, t(8;14)(q24;q32), JT of 1q onto chromosomes 21 and der(14) as well as the formation of isochromosome 1q could be detected in his bone marrow sample. Despite the expected poor prognostic outcome of these aberrations, the patient has been experiencing an event free survival of 7.5 years at the time of the present report, reflecting the excellent clinical outcome of the disease.

High frequency of telomeric associations and chromatid exchanges and breaks in human ovarian carcinoma

Cytogenetic analysis of an unselected series of twenty human serous adenocarcinomas and undifferentiated carcinomas of the ovary revealed the presence of telomeric associations (tas) and unstable chromosomal aberrations, including chromatid-type exchanges (cte) and breaks (ctb) in high proportion of tumors studied. Tas and cte & ctb were present in 75% and 55% of tumors, respectively. Involvement of different chromosome telomeres in tas seemed to be random. This is the first report describing telomeric associations in ovarian cancer. Our findings suggest that the frequency of extensive spontaneous chromosome breakage in ovarian carcinoma may be higher than that reported in the literature.

Jumping translocations

Jumping translocations (JT) are uncommon constitutional or acquired chromosome rearrangements involving one donor and several recipient chromosomes. They occur in various pathologic conditions and the mechanism of their formation remains elusive. A review of the literature showed that the major localizations of the breakpoints of JTs in human samples are nonrandomly located in pericentromeric and telomeric regions of chromosomes. Interestingly, comparison of the localization of the chromosomal breakpoints and of presence of interstitial DNA repeats showed differences between constitutional and acquired JTs suggesting differences in the mechanisms for the genesis of JTs and their consequences.

Differential radiation effects in smokers--culture time dependence of the yield of gamma ray-induced chromosome damage in first division metaphases

PURPOSE

Telomeric associations (TA) and unstable chromosomal aberration (CA) transmission through M1-M4 metphases (first to fourth division) in gamma-ray irradiated G0 lymphocytes in 2 smokers were examined, since TA in conventionally stained chromosomes were reported earlier as a sensitive cytogenetic marker in mutagen-exposed populations. The purpose of the present study is an extension of our earlier studies on unstable CA transmission through successive mitotic divisions.

MATERIALS AND METHODS

The bromodeoxyuridine (BrdU) incorporation and fluorescence plus giemsa (FPG) method for M1-M5 metaphase analysis was carried out at 50, 72, 96 h to analyse TA and CA in conventionally and FPG stained chromosomes after irradiation of human blood samples with 3 Gy of gamma-rays. In situ hybridization (ISH) with enzymatic/fluorescence detection was used to analyse radiation-induced aneuploidy and TA. Analysis was carried out on sister chromatid exchanges (SCE) in M2 cells at 72 h and micronuclei (MN) at 24, 50, 72, 96 h.

RESULTS

TA, corroborated by the absence of acentric fragments, were not detected in conventional/FPG stained/ISH chromosomes. Chromosome 21 aneuploidy was observed. Significant differences in mean frequencies of dicentrics/micronuclei (MN)/SCE with high frequency cells (HFC) were found in smokers after irradiation compared to non-smokers. Higher radiation induced CA in M1 cells were found with extended culture time. Induction of giant cells with mirror dicentrics, tricentrics and rings were found.

CONCLUSION

TA in conventional or FPG stained metaphase chromosomes is not a sensitive cytogenetic marker for mutagen exposed population screening. Higher radiation induced CA frequencies in M1 cells with extended culture time were indicative of a delay in cell cycle progression of aberrant cells or different lymphocyte subset populations. Bridge-breakage-fusion (BBF) events due to dicentrics may be instrumental in the perpetuation of chromosomal instability. Differential effects were noted in radiation-induced dicentric, SCE and MN frequencies in smokers compared to non-smokers. Heavy smoking could be a confounding variable in chromosome-based biodosimetry and biomonitoring studies. Giant cells may denote a switch to amitotic modes of cell survival, providing additional mechanisms of genotoxic resistance.

p53 intronic point mutation, aberrant splicing and telomeric associations in a case of B-chronic lymphocytic leukaemia

We report a case of chronic lymphocytic leukaemia (CLL) with telomeric associations and a p53 intronic point mutation. Karyotypic analysis revealed clonal and non-clonal telomeric associations, accompanied by clonal cytogenetic abnormalities and also in isolation. The p53 mutation, which occurred at the invariant base pair -2 of the splice acceptor site in intron 7 resulted in the abolition of correct splicing of exon 7 to exon 8. Multiple aberrant splice products were characterized, all of which differed from wildtype in the DNA binding domain. Fluorescence in situ hybridization demonstrated that the clone retained two copies of the p53 gene and wild-type p53 transcript was detected on cloning of reverse transcriptase polymerase chain reaction (RT-PCR) product, indicating that one wild-type allele remained. However, a plasmid clone with correct splicing at the exon 7/8 boundary, but with a 21 bp deletion in exon 8, was also found at low frequency. This finding indicates clonal evolution, resulting in complete loss of wild-type p53. The intronic point mutation was not present in DNA extracted from cervical tissue indicating that it was a leukaemic phenomenon. This is the first case of an intronic point mutation to be reported in CLL. This mutation led to chaotic p53 expression and, interestingly, occurred in a case showing telomeric associations, a rare phenomenon in B-CLL.

Mosaic telomeric (2;14) association in a child with motor delay

In a 6-year-old girl referred because of mild motor delay and hyperextensible joints, chromosome analysis disclosed a derivative chromosome consisting of end-to-end fusion of chromosomes 2 and 14. Two cell lines existed in which this telomere association was present, one with a 45,XX,tas(2;14)(q37;p11) karyotype and one with a 45,XX,tas(2;14) (q37;q32) karyotype. The cell line with the telomeric fusion of 2q and 14p was present in 90% of the cells; a telomeric fusion of 2q and 14q was seen in the remaining 10% of the cells. In both association complexes, only the centromere of chromosome 14 was active. Fluorescence in situ hybridization with telomere and subtelomere probes disclosed no deletion of chromosomal material. Microsatellite analysis showed that the patient had a normal biparental contribution of chromosomes 14.

