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Plasma membrane proteins and glycoproteins from Chinese hamster cells sensitive and resistant to actinomycin D
Abstract:
Plasma membrane proteins and glycoproteins have been isolated from Chinese hamster cells of the spontaneously transformed DC-3F parental cell line and the DC-3F/AD X line with a high level of acquired resistance to actinomycin D. Plasma membrane preparations from both cell lines band at 1.16 g/ml after isopycnic centrifugation. We present evidence to indicate differences in the leucylpeptide backbones of the antibiotic-sensitive cells and the drug-resistant DC-3F/AD X cells. In addition, there are differences in the plasma membrane glycopeptides of the two cell lines as revealed by sodium dodecyl gel electrophoresis. Drug-resistant cells synthesize a surface glycopeptide which is much larger than the major one present on the drug-sensitive cells. Both of these cell lines are devoid of 5'-nucleotidase and alkaline phosphatase activities. The role of plasma membrane protein differences in drug-resistant cells is discussed.
Insights
Drug-resistant Chinese hamster cells exhibit altered plasma membrane proteins and glycoproteins compared to sensitive cells. These differences, particularly in glycopeptides, may contribute to actinomycin D resistance.
Area of Science:
- Cell Biology
- Biochemistry
- Molecular Pharmacology
Background:
- Acquired resistance to chemotherapeutic agents like actinomycin D is a significant challenge in cancer treatment.
- Understanding the molecular mechanisms underlying drug resistance is crucial for developing effective therapies.
- Plasma membrane alterations are often implicated in cellular responses to drugs.
Purpose of the Study:
- To investigate differences in plasma membrane proteins and glycoproteins between actinomycin D-sensitive and resistant Chinese hamster cells.
- To identify specific molecular changes associated with acquired drug resistance.
Main Methods:
- Isolation and purification of plasma membrane proteins and glycoproteins from DC-3F (sensitive) and DC-3F/AD X (resistant) cell lines.
- Isopycnic centrifugation to characterize plasma membrane preparations.
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to analyze protein and glycopeptide profiles.
Main Results:
- Plasma membrane preparations from both cell lines showed similar buoyant densities.
- Evidence suggests differences in the leucylpeptide backbones between sensitive and resistant cells.
- SDS-PAGE revealed distinct glycopeptide profiles, with resistant cells synthesizing a larger surface glycopeptide.
Conclusions:
- Acquired resistance to actinomycin D in Chinese hamster cells is associated with significant alterations in plasma membrane protein and glycopeptide composition.
- The larger surface glycopeptide in resistant cells may play a role in mediating drug resistance.
- Further research is warranted to elucidate the functional significance of these plasma membrane changes in drug resistance.