Effects of fluorescent derivatives of TPA on HL60 cells: dissociation between the differentiation-induced and protein kinase C activity.
The four fluorescent derivatives of TPA--dansylaza-TPA, NBDaza-TPA, and (N)- and (P)-dansylamino-TPA--were synthesized and examined for their ability to induce differentiation in human promyelocytic leukemic HL60 cells. At a concentration of 20 nM, all the derivatives inhibited proliferation and induced 60-80% of the cells to differentiate into macrophage-like cells. Removal of dansylaza-TPA from the medium after 5 h did not arrest adherence or the expression of nonspecific esterase activity. However, upon removal of any of the other three compounds after 5 h, HL60 cells became nonadherent and expressed low nonspecific esterase activity after additional culture. To investigate the relationship between protein kinase C (PKC) activation and cell maturation, PKC activity and translocation were measured after 0.5, 5, 24, and 48 h of treatment with each compound. Cells induced to differentiate by dansylaza-TPA or (N)- or (P)-dansylamino-TPA exhibited enhanced PKC activity, 50-80% of which was located in the particulate fraction. In cells that differentiated with NBDaza-TPA, 65-70% of PKC activity remained in the cytosol. After removal of the TPA derivatives, all cells exhibited PKC activity in the cytosol. These results indicate that the fluorescent derivatives are as potent as TPA in inducing HL60 cell differentiation. However, in the case of NBDaza-TPA and (N)- or (P)-dansylamino-TPA, their continuous presence in the culture medium was required for the recruitment of cells to differentiate. Consequently, it is suggested that activation and translocation of PKC are among the early biochemical events that trigger HL60 cell differentiation. Nevertheless, these two events alone are not sufficient to induce differentiation.
Tran
P L
PL
Immunogénétique Moléculaire, Institut des Cordeliers, Paris, France.
Le Peuch
C
C
Basset
M
M
D002448:Cell Adhesion / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects*; D006801:Humans; D011493:Protein Kinase C / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000031:analogs & derivatives* / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate