Spontaneous and aphidicolin-sensitive fragile site 3cen co-localizes with the (TTAGGG)n telomeric sequence in Chinese hamster cells.

Aphidicolin-sensitive fragile sites were analyzed in immortalized Chinese hamster embryonal fibroblast cells (CHEF18) at three different passages along their spontaneous progression toward tumorigenicity. Five fragile sites (viz., 12q22, 3cen, 3p21, 3q31, and Xq21) were detected. Three of these sites carry spontaneous aberrations and are thus regions of chromosomal instability; however, they were not involved in the formation of the clonal rearrangements that are characteristic of CHEF 18 cells. The presence of the (TTAGGG)n telomeric sequence in chromosome bands associated with fragile sites was investigated using fluorescence in situ hybridization and primed in situ labeling. A common location of fragile sites and telomeric sequence was found at the centromere of chromosome 3.