Contrary to MLN4924, phospho-NFB/p65 in response to TNF- localized mostly to the nucleus (Figure 3B). Taken together, our findings show that MLN4924 treatment significantly impairs the passage of phosphorylated forms of NFB/p65 from the cytosol into the nucleus and simultaneously increases nuclear levels of phospho-IB-. 2.5. We also revealed that MLN4924, similar Paullinic acid to TNF-, induced phosphorylation of inhibitor of nuclear factor kappa B-alpha (IB-). However, contrary to TNF-, MLN4924 did not induce IB- degradation in treated cells. In coimmunoprecipitation experiments, nuclear IB- which formed complexes with nuclear factor kappa B p65 subunit (NFB/p65) was found to be highly phosphorylated at Ser32 in the cells treated with MLN4924, but not in the cells treated with TNF- alone. Moreover, in the presence of MLN4924, nuclear NFB/p65 complexes were found to be enriched in c-Jun Paullinic acid and cyclin dependent kinase inhibitor 1 A (CDKN1A/p21) proteins. In these cells, NFB/p65 was unable to bind to the MMP9 gene promoter, which was confirmed by the chromatin immunoprecipitation (ChIP) assay. Taken together, our findings identified MLN4924 as a suppressor of TNF–induced MMP9-driven cell migration in esophageal squamous cell carcinoma (ESCC), likely acting by affecting the nuclear ubiquitinCproteasome system that governs NFB/p65 complex formation and its DNA binding activity in regard to the MMP9 promoter, suggesting that inhibition of neddylation might be a new therapeutic strategy to prevent invasion/metastasis in ESCC patients. < 0.05) was observed. In the cells treated with TNF- combined with MLN4924, the mRNA level of MMP9 was similar to that observed in untreated cells and remarkably lower as compared with the cells stimulated with TNF- alone. The differences were statistically significant (= 0.01). To determine the role of MLN4924 in modulating the availability of transcriptional regulators of the gene promoter, the levels of NFB/p65, SP1, c-Jun and CDKN1A/p21 proteins were analyzed by Western blotting in KYSE150 cells. We observed a significant increase in levels of c-Jun and CDKN1A/p21 Paullinic acid in a dose- and time-dependent manner in the cells treated with MLN4924 as compared with non-stimulated cells or those stimulated with TNF- alone (Figure 1A, Figure 2 and Figure S1). Open in a separate window Figure 1 Effect of tumor necrosis factor-alpha (TNF-) and MLN4924 on matrix metalloproteinase 9 (MMP9) expression and esophageal squamous cell carcinoma (ESCC) cell migration. (A) After overnight serum starvation, KYSE150 cells were pretreated or not with 1?M MLN4924 for 30 min and then stimulated with TNF- at the indicated concentration for 24?h. Activity DNM3 of MMP9 and MMP2 was analyzed by gelatin zymography in the conditioned media. The protein levels of membrane type I-matrix metalloproteinase (MT1-MMP), cyclin dependent kinase inhibitor 1A (CDKN1A/p21), c-Jun, nuclear factor kappa B (NFB) and SP1 were determined by Western blotting. Fold change calculated as the ratio of relative levels of proteins normalized to -actin (ACTB) between the cells treated with TNF- in combination with MLN4924 and the cells treated with TNF- alone is shown in Figure S4. Values shown are means SEM: whiskers: minCmax. (B) MMP9 messenger RNA (mRNA) expression was analyzed by reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) in both KYSE150 and KYSE70 cells treated for 24 h with TNF- (30 ng/mL) and MLN4924 (1 M) alone or in combination. Results are presented as fold change of gene in the treated cells relative to the untreated controls normalized to the expression of the reference gene encoding glyceraldehyde 3-phosphate dehydrogenase (< 0.001, ** < 0.05 vs. control. Ctrluntreated controls. Open in a separate window Figure 2 Effect of tumor necrosis factor-alpha (TNF-) and MLN4924 on the signaling pathways mediating matrix Paullinic acid metalloproteinase 9 (MMP9) gene expression in esophageal squamous cell carcinoma (ESCC) cells. (A) Proteome profiling of the nuclear factor kappa B (NFB) pathway by antibody array analyses in the KYSE150 cells treated with MLN4924 and TNF-. Protein lysates from the untreated controls and cells treated with MLN4924 or TNF- alone or in combination were analyzed using a human NFB array (R&D). (B) Bar graphs showing the phosphorylation ratio (upper) and the protein level Paullinic acid ratio (bottom) calculated after the semi-quantitative analysis of selected proteins. Results are presented as means SEM from duplicates. * < 0.001, ** < 0.05 vs. controls. The complete array is shown in Figure S3. (C) Western blot analysis showing time-dependent activation of inhibitor of nuclear factor kappa B-alpha (IB-), NFB/p65 and c-Jun in the KYSE150 cells treated with TNF- (30 ng/mL). (D) MLN4924-dependent changes in the activation of IB-, NFB/p65 and c-Jun as well as increasing levels of cyclin dependent kinase inhibitor 1A (CDKN1a/p21) protein in the KYSE150 cells within 24 h. (E) A dose-dependent effect of MLN4924 on activation of NFB/p65 and.
Contrary to MLN4924, phospho-NFB/p65 in response to TNF- localized mostly to the nucleus (Figure 3B)