Topographic characterization of telomeres in healthy andvarious tumor cell lines determined in situ and in vivo

Nuclear and territorial positioning of p- and q- telomeres and centromeres of chromosomes 3, 8, 9, 13 and 19 were studied using repeated fluorescence in situ hybridization, high-resolution image cytometry and three-dimensional image analysis of human blood lymphocytes before and after stimulation (Amrichova et al., 2003). Our results suggest that in both G0- and stimulated lymphocytes, centromeres of HSA 3, 8, 9, and 13 are predominantly localized at the periphery of the cell nucleus; only centromere of HSA 19 in G0-lymphocytes is localized more centrally. Both p- and q-telomeres mostly adopt positions in the nuclear interior; q-telomeres are usually nearer to the center of the cell nucleus as compared to p-telomeres. Using repeated hybridization, tethering between telomeres of heterologous chromosomes 8, 9, and 19 was investigated. An attempt was made to find which particular telomeres are involved in telomere associations and whether any associations can be found also between homologous telomeres. We found no tethering of heterologous telomeres of chromosomes 8, 9, and 19. In contrary, both pairs of homologous telomeres of chromosome 19 (but not in other chromosomes) are tethered (associated) very frequently (Amrichova et al., 2003). Our interest was extended by investigation of topography of telomeres and incidence of telomere-association phenomenon in various types of tumor cells in situ and in vivo. Results of our observations will be discussed