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Induced dicentric chromosome formation promotes genomic rearrangements and tumorigenesis.

Gascoigne KE, Cheeseman IM - Chromosome Res. (2013)

Bottom Line: We find that induced dicentric chromosomes are frequently damaged and mis-segregated during mitosis, and that this leads to extensive chromosomal rearrangements including translocations with other chromosomes.Populations of pre-neoplastic cells in which a single dicentric chromosome is induced acquire extensive genomic instability and display hallmarks of cellular transformation including anchorage-independent growth in soft agar.Our results suggest that a single dicentric chromosome could contribute to tumor initiation.

View Article: PubMed Central - PubMed

Affiliation: Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, MA 02142, USA.

ABSTRACT
Chromosomal rearrangements can radically alter gene products and their function, driving tumor formation or progression. However, the molecular origins and evolution of such rearrangements are varied and poorly understood, with cancer cells often containing multiple, complex rearrangements. One mechanism that can lead to genomic rearrangements is the formation of a "dicentric" chromosome containing two functional centromeres. Indeed, such dicentric chromosomes have been observed in cancer cells. Here, we tested the ability of a single dicentric chromosome to contribute to genomic instability and neoplastic conversion in vertebrate cells. We developed a system to transiently and reversibly induce dicentric chromosome formation on a single chromosome with high temporal control. We find that induced dicentric chromosomes are frequently damaged and mis-segregated during mitosis, and that this leads to extensive chromosomal rearrangements including translocations with other chromosomes. Populations of pre-neoplastic cells in which a single dicentric chromosome is induced acquire extensive genomic instability and display hallmarks of cellular transformation including anchorage-independent growth in soft agar. Our results suggest that a single dicentric chromosome could contribute to tumor initiation.

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Dicentric chromosome induction leads to global genomic rearrangement. a Spectral karyotype (SKY) analysis of 3T3-lacO cells expressing GFP-LacI or GFP-CENP-T-ΔC-LacI at a time point 3 days after removal of IPTG. Representative images of chromosomes involved in translocations are pseudo-colored. b Quantification of the rates of chromosome translocations in a
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Fig3: Dicentric chromosome induction leads to global genomic rearrangement. a Spectral karyotype (SKY) analysis of 3T3-lacO cells expressing GFP-LacI or GFP-CENP-T-ΔC-LacI at a time point 3 days after removal of IPTG. Representative images of chromosomes involved in translocations are pseudo-colored. b Quantification of the rates of chromosome translocations in a

Mentions: In addition to these results using chromosome 3-specific probes, we conducted SKY analysis to visualize the entire range of chromosome sequences in 3T3-lacO cells following dicentric chromosome induction (Fig. 3). In addition to translocations involving the induced dicentric chromosome (chromosome 3), this analysis revealed an increased frequency of rearrangement events not involving chromosome 3 following induction of the dicentric chromosome (Fig. 3a, b). The 3T3-lacO cell line used in this study contained two stable rearrangements: t(1:X) and t(8:17) (Soutoglou et al. 2007). Clonal 3T3-lacO cell lines expressing CENP-T-LacI generated in this background, but grown in the presence of IPTG, contained three additional stable rearrangements (Fig. 3a) likely formed during selection of this clone. However, these rearrangements appeared to be very stable as they were detected in virtually all cells analyzed, without additional rearrangement occurring. Importantly, following induction of the dicentric chromosome, 13 additional rearrangements were observed, ten of which did not involve chromosome 3 (Fig. 3b). Distinct patterns of translocations were observed in individual cells, and on average, each induced dicentric cell analyzed contained at least one additional unique translocation. This pattern of translocations likely reflects the occurrence of random events rather than selection of stable clones in the population. These data suggest the presence of an underlying genomic instability following dicentric chromosome induction. Taken together, these data suggest that the dicentric chromosome can be damaged and broken during mitosis, and that the broken chromosome ends are repaired by fusion and translocation with other chromosomes. In addition, such events appear to cause global genome instability, leading to a variety of genomic rearrangements involving different chromosomes.Fig. 3


Induced dicentric chromosome formation promotes genomic rearrangements and tumorigenesis.

