Enhancement of TPA-induced growth inhibition and apoptosis in myeloid leukemia cells by BAY 11-7082, an NF-kappaB inhibitor

• Published in: International journal of oncology Vol. 27; no. 4; p. 941
• Main Authors: Hansson, Annette, Marín, Yarí E, Suh, Junghan, Rabson, Arnold B, Chen, Suzie, Huberman, Eliezer, Chang, Richard L, Conney, Allan H, Zheng, Xi
• Format: Journal Article
• Language: English
• Published: Greece 01-10-2005
• Subjects: Active Transport, Cell Nucleus; Apoptosis; Cell Adhesion; Cell Differentiation; Cell Line, Tumor; Cell Nucleus - metabolism; Cell Proliferation - drug effects; Cell Survival; DNA - chemistry; DNA Damage; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Gene Expression Regulation, Neoplastic; HL-60 Cells; Humans; I-kappa B Proteins - metabolism; Immunophenotyping; Leukemia, Myeloid - drug therapy; NF-kappa B - antagonists & inhibitors; NF-kappa B - metabolism; NF-KappaB Inhibitor alpha; Nitriles - pharmacology; Phosphorylation; Propidium - pharmacology; Protein Kinase C - metabolism; Protein Kinase C beta; Sulfones - pharmacology; Tetradecanoylphorbol Acetate - pharmacology; Time Factors
• ISSN: 1019-6439

The phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA) is a potent stimulator of differentiation and apoptosis in myeloid leukemia cells. In the present study, we investigated the role of the transcription factor NF-kappaB in TPA-induced growth inhibition and apoptosis in the myeloid leukemia HL-60 cell line and its TPA-resistant cell variant HL-525. Unlike the parental cell line, HL-525 cells are protein kinase C (PKC)-beta deficient and resistant to TPA-induced differentiation and apoptosis. We found that treatment of HL-60 cells with TPA resulted in a concentration-dependent growth inhibition and an increase in apoptotic cells. TPA only had a small effect on growth and apoptosis in HL-525 cells. Treatment of HL-60 cells with TPA (0.64-3.2 nM) caused a rapid activation of NF-kappaB as determined by electrophoresis mobility shift assay (EMSA) and immunocytochemistry. Although the basal level of NF-kappaB activity was low in HL-60 cells, TPA-resistant HL-525 cells had a high basal level of NF-kappaB activity. Treatment of HL-525 cells with higher concentrations of TPA (16-80 nM) resulted in a further increase in NF-kappaB activity. (E)3-[(4-methylphenyl)-sulfonyl]-2-propenenitrile (BAY 11-7082; BAY), which inhibits IkappaB alpha phosphorylation and thus decreases NF-kappaB activation, was found to decrease TPA-induced nuclear translocation of NF-kappaB. Furthermore, BAY enhanced TPA-induced growth inhibition and apoptosis in both HL-60 and HL-525 cells. Results from the present study indicate that inhibition of NF-kappaB by BAY was associated with enhanced TPA-induced growth inhibition and apoptosis in human myeloid leukemia cells. TPA in combination with pharmacological inhibitors of NF-kappaB may improve the therapeutic efficacy of TPA and overcome the resistance to TPA in some myeloid leukemia patients.