| 1. |
- Gisselsson Nord, David, et al.
(författare)
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Differentially amplified chromosome 12 sequences in low- and high-grade osteosarcoma.
- 2002
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Ingår i: Genes, Chromosomes and Cancer. - : Wiley. - 1045-2257. ; 33:2, s. 133-140
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Tidskriftsartikel (refereegranskat)abstract
- Most osteosarcomas are highly aggressive malignancies characterized by a complex pattern of chromosome abnormalities. However, a subgroup of low-grade, parosteal tumors exhibits a relatively simple aberration pattern dominated by ring chromosomes carrying amplified material from chromosome 12. To assess whether sequences from this chromosome were differentially amplified in low- and high-grade osteosarcomas, copy numbers of the CCND2, ETV6, KRAS2, and D12S85 regions in 12p and the MDM2 region in 12q were evaluated by interphase or metaphase fluorescence in situ hybridization (FISH) in 24 osteosarcomas. Amplification of MDM2 was detected in all five low-grade and four high-grade osteosarcomas, all of which showed ring chromosomes. An overrepresentation of 12p sequences was found in 1/5 low-grade and in 9/19 high-grade tumors. Multicolor single-copy FISH analysis of metaphase cells from six high-grade tumors showed that extra 12p material either occurred together with MDM2 in ring chromosomes or was scattered over the genome as a result of complex structural rearrangements. Most tumors (8/10) not containing amplification of the assessed chromosome 12 loci exhibited a nondiploid pattern at evaluation with probes for centromeric alpha satellite sequences. These findings indicate that gain of sequences from the short arm of chromosome 12 could be a possible genetic pathway in the development of aggressive osteosarcoma.
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| 2. |
- Gisselsson Nord, David, et al.
(författare)
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PLAG1 alterations in lipoblastoma: involvement in varied mesenchymal cell types and evidence for alternative oncogenic mechanisms
- 2001
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Ingår i: American Journal of Pathology. - 1525-2191. ; 159:3, s. 955-962
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Tidskriftsartikel (refereegranskat)abstract
- Lipoblastomas are rare soft tissue tumors that occur primarily in young children. They typically contain variably differentiated adipocytes, primitive mesenchymal cells, myxoid matrix, and fibrous trabeculae. Abnormalities in chromosome 8, leading to rearrangements of the PLAG1 gene, were demonstrated recently in four lipoblastomas. In the present report, we determine the frequency of PLAG1 alterations in 16 lipoblastomas from children aged 13 years or younger, and we also evaluate the stages of lipoblastoma differentiation at which PLAG1 genomic alterations are found. Eleven lipoblastomas (69%), including those with either classic or lipoma-like histology, had rearrangements of the 8q12 PLAG1 region. Another three lipoblastomas had polysomy for chromosome 8 in the absence of PLAG1 rearrangement. Only two cases (13%) lacked a chromosome 8 abnormality. Notably, the lipoblastomas with chromosome 8 polysomy had up to five copies of chromosome 8 as an isolated cytogenetic finding in an otherwise diploid cell. We also demonstrate that PLAG1 alterations are found in a spectrum of mesenchymal cell types in lipoblastomas, including lipoblasts, mature adipocytes, primitive mesenchymal cells, and fibroblast-like cells. This finding is consistent with neoplastic origin in a primitive mesenchymal precursor and with variable differentiation to a mature adipocyte end-point. Hence, our studies provide biological validation for the clinical observation that lipoblastomas can evolve into mature, lipoma-like, lesions. They also suggest that PLAG1 dosage alterations caused by polysomy 8 might represent an alternative oncogenic mechanism in lipoblastoma.
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| 3. |
- Gisselsson Nord, David, et al.
(författare)
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Telomere dysfunction triggers extensive DNA fragmentation and evolution of complex chromosome abnormalities in human malignant tumors
- 2001
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 98:22, s. 12683-12688
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Tidskriftsartikel (refereegranskat)abstract
- Although mechanisms for chromosomal instability in tumors have been described in animal and in vitro models, little is known about these processes in man. To explore cytogenetic evolution in human tumors, chromosomal breakpoint profiles were constructed for 102 pancreatic carcinomas and 140 osteosarcomas, two tumor types characterized by extensive genomic instability. Cases with few chromosomal alterations showed a preferential clustering of breakpoints to the terminal bands, whereas tumors with many changes showed primarily interstitial and centromeric breakpoints. The terminal breakpoint frequency was negatively correlated to telomeric TTAGGG repeat length, and fluorescence in situ hybridization with telomeric TTAGGG probes consistently indicated shortened telomeres and >10% of chromosome ends lacking telomeric signals. Because telomeric dysfunction may lead to formation of unstable ring and dicentric chromosomes, mitotic figures were also evaluated. Anaphase bridges were found in all cases, and fluorescence in situ hybridization demonstrated extensive structural rearrangements of chromosomes, with terminal transferase detection showing fragmented DNA in 5-20% of interphase cells. Less than 2% of cells showed evidence of necrosis or apoptosis, and telomerase was expressed in the majority of cases. Telomeric dysfunction may thus trigger chromosomal fragmentation through persistent bridge-breakage events in pancreatic carcinomas and osteosarcomas, leading to a continuous reorganization of the tumor genome. Telomerase expression is not sufficient for completely stabilizing the chromosome complement but may be crucial for preventing complete genomic deterioration and maintaining cellular survival.
