Homogeneously staining region in anthracycline-resistant HL-60/AR cells not associated with MDR1 amplification.


Anthracycline-resistant HL-60/AR cells and their drug-sensitive HL-60/S counterparts were characterized by karyotypic analysis and examined for the overexpression of DNA and mRNA sequences coding for P-glycoprotein (Pgp). The HL-60/S cells were karyotypically stable over a 5-year period of study (1986-1991), except for an additional small Giemsa-positive band noted at 7q22 in cultures harvested in 1987, but not in 1986. This change did not affect drug sensitivity. The drug-resistant HL-60/AR cells examined in 1986, 1987, and 1991 demonstrated a very stable karyotype. The most striking feature was a large homogeneously staining region in the long arm of chromosome 7 (7q11.2), and translocation of the remainder of the long arm to another centromere. Other changes in the HL-60/AR cells included inversion in 9q, partial deletion of the short arm of chromosome 10p, addition of material to the p arm of der(16), loss of chromosome 22, and the appearance of a new marker chromosome. Both HL-60/S and the HL-60/AR cells were found not to amplify DNA or mRNA sequences coding for the Pgp. Thus, although the HL-60/AR cells possess the classical multidrug resistance phenotype and demonstrate a homogeneously staining region near the region of the MDR1 gene, their resistance is due to mechanisms other than those coded for by MDR1.

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@article{Gervasoni1992HomogeneouslySR, title={Homogeneously staining region in anthracycline-resistant HL-60/AR cells not associated with MDR1 amplification.}, author={Julie Gervasoni and Robert N. Taub and M. T. Yu and David M. Warburton and Marlene Sabbath and Stephanie Gilleran and D L Coppock and John D'Alessandri and Sudhir Krishna and Michelle Rosado}, journal={Cancer research}, year={1992}, volume={52 19}, pages={5244-9} }