Quinacrine dihydrochloride, the non-surgical female sterilant induces dicentrics, rings, and marker chromosomes in human peripheral blood lymphocytes treated in vitro: a preliminary report

During the last decade, quinacrine dihydrochloride (QDH) has been promoted for clinical trials as a much needed non-surgical female sterilant, largely in the Third World. Recently, however, these human trials have come under severe criticism due to lack of adequate evidence of biological safety of QDH, particularly of its genotoxicity in mammalian systems. In the present study, the cytogenetic analysis of QDH-treated human lymphocytes, grown as whole blood cultures in vitro, surprisingly showed a wide range of chromosomal aberrations. At a concentration of 3.0 and 6.0 microg/ml in culture, QDH was cytotoxic, as shown by the very few analyzable metaphases that could be observed. G(0) lymphocytes, treated with 0. 6 microg/ml QDH, exhibited chromosome aberrations including dicentrics, ring configurations, translocations, inversions, and marker chromosomes. Near haploid, polyploid, and endoreduplicated cells were also observed. All the rings appeared to be formed as a result of telomere fusion/association. Twenty percent of the dicentrics observed also indicated telomere fusion/association in the D and G groups of chromosomes. Overall, a frequent involvement of chromosomes 1, 2, and 3 in both unstable and stable chromosome rearrangements was also observed. Exposure of 72-h cultures to 0.45 microg/ml QDH at 69 h resulted in an accumulation of C-metaphases, suggesting that probably QDH behaves as a mitotic spindle inhibitor. The G(2) lymphocytes from two donors exposed to 0.6, 1.5 or 3.0 microg/ml of QDH showed no increase in chromatid aberrations in two donors. However, QDH at 0.6 microg/ml increased the frequency of micronucleated binucleate cells. No increase in sister chromatid exchanges was observed at this concentration. Though preliminary, these observations demonstrate the chromosome damaging ability of QDH in human lymphocytes treated in vitro. Surprisingly, like ionizing radiation, QDH acted by an S-phase-independent mechanism, unlike most of the chemical mutagens. These results warrant detailed investigations on the cytogenetic effects of QDH in vitro, as well as among women exposed to this agent during clinical trials for non-surgical sterilization. The interesting cytogenetic profile of QDH deserves to be pursued and the underlying mechanisms, in particular, the DNA topoisomerase II inhibitory effect, if any, needs to be elucidated.

Trisomy of the long arm of chromosome 1 resulting in a dicentric derivative (6)t(1;6) chromosome in a child with myelodysplastic syndrome following treatment for a primitive neuroectodermal tumor

We report the clinical, hematologic, and cytogenetic findings for a child with secondary myelodysplastic syndrome (MDS) after treatment for a primitive neuroectodermal tumor. At the time of conversion to MDS, conventional cytogenetics revealed an unbalanced der(6)t(1;6) that resulted in trisomy of the long arm of chromosome 1 and partial monosomy and duplication of 6p. Using alpha satellite probes, fluorescence in situ hybridization of bone marrow cells showed that the rearranged chromosome contained the centromeres of both chromosomes 1 and 6, thus forming a dic(1;6) resulting in trisomy 1q. This report is the first to describe a case of childhood secondary myelodysplastic syndrome associated with a trisomy 1q involving chromosome 6.

Shortening of telomeres in recipients of both autologous and allogeneic hematopoietic stem cell transplantation

Telomere length of peripheral blood mononuclear cells (PBMCs) from 23 autologous HSCT patients ranging from 4 to 61 years old, and 46 allogeneic HSCT recipients from 6 to 52 years old were studied to confirm whether excessive shortening of telomeres is associated with HSCT. After autologous HSCT, telomere length of PBMCs ranged from 6.8 to 12.0 kb. The comparison between transplanted PBMCs and PBMCs after autologous HSCT showed shortening by up to 1.9 kb (mean +/- s.d.: 0.64 +/- 0.50 kb). There was a difference between autologous HSCT patients and normal volunteers in the slopes of regression lines. After allogeneic HSCT, telomere length of PBMCs ranged from 6.8 to 12.0 kb. Telomeres of recipients were up to 2.1 kb (0.60 +/- 0.468 kb) shorter than those of donors. The slope of regression lines for allogeneic HSCT patients and normal volunteers were parallel. Although all patients were transplanted with more than 2.0 x 10(8) cells/kg, telomere length did not correlate with the number of transplanted cells. There was no significant correlation between telomere length and recovery of hematological parameters. However, three patients with an average telomere length of 6.8 kb after HSCT took a longer period to reach the normal hematological state. Taken together, these data suggest that most HSCTs are performed within the biological safety range of telomeres, while the patients who have telomeres shorter than 7.0 kb after HSCT should be observed carefully for long-term hematopoiesis and the occurrence of hematopoietic disorders.

Jumping translocations involving 11q in a non-Hodgkin lymphoma

This paper presents the results of a cytogenetic analysis in an 11-year-old boy with non-Hodgkin lymphoma. The investigation was performed on slides obtained from short-term culture of lymph node cells. The analyses revealed an abnormal clone with loss of Y, gain of an X chromosome, t(3;22), trisomy 11, and three cytogenetically-related subclones with jumping translocations involving 11q13 as the common breakpoint region. This region is an unusual site of chromosome breakage in jumping translocations, and has not been reported thus far. Contrary to most published reports, the jumping translocation in our patient is associated with long survival.

Fine mapping of an apparently targeted latent human herpesvirus type 6 integration site in chromosome band 17p13.3

An unusually high level of latent HHV-6 infection has been documented in the peripheral blood and/or bone marrow cells of a small group of patients with predominantly malignant lymphoid disorders, and in at least one healthy individual. We have shown previously in peripheral blood mononuclear cells (PBMCs) of three patients, two with a history of lymphoma and one with multiple sclerosis, a specific target site for latent integration of the full-length HHV-6 viral genome on the distal short arm of chromosome 17, in band p13.3. Fluorescence in situ hybridization (FISH) procedures were used to map more precisely the location of the viral integration site in one of those patients, relative to two known oncogenes mapped previously, namely CRK, and the more telomeric ABR oncogene. It is shown that the HHV-6 integration site is located at least 1,000 kb telomeric of ABR, and is very likely to map close to or within the telomeric sequences of 17p. This finding is significant given that human telomeric-like repeats flank the terminal ends of the HHV-6 genome. Cytogenetic studies showed evidence of karyotype instability in the peripheral blood cells infected latently.

