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FK506 reverses adriamycin resistance in a multidrug-resistant human leukemia cell line
1Department of Medicine, Kobe University School of Medicine.
Abstract:
We have examined the effect of FK506 on the Adriamycin sensitivity of the multidrug resistant human chronic myelocytic leukemia cell line (K562/ADM). In K562/ADM cells, 1.0 microgram/ml FK506 reversed the resistance of Adriamycin, and increased the IC50 value for Adriamycin up to 17 fold. However, IC50 value for the parent cells (K562) increased only 1.5 fold. By cell cycle analysis, the accumulation in late S-G2M phase was confirmed on K562/ADM cells, treated with 1.0 microgram/ml FK506 and low-dose of Adriamycin. Cyclosporin A (CsA) could also restored the Adriamycin sensitivity in the K562/ADM cells, as previously reported. 1.0 microgram/ml FK506 as well as CsA significantly increased radioactive Adriamycin accumulation in K562/ADM cells and blocked [3H]azidopien photoaffinity labeling of P-glycoprotein. These results suggest that 1.0 microgram/ml FK506 could reverse the Adriamycin resistance in a MDR human leukemia cells through the interaction with P-glycoprotein.
Insights
FK506 effectively reverses Adriamycin resistance in multidrug-resistant leukemia cells by interacting with P-glycoprotein. This finding offers potential new strategies for overcoming drug resistance in cancer therapy.
Area of Science:
- Pharmacology
- Cancer Biology
- Molecular Biology
Background:
- Multidrug resistance (MDR) is a major challenge in leukemia treatment.
- P-glycoprotein (P-gp) is a key efflux pump contributing to MDR.
- Adriamycin is a common chemotherapeutic agent often rendered ineffective by MDR.
Purpose of the Study:
- To investigate the effect of FK506 on Adriamycin sensitivity in a human chronic myelocytic leukemia cell line (K562/ADM).
- To explore the mechanism by which FK506 modulates Adriamycin resistance.
Main Methods:
- Cell viability assays to determine IC50 values for Adriamycin in K562/ADM and parent K562 cells with and without FK506.
- Cell cycle analysis to assess the impact of FK506 and Adriamycin on cell proliferation.
- Radioactive Adriamycin accumulation studies and P-glycoprotein photoaffinity labeling to investigate drug-efflux mechanisms.
Main Results:
- FK506 (1.0 microgram/ml) significantly reversed Adriamycin resistance in K562/ADM cells, increasing Adriamycin's IC50 by up to 17-fold.
- FK506 treatment, along with low-dose Adriamycin, led to accumulation of cells in the late S-G2M phase.
- FK506, similar to Cyclosporin A, enhanced Adriamycin accumulation in K562/ADM cells and inhibited P-glycoprotein labeling.
Conclusions:
- FK506 demonstrates potential as an agent to overcome Adriamycin resistance in multidrug-resistant leukemia.
- The mechanism of FK506 involves interaction with P-glycoprotein, inhibiting its efflux function.
- These findings suggest FK506 as a promising therapeutic adjunct for treating resistant leukemia.