An intact NF-kappaB pathway is required for histone deacetylase inhibitor-induced G1 arrest and maturation in U937 human myeloid leukemia cells.
The role of NFkappaB in regulating G1 arrest and maturation induced by the histone deacetylase inhibitor sodium butyrate (NaB) was examined in human myelomonocytic leukemia cells (U937). Cells stably transfected with an IkappaBalpha "super-repressor" lacking phosphorylation sites necessary for proteasomal degradation exhibited diminished IkBa phosphorylation and NF-kappaB DNA binding upon exposure to TNFalpha When exposed to NaB (1 mM; 48 hr) or PMA (5 nM; 24 hr), IkappaBalphaM cells displayed a marked reduction in G1 arrest compared to Neo controls. In each case, this was accompanied by a significant reduction in the percentage of cells expressing the differentiation markers CD11a, CD11b, and CD18. The impairment in NaB-induced maturation in mutant cells was associated with a reciprocal increase in apoptosis. In contrast to impairment in NaB- or PMA-induced NF-kappaB DNA binding, stable expression of the IkappaBalphaM did not modify DNA binding of SP1 or AP2 transcription factors. IkappaBalphaM cells also displayed impairment in NaB- and PMA-mediated induction of p21CIP1 and phosphorylation (inactivation) of p34cdc2, as well as diminished levels of pRb-bound E2F1. Finally, the NF-kappaB inhibitor CAPE antagonized NaB- and PMA-related NF-kappaB DNA binding as well as induction of p21CIP1. Together, these findings suggest that NF-kappaB plays an important functional role in mediating NaB-induced p21CIP1 induction, G1 arrest, and maturation in human myelomonocytic leukemia cells, and that disruption of the NF-kappaB pathway causes cells to engage an alternative, apoptotic program.
Dai
Yun
Y
Division of Hematology/Oncology, Department of Medicine, Virginia Commonwealth University, Medical College of Virginia, Richmond, Virginia 23298, USA.
Rahmani
Mohamed
M
Grant
Steven
S
D017209:Apoptosis / Q000502:physiology; D002087:Butyrates / Q000633:toxicity; D018845:CD11 Antigens / Q000378:metabolism; D018821:CD18 Antigens / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000378:metabolism; D005786:Gene Expression Regulation; D006655:Histone Deacetylases / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D020298:U937 Cells; D054462:p21-Activated Kinases
D002087:Butyrates; D018845:CD11 Antigens; D018821:CD18 Antigens; D004791:Enzyme Inhibitors; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases; D006655:Histone Deacetylases