Recombination and its roles in DNA repair, cellular immortalization and cancer

Genetic recombination is the creation of new gene combinations in a cell or gamete, which differ from those of progenitor cells or parental gametes. In eukaryotes, recombination may occur at mitosis or meiosis. Mitotic recombination plays an indispensable role in DNA repair, which presumably directed its early evolution; the multiplicity of recombination genes and pathways may be best understood in this context, although they have acquired important additional functions in generating diversity, both somatically (increasing the immune repertoire) and in germ line (facilitating evolution). Chromosomal homologous recombination and HsRad51 recombinase expression are increased in both immortal and preimmortal transformed cells, and may favor the occurrence of multiple oncogenic mutations. Tumorigenesis in vivo is frequently associated with karyotypic instability, locus-specific gene rearrangements, and loss of heterozygosity at tumor suppressor loci - all of which can be recombinationally mediated. Genetic defects which increase the rate of somatic mutation (several of which feature elevated recombination) are associated with early incidence and high risk for a variety of cancers. Moreover, carcinogenic agents appear to quite consistently stimulate homologous recombination. If cells with high recombination arise, either spontaneously or in response to "recombinogens," and predispose to the development of cancer, what selective advantage could favor these cells prior to the occurrence of growth-promoting mutations? We propose that the augmentation of telomere-telomere recombination may provide just such an advantage, to hyper-recombinant cells within a population of telomerase-negative cells nearing their replicative (Hayflick) limit, by extending telomeres in some progeny cells and thus allowing their continued proliferation.

Jumping translocations involving chromosome 1q in a patient with Crohn disease and acute monocytic leukemia: a review of the literature on jumping translocations in hematological malignancies and Crohn disease

A 36-year-old man with a 10-year history of Crohn disease (CD) presented with gross hematuria and blasts in his peripheral blood. A chromosome analysis revealed one normal cell and 33 abnormal cells. The stem line was 47,XY,+8. The multiple side lines also had a jumping translocation between chromosome 1q31-32 and 4, 8, 10, 17, and 18 terminal regions. A cytogenetic, morphologic, and immunophenotypic analysis of a bone marrow aspirate and biopsy demonstrated acute myeloid leukemia of monocytic lineage, AML-M5b. In this paper are reviewed (a) the unusual and rare phenomenon of jumping translocations in hematological malignancies and (b) leukemia in CD.

Jumping translocation of homogeneously staining region and tetraploidy with double minutes in acute myelomonocytic leukemia

We report a 71-year-old patient with acute myelomonocytic leukemia (AMMoL) who had complicated chromosomal abnormalities showing diploidy with a jumping translocation of a homogeneously staining region (hsr) and tetraploidy with double minutes (dmin). The analysis of gene amplification showed that hsr and dmin were the results of C-ETS 1 gene amplification. After induction chemotherapy, tetraploidy with dmin completely disappeared, while diploidy with hsr and del(11)(q23) remained until the patient died. It is speculated that hsr is more stable than dmin during chemotherapy and that the presence of tetraploidy is not necessarily a factor of poor response to chemotherapy for acute leukemia.

Jumping translocation of 1q as the sole aberration in a case of follicular lymphoma

Cytogenetic and fluorescence in situ hybridization (FISH) studies in a case of follicular lymphoma grade III showed a "jumping translocation" of chromosome 1q21-qter to chromosomes Xq28 and 18q23, which resulted in a partial trisomy 1q as the only chromosome aberration. This case represents, to the best of our knowledge, the first report of a jumping translocation in a malignant lymphoma occurring as the sole aberration.

Unusual presentation of multiple myeloma with "jumping translocation" involving 1q21. A case report and review of the literature

We describe a case of multiple myeloma with unusual manifestations consisting of cutaneous xanthomatosis, temporal arteritis, retinal vasculitis with a complex karyotype, and a "jumping translocation" involving 1q21. The literature of cytogenetic studies of multiple myeloma and of jumping translocation is reviewed.

Telomeric associations of chromosomes in patients with esophageal squamous cell carcinomas

AIM: To investigate the role of telomeric association in the development of esophageal cancer.

METHODS: Using chromosome R banding technique,telomeric association of chromosome in peripheral blood lymphocytes from 16 untreated patients with esophageal squamous cell carcinoma were observed and 16 healthy adults served as controls.

RESULTS: The teloemeric association frequencies of cell and chromosomes were significantly higher than those of controls (χ² = 9.56, P < 0.01), but its distribution on the chromosome showed no significant difference (χ² = 1.01, P > 0.05) between the two groups.

CONCLUSION: Chromosomal instability can be initiated by telomeric associations, and sequential chromosome analysis can aid the understanding of the tumor occurrence and progression.

Nonrandom pattern of telomeric associations in atypical lipomatous tumors with ring and giant marker chromosomes

Atypical lipomatous tumors (ALTs) are cytogenetically characterized by supernumerary ring and giant marker chromosomes. Another common finding in ALT is that the tumor cells are cytogenetically heterogeneous with a variety of mostly nonclonal numerical and structural chromosome aberrations, including telomeric associations. In a series of 48 cytogenetically investigated ALTs, all chromosomal aberrations, clonal as well as nonclonal, were registered. Clonal ring chromosomes were present in 47 cases and giant markers in 11 cases. In 7 cases, 12 clonal telomeric associations were found and 37 cases showed nonclonal associations involving 344 identified telomeres. The telomere associations were nonrandomly distributed, with the telomeres of 11p, 20p, 20q, 9q, 15p, 19q, and 22q being most frequently (8.7-4.1% of all associations) involved; only Xp and Xq were never affected. The pattern of telomeric associations in ALT was compared with literature data on 47 giant cell tumors (880 telomeres), previously reported to show a nonrandom distribution of associations, and 36 sporadic cases of a variety of other human neoplasms (583 telomeres). The analysis indicated that the telomeres of 11p, 19q, and 20q are preferentially involved in associations in several tumor types. Among other structural aberrations in the ALT series, 221 nonclonal and 52 clonal breakpoints were identified, as well as 342 nonclonal and 14 clonal numerical aberrations. The combined data suggest that telomeric associations may predispose to acquired chromosome aberrations in neoplasia.

