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| 2. |
- Stewénius, Ylva, et al.
(författare)
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Cryptic terminal chromosome rearrangements in colorectal carcinoma cell lines detected by subtelomeric FISH analysis.
- 2006
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Ingår i: Cytogenetic and Genome Research. - : S. Karger AG. - 1424-859X .- 1424-8581. ; 114:3-4, s. 257-262
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Tidskriftsartikel (refereegranskat)abstract
- Epithelial tumour karyotypes are often difficult to study by standard cytogenetic methods because of poor chromosome preparation quality and the high complexity of their genomic rearrangements. Subtelomeric fluorescence in situ hybridisation (FISH) has proved to be a useful method for detecting cryptic constitutional chromosomal rearrangements but little is known about its usefulness for tumour cytogenetic analysis. Using a combination of chromosome banding, multicolour karyotyping and subtelomeric FISH, five colorectal cancer cell lines were characterised. The resulting data were compared to results from previous studies by comparative genomic hybridisation and spectral karyotyping or multicolour FISH. Subtelomeric FISH made it possible to resolve several highly complex chromosome rearrangements, many of which had not been detected or were incompletely characterised by the other methods. In particular, previously undetected terminal imbalances were found in the two cell lines not showing microsatellite instability. Copyright (c) 2006 S. Karger AG, Basel
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| 3. |
- Gisselsson, D, et al.
(författare)
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Centrosomal abnormalities, multipolar mitoses, and chromosomal instability in head and neck tumours with dysfunctional telomeres.
- 2002
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Ingår i: British Journal of Cancer. - : Springer Science and Business Media LLC. - 1532-1827 .- 0007-0920. ; 87:2, s. 202-207
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Tidskriftsartikel (refereegranskat)abstract
- Carcinomas of the head and neck typically exhibit complex chromosome aberrations but the underlying mutational mechanisms remain obscure. Evaluation of cell division dynamics in low-passage cell lines from three benign and five malignant head and neck tumours revealed a strong positive correlation between multipolarity of the mitotic spindle and the formation of bridges at anaphase in both benign and malignant tumours. Cells exhibiting a high rate of mitotic abnormalities also showed several chromosome termini lacking TTAGGG repeats and a high frequency of dicentric chromosomes. Multicolour karyotyping demonstrated a preferential involvement in structural rearrangements of chromosomes with deficient telomeres. The majority of malignant, mitotically unstable tumours expressed the reverse transcriptase subunit of telomerase. These data indicate that some of the genomic instability in head and neck tumours is initiated by telomere dysfunction, leading to the formation of dicentric chromosomes. These form chromosome bridges at mitosis that could prevent the normal anaphase-telophase transition. In turn, this may cause an accumulation of centrosomes and mitotic multipolarity. Telomerase expression does not confer total stability to the tumour genome but could be crucial for moderating the rate of chromosomal evolution.
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| 4. |
- Gisselsson Nord, David, et al.
(författare)
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Chromosomal breakage-fusion-bridge events cause genetic intratumor heterogeneity
- 2000
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 97:10, s. 5357-5362
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Tidskriftsartikel (refereegranskat)abstract
- It has long been known that rearrangements of chromosomes through breakage-fusion-bridge (BFB) cycles may cause variability of phenotypic and genetic traits within a cell population. Because intercellular heterogeneity is often found in neoplastic tissues, we investigated the occurrence of BFB events in human solid tumors. Evidence of frequent BFB events was found in malignancies that showed unspecific chromosome aberrations, including ring chromosomes, dicentric chromosomes, and telomeric associations, as well as extensive intratumor heterogeneity in the pattern of structural changes but not in tumors with tumor-specific aberrations and low variability. Fluorescence in situ hybridization analysis demonstrated that chromosomes participating in anaphase bridge formation were involved in a significantly higher number of structural aberrations than other chromosomes. Tumors with BFB events showed a decreased elimination rate of unstable chromosome aberrations after irradiation compared with normal cells and other tumor cells. This result suggests that a combination of mitotically unstable chromosomes and an elevated tolerance to chromosomal damage leads to constant genomic reorganization in many malignancies, thereby providing a flexible genetic system for clonal evolution and progression.
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| 5. |
- Jin, Charlotte, et al.
