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Characterization and modulation of transitional cell carcinoma cell lines with acquired multidrug resistance
1Department of Surgery, Tri-Service General Hospital, National Defence Medical Centre, Taipei, Taiwan, Republic of China.
Objectives:
To characterize in vitro drug-induced multidrug resistance (MDR) in transitional cell carcinoma (TCC) cell lines, and to elucidate the possible mechanisms of acquired MDR and their modulation.
Materials And Methods:
Two drug-resistant cell lines, TCC8702/A1000 (adriamycin 1000 ng/mL) and TCC8803/A200 (adriamycin 200 ng/mL), were established after long-term adriamycin treatment for at least 16 months. Their biological characteristics, including growth morphology, doubling time and cell cycle, were analysed. The drug-resistance pattern to various anticancer drugs was measured using a microplate cytotoxicity assay. The modulation of drug sensitivity by calcium-channel blockers and protein kinase C inhibitor was assessed among the different cancer cell lines.
Results:
Both MDR sublines had lower growth rates, lower saturation densities and higher nuclear/cytoplasmic ratios than the parent cell lines. DNA staining and cell cycle analysis revealed that both TCC8702/A1000 and TCC8803/A200 cells had a decreased S-phase fraction and the TCC8803/A200 cells a changed stem line; both sublines showed increased expression of membranous glycoprotein gp-170. The cytoplasmic content of glutathione and glucose-6-phosphate dehydrogenase were not related to the MDR development in the sublines. The drug-resistance index of TCC8702/A1000 to adriamycin was 121-fold higher than the native cell line and TCC8803/A200 was 189-fold higher. TCC8803/A200 also had a broader MDR to cisplatin, vinblastine and vincristine. Calcium-channel blockers (verapamil, quinidine) and protein kinase C inhibitors (tamoxifen) inhibited gp-170 activity and slowed the drug-efflux pump, with the acquired-MDR cells subsequently accumulating anticancer drugs. A calcium antagonist-based combination of modulators all presented synergistic cytotoxic enhancement of the anticancer drugs. Parent TCC cell lines had a poorer response to modulator treatment than their MDR sublines.
Conclusion:
Different MDR mechanisms and subsequent modulator responses exist between native and acquired drug resistance in TCC cells. Acquired MDR seems strongly related to increased gp-170 expression and responds well to calcium antagonists. This phenomenon may be applicable in clinical conditions.
Insights
Drug-induced multidrug resistance (MDR) in transitional cell carcinoma (TCC) involves increased glycoprotein gp-170. Calcium antagonists effectively reverse MDR by inhibiting gp-170, offering potential clinical applications for TCC treatment.
Area of Science:
- Oncology
- Pharmacology
- Molecular Biology
Background:
- Transitional cell carcinoma (TCC) is a significant cause of cancer morbidity.
- Acquired multidrug resistance (MDR) is a major challenge in TCC treatment.
- Understanding MDR mechanisms is crucial for developing effective therapeutic strategies.
Purpose of the Study:
- To characterize in vitro drug-induced MDR in TCC cell lines.
- To identify mechanisms underlying acquired MDR in TCC.
- To evaluate the modulation of MDR by specific inhibitors.
Main Methods:
- Establishment of adriamycin-resistant TCC cell lines (TCC8702/A1000, TCC8803/A200) through long-term drug exposure.
- Analysis of biological characteristics: growth morphology, doubling time, cell cycle.
- Cytotoxicity assays to determine drug resistance patterns.
- Assessment of drug sensitivity modulation using calcium-channel blockers and protein kinase C inhibitors.
Main Results:
- MDR sublines exhibited reduced growth rates and increased expression of glycoprotein gp-170.
- TCC8803/A200 showed broader MDR to multiple chemotherapeutic agents.
- Calcium-channel blockers (verapamil, quinidine) and tamoxifen inhibited gp-170, enhancing drug accumulation and cytotoxicity.
- Combination therapy with calcium antagonists showed synergistic effects.
Conclusions:
- Acquired MDR in TCC is strongly associated with increased gp-170 expression.
- Calcium antagonists are effective in overcoming MDR by targeting gp-170.
- These findings suggest potential clinical utility of calcium antagonists in managing MDR-TCC.