Small Molecule Inhibitors Targeting Nuclear Factor κB Activation Markedly Reduce Expression of Interleukin-2, but Not Interferon-γ, Induced by Phorbol Esters and Calcium Ionophores.

The T-box transcription factor Eomesodermin (Eomes) promotes the expression of interferon-γ (IFN-γ). We recently reported that the small molecule inhibitors, TPCA-1 and IKK-16, which target nuclear factor κB (NF-κB) activation, moderately reduced Eomes-dependent IFN-γ expression in mouse lymphoma BW5147 cells stimulated with phorbol 12-myristate 13-acetate (PMA) and ionomycin (IM). In the present study, we investigated the direct effects of NF-κB on IFN-γ expression in mouse lymphoma EL4 cells and primary effector T cells. Eomes strongly promoted IFN-γ expression and the binding of RelA and NFATc2 to the IFN-γ promoter when EL4 cells were stimulated with PMA and IM. Neither TPCA-1 nor IKK-16 reduced IFN-γ expression; however, they markedly decreased interleukin (IL)-2 expression in Eomes-transfected EL4 cells. Moreover, TPCA-1 markedly inhibited the binding of RelA, but not that of Eomes or NFATc2 to the IFN-γ promoter. In effector CD4+ and CD8+ T cells activated with anti-CD3 and anti-CD28 antibodies, IFN-γ expression induced by PMA and A23187 was not markedly decreased by TPCA-1 or IKK-16 under conditions where IL-2 expression was markedly reduced. Therefore, the present results revealed that NF-κB is dispensable for IFN-γ expression induced by PMA and calcium ionophores in EL4 cells expressing Eomes and primary effector T cells.

Eomesodermin promotes interaction of RelA and NFATc2 with the Ifng promoter and multiple conserved noncoding sequences across the Ifng locus in mouse lymphoma BW5147 cells.

The T-box transcription factor Eomesodermin (Eomes) regulates the lineage-dependent expression of interferon γ (IFN-γ). We previously showed that Eomes promotes IFN-γ production and interacts with multiple conserved noncoding sequences (CNS) across the Ifng locus in mouse lymphoma BW5147 cells. In the present study, we investigated the transcriptional regulation of IFN-γ by the nuclear factor κB (NF-κB) subunit RelA and nuclear factor of activated T cells c2 (NFATc2, also known as NFAT1) in Eomes-transfected BW5147 cells. Eomes promoted the interaction of RelA and NFATc2 with the Ifng promoter and five CNS, including CNS-22 and CNS+30 upon stimulation with phorbol 12-myristate 13-acetate (PMA) and ionomycin (IM). The dual NF-κB and STAT3 inhibitor TPCA-1 moderately reduced the PMA- and IM-induced IFN-γ transcription in Eomes-transfected BW5147 cells. TPCA-1 interfered with RelA binding to the Ifng promoter, CNS-22 and CNS+30. Moreover, TPCA-1 reduced the interaction of Eomes or NFATc2 with the Ifng promoter and CNS+30. The present results indicate that Eomes promotes the interaction of RelA and NFATc2 with the Ifng promoter and multiple CNS across the Ifng locus in BW5147 cells.

4-Hydroxypanduratin A and Isopanduratin A Inhibit Tumor Necrosis Factor α-Stimulated Gene Expression and the Nuclear Factor κB-Dependent Signaling Pathway in Human Lung Adenocarcinoma A549 Cells.

Tumor necrosis factor α (TNF-α), a pro-inflammatory cytokine, regulates inflammatory and immune responses by up-regulating gene expression in a manner that is dependent on the transcription factor nuclear factor κB (NF-κB). In the present study, we found that 4-hydroxypanduratin A and isopanduratin A, constituents of the rhizomes of Boesenbergia pandurata, inhibited the TNF-α-stimulated up-regulation of intercellular adhesion molecule-1 (ICAM-1) in human lung adenocarcinoma A549 cells. 4-Hydroxypanduratin A and isopanduratin A also reduced ICAM-1 mRNA expression and NF-κB-responsive luciferase activity in TNF-α-stimulated A549 cells. Moreover, 4-hydroxypanduratin A and isopanduratin A prevented the TNF-α-stimulated translocation of the NF-κB subunit p65 to the nucleus and the phosphorylation and proteasomal degradation of the inhibitor of the NF-κB α protein. The present results revealed that 4-hydroxypanduratin A and isopanduratin A inhibit TNF-α-stimulated gene expression and the NF-κB-dependent signaling pathway in A549 cells.

