Previous investigations have demonstrated the presence of conventional lipid kinases and phospholipase C (PLC) activities in nuclei of Friend erythroleukemia cells. Moreover, when Friend erythroleukemia cells are treated for 96 h with the antitumor drug tiazofurin, the induction of erythroid differentiation is accompanied by changes in amounts of both phosphatidylinositol and phosphatidylinositol 4,5-bisphosphate due to the inhibition of an uncharacterized nuclear PLC activity. Here, we show that the nuclear PLC β1 isoform is down-regulated by tiazofurin (5 µm) treatment of Friend erythroleukemia cells as shown by both Western blot and Northern blot analyses for PLC β1 message. This indicates that PLC β1 down-regulation is tightly linked with erythroid differentiation of Friend erythroleukemia cells and that the autonomous nuclear signaling via inositol lipid cycle can be controlled by the antitumor drug tiazofurin.


This work was supported by Italian Consiglio Nazionale delle Ricerche Grants PF IG and PF ACRO and by AFRC International Scientific Interchange Scheme.

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