Gascoigne KE, Cheeseman IM - Chromosome Res. (2013)

Dicentric chromosome induction leads to global genomic rearrangement. a Spectral karyotype (SKY) analysis of 3T3-lacO cells expressing GFP-LacI or GFP-CENP-T-ΔC-LacI at a time point 3 days after removal of IPTG. Representative images of chromosomes involved in translocations are pseudo-colored. b Quantification of the rates of chromosome translocations in a
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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Fig3: Dicentric chromosome induction leads to global genomic rearrangement. a Spectral karyotype (SKY) analysis of 3T3-lacO cells expressing GFP-LacI or GFP-CENP-T-ΔC-LacI at a time point 3 days after removal of IPTG. Representative images of chromosomes involved in translocations are pseudo-colored. b Quantification of the rates of chromosome translocations in a
Mentions: In addition to these results using chromosome 3-specific probes, we conducted SKY analysis to visualize the entire range of chromosome sequences in 3T3-lacO cells following dicentric chromosome induction (Fig. 3). In addition to translocations involving the induced dicentric chromosome (chromosome 3), this analysis revealed an increased frequency of rearrangement events not involving chromosome 3 following induction of the dicentric chromosome (Fig. 3a, b). The 3T3-lacO cell line used in this study contained two stable rearrangements: t(1:X) and t(8:17) (Soutoglou et al. 2007). Clonal 3T3-lacO cell lines expressing CENP-T-LacI generated in this background, but grown in the presence of IPTG, contained three additional stable rearrangements (Fig. 3a) likely formed during selection of this clone. However, these rearrangements appeared to be very stable as they were detected in virtually all cells analyzed, without additional rearrangement occurring. Importantly, following induction of the dicentric chromosome, 13 additional rearrangements were observed, ten of which did not involve chromosome 3 (Fig. 3b). Distinct patterns of translocations were observed in individual cells, and on average, each induced dicentric cell analyzed contained at least one additional unique translocation. This pattern of translocations likely reflects the occurrence of random events rather than selection of stable clones in the population. These data suggest the presence of an underlying genomic instability following dicentric chromosome induction. Taken together, these data suggest that the dicentric chromosome can be damaged and broken during mitosis, and that the broken chromosome ends are repaired by fusion and translocation with other chromosomes. In addition, such events appear to cause global genome instability, leading to a variety of genomic rearrangements involving different chromosomes.Fig. 3

Bottom Line: We find that induced dicentric chromosomes are frequently damaged and mis-segregated during mitosis, and that this leads to extensive chromosomal rearrangements including translocations with other chromosomes.Populations of pre-neoplastic cells in which a single dicentric chromosome is induced acquire extensive genomic instability and display hallmarks of cellular transformation including anchorage-independent growth in soft agar.Our results suggest that a single dicentric chromosome could contribute to tumor initiation.

View Article: PubMed Central - PubMed

Affiliation: Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, MA 02142, USA.

ABSTRACT
Chromosomal rearrangements can radically alter gene products and their function, driving tumor formation or progression. However, the molecular origins and evolution of such rearrangements are varied and poorly understood, with cancer cells often containing multiple, complex rearrangements. One mechanism that can lead to genomic rearrangements is the formation of a "dicentric" chromosome containing two functional centromeres. Indeed, such dicentric chromosomes have been observed in cancer cells. Here, we tested the ability of a single dicentric chromosome to contribute to genomic instability and neoplastic conversion in vertebrate cells. We developed a system to transiently and reversibly induce dicentric chromosome formation on a single chromosome with high temporal control. We find that induced dicentric chromosomes are frequently damaged and mis-segregated during mitosis, and that this leads to extensive chromosomal rearrangements including translocations with other chromosomes. Populations of pre-neoplastic cells in which a single dicentric chromosome is induced acquire extensive genomic instability and display hallmarks of cellular transformation including anchorage-independent growth in soft agar. Our results suggest that a single dicentric chromosome could contribute to tumor initiation.

Show MeSH
Related in: MedlinePlus