(författare)
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Characterization of chromosome aberrations in salivary gland tumors by FISH, including multicolor COBRA-FISH
- 2001
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Ingår i: Genes, Chromosomes and Cancer. - 1045-2257. ; 30:2, s. 161-167
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Tidskriftsartikel (refereegranskat)abstract
- Fluorescence in situ hybridization (FISH), including COBRA-FISH, was used to characterize 11 salivary gland tumors that had been investigated by banding analysis. Five cases were pleomorphic adenoma (PA), three were adenoid cystic carcinoma, and one case each was mucoepidermoid carcinoma, carcinoma ex-pleomorphic adenoma (CaPA), and adenocarcinoma. All 11 cases were selected on the basis that they had shown rearrangement of 6q or 9p or had unresolved aberrations after karyotyping. The COBRA-FISH and FISH analyses led to a revised karyotype in all informative cases and made it possible to clarify almost all chromosomal rearrangements occurring in the tumors. Of particular note were the confirmation of the existence of 6q deletions, a common change in salivary gland carcinomas, and the demonstration that a seemingly balanced t(6;9) resulted in del(6q). Other rearrangements that were revealed by FISH included amplification of 12q sequences (MDM2 and CDK4) in one PA. We also investigated the status of the PLAG1 gene in four cases (one PA, one CaPA, one adenoid cystic carcinoma, and one mucoepidermoid carcinoma) with 8q12 rearrangements. Only in the former two cases were the FISH results compatible with intragenic rearrangements. Overall, the results of the study show that, even with good banding quality and in karyotypes of modest complexity, much new information will be gained by supplementing the banding analysis with a multicolor FISH approach, such as COBRA-FISH.
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| 6. |
- Jin, Yuesheng, et al.
(författare)
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Cytogenetic and molecular genetic characterization of immortalized human ovarian surface epithelial cell lines: consistent loss of chromosome 13 and amplification of chromosome 20
- 2004
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Ingår i: Gynecologic Oncology. - : Elsevier BV. - 1095-6859 .- 0090-8258. ; 92:1, s. 183-191
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Tidskriftsartikel (refereegranskat)abstract
- Objectives. This study aimed at identifying the genetic events involved in immortalization of ovarian epithelial cells, which might be important steps in ovarian carcinogenesis. Methods. The genetic profiles of five human ovarian surface epithelial (HOSE) cell lines immortalized by retroviral transfection of the human papillomavirus (HPV) E6/E7 genes were thoroughly characterized by chromosome banding and fluorescence in situ hybridization (FISH), at various passages pre- and post-crisis. Results. In pre-crisis, most cells had simple, non-clonal karyotypic changes. Telomere association was the commonest aberration, suggesting that tolermase dysfunction might be an important genetic event leading to cellular crisis. After immortalization post-crisis, however, the karyotypic patterns were non-random. Loss of genetic materials was a characteristic feature. The commonest numerical aberrations were -13, -14, -16, -17, -18, and +5. Among them, loss of chromosome 13 was common change observed in all lines. The only recurrent structural aberration was homogeneously staining regions (hsr) observed in three lines. FISH and combined binary ratio labeling (COBRA)-FISH showed in two cases that the lists were derived from chromosome 20. Clonal evolution was observed in four of the lines. In one line, hsr was the only change shared by all subclones, suggesting that it might be a primary event in cell immortalization. Conclusion. The results of the present study suggested that loss of chromosome 13 and the amplification of chromosome 20 might be early genetic events involved in ovarian cell immortalization, and might be useful targets for the study of genomic aberrations in ovarian carcinogenesis. (C) 2003 Elsevier Inc. All rights reserved.
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| 7. |
- Storlazzi, Tiziana, et al.
(författare)
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Ring chromosomes and low-grade gene amplification in an atypical lipomatous tumor with minimal nuclear atypia
- 2003
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Ingår i: International Journal of Oncology. - 1019-6439. ; 23:1, s. 67-71
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Tidskriftsartikel (refereegranskat)abstract
- Atypical lipomatous tumors (ALTs) are characterized by supernumerary ring chromosomes and/or giant marker chromosomes, which typically are composed of interspersed, amplified 12q-sequences, are C-band negative, lack a-satellite sequences, and display high copy numbers of several oncogenes, including HMGA2 (a.k.a. HMGIC) and MDM2, from the 12q13-15 region. In the present study, we report the cytogenetic and molecular genetic findings in an ALT with minimal nuclear atypia from a 16-year-old boy. At G-banding analysis, 1-3 supernumerary ring chromosomes were detected. Combined binary ratio labeling fluorescence in situ hybridization (COBRA-FISH) showed that the rings were entirely composed of material from chromosome 12, and by further FISH analysis with locus-specific probes it was revealed that they consisted of two tandemly arranged copies of the segment 12p11.2-p13.2 to 12q21.2-q23.1. Within that segment of chromosome 12, there was a small deletion including the HMGA2 locus. There was no variation in ring size and no interphase bridges could be detected, indicating that the ring chromosomes were mitotically relatively stable. The present case thus adds support to the concept that there exists a subset of ALT with limited or minimal nuclear atypia and low-level amplification of 12q sequences, further suggesting the possibility of a molecular genetic continuum between lipoma and classical examples of ALT. Furthermore, the present data strongly imply that it is the composition of the rings rather than the ring chromosome formation as such that causes the genetic instability and nuclear atypia frequently seen in ALTs.
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