Establishment of Proliferative Tetraploid Cells from Nontransformed Human Fibroblasts.

Polyploid (mostly tetraploid) cells are often observed in preneoplastic lesions of human tissues and their chromosomal instability has been considered to be responsible for carcinogenesis in such tissues. Although proliferative polyploid cells are requisite for analyzing chromosomal instability of polyploid cells, creating such cells from nontransformed human cells is rather challenging. Induction of tetraploidy by chemical agents usually results in a mixture of diploid and tetraploid populations, and most studies employed fluorescence-activated cell sorting or cloning by limiting dilution to separate tetraploid from diploid cells.

Establishment of proliferative tetraploid cells from telomerase-immortalized normal human fibroblasts.

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.

Establishment of proliferative tetraploid cells from normal human fibroblasts.

The chromosomal instability of polyploid cells, which leads to the formation of aneuploid cells, is causally related to carcinogenesis in human tissues. However, the precise link between the chromosomal instability of polyploid cells and oncogenic transformation of them remains elusive. This is partly because we lack an experimental model in which non-transformed polyploid human cells can propagate in vitro.

Formation of bipolar spindles with two centrosomes in tetraploid cells established from normal human fibroblasts.

Tetraploid cells with unstable chromosomes frequently arise as an early step in tumorigenesis and lead to the formation of aneuploid cells. The mechanisms responsible for the chromosome instability of polyploid cells are not fully understood, although the supernumerary centrosomes in polyploid cells have been considered the major cause of chromosomal instability. The aim of this study was to examine the integrity of mitotic spindles and centrosomes in proliferative polyploid cells established from normal human fibroblasts.

Significant Correlation between Chromosomal Aberration and Nuclear Morphology in Urothelial Carcinoma.

We aimed to identify whether there is any correlation between chromosomal/genetic changes, nuclear morphology and the histological grade of urothelial carcinomas of the urinary bladder. Morphometry and multicolour fluorescence in situ hybridisation (FISH) techniques were applied to 250 cells in five low-grade cases and 350 cells in seven high-grade cases of urothelial carcinoma. Compared with low-grade carcinomas, most high-grade cases showed larger and more variable nuclear size, more frequent polysomy of centromere enumeration probes (CEPs) 3, 7 and 17, and the loss of the 9p21 locus.