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Induced interphase cell retraction: its reversal and EGF potentiation
Tissue & Cell
|January 1, 1989
Summary
Epidermal growth factor (EGF) induces cell retraction in carcinoma cells by altering pH and sodium transport. Normal cells also retract under specific conditions, with EGF potentiating this effect.
Area of Science:
- Cell biology
- Biophysics
- Cancer research
Background:
- Epidermal growth factor (EGF) is known to influence cell behavior.
- Carcinoma cells exhibit distinct responses to stimuli compared to normal cells.
- Cell shape and attachment are critical for cellular functions.
Purpose of the Study:
- To investigate the phenomenon of cell retraction induced by epidermal growth factor (EGF).
- To explore the role of ion transport, specifically sodium (Na+) and proton (H+) exchange, in EGF-mediated cell retraction.
- To compare the retraction response in carcinoma cells versus normal anchor-dependent cells.
Main Methods:
- Utilizing human epidermoid A431 carcinoma cells and normal anchor-dependent cells.
- Inducing cell retraction via saline incubation with pH upshifting and EGF prepulsing.
- Quantifying cell shape changes using profile area and perimeter measurements.
- Assessing ion flux with 22Na+ uptake studies and measuring intracellular pH (pHi).
- Employing inhibitors like trifluoperazine and amiloride, and manipulating extracellular sodium concentrations to block or reverse retraction.
Main Results:
- EGF significantly potentiates cell retraction in A431 cells, a phenomenon also observed to a lesser extent in normal cells under pH changes.
- Cell retraction is dependent on Na+/H+ exchange, as evidenced by blockage with inhibitors and Na+ omission.
- Reversal of retraction occurs in low extracellular sodium, accompanied by rapid 22Na+ efflux, with a dose-dependent inhibition by ouabain.
- Ouabain does not prevent reversal in low Na+ or in high Na+ with calcium.
Conclusions:
- EGF-induced cell retraction is mediated by alterations in ion transport, particularly Na+/H+ exchange.
- Normal cells exhibit a similar, though less pronounced, retraction response to altered pH, which can be potentiated by EGF.
- The reversal of cell retraction is linked to sodium efflux and is modulated by extracellular sodium concentration and ouabain sensitivity.