Establishment of proliferative tetraploid cells from telomerase‐immortalized normal human fibroblasts

Abstract

Aneuploidy is observed in the majority of human cancers and is considered to be causally related to carcinogenesis. Although malignant aneuploid cells are suggested to develop from polyploid cells formed in precancerous lesions, the mechanisms of this process remain elusive. This is partly because no experimental model is available where nontransformed polyploid human cells propagate in vitro. We previously showed that proliferative tetraploid cells can be established from normal human fibroblasts by treatment with the spindle poison demecolcine (DC). However, the limited lifespan of these cells hampered detailed analysis of a link between chromosomal instability and the oncogenic transformation of polyploid cells. Here, we report the establishment of proliferative tetraploid cells from the telomerase-immortalized normal human fibroblast cell line TIG-1. Treatment of immortalized diploid cells with DC for 4 days resulted in proliferation of cells with tetraploid DNA content and near-tetraploid/tetraploid chromosome counts. Established tetraploid cells had functional TP53 despite growing at almost the same rate as diploid cells. The frequency of clonal and sporadic chromosome aberrations in tetraploid cells was higher than in diploid cells and in one experiment, gradually increased with repeated subculture. This study suggests that tetraploid cells established from telomerase-immortalized normal human fibroblasts can be a valuable model for studying chromosomal instability and the oncogenic potential of polyploid cells. © 2016 Wiley Periodicals, Inc.

Thermodynamic energetics underlying genomic instability and whole-genome doubling in cancer

“…Many processes such as DNA damage repair defects, replication stress, breakage-fusion-bridge cycles, telomere attrition, lagging chromosomes, nuclear envelope defects, defective mitosis, and epigenetic-guided mechanisms can lead to CNA (2)(3)(4)(5)(6). Defective mitosis can lead to whole-genome duplication (WGD), which can also be observed in experimental systems (2,7,8). Analysis of somatic and germline single-nucleotide polymorphism (SNP) patterns supports WGD as typically an early event in the genomic instability components of tumorigenesis (2,7,9,10).…”

Establishment of Proliferative Tetraploid Cells from Nontransformed Human Fibroblasts

“…If this hypothesis is correct, p53 signaling in proliferating tetraploid cells should be inactivated. However, tetraploid cells established by our protocol seem to have functional p53 despite growing at almost the same rate as diploid cells 15,16 . The reason for this discrepancy is not known at present, and significance of p53 inactivation in the proliferation of tetraploid cells should be examined precisely in future studies.…”

“…Using this protocol, we have to date produced tetraploid cells from the human fibroblast strains TIG-1, BJ, IMR-90 and telomerase-immortalized TIG-1 up to now [14][15][16] . Among these cell strains, TIG-1 is rather unusual because this cell strain becomes almost completely tetraploid when treated continuously with DC, without shake-off, for 4 days.…”