UC Irvine

The amount of polyadenylic acid [poly(A)]-containing cytoplasmic RNA in malignant and 'differentiated' mouse neuroblastoma cells in culture was determined. 4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone (R020-1724), prostaglandin (PG)E1, serum-free medium, X-irradiation and sodium butyrate were used to induce 'differentiation'. The cAMP-induced 'differentiated' cells had more poly(A)-containing cytoplasmic RNA than the malignant cells; the increase in poly-(A)-RNA was greatest in R020-1724-treated cells. The amount of poly(A)-containing cytoplasmic RNA did not significantly change in serum-free medium- or sodium butyrate-treated cells; however, it decreased in cells of confluent phase of growth. The percentage of total radioactive RNA in the cytoplasms of cAMP-induced 'differentiated' cells after 1 h of labeling was three-fold greater than that in malignant cells, indicating that transport of RNA from nucleus to cytoplasm occurs at relatively higher rate in 'differentiated' cells. The stability of RNA in cAMP-induced 'differentiated' cells increased in comparison to malignant cells. The binding of actinomycin D with DNA suggests that the proportion of guanine residues that are accessible to actinomycin D are similar in the nuclei of malignant and cAMP-induced 'differentiated' cells. The present and previous studies suggest that cAMP induces many differentiated functions in neuroblastoma cells by increasing both the transcription and translation of genetic information which is probably masked during malignant transformation of nerve cells. © 1975.