NF-κB activation induced by Notch ligand stimulation in acute myeloid leukemia cells

There are conflicting reports regarding the effects of Notch activation on nuclear factor-kappa B (NF-kappa B) activity. The relationships are cell type-dependent and have not been fully elucidated. We examined the effects of Notch activation induced by a recombinant Notch ligand, Delta-like1 (DIII), on the NF-kappa B activity in two acute myeloid leukemia (AML) cell lines. We found that Deltal-induced Notch activation activated the NF-kappa B pathway in THP-1 cells. Regarding the possible mechanisms, D111 stimulation increased the mRNA and protein expression levels of some components of the NF-kappa B pathway and induced phosphorylation of IKK alpha/beta, I kappa B and RelA proteins after 24 or 48 It of stimulation. Since the phosphorylation required a long time, it did not appear to be caused by physical interactions between Notch and NF-kappa B proteins, but rather by indirect effects. One possible mechanism for the indirect effects was the observed induction of IL-I beta expression by Dill stimulation. On the other hand, Notch activation did not affect NF-kappa B activity in TMD7 cells. RelA was phosphorylated without stimulation, indicating that NF-kappa B was constitutively activated in TMD7 cells. To the best of our knowledge, this is the first study to investigate AML, cells and use a recombinant Notch ligand to activate Notch. The present findings lead to better understanding of Notch functions, which have not been fully elucidated.