Jumping Translocations of Chromosome 1q in Multiple Myeloma: Evidence for a Mechanism Involving Decondensation of Pericentromeric Heterochromatin

Karyotypes in multiple myeloma (MM) are complex and exhibit numerous structural and numerical aberrations. The largest subset of structural chromosome anomalies in clinical specimens and cell lines involves aberrations of chromosome 1. Unbalanced translocations and duplications involving all or part of the whole long arm of chromosome 1 presumably occur as secondary aberrations and are associated with tumor progression and advanced disease. Unfortunately, cytogenetic evidence is scarce as to how these unstable whole-arm rearrangements may take place. We report nonrandom, unbalanced whole-arm translocations of 1q in the cytogenetic evolution of patients with aggressive MM. Whole-arm or “jumping translocations” of 1q were found in 36 of 158 successive patients with abnormal karyotypes. Recurring whole-arm translocations of 1q involved chromosomes 5,8,12,14,15,16,17,19,21, and 22. A newly delineated breakpoint present in three patients involved a whole-arm translocation of 1q to band 5q15. Three recurrent translocations of 1q10 to the short arms of different acrocentric chromosomes have also been identified, including three patients with der(15)t(1;15)(q10;p10) and two patients each with der(21)t(1;21)(q10;p13) and der(22)t(1;22) (q10;p10). Whole-arm translocations of 1q10 to telomeric regions of nonacrocentric chromosomes included der(12)t(1;12) (q10;q24.3) and der(19)t(1;19)(q10;q13.4) in three and two patients, respectively. Recurrent whole-arm translocations of 1q to centromeric regions included der(16)t(1;16)(q10;q10) and der(19)t(1;19)(q10;p10). The mechanisms involved in the 1q instability in MM may be associated with highly decondensed pericentromeric heterochromatin, which may permit recombination and formation of unstable translocations of chromosome 1q. The clonal evolution of cells with extra copies of 1q suggests that this aberration directly or indirectly provides a proliferative advantage.

Shortened Telomeres Involved in a Case With a Jumping Translocation at 1q21

The jumping translocation (JT) is a rare chromosomal abnormality in which a specific chromosomal segment translocates onto the ends of various chromosomes (jumps). In most cases, the region distal to 1q21 jumps onto numerous different telomeres. Here we report a molecular study of the JT involving 1q21 found in a patient with acute myelomonocytic leukemia that had transformed from myelodysplastic syndrome (MDS). This is the first report describing the analysis of the molecular structure of the JT. We demonstrated the presence of a stretch of telomeric repeats at the breakpoint by means of a fluorescence in situ hybridization experiment, molecular cloning, and nucleotide sequencing of the fused region. A significant amount of variant telomeric repeats (a telomeric sequence having one-base mismatch within the authentic telomeric repeat TTAGGG) was found in this region. The variant telomeric repeat has been shown to be present in the proximal region of telomeres and does not perform telomeric functions by itself. Therefore, these results indicated that the telomeres had already been critically shortened when the jumps occurred. We suggest that the extended proliferation of cancer cells during the premalignant stage, such as MDS, results in chromosomal instability due to the loss of telomeric functions.

Shortened Telomeres Involved in a Case With a Jumping Translocation at 1q21

The jumping translocation (JT) is a rare chromosomal abnormality in which a specific chromosomal segment translocates onto the ends of various chromosomes (jumps). In most cases, the region distal to 1q21 jumps onto numerous different telomeres. Here we report a molecular study of the JT involving 1q21 found in a patient with acute myelomonocytic leukemia that had transformed from myelodysplastic syndrome (MDS). This is the first report describing the analysis of the molecular structure of the JT. We demonstrated the presence of a stretch of telomeric repeats at the breakpoint by means of a fluorescence in situ hybridization experiment, molecular cloning, and nucleotide sequencing of the fused region. A significant amount of variant telomeric repeats (a telomeric sequence having one-base mismatch within the authentic telomeric repeat TTAGGG) was found in this region. The variant telomeric repeat has been shown to be present in the proximal region of telomeres and does not perform telomeric functions by itself. Therefore, these results indicated that the telomeres had already been critically shortened when the jumps occurred. We suggest that the extended proliferation of cancer cells during the premalignant stage, such as MDS, results in chromosomal instability due to the loss of telomeric functions.

Jumping Translocations of Chromosome 1q in Multiple Myeloma: Evidence for a Mechanism Involving Decondensation of Pericentromeric Heterochromatin

Karyotypes in multiple myeloma (MM) are complex and exhibit numerous structural and numerical aberrations. The largest subset of structural chromosome anomalies in clinical specimens and cell lines involves aberrations of chromosome 1. Unbalanced translocations and duplications involving all or part of the whole long arm of chromosome 1 presumably occur as secondary aberrations and are associated with tumor progression and advanced disease. Unfortunately, cytogenetic evidence is scarce as to how these unstable whole-arm rearrangements may take place. We report nonrandom, unbalanced whole-arm translocations of 1q in the cytogenetic evolution of patients with aggressive MM. Whole-arm or “jumping translocations” of 1q were found in 36 of 158 successive patients with abnormal karyotypes. Recurring whole-arm translocations of 1q involved chromosomes 5,8,12,14,15,16,17,19,21, and 22. A newly delineated breakpoint present in three patients involved a whole-arm translocation of 1q to band 5q15. Three recurrent translocations of 1q10 to the short arms of different acrocentric chromosomes have also been identified, including three patients with der(15)t(1;15)(q10;p10) and two patients each with der(21)t(1;21)(q10;p13) and der(22)t(1;22) (q10;p10). Whole-arm translocations of 1q10 to telomeric regions of nonacrocentric chromosomes included der(12)t(1;12) (q10;q24.3) and der(19)t(1;19)(q10;q13.4) in three and two patients, respectively. Recurrent whole-arm translocations of 1q to centromeric regions included der(16)t(1;16)(q10;q10) and der(19)t(1;19)(q10;p10). The mechanisms involved in the 1q instability in MM may be associated with highly decondensed pericentromeric heterochromatin, which may permit recombination and formation of unstable translocations of chromosome 1q. The clonal evolution of cells with extra copies of 1q suggests that this aberration directly or indirectly provides a proliferative advantage.

