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 particu lar 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 hybr idization spots per nucleus, indicating chromosomal ploidy and/or aber rations, thus marks the possible cell subpopulations having an abnorma l karyotype. Applying such an interphase cytogenetics approach on the MCF-7 human breast cancer cell line with centromeric (pUC 1.77) and te lomeric (1p-79) probes specific for repetitive sequences on the chromo some 1, we investigated the heterogeneity of the cell population on th e basis of the number of fluorescent in situ hybridization (FISH) spot s per nucleus and their location with respect to the others. We also f ollowed the chromosome 1 genetic drift as the cell population aged. Ou r 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 chromo somes 1 representing a few percent of the population was transiently d etected.