Analysis of p53-dependent mechanisms in the maintenance of genetic stability in diploid tumourigenic line SK-UT-1B of human uterine leiomyosarcoma.

The cells of tumourigenic line SK-UT-1B combine features characteristic both of normal (diploid karyotype, a low level of polyploid cells, absence of chromosomal marker) and tumour cells (high level of chromosomal instability, high malignancy). We suggest that maintenance of diploid karyotype in this line is controlled via the p53/p21 pathway. We demonstrate that the amount of p53 increases following gamma-irradiation and accumulated p53 protein seems to be functional as p53-luc and p21/Waf-luc reporter plasmids were found to be activated.

A new and rapid method for visualising DNA replication in spread DNA by immunofluorescence detection of incorporated 5-iododeoxyuridine.

We have developed a new and rapid immunofluorescent method for visualisation of replicated regions on fixed DNA fibers. Using this method we have found in 5-fluorodeoxyuridine (FrdU)-blocked human cells distinct replication units covering about 60 kb of DNA and corresponding in size to single replicons or chromatin loops. Our results also suggest that nonadjacent replicons within a replicon cluster may be activated after FrdU arrest and that the method may be adapted for localization on fibers of specific DNA sequences.