Telomeric association in women with breast and uterine cervix cancer

This study compares the frequency of telomeric associations in the peripheral blood of women suffering breast and cervix uterine cancer with a healthy control group. Two kinds of cultures were developed for each individual: with and without aphidicolin. In the normal cultures, the number of telomeric associations observed was 95.5 times higher in individuals affected by breast cancer and 41.3 times higher in those affected by cervix uterine cancer when compared to the control group (p < 0.001). In the cultures with aphidicolin, higher numbers of altered metaphases were observed in both groups as compared to the control groups (p < 0.001). Statistically significant differences (p < 0.001) could also be observed when comparing telomeric associations between the two types of cancer in both cultures. When we compared individuals affected by breast cancer in both types of cultures statistical differences were found (p < 0.05), and similar results were found in individuals affected by uterine cervix cancer (p < 0.001). The findings suggest that telomeric associations may be reflecting chromosome instability observed in cancer and that this instability behaves differently for various types of cancer.

t(High) frequency of telomeric associations in human ovarian surface epithelial cells transformed by human papilloma viral oncogenes

Viral oncogenes are commonly used to transform and extend the in vitro life span of human epithelial cells. We have established 7 cell lines of human ovarian surface epithelial cells using human papilloma viral oncogenes (HPV-E6E7 ORFs). Cytogenetic analysis of the cell lines revealed a high frequency of telomeric associations ranging from 30% to 100% of the metaphases examined. The short arms of chromosomes 16, 19, 21, and 22 showed a higher rate of telomeric association. Telomeric association with other chromosomal ends appears to be random. Fusion of 2 chromosomes ends may contribute to the genomic instability of transformed cells and lead to further genetic alterations involved in malignant transformation such as gene amplication and loss of heterozygosity. This is the first report describing a high frequency of telomeric associations in human ovarian epithelial cells transformed by HPV oncogenes.

Telomeres and telomerase in normal and malignant haematopoietic cells

The normal haematopoietic system harbours telomerase-competent cells with a capacity to upregulate the activity to notable levels in a telomere length-independent manner. Strong telomerase activity is found in progenitor stem cells and activated lymphocytes in vitro as well as in vivo, indicating that cells with high growth requirements can readily upregulate telomerase. Despite detection of telomerase activity, a gradual telomere erosion occurs in stem cells and lymphocytes, with significantly shortened telomeres at higher ages, a phenomenon that might be of importance for developing immunosenescence and exhausted haematopoiesis. In malignant haematopoietic disorders telomerase activity is a general finding with large differences in activity levels. The strongest telomerase expression has been shown in acute leukaemias and non-Hodgkin's lymphomas, especially high grade cases. There are indications that the level of activity might parallel tumour progression and be of prognostic relevance, but studies of larger patient materials are needed. An association between the cell cycle and telomerase activity exists, especially for normal haematopoietic cells, and induction of a differentiation programme in immortalised cell lines downregulates telomerase activity. The expression of telomerase activity seems to be regulated at different levels, since for immature bone marrow cells the level of activity seemed to parallel better the phenotype than the proliferation state. The frequent expression of telomerase in leukaemias and lymphomas makes these disorders interesting targets for future anti-telomerase therapy.

Acute lymphoblastic leukemia and chromosome 21

A short review of chromosome 21 abnormalities in acute lymphoblastic leukemia (ALL) is presented. Trisomy and polysomy 21 are nonrandom anomalies that are frequently observed in ALL. Their occurrence, although not specific, as well as the high incidence of acute leukemia in subjects with constitutional trisomy 21, suggests that chromosome 21 plays a particular role in leukemogenesis. More specific to ALL, t(12;21)(p13;q22), resulting in a fusion TEL-AML1, gene has recently been shown to be the most frequent translocation in childhood B-cell lineage ALL (20-30% of cases). In addition, the importance of analysis of marker chromosomes with fluorescence in situ hybridization (FISH) techniques is underscored as partial amplifications or rearrangements of chromosome 21 may be implicated.

Telomere associations in desmoplastic infantile ganglioglioma

A four and a half year old male was diagnosed with desmoplastic infantile ganglioglioma. To our knowledge, the cytogenetics of this tumor have never been reported. In our analysis of 40 cells, no consistent clonal abnormalities were observed; however, the majority of cells (25 of 40) showed structural rearrangements (telomere associations) resulting in dicentrics and other derivative chromosomes. Breakpoints most often observed included 17q25 (6 of 40), 19p13.3 (4 of 40), 17p13 (3 of 40), 14q32 (3 of 40), 11q25 (3 of 40), 9p24 (2 of 40), 5q35 (2 of 40), and 22q13 (2 of 40).

Accelerated telomere shortening in ataxia telangiectasia

Ataxia telangiectasia (AT) is characterized by neurological deterioration, immunodeficiency, spontaneous chromosomal instability, hypersensitivity to ionizing radiation, predisposition to cancer, particularly T cell leukaemia and lymphoma, and premature ageing. The most commonly observed defect affecting telomeres in humans is telomeric fusions, particularly in T lymphocytes in AT patients. Rarely, some tumour cells, like senescent cells, have dicentric chromosomes that may arise as a result of telomeric sequence loss. We show that the AT mutation in the homozygous state confers a predisposition to accelerated telomere shortening with increasing age in peripheral blood lymphocytes (PBLs), which may be linked to premature senescence. We also show that telomeric fusions are associated with large (> 90%) preleukaemic translocation clones in T cells. We propose that these fusions may result from a compound effect of accelerated telomere shortening, together with a growth advantage of cells in large clones which leads to further telomere loss. Fusions are not observed in leukaemic cells in these patients. There is no evidence that either accelerated telomere loss per se or telomeric fusions are important in tumourigenesis. Telomerase is present in both normal and AT lymphocytes and so neither telomere shortening nor telomeric fusions can be explained by the absence of telomerase.

