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Proliferation of aneuploid human cells is limited by a p53-dependent mechanism.

Thompson SL, Compton DA - J. Cell Biol. (2010)

Bottom Line: However, the relationship of aneuploidy and CIN is unclear because the proliferation of cultured diploid cells is compromised by chromosome missegregation.The mechanism for this intolerance of nondiploid genomes is unknown.These data fit with the concordance of aneuploidy and disruption of the p53 pathway in many tumors, but the presence of aneuploid cells in some normal human and mouse tissues indicates that there are known exceptions to the involvement of p53 in aneuploid cells and that tissue context may be important in how cells respond to aneuploidy.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biochemistry, Dartmouth Medical School, Hanover, NH 03755, USA.

ABSTRACT
Most solid tumors are aneuploid, and it has been proposed that aneuploidy is the consequence of an elevated rate of chromosome missegregation in a process called chromosomal instability (CIN). However, the relationship of aneuploidy and CIN is unclear because the proliferation of cultured diploid cells is compromised by chromosome missegregation. The mechanism for this intolerance of nondiploid genomes is unknown. In this study, we show that in otherwise diploid human cells, chromosome missegregation causes a cell cycle delay with nuclear accumulation of the tumor suppressor p53 and the cyclin kinase inhibitor p21. Deletion of the p53 gene permits the accumulation of nondiploid cells such that CIN generates cells with aneuploid genomes that resemble many human tumors. Thus, the p53 pathway plays an important role in limiting the propagation of aneuploid human cells in culture to preserve the diploid karyotype of the population. These data fit with the concordance of aneuploidy and disruption of the p53 pathway in many tumors, but the presence of aneuploid cells in some normal human and mouse tissues indicates that there are known exceptions to the involvement of p53 in aneuploid cells and that tissue context may be important in how cells respond to aneuploidy.

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Growth arrest after chromosome missegregation. (A) Schematic for proper segregation and missegregation of a single GFP-marked chromosome. (B) GFP (left) and phase-contrast images of daughter cells that either segregated the marked chromosome normally (top) or abnormally (bottom) at the indicated times after drug washout. Arrowheads point to the LacIGFP/lacO chromosome mark. (C) Number of cells per clone after no treatment, monastrol washout, and monastrol washout with missegregation (mis-seg) of the marked chromosome. Bars represent mean ± SEM (independent clones counted for control, n = 49; monastrol, n = 15; and monastrol/mis-seg, n = 22). Bars: (B, left) 10 µm; (B, right) 50 µm.
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fig2: Growth arrest after chromosome missegregation. (A) Schematic for proper segregation and missegregation of a single GFP-marked chromosome. (B) GFP (left) and phase-contrast images of daughter cells that either segregated the marked chromosome normally (top) or abnormally (bottom) at the indicated times after drug washout. Arrowheads point to the LacIGFP/lacO chromosome mark. (C) Number of cells per clone after no treatment, monastrol washout, and monastrol washout with missegregation (mis-seg) of the marked chromosome. Bars represent mean ± SEM (independent clones counted for control, n = 49; monastrol, n = 15; and monastrol/mis-seg, n = 22). Bars: (B, left) 10 µm; (B, right) 50 µm.

Mentions: To follow the fate of live cells that missegregate chromosomes, we generated HCT116 cells that expressed LacIGFP and had multiple copies of lacO integrated into a single chromosomal locus (Robinett et al., 1996; Straight et al., 1996). We chose to use HCT116 cells for this purpose because it is an established near-diploid colon cancer cell line that faithfully segregates chromosomes to maintain a stable karyotype (Lengauer et al., 1997). Cells with integrated lacO and expressing LacIGFP remained near diploid. The expressed LacIGFP bound to the chromosomal lacO site, producing a single, bright fluorescent mark in each interphase nucleus and unique marks on sister chromatids of mitotic chromosomes (Fig. 1). Accurate segregation of this chromosome during mitosis yielded daughter cells with single marks in each nucleus, whereas missegregation yielded one daughter cell with no marks and the other with two (Fig. 2 A).


Proliferation of aneuploid human cells is limited by a p53-dependent mechanism.

