| Abstract: | We previously established a serum-free hormone-supplemented medium for the induction of adipocyte differentiation of 3T3-L1 cells (Gamou, S. and N. Shimizu. in "Growth and Differentiation of Cells in Defined Environment", H. Murakami et al., ed., Kodansha/Springer-Verlag, pp. 173-178, 1985). Under those conditions the stage of the cell's commitment to adipocyte differentiation was separated from the stage of expression of the adipocyte phenotype. In the current study, the relationship between cell division of the growth-arrested 3T3-L1 cells and their entry into the differentiation program was examined by autoradiography at the individual cell level. It was found that cells treated with the inducers dexamethasone and 1-methyl-3-isobutylxanthine went through DNA synthesis (S phase) prior to lipid accumulation and that insulin enhanced this differentiation process. Under these serum-free hormone-supplemented conditions, the tumor promoter dihydroteleocidin B was found to be a strong inhibitor of adipocyte differentiation. |
