CG5 DX HUMAN BREAST-CANCER CELL-LINE - CHARACTERIZATION OF A NEW DOXORUBICIN-RESISTANT VARIANT/

By continuous exposure of CG5 human brest cancer cell line to increasi ng doxorubicin (Dx) concentrations, a multidrug-resistant (MDR) sublin e (CG5/Dx) was obtained. The resistant variant showed P-glycoprotein ( P-gp) expression and a lower intracellular doxorubicin level than the parental cells. CG5/Dx cells were 19.4 fold more resistant to Dx than CG5 cells and showed a cross-resistance to some structurally related a nd unrelated compounds. Differences in kinetics, biological and ultras tructural features between the two cell lines were investigated. The C G5/Dx cells grew more slowly, produced higher CEA levels and showed a reduced progesterone receptor (PgR) content than the parental cells. U ltrastructural studies revealed differences involving, polyribosomes, rough endoplasmic reticulum, [mithocondria] and cytoskeleton.