Related Experiment Videos
Effects of epidermal growth factor receptor blocking in cultured glioma spheroids
J Capala1, H Acker, A Lindström
1Department of Radiation Sciences, Uppsala University, Sweden.
Abstract:
A concentration as high as 1 microgram/ml of non-radioactive epidermal growth factor, EGF/was necessary to inhibit effectively the binding of 125I-EGF in glioma U-343MGaC12:6 cells. This concentration blocked the available EGF receptors within 30 minutes in monolayers, while 24 hour treatments were required in spheroids. The effects on growth, incorporation of radioactive thymidine, cell density and on extracellular pH were analysed in spheroids after exposure to 1 microgram/ml EGF. The high EGF concentration did not significantly modify the growth curves for monolayers and small spheroids but increased the volume growth of large spheroids. The increase was partly due to lower cell density and partly to increased proliferation. The EGF treatment gave an increased incorporation of thymidine in spheroids, for at least up to 5 days after the administration, while no effect was seen in monolayers. The cell density decreased after the EGF treatment as seen from morphometric analysis in histological sections and by counting the number of cells per volume unit after trypsinization. The capacity to take up radiolabelled dextran increased, probably due to the decreased cell density. Other EGF-induced changes were also recognized, such as a reduction in extracellular pH by 0.1 units in the central regions of spheroids and an increase in intracellular pH by 0.47 units in analysed monolayer cells. The results showed that it is not possible to block the EGF-receptors without imposing changes in growth and metabolism.
Insights
High concentrations of epidermal growth factor (EGF) blocked EGF receptors in glioma cells. This blockade altered cell growth, proliferation, and pH, indicating complex cellular responses to EGF receptor inhibition.
Area of Science:
- Cell Biology
- Molecular Biology
- Cancer Research
Background:
- Epidermal Growth Factor (EGF) plays a crucial role in cell growth and proliferation.
- EGF receptors are frequently dysregulated in various cancers, including gliomas.
- Understanding the effects of EGF receptor blockade is vital for developing targeted cancer therapies.
Purpose of the Study:
- To investigate the effects of non-radioactive epidermal growth factor (EGF) on EGF receptor binding and cellular responses in glioma cells.
- To analyze the impact of EGF receptor blockade on cell growth, proliferation, cell density, and pH in both monolayer and spheroid cultures.
- To determine if complete blockade of EGF receptors can be achieved without inducing significant cellular changes.
Main Methods:
- Utilized 1 microgram/ml of non-radioactive EGF to inhibit 125I-EGF binding in U-343MGaC12:6 glioma cells.
- Compared treatment durations (30 minutes vs. 24 hours) for monolayers and spheroids.
- Assessed effects on growth curves, thymidine incorporation, cell density, extracellular pH, and radiolabeled dextran uptake.
Main Results:
- A high concentration of EGF (1 microgram/ml) was required to effectively block EGF receptors, with longer treatment times needed for spheroids.
- EGF treatment increased the volume growth of large spheroids, attributed to decreased cell density and increased proliferation.
- Significant changes in thymidine incorporation, cell density, extracellular pH, and intracellular pH were observed in response to EGF treatment, even with receptor blockade.
Conclusions:
- Complete blockade of EGF receptors in glioma cells necessitates high EGF concentrations and induces significant alterations in cellular growth and metabolism.
- The study highlights the complex interplay between EGF signaling, cell density, and pH regulation in glioma.
- It is not feasible to block EGF receptors without impacting fundamental cellular processes, underscoring the challenges in targeting this pathway.