Related Experiment Videos
Membrane transport changes in an adriamycin-resistant murine leukemia cell line and in its sensitive parental cell
1Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Canada.
Abstract:
Multidrug resistance in cancer chemotherapy occurs when cells develop resistance towards structurally and functionally unrelated drugs. It is speculated that alteration of some fundamental process(es) in the cells leads to the development of multidrug resistance. The sodium pump activity of murine leukemia cell lines P388/S (sensitive) and P388/ADR (resistant) was measured and found to be different in the two cell lines. The rate of sodium pumping, i.e., the ouabain-sensitive rubidium uptake, was consistently lower in the resistant cells compared to their parental controls. Uptake of adriamycin was lower in the resistant cells. Depolarizing the cells with potassium chloride or by inhibiting the pump with ouabain increased the adriamycin uptake in the sensitive cells but not in the resistant cells. Adriamycin did not have any acute effects on the sodium pump activity. It is concluded that the development of drug resistance in cell line P388 is associated with a decrease in sodium pump activity and a lack of depolarization-induced adriamycin uptake; these processes may be causally linked via alterations in cytosolic calcium concentration.
Insights
Multidrug resistance in cancer involves cells resisting multiple chemotherapy drugs. This study found resistant cells have lower sodium pump activity and reduced adriamycin uptake, potentially linked to altered calcium levels.
Area of Science:
- Oncology
- Cell Biology
- Pharmacology
Background:
- Multidrug resistance (MDR) is a major challenge in cancer chemotherapy, where cancer cells become resistant to structurally and functionally unrelated drugs.
- The underlying mechanisms of MDR are complex and may involve alterations in fundamental cellular processes.
Purpose of the Study:
- To investigate the role of sodium pump activity in the development of multidrug resistance in cancer cells.
- To explore the relationship between sodium pump function, adriamycin uptake, and cellular depolarization in drug-resistant leukemia cells.
Main Methods:
- Comparative analysis of sodium pump activity (ouabain-sensitive rubidium uptake) in drug-sensitive (P388/S) and drug-resistant (P388/ADR) murine leukemia cell lines.
- Measurement of adriamycin uptake in both cell lines under basal conditions and after cellular depolarization (using potassium chloride) or sodium pump inhibition (using ouabain).
Main Results:
- Resistant P388/ADR cells exhibited significantly lower sodium pump activity compared to sensitive P388/S cells.
- Adriamycin uptake was reduced in resistant cells.
- Depolarization or ouabain treatment enhanced adriamycin uptake in sensitive cells but not in resistant cells, indicating a loss of this mechanism in MDR.
Conclusions:
- The development of multidrug resistance in the P388 leukemia cell line is associated with decreased sodium pump activity.
- A lack of depolarization-induced adriamycin uptake in resistant cells suggests a functional link between sodium pump activity and drug transport.
- Alterations in cytosolic calcium concentration may be a key factor mediating these observed changes in drug resistance.