Thompson SL, Compton DA - J. Cell Biol. (2010)

Growth arrest after chromosome missegregation. (A) Schematic for proper segregation and missegregation of a single GFP-marked chromosome. (B) GFP (left) and phase-contrast images of daughter cells that either segregated the marked chromosome normally (top) or abnormally (bottom) at the indicated times after drug washout. Arrowheads point to the LacIGFP/lacO chromosome mark. (C) Number of cells per clone after no treatment, monastrol washout, and monastrol washout with missegregation (mis-seg) of the marked chromosome. Bars represent mean ± SEM (independent clones counted for control, n = 49; monastrol, n = 15; and monastrol/mis-seg, n = 22). Bars: (B, left) 10 µm; (B, right) 50 µm.
© Copyright Policy - openaccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2819684&req=5

fig2: Growth arrest after chromosome missegregation. (A) Schematic for proper segregation and missegregation of a single GFP-marked chromosome. (B) GFP (left) and phase-contrast images of daughter cells that either segregated the marked chromosome normally (top) or abnormally (bottom) at the indicated times after drug washout. Arrowheads point to the LacIGFP/lacO chromosome mark. (C) Number of cells per clone after no treatment, monastrol washout, and monastrol washout with missegregation (mis-seg) of the marked chromosome. Bars represent mean ± SEM (independent clones counted for control, n = 49; monastrol, n = 15; and monastrol/mis-seg, n = 22). Bars: (B, left) 10 µm; (B, right) 50 µm.
Mentions: To follow the fate of live cells that missegregate chromosomes, we generated HCT116 cells that expressed LacIGFP and had multiple copies of lacO integrated into a single chromosomal locus (Robinett et al., 1996; Straight et al., 1996). We chose to use HCT116 cells for this purpose because it is an established near-diploid colon cancer cell line that faithfully segregates chromosomes to maintain a stable karyotype (Lengauer et al., 1997). Cells with integrated lacO and expressing LacIGFP remained near diploid. The expressed LacIGFP bound to the chromosomal lacO site, producing a single, bright fluorescent mark in each interphase nucleus and unique marks on sister chromatids of mitotic chromosomes (Fig. 1). Accurate segregation of this chromosome during mitosis yielded daughter cells with single marks in each nucleus, whereas missegregation yielded one daughter cell with no marks and the other with two (Fig. 2 A).

Bottom Line: However, the relationship of aneuploidy and CIN is unclear because the proliferation of cultured diploid cells is compromised by chromosome missegregation.The mechanism for this intolerance of nondiploid genomes is unknown.These data fit with the concordance of aneuploidy and disruption of the p53 pathway in many tumors, but the presence of aneuploid cells in some normal human and mouse tissues indicates that there are known exceptions to the involvement of p53 in aneuploid cells and that tissue context may be important in how cells respond to aneuploidy.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biochemistry, Dartmouth Medical School, Hanover, NH 03755, USA.

ABSTRACT
Most solid tumors are aneuploid, and it has been proposed that aneuploidy is the consequence of an elevated rate of chromosome missegregation in a process called chromosomal instability (CIN). However, the relationship of aneuploidy and CIN is unclear because the proliferation of cultured diploid cells is compromised by chromosome missegregation. The mechanism for this intolerance of nondiploid genomes is unknown. In this study, we show that in otherwise diploid human cells, chromosome missegregation causes a cell cycle delay with nuclear accumulation of the tumor suppressor p53 and the cyclin kinase inhibitor p21. Deletion of the p53 gene permits the accumulation of nondiploid cells such that CIN generates cells with aneuploid genomes that resemble many human tumors. Thus, the p53 pathway plays an important role in limiting the propagation of aneuploid human cells in culture to preserve the diploid karyotype of the population. These data fit with the concordance of aneuploidy and disruption of the p53 pathway in many tumors, but the presence of aneuploid cells in some normal human and mouse tissues indicates that there are known exceptions to the involvement of p53 in aneuploid cells and that tissue context may be important in how cells respond to aneuploidy.

Show MeSH
Related in: MedlinePlus