Enhancement of cytokine-mediated NF-kappaB activation by phosphatidylinositol 3-kinase inhibitors in monocytic cells.
Nuclear factor-kappaB (NF-kappaB) is a transcription factor that plays crucial roles in inflammation and immunity. Understanding the positive and negative regulation of NF-kappaB activity is therefore of fundamental importance. A few previous studies reported that inhibition of the phosphatidylinositol 3-kinase (PI3K)-Akt pathway enhances lipopolysaccharide (LPS)-induced activation of NF-kappaB. However, many aspects of the PI3K negative regulation of NF-kappaB activation remain to be clarified. The present study was conducted to shed light on cell-type specificity, stimulus specificity, and upstream mechanisms of the enhanced NF-kappaB activation by PI3K inhibitors. Gel shift assays showed that LY294002 (LY29) potently increased interleukin (IL)-1-induced NF-kappaB DNA binding in human monocytic THP-1 cells. Moreover, another PI3K inhibitor 3-methyladenine also strongly enhanced IL-1-induced NF-kappaB DNA binding, while LY303511, an inactive analogue of LY29, did not increase the NF-kappaB DNA binding. Compared with LY29, wortmannin (WM) effected only a marginal enhancement of NF-kappaB DNA binding. LY29 treatment also augmented tumor necrosis factor (TNF)-mediated NF-kappaB DNA binding. Furthermore, LY29, but not WM, increased cyclooxygenase (COX)-2 mRNA expression by IL-1 or TNF in THP-1 cells. Likewise, prostaglandin E2 production by IL-1 was increased by LY29, but not by WM. Western blot analysis demonstrated that IkappaB kinase (IKK) activation as well as IkappaB-alpha degradation and NF-kappaB nuclear translocation was elevated by LY29 and WM. Among the tested cell lines (HL-60, ECV304, Hep-2, and Molt-4), only HL-60, a promyelocytic cell line, showed enhanced NF-kappaB DNA binding by LY29. These results suggest that pharmacological inhibition of PI3K enhances the NF-kappaB-activating pathways by IL-1 through augmentation of IKK activation in myeloid/monocytic cells and the NF-kappaB enhancement is more robustly achieved by LY29 than by WM.
Choi
Eun-Kyoung
EK
Dental Science Research Institute, Chonnam National University Dental School, 300 Yongbong-Dong, Puk-Gu, Kwangju 500-757, South Korea.
Jang
Ho-Cheol
HC
Kim
Jae-Hyung
JH
Kim
Hyun-Jin
HJ
Kang
Ho-Cheol
HC
Paek
Yun-Woong
YW
Lee
Hyun-Chul
HC
Lee
Seung-Hoon
SH
Oh
Won-Mann
WM
Kang
In-Chol
IC
D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D002460:Cell Line; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002867:Chromones / Q000494:pharmacology; D051546:Cyclooxygenase 2 / Q000235:genetics; D016207:Cytokines / Q000494:pharmacology*; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D018922:HL-60 Cells; D006801:Humans; D051550:I-kappa B Kinase / Q000378:metabolism; D007375:Interleukin-1 / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008214:Lymphocytes / Q000187:drug effects / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism*; D009025:Morpholines / Q000494:pharmacology; D016328:NF-kappa B / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D010879:Piperazines / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D002867:Chromones; D016207:Cytokines; D004791:Enzyme Inhibitors; D007375:Interleukin-1; D008070:Lipopolysaccharides; D008565:Membrane Proteins; D009025:Morpholines; D016328:NF-kappa B; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010879:Piperazines; D014409:Tumor Necrosis Factor-alpha; C093555:LY 303511; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D051550:I-kappa B Kinase