Asiatic Acid, Corosolic Acid, and Maslinic Acid Interfere with Intracellular Trafficking and N-Linked Glycosylation of Intercellular Adhesion Molecule-1.

The pentacyclic triterpenoid ursolic acid was previously shown to inhibit the intracellular trafficking of intercellular adhesion molecule-1 (ICAM-1) from the endoplasmic reticulum (ER) to the Golgi apparatus. In the present study, we further investigated the biological activities of three pentacyclic triterpenoids closely related to ursolic acid on the interleukin 1α-induced expression and intracellular trafficking of ICAM-1. In human lung adenocarcinoma A549 cells, asiatic acid, corosolic acid, and maslinic acid interfered with the intracellular transport of ICAM-1 to the cell surface. Endoglycosidase H-sensitive glycans were linked to ICAM-1 in asiatic acid-, corosolic acid-, and maslinic acid-treated cells. Unlike corosolic acid, asiatic acid and maslinic acid increased the amount of the ICAM-1 protein. Moreover, asiatic acid increased the co-localization of ICAM-1 with calnexin (an ER marker), but not GM130 (a cis-Golgi marker). Asiatic acid, corosolic acid, and maslinic acid inhibited yeast α-glucosidase activity, but not Jack bean α-mannosidase activity. These results indicate that asiatic acid, corosolic acid, and maslinic acid interfere with the intracellular transport of ICAM-1 to the cell surface and cause the accumulation of ICAM-1 linked to endoglycosidase H-sensitive glycans.

Kujigamberol interferes with pro-inflammatory cytokine-induced expression of and N-glycan modifications to cell adhesion molecules at different stages in human umbilical vein endothelial cells.

Kujigamberol is the norlabdane compound isolated from Kuji amber and has recently been shown to prevent Ca2+-signal transduction and exert anti-allergy effects in vitro and in vivo. However, the anti-inflammatory activities of kujigamberol remain unclear. In the present study, we investigated the biological activities of kujigamberol on cell adhesion molecules expressed on human umbilical vein endothelial cells (HUVEC) in response to pro-inflammatory cytokines. Kujigamberol decreased the molecular weight of intercellular adhesion molecule-1 (ICAM-1) by altering N-glycan modifications. In contrast to ICAM-1, kujigamberol reduced the interleukin-1α- or tumor necrosis factor α-induced expression of vascular cell adhesion molecule-1 (VCAM-1) and E-selectin at the mRNA and protein levels. Kujigamberol B, but not kujiol A, decreased the molecular weight of the ICAM-1 protein. Kujigamberol moderately inhibited yeast α-glucosidases, whereas it was only weakly inhibited by kujigamberol B and more weakly by kujiol A. Three compounds did not inhibit Jack bean α-mannosidases. The present results reveal new biological activities of kujigamberol, which interfere with the pro-inflammatory cytokine-induced expression of and N-glycan modifications to cell adhesion molecules in HUVEC.

Allantopyrone A interferes with multiple components of the TNF receptor 1 complex and blocks RIP1 modifications in the TNF-α-induced signaling pathway.

Allantopyrone A is a fungal metabolite that uniquely possesses two α,ß-unsaturated carbonyl moieties. We recently reported that allantopyrone A inhibited the nuclear factor-κB (NF-κB) signaling pathway induced by tumor necrosis factor (TNF)-α in human lung carcinoma A549 cells. In the present study, the mechanism by which allantopyrone A inhibits the TNF-α-induced signaling pathway was investigated in more detail. Allantopyrone A blocked extensive modifications to receptor-interacting protein 1 (RIP1) in the TNF receptor 1 (TNF-R1) complex. Allantopyrone A augmented the high-MW bands of TNF-R1, TNF receptor-associated factor 2, RIP1, the NF-κB subunit RelA and inhibitor of NF-κB kinase ß in A549 cells, suggesting that it binds to and promotes the crosslinking of these proteins. The extracellular cysteine-rich domains of TNF-R1 were crosslinked by allantopyrone A more preferentially than its intracellular portion. The present results demonstrate that allantopyrone A interferes with multiple components of the TNF-R1 complex and blocks RIP1 modifications in the TNF-α-induced NF-κB signaling pathway.