Whole chromosome loss and associated breakage–fusion–bridge cycles transform mouse tetraploid cells

Abstract

Whole chromosome gains or losses (aneuploidy) are a hallmark of ~70% of human tumors. Modeling the consequences of aneuploidy has relied on perturbing spindle assembly checkpoint (SAC) components, but interpretations of these experiments are clouded by the multiple functions of these proteins. Here, we used a Cre recombinase-mediated chromosome loss strategy to individually delete mouse chromosomes 9, 10, 12, or 14 in tetraploid immortalized murine embryonic fibroblasts. This methodology also involves the generation of a dicentric chromosome intermediate, which subsequently undergoes a series of breakage-fusion-bridge (BFB) cycles. While the aneuploid cells generally display a growth disadvantage , they grow significantly better in low adherence sphere-forming conditions and three of the four lines are transformed, forming large and invasive tumors in immunocompromised mice. The aneuploid cells display increased chromosomal instability and DNA damage, a mutator phenotype associated with tumorigenesis Thus, these studies demonstrate a causative role for whole chromosome loss and the associated BFB-mediated instability in tumorigenesis and may shed light on the early consequences of aneuploidy in mammalian cells.

Establishment and Characterization of a Reliable Xenograft Model of Hodgkin Lymphoma Suitable for the Study of Tumor Origin and the Design of New Therapies

“…Consistent with these results, we speculate that telomere loss can induce dicentric chromosome formation or micronucleus formation as well as chromosome lagging. These data extend and underscore our previous findings concerning the implication of telomere dysfunction in HL chromosomal instability via B/F/B cycles and micronucleus formation [ 28 , 29 ]. Of note, we provide in this study the first complete karyotype of the L428 cell line and demonstrate the feasibility of cytogenetic analysis in a xenograft HL model.…”

Applications of Genome Editing Technology in Research on Chromosome Aneuploidy Disorders

“…However, recent studies using genetic engineering have revealed the possibility of performing aneuploidy therapy in cultured cells. Here, we summarize some of the main studies aimed at eliminating an entire chromosome using the Cre/loxP system [79][80][81][82][83][84][85], the TKneo transgene for positive and negative antibiotic selection [86], CRISPR/Cas9 system-mediated multiple cleavage [87,88], and zinc finger nuclease (ZFN)-mediated knock-in of the XIST gene to silence one copy of chromosome 21 [89] (cited in Table 2).…”

“…Moreover, Matsumura et al [85] applied a chromosome elimination cassette (CEC), featuring fluorescent-protein and puromycin resistance genes surrounded by inverted loxP sites into chromosome deletions in cultured cells in vitro. Mouse tetraploid (4n = 80,XXXY) ES cells fused with two diploid ES cells differentiated but did not proliferate [79,85]. The elimination of two copies of chromosome 6 tagged with CEC in the tetraploid ES cells enabled survival in an undifferentiated state and the capability of teratoma formation, implying that chromosome 6 including the Nanog gene is indispensable for the self-renewal and pluripotency of mouse ES cells.…”

Aneuploidy and oncoviruses

“…The rearrangement of chromosomes through the breakage‐fusion‐bridge (BFB) cycles may be one more feasible source of aneuploidy . BFB is a mechanism initiated by shortened and defective telomeres or when a chromosome subjected to a double‐stranded break (DSB) replicates and the sister chromatids join at their ends.…”