Detection of chromosome 1 aberrations by fluorescent in situ hybridization (FISH) in the human breast cancer cell line MCF-7.

In situ hybridization using nucleic acid probes specific for a particular chromosome repetitive sequence makes it possible to determine the number of corresponding chromosomes and potential aberrations in each cell of the population under investigation. The number of in situ hybridization spots per nucleus, indicating chromosomal ploidy and/or aberrations, thus marks the possible cell subpopulations having an abnormal karyotype. Applying such an interphase cytogenetics approach on the MCF-7 human breast cancer cell line with centromeric (pUC 1.77) and telomeric (1p-79) probes specific for repetitive sequences on the chromosome 1, we investigated the heterogeneity of the cell population on the basis of the number of fluorescent in situ hybridization (FISH) spots per nucleus and their location with respect to the others. We also followed the chromosome 1 genetic drift as the cell population aged. Our results confirmed the already known trisomy for the chromosome 1 in this cell line and demonstrated a deletion and a translocation of its telomeric sequence. Moreover, a subpopulation of cells with six chromosomes 1 representing a few percent of the population was transiently detected.