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Externalization of transferrin receptor in established human cell lines
Y Kohgo1, Y Niitsu, T Nishisato
1Department of Internal Medicine, Sapporo Medical College, Japan.
Cell Biology International Reports
|December 1, 1987
Summary
Human tumor cells release transferrin receptors into the medium, a process influenced by temperature and specific inhibitors. This release occurs in a vesicular form, indicating a regulated cellular mechanism.
Area of Science:
- Cell biology
- Molecular biology
- Cancer research
Background:
- Transferrin receptors (TfR) are crucial for cellular iron uptake.
- Understanding TfR trafficking is vital for cancer biology and drug development.
Purpose of the Study:
- To investigate the process of transferrin receptor externalization in human tumor cells.
- To identify factors that regulate TfR release and its mechanism.
Main Methods:
- Incubation of human tumor cell lines with transferrin at varying temperatures (37°C and 4°C).
- Treatment with metabolic inhibitors (sodium azide, colchicine, cytochalasin B, chloroquine).
- Analysis of released TfR using high-speed centrifugation.
Main Results:
- Transferrin receptors were externalized at a rate of 10-35 ng/hour/10(6) cells at 37°C.
- Externalization was significantly inhibited by lower temperatures, ligand removal, and metabolic inhibitors.
- Approximately 95% of released TfR was found in a vesicular form after ultracentrifugation.
Conclusions:
- Transferrin receptor externalization in tumor cells is an active, regulated process.
- The release mechanism involves vesicular transport, influenced by cellular metabolism and environmental conditions.
- Findings suggest potential therapeutic targets related to TfR trafficking in cancer.