TIAZOFURIN-INDUCED CHANGES IN INOSITOL LIPID CYCLE IN NUCLEI OF FRIEND-ERYTHROLEUKEMIA CELLS

When murine erythroleukemia cells are treated up to 96 hrs with the antitumor drug tiazofurin the induction of erythroid differentiation is accompanied by changes in both synthesis and breakdown of phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5 bisphosphate in the nucleus. These changes, which parallel the effect of dimethylsulfoxide, a well known inducer of erythroid differentiation in vitro, are due to the inhibition of the nuclear phosphoinositidase C activity. Therefore the present data indicate the nuclear inositol lipid cycle as a target of tiazofurin in addition to its inhibition of IMP dehydrogenase (EC 1.1.1.205) activity. © 1993 Academic Press, Inc.