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| 4. |
- Ladanyi, Marc, et al.
(författare)
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The der(17)t(X;17)(p11;q25) of human alveolar soft part sarcoma fuses the TFE3 transcription factor gene to ASPL, a novel gene at 17q25
- 2001
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Ingår i: Oncogene. - : Springer Science and Business Media LLC. - 1476-5594 .- 0950-9232. ; 20:1, s. 48-57
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Tidskriftsartikel (refereegranskat)abstract
- Alveolar soft part sarcoma (ASPS) is an unusual tumor with highly characteristic histopathology and ultrastructure, controversial histogenesis, and enigmatic clinical behavior. Recent cytogenetic studies have identified a recurrent der(17) due to a non-reciprocal t(X;17)(p11.2;q25) in this sarcoma. To define the interval containing the Xp11.2 break, we first performed FISH on ASPS cases using YAC probes for OATL1 (Xp11.23) and OATL2 (Xp11.21), and cosmid probes from the intervening genomic region. This localized the breakpoint to a 160 kb interval. The prime candidate within this previously fully sequenced region was TFE3, a transcription factor gene known to be fused to translocation partners on 1 and X in some papillary renal cell carcinomas. Southern blotting using a TFE3 genomic probe identified non-germline bands in several ASPS cases, consistent with rearrangement and possible fusion of TFE3 with a gene on 17q25. Amplification of the 5' portion of cDNAs containing the 3' portion of TFE3 in two different ASPS cases identified a novel sequence, designated ASPL, fused in-frame to TFE3 exon 4 (type 1 fusion) or exon 3 (type 2 fusion). Reverse transcriptase PCR using a forward primer from ASPL and a TFE3 exon 4 reverse primer detected an ASPL-TFE3 fusion transcript in all ASPS cases (12/12: 9 type 1, 3 type 2), establishing the utility of this assay in the diagnosis of ASPS. Using appropriate primers, the reciprocal fusion transcript, TFE3-ASPL, was detected in only one of 12 cases, consistent with the non-reciprocal nature of the translocation in most cases, and supporting ASPL-TFE3 as its oncogenically significant fusion product. ASPL maps to chromosome 17, is ubiquitously expressed, and matches numerous ESTs (Unigene cluster Hs.84128) but no named genes. The ASPL cDNA open reading frame encodes a predicted protein of 476 amino acids that contains within its carboxy-terminal portion of a UBX-like domain that shows significant similarity to predicted proteins of unknown function in several model organisms. The ASPL-TFE3 fusion replaces the N-terminal portion of TFE3 by the fused ASPL sequences, while retaining the TFE3 DNA-binding domain, implicating transcriptional deregulation in the pathogenesis of this tumor, consistent with the biology of several other translocation-associated sarcomas.
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| 5. |
- Mertens, Fredrik, et al.
(författare)
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Prognostically important chromosomal aberrations in soft tissue sarcomas: a report of the Chromosomes and Morphology (CHAMP) Study Group.
- 2002
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Ingår i: Cancer Research. - 1538-7445. ; 62:14, s. 3980-3984
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Tidskriftsartikel (refereegranskat)abstract
- Cytogenetic analysis has not only provided important information on the pathogenesis of soft tissue tumors but, by disclosing distinct chromosomal rearrangements in different histopathological entities, has also come to serve as a valuable diagnostic tool. Little is known as yet about the potential prognostic impact of cytogenetic features detected in these tumors. A total of 239 benign and 221 malignant soft tissue tumors with clonal chromosome aberrations were subdivided according to general karyotypic features, such as degree of complexity and ploidy level, and rearrangements of specific chromosomal regions. The cytogenetic variables were analyzed regarding clinical outcome, using time to metastasis as the end point. Selected variables were then compared with established clinicopathological predictors of metastasis development. When the entire material was considered, 167 of 268 investigated cytogenetic variables were associated with clinical outcome. Focusing on the subset of 151 patients with high-grade sarcoma, 17 variables were identified that, besides grade and size, were associated with increased risk of metastasis development. A final Cox regression analysis identified five independent cytogenetic predictors of adverse outcome; breakpoints in chromosome regions 1p1, 1q4, 14q1, and 17q2, and gain of regions 6p1/p2. An increasing effect on metastatic risk was seen with increasing involvement of the selected cytogenetic variables, even when different histopathological types were studied separately. We conclude that cytogenetic data provide independent prognostic information in soft tissue sarcomas. Furthermore, our results point to specific areas of the genome harboring genes that may influence the metastatic potential of sarcoma cells.