Jumping translocation in a phenotypically normal female

"Jumping translocation" jt refers to a rare type of chromosome mosaic, in which the same portion of a (donor) chromosome is translocated to different (recipient) chromosome sites. Jt have mainly been observed in lymphocyte cultures of patients with hematologic malignancies. We report a phenotypically normal female carrying a mosaic of two cell lines with the Xq26-qter segment translocated to the short arm of chromosomes 15 or 21 in peripheral blood lymphocytes. In skin fibroblasts, only the X/21 translocation was detected. We speculate that recombination between homologous repetitive sequences on non-homologous human acrocentrics may be the cause of such chromosomal rearrangements.

Centromeric instability of chromosome 1 resulting in multibranched chromosomes, telomeric fusions, and "jumping translocations" of 1q in a human immunodeficiency virus-related non-Hodgkin's lymphoma

BACKGROUND

Acquired immunodeficiency syndrome-related non-Hodgkin's lymphomas are associated with the B-cell chromosomal translocation t(8;14)(q24; q32). The most common secondary chromosome aberrations in these patients involve 1q and are believed to be associated with tumor progression. A mechanism for the origin of these 1q aberrations has not been demonstrated. To their knowledge, the authors report the first human immunodeficiency virus (HIV)-positive patient to have centromeric decondensation and multibranched chromosome aberrations of chromosomes 1 and 16 resulting in telomeric associations and "jumping translocations" of 1q.

METHODS

Tumor cells from peritoneal fluid of an HIV-positive patient were cultured for 24, 48, and 72 hours and analyzed by both conventional G-banding and fluorescence in situ hybridization.

RESULTS

G-band analysis showed a stemline with t(8;14)(q24;q32), but also showed the progression from centromeric decondensation to multibranched chromosome configurations of chromosomes 1 and 16. The interchange and duplications of chromosome arms resulted in the gain of extra copies of 1q material on a number of different chromosomes, but also the loss of 16q in at least one sideline and the formation of micronuclei. Fluorescence in situ hybridization analysis demonstrated that micronuclei predominantly involved chromosome 1 and, to a lesser extent, chromosome 16.

CONCLUSIONS

The cytogenetic findings in this unique case suggest that immunodeficiency may be a factor involved in centromeric instability, multibranching, and the progression to the subsequent formation of telomeric fusions and multiple unbalanced translocations of 1q (jumping translocations). The striking similarity of the centromeric instability in this patient to those with ICF syndrome (variable immunodeficiency, centromeric heterochromatin instability, and facial anomalies) suggests hypomethylation as the etiologic mechanism for the chromosome instability.

Chromosome rearrangements at telomeric level in hematologic disorders

Following retrospective screening of our karyotype data from 414 consecutive non-childhood, neoplastic, and preneoplastic hematologic diseases, we have isolated 11 cases with alterations involving one or two chromosome termini, including: a) nonclonal telomeric telomeric associations (tas), b) subclonal terminal rearrangements consisting of additional (add) material of unknown origin fused at the end of the chromosome, c) clonal telomere-centromere fusion (t telcen) with pseudodicentric structure. Most of these abnormalities were present in karyotypes with multiple alterations and associated to an evolutive stage of the disease (9 of 94 cases studied in progression, including three of 22 CML studied in blast crisis). The immunophenotype of the cell populations was lymphoid in eight cases, six of which were NHL, and myeloid, erythroid, and undifferentiated in the other three. More data on telomeric abnormalities may clarify whether there is ubiquitous genomic instability of neoplastic cells or an inborn cell lineage predisposition favoring rearrangements involving telomeres.

Rearrangements involving 12p12 in two cases of cardiac myxoma

Recently, we reported on the cytogenetic analysis of a case of cardiac myxoma, revealing a 46,XY,der(7)t(7;17)(p21;p11), add (10) (q22), add (12) (p12), del(17)(p11) chromosomal pattern. In this article we present the cytogenetic analysis of another case of cardiac myxoma, in which we found several clonal and nonclonal abnormalities including dicentric chromosomes and telomeric associations (tas). One of the clonal aberrations was a translocation between chromosomes 1 and 12, involving a breakpoint at 12p12, as observed in the case described earlier. This finding suggest that 12p12 might play an important role in the histogenesis of cardiac myxomas.

Giant cell rich parosteal osteosarcoma

A parosteal osteosarcoma of the distal femur with a typical radiographic and macroscopic appearance is reported. On histology the tumour was dominated by large numbers of osteoclast-like giant cells in a fibro-osseous background and islands of immature bone. Most of the neoplastic bone lacked osteoblastic rimming. There was no spatial relationship between the giant cells and areas of haemorrhage. Signs of 'dedifferentiation' were lacking. Cytogenetic a analysis revealed telomeric associations which are frequently found in giant cell tumours of bone. Parosteal osteosarcoma may, on histological appearances, hardly be recognizable as malignant. In addition, unusual changes such as abundant giant cells may be misleading in the absence of clinico-pathological correlation.

Cytogenetic findings in 200 patients with multiple myeloma

Cytogenetic studies were performed in 200 consecutive patients with multiple myeloma and related disorders. Structurally or numerically abnormal clones were found in 63 patients (32%), including 8 of 45 untreated patients (18%), and 55 of 155 treated patients (35%). The abnormal karyotypes generally showed numerous numerical and structural aberrations and in some patients multiple abnormal clones. The most striking feature of patients with hyperdiploid karyotypes was the finding of consistent recurring trisomies for chromosomes 3, 5, 7, 9, 11, 15, 19, and 21, cosegregating together in many cases. Monosomy for chromosome 13 was the most common chromosome loss, occurring in 18 abnormal patients (29%), while interstitial deletions involving band 13q14 occurred in an additional 9 patients, indicating a loss of all or part of chromosome 13 in a high percentage of patients with abnormal karyotypes (43%). Structural aberrations of chromosome 1 were most frequent, occurring in 30 of 63 patients (48%), and involved almost equally the short and long arms. The single most frequent chromosome breakpoint involved band 14q32 and was found in 21 patients (33%), including 11 patients with a 14q+ chromosome, 8 with t(11;14)(q13;q32), and 2 with t(8;14)(q24;132).

