Activation of NF-kappaB binding in HT-29 colon cancer cells by inhibition of phosphatidylinositol 3-kinase.
The ubiquitous transcription factor NF-kappaB, which is activated in cells by diverse stimuli including phosphatidylinositol 3-kinase (PI3-kinase), is a critical factor for cell survival and growth. Inhibition of PI3-kinase enhances enterocyte-like differentiation of the human colon cancer cell line HT-29. The purpose of our study was to determine whether PI3-kinase alters NF-kappaB in HT-29 cells. Wortmannin, a specific PI3-kinase inhibitor, stimulated NF-kappaB binding activity in HT-29 cells by 4 h after treatment. Activation of NF-kappaB occurred without degradation of IkappaBalpha, a protein that sequesters NF-kappaB in the cytosol. In addition to increasing NF-kappaB binding, either wortmannin or cotransfection with a dominant negative mutant of the p85 regulatory subunit of PI3-kinase (Deltap85) induced NF-kappaB transactivation. Taken together, these results suggest that inhibition of PI3-kinase in HT-29 cells results in induction of NF-kappaB binding activity and transactivation which is independent of IkappaBalpha degradation.
Wang
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Department of Surgery, University of Texas Medical Branch, Galveston, Texas 77555, USA.
Kim
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S
Wang
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X
Evers
B M
BM
D003110:Colonic Neoplasms / Q000378:metabolism* / Q000473:pathology; D004268:DNA-Binding Proteins / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D019073:HT29 Cells; D006801:Humans; D006868:Hydrolysis; D020672:I-kappa B Proteins; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011485:Protein Binding; D014162:Transfection
D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D000081082:Phosphoinositide-3 Kinase Inhibitors; D000072000:NF-KappaB Inhibitor alpha