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Multifactorial drug resistance in an adriamycin-resistant human small cell lung carcinoma cell line
Abstract:
In a human small cell lung carcinoma cell line, GLC4, Adriamycin (ADR) resistance was induced. In the resistant cell line, GLC4/ADR, a 45% decreased intracellular ADR level was found compared to GLC4, but this could not fully explain the resistance. Evaluation of DNA damage in both cell lines after incubation with ADR by alkaline and neutral elution revealed single-strand breaks, DNA-protein cross-links, and double-strand breaks (DSB). At all incubation concentrations there was a decreased amount of all types of DNA damage in GLC4/ADR. The number of DSB was decreased also when corrected for the decreased intracellular concentration. This can at least partly be explained by the decreased stability of ADR induced DSB. After removal of ADR, 80% of DSB was repaired in 1 h in GLC4/ADR against no repair in GLC4. X-ray induced DSBs were also repaired faster: in GLC4/ADR t1/2 = 10 min and in GLC4 t1/2 = 23 min. Ratios for single strand breaks/DSBs and single strand breaks/DNA-protein cross-links between GLC4 and GLC4/ADR after exposure to ADR differed; these differences were compatible with differences in the distribution of the various types of DNA damage induced in the cell lines due to an altered ADR-topoisomerase II interaction. In this human small cell lung carcinoma cell line the resistance is multifactorial with decreased intracellular ADR levels, increased DNA repair, and altered ADR-topoisomerase interaction.
Insights
Adriamycin (ADR) resistance in lung cancer cells involves multiple factors. These include lower intracellular drug levels, enhanced DNA repair mechanisms, and altered interactions between ADR and topoisomerase II, contributing to multifactorial resistance.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Adriamycin (ADR) is a key chemotherapy agent for small cell lung carcinoma.
- Understanding ADR resistance mechanisms is crucial for improving treatment efficacy.
Purpose of the Study:
- To investigate the mechanisms of Adriamycin resistance in a human small cell lung carcinoma cell line (GLC4/ADR).
- To elucidate the roles of intracellular drug levels, DNA damage, and DNA repair in ADR resistance.
Main Methods:
- Induction of ADR resistance in GLC4 cells to create GLC4/ADR.
- Quantification of intracellular ADR levels.
- Evaluation of DNA damage (single-strand breaks, DNA-protein cross-links, double-strand breaks) using alkaline and neutral elution.
- Assessment of DNA repair kinetics for ADR- and X-ray-induced double-strand breaks.
- Analysis of ADR-topoisomerase II interaction.
Main Results:
- GLC4/ADR cells showed a 45% decrease in intracellular ADR levels.
- Reduced DNA damage (single-strand breaks, DNA-protein cross-links, double-strand breaks) was observed in GLC4/ADR cells.
- Enhanced repair of double-strand breaks occurred in GLC4/ADR cells compared to GLC4 cells.
- Altered ratios of DNA damage types suggested changes in ADR-topoisomerase II interaction.
Conclusions:
- Adriamycin resistance in this small cell lung carcinoma model is multifactorial.
- Key contributing factors include decreased intracellular ADR accumulation, increased DNA repair capacity, and altered topoisomerase II interaction with ADR.