Spectral karyotyping identifies recurrent complex rearrangements of chromosomes 8, 17, and 20 in osteosarcomas.
ABSTRACT Conventional cytogenetic studies have shown that osteosarcomas (OSs) are often highly aneuploid, with a large number of both structural and numerical chromosomal alterations. To investigate the complexity of OS karyotypes in detail, we applied spectral karyotyping (SKY) to a series of 14 primary OS tumors and four established OS cell lines. A total of 531 rearrangements were identified by SKY, of which 300 breakpoints could be assigned to a specific chromosome band. There was an average of 38.5 breakpoints identified by SKY per primary tumor. Chromosome 20 was involved in a disproportionately high number of structural rearrangements, with 38 different aberrations being detected. Chromosomal rearrangements between chromosomes 20 and 8 were evident in four tumors. FISH analysis using a 20q13 subtelomeric probe identified frequent involvement of 20q in complex structural rearrangements of OS cell lines. Characterization of the structural aberrations of chromosomes 8 and 17 by use of SKY demonstrated frequent duplication or partial gains of chromosome bands 8q23-24 and 17p11-13. Other chromosomes frequently involved in structural alteration were chromosomes 1 (47 rearrangements) and 6 (38 rearrangements). Centromeric rearrangements often involving chromosomes 1, 6, 13, 14, 17, and 20 were present. Four of the 14 primary OS tumors were characterized by nonclonal changes that included both structural and numerical alterations. In summary, OS tumors have a very high frequency of structural and numerical alterations, compounded by gross changes in ploidy. This intrinsic karyotype instability leads to a diversity of rearrangements and the acquisition of composite chromosomal rearrangements, with the highest frequency of alteration leading to gain of 8q23-24 and 17p11-13 and rearrangement of 20q. These findings suggest that specific sequences mapping to these chromosomal regions will likely have a role in the development and progression of OS.
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ABSTRACT: Background:Aurora kinases are key regulators of cell cycle and represent new promising therapeutic targets in several human tumours.Methods:Biological relevance of Aurora kinase-A and -B was assessed on osteosarcoma clinical samples and by silencing these genes with specific siRNA in three human osteosarcoma cell lines. In vitro efficacy of two Aurora kinases-targeting drugs (VX-680 and ZM447439) was evaluated on a panel of four drug-sensitive and six drug-resistant human osteosarcoma cell lines.Results:Human osteosarcoma cell lines proved to be highly sensitive to both drugs. A decreased drug sensitivity was observed in doxorubicin-resistant cell lines, most probably related to ABCB1/MDR1 overexpression. Both drugs variably induced hyperploidy and apoptosis in the majority of cell lines. VX-680 also reduced in vitro cell motility and soft-agar cloning efficiency. Drug association experiments showed that VX-680 positively interacts with all conventional drugs used in osteosarcoma chemotherapy, overcoming the cross-resistance observed in the single-drug treatments.Conclusion:Aurora kinase-A and -B represent new candidate therapeutic targets for osteosarcoma. In vitro analysis of the Aurora kinases inhibitors VX-680 and ZM447439 indicated in VX-680 a new promising drug of potential clinical usefulness in association with conventional osteosarcoma chemotherapeutic agents.British Journal of Cancer advance online publication, 15 October 2013; doi:10.1038/bjc.2013.643 www.bjcancer.com.British Journal of Cancer 10/2013; · 5.08 Impact Factor
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ABSTRACT: Polyploidy has been recognized for many years as an important hallmark of cancer cells. Polyploid cells can arise through cell fusion, endoreplication and abortive cell cycle. The inner nuclear membrane protein LAP2beta plays key roles in nuclear envelope breakdown and reassembly during mitosis, initiation of replication and transcriptional repression. Here we studied the function of LAP2beta in the maintenance of cell ploidy state, a role which has not yet been assigned to this protein. By knocking down the expression of LAP2beta, using both viral and non-viral RNAi approaches in osteosarcoma derived U2OS cells, we detected enlarged nuclear size, nearly doubling of DNA content and chromosomal duplications, as analyzed by fluorescent in situ hybridization and spectral karyotyping methodologies. Spectral karyotyping analyses revealed that near-hexaploid karyotypes of LAP2beta knocked down cells consisted of not only seven duplicated chromosomal markers, as could be anticipated by genome duplication mechanism, but also of four single chromosomal markers. Furthermore, spectral karyotyping analysis revealed that both of two near-triploid U2OS sub-clones contained the seven markers that were duplicated in LAP2beta knocked down cells, whereas the four single chromosomal markers were detected only in one of them. Gene expression profiling of LAP2beta knocked down cells revealed that up to a third of the genes exhibiting significant changes in their expression are involved in cancer progression. Our results suggest that nuclear fusion mechanism underlies the polyploidization induction upon LAP2beta reduced expression. Our study implies on a novel role of LAP2beta in the maintenance of cell ploidy status. LAP2beta depleted U2OS cells can serve as a model to investigate polyploidy and aneuploidy formation by nuclear fusion mechanism and its involvement in cancerogenesis.Molecular Cytogenetics 01/2014; 7(1):9. · 2.66 Impact Factor