Abstract
Purpose: Aneuploidy occurs in 90% of solid human tumors but a role of aneuploidy in carcinogenesis was unclear. We examined the role of aneuploidy in carcinogenesis.
Methods: To isolate the diploid, the triploid and the tetraploid clones, 9 clones were cloned from p53 (-/-) mouse embryonic cells and the chromosome number of these clones was counted. These cells were cultured in Eagle's Minimum Essential Medium (MEM) supplemented with 10% fetal bovine serum. To study whether aneuploidy contributed to carcinogenesis, we examined (1) anchorage-independent growth, (2) tumorigenicity (3) micronuclei frequency, (4) a number of co-localized p-H2AX and 53BP1 foci, (5) chromosome structural aberration, (6) reactive oxygen species (ROS) levels using the fluorescent dye DCFH-DA, (7) cell growth and (8) the gene expression profiles by microarray analysis.
Results: Anchorage-independent growth and tumorigenicity were observed in triploid clones but not in both diploid and tetraploid clones. Micronuclei frequencies, the number of foci containing co-localized p-H2AX and 53BP1 and chromosome structural aberration were increased in the triploid clones compared with the diploid clones. There were no differences in the diploid clones and the tetraploid clones. The triploid clones contained much lower levels of ROS than both the diploid clones and the tetraploid clones. Number of genes 10-fold altered compared with the diploid clones in the triploid clones was markedly increased. Despite lower levels of ROS, both chromosome structural aberrations and DNA double strand breaks occurred in triploid clones.
Conclusion: Triploidy resulted in chromosome and DNA instability, and disruption of global gene expression, finally gave rise to cancer.
