Cell surface and other morphological changes accompanying growth inhibition in simian virus 40-transformed 3T3 mouse fibroblasts cells induced by glucocorticoids§

Abstract

A number of morphological changes accompany the G2 blockage caused by glucocorticosteroids in simian virus 40-transformed 3T3 mouse fibroblasts cells. Under phase contrast microscopy dexamethasone-treated cells have darkened and raised nuclear regions with ‘lines’ running over their cytoplasmic areas. They are more resistant to trypsinization and smaller in volume. Since inhibitors of DNA and protein synthesis prevent this ‘glucocorticoid morphology’, the ‘darkening’ may be due to the accumulation of macromolecules within G2-blocked cells and the induction of a protein(s) may be needed for the morphological changes. Colchicine and cytochalasin B do not bring about the glucocorticoid morphology, suggesting that it is not due to a general de-polymerization of microtubules or microfilaments. With scanning electron microscopy treated cells show a great reduction in the amount and a re-organization of microvilli and microplicae. Granules of lead precipitate at the periphery are also clearly evident in transmission electron micrographs. These observations reveal profound morphological alterations, including cell surface changes, induced by glucocorticosteroids.