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| 6. |
- Panagopoulos, Ioannis, et al.
(författare)
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Molecular genetic characterization of the EWS/CHN and RBP56/CHN fusion genes in extraskeletal myxoid chondrosarcoma.
- 2002
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Ingår i: Genes, Chromosomes and Cancer. - : Wiley. - 1045-2257. ; 35:4, s. 340-352
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Tidskriftsartikel (refereegranskat)abstract
- Extraskeletal myxoid chondrosarcoma (EMC) is a soft-tissue neoplasm cytogenetically characterized by the translocations t(9;22)(q22;q11-12) or t(9;17)(q22;q11), generating EWS/CHN or RBP56/CHN fusion genes, respectively. In the present study, 18 EMCs were studied both cytogenetically and at the molecular level. Chromosomal aberrations were detected in 16 samples: 13 with involvement of 9q22 and 22q11-12, and three with rearrangements of 9q22 and 17q11. Fifteen cases had an EWS/CHN fusion transcript and three had an RBP56/CHN transcript. The most frequent EWS/CHN transcript (type 1; 10 tumors), involved fusion of EWS exon 12 with CHN exon 3, and the second most common (type 5; two cases) was fusion of EWS exon 13 with CHN exon 3. In all tumors with RBP56/CHN fusion, exon 6 of RBP56 was fused to exon 3 of CHN. By genomic XL PCR and sequence analyses, the breakpoints from 14 cases were mapped in the EWS, RBP56, and CHN genes. In CHN, 12 breakpoints were found in intron 2 and only two in intron 1. In EWS, the breaks occurred in introns 7 (one break), 12 (eight breaks), and 13 (one break), and in RBP56 in intron 6. Repetitive elements such as Alu and LINE sequences seem to have limited, if any, importance in the genesis of EWS/CHN and RBP56/CHN chimeras. Furthermore, there were no chi, chi-like, topoisomerase II, or translin consensus sequences in the introns harboring the translocation breakpoints, nor could the number of topo I sites in EWS, RBP56, and CHN introns explain the uneven distribution of the breakpoints among EWS or CHN introns. Additional genetic events, such as nucleotide insertions, homologies at the junction, deletions, duplications, and inversions, were found to accompany the translocations, indicating that the chromosomal translocations do not require sequence-specific recombinases or extensive homology between the recombined sequences. Copyright 2002 Wiley-Liss, Inc.
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| 7. |
- Sjöblom, Tobias, et al.
(författare)
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Growth inhibition of dermatofibrosarcoma protuberans tumors by the platelet-derived growth factor receptor antagonist STI571 through induction of apoptosis.
- 2001
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Ingår i: Cancer Res. - 0008-5472. ; 61:15, s. 5778-83
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Tidskriftsartikel (refereegranskat)abstract
- Dermatofibrosarcoma protuberans (DFSP) and giant cell fibroblastoma (GCF) are recurrent, infiltrative skin tumors that presently are treated with surgery. DFSP and GCF tumors are genetically characterized by chromosomal rearrangements fusing the collagen type Ialpha1 (COLIA1) gene to the platelet-derived growth factor B-chain (PDGFB) gene. It has been shown that the resulting COL1A1/PDGF-B fusion protein is processed to mature PDGF-BB. Autocrine PDGF receptor stimulation has therefore been predicted to contribute to DFSP and GCF tumor development and growth. Here we demonstrate presence of activated PDGF receptors in primary cultures derived from six different DFSP and GCF tumors. Three of the primary cultures were further characterized; their in vitro growth displayed an increased sensitivity to treatment with the PDGF receptor tyrosine kinase inhibitor STI571, as compared with normal fibroblasts. Transplantable tumors, displaying a DFSP-like histology, were established from one of the DFSP primary cultures. Treatment of tumor-bearing severe combined immunodeficient mice with STI571 reduced tumor growth. The growth-inhibitory effects in vitro and in vivo occurred predominantly through induction of tumor cell apoptosis. Our study demonstrates growth-inhibitory effects of PDGF receptor antagonists on human DFSP- and GCF-derived tumor cells and demonstrates that autocrine PDGF receptor stimulation provides antiapoptotic signals contributing to the growth of these cells. These findings suggest targeting of PDGF receptors as a novel treatment strategy for DFSP and GCF.
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