dolichol-monophosphate and Leukemia--Monocytic--Acute

Treatment of U937 cells with dolichyl phosphate led to an increase in the activity of the ICE family protease CPP32, accompanied with cleavage of pre-CPP32 to generate p17. Peptide inhibitors YVAD-cmk and Z-Asp-CH2-DCB (specific to ICE) and DEVD-CHO (specific to CPP32) blocked the dolichyl phosphate-induced apoptosis. The dolichyl phosphate-induced increase of CPP32 activity was inhibited by adenylate cyclase inhibitors, SQ 22536 and 2',5'-dideoxyadenosine. Dolichyl phosphate caused a transient increase of intracellular cAMP concentration. The results suggest that modulation of cAMP synthesis due to the stimulation of adenylate cyclase by dolichyl phosphate plays a critical role in CPP32 activation and apoptosis.

Topics: Adenine; Adenylyl Cyclase Inhibitors; Adenylyl Cyclases; Apoptosis; Caspase 3; Caspases; Cyclic AMP; Cysteine Endopeptidases; Dideoxyadenosine; DNA Fragmentation; Dolichol Phosphates; Enzyme Activation; Enzyme Inhibitors; Enzyme Precursors; Humans; Kinetics; Leukemia, Monocytic, Acute; Tumor Cells, Cultured

Exogenous dolichyl phosphate (Dol-P) induced apoptosis in the human monoblastic leukemia cell line U937 within 4 hours. Phosphorylation of p42 mitogen-activated protein kinase (MAP kinase) increased prior to DNA fragmentation. MAP kinase activation occurred within 5 min, and the maximum response was observed at 30 min. Inhibition of tyrosine phosphorylation of MAP kinase by herbimycin A resulted in complete inhibition of DNA fragmentation and partial inhibition of cell death. These results suggested that Dol-P-induced apoptosis is mediated by the MAP kinase cascade.

Topics: Antibiotics, Antineoplastic; Apoptosis; Benzoquinones; Calcium-Calmodulin-Dependent Protein Kinases; Cell Line; Cell Survival; DNA Damage; DNA, Neoplasm; Dolichol Phosphates; Enzyme Activation; Humans; Kinetics; Lactams, Macrocyclic; Leukemia, Monocytic, Acute; Quinones; Rifabutin; Time Factors; Tumor Cells, Cultured