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Characterisation of adriamycin- and amsacrine-resistant human leukaemic T cell lines
Abstract:
Cell lines resistant to adriamycin and amsacrine were derived from cloned sublines of the human T cell line Jurkat. Most of the lines resemble atypical MDR cells (Danks et al., 1987; Beck et al., 1987). Thus, resistant Jurkat sublines were cross resistant to several topoisomerase II inhibiting drugs but had low or no resistance to other classes of drugs, resistance was not reversed by verapamil, Pgp was not overexpressed, and drug accumulation was unaltered in resistant compared to parental (control) sublines. Other findings were that anthracycline metabolism differed between resistant and parental sublines, and that resistant sublines displayed altered expression of small polypeptides (less than 20K MW) and an 85K MW protein. Drug resistant cells showed resistance to the production of drug induced cytogenetic aberrations, DNA breaks, and protein-DNA complexes. Resistance was not mediated by altered binding of drugs to DNA or by increased repair of DNA damage. Indirect evidence suggests that the resistant cells had an altered drug-DNA-topoisomerase II association. The study highlights the complex relationships between DNA breaks, cytogenetic aberrations, protein-DNA complexes and drug cytotoxicity, and shows that the relationships differ for adriamycin and amsacrine, suggesting some differences in the modes of action and/or resistance for the drugs and cell lines.
Insights
Drug-resistant Jurkat cells exhibit cross-resistance to topoisomerase II inhibitors, but not through typical multidrug resistance mechanisms. Altered drug metabolism and protein expression suggest unique resistance pathways.
Area of Science:
- Cell Biology
- Molecular Pharmacology
- Genetics
Background:
- Multidrug resistance (MDR) is a significant challenge in cancer chemotherapy.
- Adriamycin and amsacrine are topoisomerase II inhibiting drugs used in cancer treatment.
- Understanding novel resistance mechanisms is crucial for improving therapeutic efficacy.
Purpose of the Study:
- To characterize drug resistance mechanisms in adriamycin- and amsacrine-resistant Jurkat T cell lines.
- To investigate whether these resistant cell lines exhibit typical MDR phenotypes.
- To explore the molecular basis of resistance to topoisomerase II inhibitors.
Main Methods:
- Derivation of adriamycin- and amsacrine-resistant Jurkat sublines.
- Cross-resistance profiling against various drug classes.
- Assessment of P-glycoprotein (Pgp) expression and drug accumulation.
- Analysis of anthracycline metabolism and protein expression.
- Evaluation of drug-induced DNA damage, cytogenetic aberrations, and protein-DNA complexes.
Main Results:
- Resistant Jurkat sublines showed cross-resistance to topoisomerase II inhibitors but not other drug classes.
- Resistance was not associated with Pgp overexpression or altered drug accumulation.
- Differences in anthracycline metabolism and expression of specific polypeptides were observed.
- Resistant cells were less susceptible to drug-induced DNA breaks, cytogenetic aberrations, and protein-DNA complexes.
- Altered drug-DNA-topoisomerase II association is suggested as a resistance mechanism.
Conclusions:
- The derived Jurkat sublines represent atypical MDR cells with unique resistance mechanisms.
- Resistance is not mediated by classical Pgp-dependent efflux or enhanced DNA repair.
- Complex interplay between drug-DNA-topoisomerase II interactions and cellular responses dictates cytotoxicity.
- Adriamycin and amsacrine may exhibit distinct modes of action and resistance profiles in these cell lines.