Telomeric DNA in normal and leukemic blood cells

We studied telomeric DNA in leukemic cells as well as in normal T cells, B cells, monocytes, polymorphonuclear leukocytes, and bone marrow hematopoietic progenitor cells. No marked differences were observed in the sizes of the telomeric repeats in the various populations of normal blood cells obtained from donors in their twenties to sixties, and the telomere length ranged between 8.5 and 9.0 kb. The leukemic cells of 12 patients with acute leukemia (seven with myeloid and five with lymphoid leukemia) showed a variable reduction in the length of telomeric DNA, ranging from 2.7 to 6.4 kb. The average telomere length was 4.8 and 4.7 kb in myeloid and lymphoid leukemia, respectively, while the telomere length in peripheral blood mononuclear cells obtained from the same patients during complete remission was 8.5 and 7.9 kb, respectively. When the same Southern blots were hybridized with Alu or alphoid sequences, no marked changes in the sizes of the repetitive DNA sequences were observed, indicating that the DNA abnormality in the leukemic cells was specific to the telomere region. Investigation of telomeric DNA changes may be helpful in determining the biological properties of leukemic cells.

Jumping translocation in a newborn boy with dup(4q) and severe hydrops fetalis

We report on the unusual cytogenetic findings in a newborn boy with severe hydrops fetalis. He has a mosaic for 2 unbalanced chromosome rearrangements: a der(18)-t(4;18)(q31;q23) and a der(18)t(4;18)(q31;p11). As a result, this patient had a duplication of 4q31-qter in all cells, and was possibly monosomic for the distal ends of 18p and 18q, respectively in the 2 cell lines. Since in both rearrangements the same chromosome 4 segment was translocated to 2 different chromosome regions, we consider the present finding as a peculiar type of jumping translocation.

Jumping translocations of 1q in Burkitt lymphoma and acute nonlymphocytic leukemia

"Jumping translocations" have been observed mostly in cultured cells. Reports of such translocations in hematologic malignancies are few, and the associated clinical picture is unclear. We report three cases of hematologic malignancies with various unbalanced translocations (so-called jumping translocation) involving trisomy of the long arm of chromosome 1. The first case was a 13-year-old boy with Burkitt lymphoma who showed a very aggressive clinical course. The second case was a 10-month-old girl with acute nonlymphocytic leukemia [ANNL, French-American-British (FAB) classification M0] who had high risk factors, including hyperleukocytosis with a peripheral white blood cell (WBC) count of 300,000/microliters, and who died 7 months after diagnosis. The third case was a 6-year-old boy with Burkitt-like leukemia whose first remission lasted only 1 month. Only 10 cases with jumping translocations, including two cases with Burkitt-like leukemia/lymphoma, have been reported previously. This rare phenomenon may occur with increased frequency in Burkitt-like leukemia/lymphoma and may be an adverse prognostic factor.

Oligoclonal B-cell leukemia characterized by spontaneous cell division and telomere association

Cytogenetic analysis of unstimulated cultures from a female patient with chronic B-cell leukemia (CLL) revealed three cytogenetically distinct clones, suggesting that the patient's leukemia was oligoclonal. Immunoglobulin heavy chain gene rearrangement studies revealed 1 germline and 4 rearranged bands, indicative of an oligoclonal leukemic population. Further evidence of oligoclonality was provided by X-linked RFLP studies. This is the first report of oligoclonality in CLL demonstrated by cytogenetic, immunoglobulin gene rearrangement, and X-chromosome inactivation studies. In addition to oligoclonality, the patient's leukemic cells exhibited telomere association, a Robertsonian translocation, and clonal evolution, suggesting an underlying genomic instability.

Cytogenetic study of 249 consecutive patients examined for a bone tumor

Chromosome analysis was performed on 304 samples of 249 consecutive patients examined for a possible bone tumor. The series consisted of 86 nonneoplastic disorders, 108 benign and 78 malignant primary bone tumors, and 32 other bone malignancies. In the group of nonneoplastic disorders, one sample from an infectious lesion demonstrated a clonal chromosome aberration, i.e., additional material in the short arm of chromosome 1. Simple clonal aberrations were noted in six of 75 successfully cultured benign tumors, e.g., a chondromyxoid fibroma with an insertion type translocation from 2p21p25 to 5q13 and 2p deletion and a nonossifying fibroma with del(4)(p14). Complex clonal aberrations were evident in 21 of 54 successfully cultured malignant primary bone tumors and eight of 21 secondary bone malignancies. The complexity of clonal aberrations correlated with the grade of malignancy as the osteosarcomas and chondrosarcomas of high-grade demonstrated chaotic abnormalities. Six Ewing's sarcomas demonstrated the t(11;22)(q24;q12); in one this was the sole abnormality, and in five additional changes were evident: der(1;16)(q10;p10) in one. Homogeneously staining elongated areas interpreted as HSR were observed in three patients, all of whom had a highly malignant tumor. The most frequent nonclonal abnormality was telomeric association, which was observed mainly in giant cell tumors.

Telomeric associations in a patient with B-cell prolymphocytic leukaemia

Telomeric associations were determined in bone marrow preparations from a patient with B-cell prolymphocytic leukaemia and a clonal isochromosome of the long arm of chromosome 17. Thirteen associations involved 16 chromosome arms, with preferential involvement of the short arm of chromosome 19 and the long arm of 17.

