Retinoid-induced activation of NF-kappaB in APL cells is not essential for granulocytic differentiation, but prolongs the life span of mature cells.
All-trans retinoic acid (ATRA) significantly improves the survival of patients with acute promyelocytic leukemia (APL) by inducing granulocytic differentiation of leukemia cells. Since an activation of the transcription factor NF-kappaB occurs during ATRA-induced maturation of APL cells, a mechanistic link between these two processes was investigated. Using an in vitro model for APL, we report that ectopic overexpression of a repressor of NF-kappaB activation did not affect granulocytic differentiation. Importantly, NF-kappaB inhibition markedly resulted in a decreased viability of the differentiated cells, which correlated with increased apoptosis. Apoptosis was accompanied by a sustained activation of the c-Jun N-terminal kinase (JNK). Inhibition of JNK by the specific inhibitor SP600125 or by transfection of a dominant-negative mutant of JNK1 reduced the percentage of apoptotic cells, thus showing that JNK activation constitutes a death signal. Furthermore, impairment of NF-kappaB activation resulted in increased levels of reactive oxygen species (ROS) upon ATRA treatment. ROS accumulation was suppressed by the antioxidant butylated hydroxyanisol, which also abolished ATRA-induced JNK activation and apoptosis. Altogether, our results demonstrate an anti-apoptotic effect of NF-kappaB activation during ATRA-induced differentiation of NB4 cells and identify repression of ROS-mediated JNK activation as a mechanism for this effect. Our observations also suggest that NF-kappaB signalling may contribute to an accumulation of mature APL cells and participate in the development of ATRA syndrome.
Mathieu
Julie
J
INSERM U685, Centre Hayem, Hôpital St Louis, 1 avenue Claude Vellefaux, 75475 Paris, France.
Giraudier
Stéphane
S
Lanotte
Michel
M
Besançon
Françoise
F
D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002083:Butylated Hydroxyanisole / Q000494:pharmacology; D039521:CD11c Antigen / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D016922:Cellular Senescence / Q000187:drug effects*; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects; D005434:Flow Cytometry; D019085:Fluorescent Antibody Technique, Direct; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D006098:Granulocytes / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D015473:Leukemia, Promyelocytic, Acute / Q000378:metabolism / Q000473:pathology*; D016328:NF-kappa B / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics; D013052:Spectrometry, X-Ray Emission; D014212:Tretinoin / Q000494:pharmacology*
D000975:Antioxidants; D039521:CD11c Antigen; D016328:NF-kappa B; D017382:Reactive Oxygen Species; D002083:Butylated Hydroxyanisole; D014212:Tretinoin; D048031:JNK Mitogen-Activated Protein Kinases