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Protein phosphorylation in multidrug resistant Chinese hamster cells
1Laboratory of Cellular and Biochemical Genetics, Memorial Sloan-Kettering Cancer Center, New York NY 10021.
Cancer Communications
|January 1, 1989
Summary
Multidrug resistance in cells involves altered protein phosphorylation, affecting key proteins like P-glycoprotein. These changes in protein phosphorylation may link to resistance development and cell transformation.
Area of Science:
- Biochemistry
- Cell Biology
- Molecular Pharmacology
Background:
- Multidrug resistance (MDR) is a complex cellular phenomenon.
- Reverse transformation is observed in some MDR cells.
- Protein phosphorylation plays a crucial role in cellular regulation.
Purpose of the Study:
- To investigate alterations in protein phosphorylation in multidrug resistant cells.
- To compare phosphorylation patterns between drug-sensitive and drug-resistant Chinese hamster cells.
- To identify specific proteins affected by altered phosphorylation in MDR cells.
Main Methods:
- Gel electrophoretic analysis of in vitro protein phosphorylation using [gamma-32P]ATP.
- Metabolic labeling of cells with [32P]-orthophosphate.
- Comparison of phosphorylation levels in drug-sensitive (DC-3F) and drug-resistant (DC-3F/VCRd-5L, DC-3F/AD X) cell lines.
Main Results:
- Increased 32P incorporation into proteins of resistant cells compared to sensitive cells.
- Demonstrated phosphorylation of P-glycoprotein and sorcin in resistant cells.
- Protein phosphorylation differences in cell-free extracts reflect events in intact cells.
Conclusions:
- Altered protein phosphorylation is evident in multidrug resistant Chinese hamster cells.
- Changes in kinase and/or phosphatase activities are likely involved in MDR.
- Altered phosphorylation may be associated with P-glycoprotein function, reverse transformation, and proliferation inhibition.
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