Correlation between cytogenetic and histopathological findings in 75 human meningiomas

The correlations between cytogenetic and histopathological findings were analyzed in 75 human meningiomas. The tumors were classified according to increasing degrees of anaplasia into three grades: Grade I, benign; Grade II, atypical; Grade III, anaplastic. In 45 tumors of Grade I (benign), we more often observed a normal karyotype or monosomy 22. In 23 tumors of Grade II (atypical), we observed karyotypes with structural and/or numerical abnormalities with the presence of telomeric associations in 8 of them. These last tumors were fibroblastic. In seven Grade III tumors (anaplastic), we also observed complex abnormalities, and in one case, we observed telomeric associations. Our observations show that complex chromosome abnormalities and telomeric associations are observed in tumors that histologically display a certain degree of anaplasia. It is possible that the result of histopathological and cytogenetic correlations might represent a prognostic factor in meningiomas.

Molecular analysis of transforming growth factor beta in giant cell tumor of bone

Giant cell tumor of bone (GCT) is a primary bone neoplasm with unique cytogenetic findings including telomeric associations. Elevated expression of message RNA for transforming growth factor beta (TGF beta), but not transforming growth factor alpha (TGF alpha), has been reported in this tumor. Further investigation of GCT was undertaken to determine whether genetic loci for TGF beta in GCT patients with and without chromosome abnormalities are altered. Due to the reported TGF beta overexpression in GCT, qualitative and quantitative Southern blot analyses with TGF beta 1 and TGF beta 2 and an internal control probe (p3-21) were performed with tumor DNA and DNA from normal tissue on ten patients with GCT and control individuals. No obvious TGF beta 1 or TGF beta 2 gene alterations were detected. Normal copy numbers were calculated when comparing tumor and normal DNA from GCT patients as well as DNA from control individuals. Abnormal chromosome findings, including telomeric associations, marker chromosome, double minutes, chromosome fragments, ring chromosomes (possibly representing intra-chromosome telomeric associations), and polyploid cells were observed in seven of the ten patients with GCT. Chromosomes 11, 16, 19, 20, and 21 were most commonly observed in telomeric associations, with the terminus of the long arm of chromosome 19 being the most frequent. We conclude that there are no TGF beta 1 or TGF beta 2 gene alterations detected in GCT with the methodologies described, and that telomeric associations are a reproducible cytogenetic characteristic of this neoplasm.

Monocyte-macrophage lineage of giant cell tumor of bone. Establishment of a multinucleated cell line

METHOD

A new neoplastic cell line, UISO-GCT-1, was established from a giant cell tumor of the right tibia in an 18-year-old man. Immunohistochemical, cytogenetic, ultrastructural, and growth studies were performed.

RESULTS

Multinucleated giant cells (> 4-6 nuclei/cell) persisted in a culture relatively late in passage (passage 17), which is unique in cell lines of giant cell tumor of bone. Mononuclear and multinucleated cells in monolayer culture expressed vimentin and tartrate-resistant acid phosphatase and reacted with monoclonal antibodies to CD13 and CD68, suggesting a monocytic-macrophage origin of these cells. Mononuclear and multinuclear cells also selectively expressed high molecular weight cell membrane antigens specifically associated with soft tissue sarcomas and osteosarcomas. Karyotypically, UISO-GCT-1 cells were hypodiploid, hypotetraploid, and multiploid, with more than 200 chromosomes per mitosis present in some cells. Other chromosomal aberrations observed included ring chromosomes, double minutes, translocations, multiple fragments, and multiradials.

CONCLUSION

Collectively, observations of this study suggest that karyotypically abnormal giant cell tumors of bone arise from a monocyte-macrophage lineage and subsequently express an antigenic profile similar to malignant mesenchymal tumors.

Telomeric structure in cells with chromosome end associations

End-to-end associations of metaphase chromosomes have been observed in a variety of human tumors, ageing cells, and several chromosome instability syndromes. Since telomeres of tumor cells and ageing tissues are often reduced in length, it has been suggested that chromosome end associations may be due to loss of telomeric repeats. We report the molecular structure of telomeres of two human tumor cell lines with frequent end-to-end associations of metaphase chromosomes. These telomeres were shown to be severely reduced compared with most other human cells with functional telomeres. However, we also describe two cell lines with severely shortened telomeres that are not detectably compromised in their function. We suggest that telomeric length is not the only determinant of the fusigenic behavior of human telomeres in tumor cells.

Clonal cytogenetic abnormalities and telomeric associations in a fibroxanthoma of the stomach

A cytogenetic study of a fibroxanthoma (fibrous histiocytoma) of the stomach revealed a clonal structural abnormality involving chromosome 12 and frequent telomeric associations between the short arm of chromosome 12 and different chromosomes. A marker chromosome possibly derived from chromosome 11 was also present. This is the second reported case of gastric fibroxanthoma and the first studied cytogenetically.

Jumping translocations originate clonal rearrangements in SV40-transformed human fibroblasts

A comparative study of chromosomal rearrangements occurring in 4 independent clones obtained from SV40-transformed cornea and skin human fibroblasts was performed. Rearrangements principally affect some constitutive heterochromatin and, to a lesser degree, telomeric regions. This results in multiple exchanges between a limited number of chromosome structures, i.e., in jumping translocations. Such rearrangements occur even at early passages and some of them give rise to clonal rearrangements that accumulate at late passages. This process is responsible for progressive modification of the karyotypes, principally characterized by deletion of a number of chromosome segments. Thus, clonal rearrangements are selected among many others not occurring at random. The selective pressure retaining clonal rearrangement seems to be similar for the 4 independent clones, since selection of the derivative chromosomes leads to the same imbalances, whatever the origin of the clone. This sequence of events recalls that of human solid tumors, since jumping rearrangements are generally observed in pre-malignant conditions or in low-grade malignancies, whereas clonal rearrangements leading to typical imbalances are detected in more advanced malignant tumors.

Significant telomere shortening in childhood leukemia

Telomere length was studied by Southern analysis in five cases of childhood acute leukemia. In four cases, the length of the telomere sequence of the blast phase cells was shortened as compared with that of the cells examined during remission. Study of telomere length during chemotherapy for hematologic malignancies may show rapidly dividing subpopulations of malignant cells and thereby guide further treatment needs. In addition, such loss of telomere sequence would give rise to chromosomal instability and could be one of the mechanisms of oncogene activation in acute leukemia.