Expression of cell-cycle-dependent genes in serum stimulated cells whose entry into S phase is blocked by cytochalasin D

Abstract

A low concentration (0.6 μg/ml) of cytochalasin D inhibits the initiation of DNA synthesis after serum stimulation of growth-arrested GC-7 cells. Since actin-containing structures are suggested to be involved in the transfer of the growth signal to nuclei and in the synthesis and transport of nascent RNA, the effect of cytochalasin D on the expression of cell-cycle-regulated genes after serum stimulation was studied by Northern blot analysis. Cytoplasmic accumulation of such mRNAs as for c- fos, c- myc, β-actin and ornithine decarboxylase occurred in serum-stimulated cells regardless of the presence of cytochalasin D, whereas that of thymidine kinase and histone H3 was blocked by the drug.