Okadaic acid stimulates expression of Fas receptor and Fas ligand by activation of nuclear factor kappa-B in human oral squamous carcinoma cells.

Abstract

In the present study, we used western blot and RT-PCR analysis to examine the expression of proteins and mRNAs of Fas receptor and Fas ligand in human oral squamous carcinoma SCC-25 cells treated with okadaic acid. Treatment with okadaic acid enhanced the expression of proteins and mRNAs of both Fas receptor and Fas ligand in SCC-25 cells. The amount of IkappaB-alpha in whole cell lysates decreased, while the level of NF-kappaB in nucleus increased, in the okadaic acid-treated cells. Okadaic acid-treatment also alters the cellular localization of NF-kappaB, from cytoplasm to nuclei. To investigate the activation of NF-kappaB in okadaic acid-treated SCC-25 cells, we performed electrophoretic mobility gel shift assay using nuclear extracts and the consensus oligonucleotide for NF-kappaB DNA binding site. The binding of nuclear proteins to the oligonucleotide of NF-kappaB increased when the cells had been treated with 20 nM okadaic acid for 4 h. We transfected the cells with pFLF1, which has the promoter region of Fas receptor gene containing NF-kappaB binding site. A luciferase reporter gene assay demonstrated that the activity in the cells transfected with pFLF1 and treated with 20 nM okadaic acid increased in a time-dependent manner and that the activity was more than three-fold over that in the control cells. Our results suggest that NF-kappaB activated at early stages in the okadaic acid-treated SCC-25 cells stimulated the promoter activity of Fas receptor in the cells leading to the apoptotic death of these cells.

• Authors: M Fujita, K Goto, K Yoshida, H Okamura, H Morimoto, S Kito, J Fukuda, T Haneji
• Journal: Oral oncology (Oral Oncol) Vol. 40 Issue 2 Pg. 199-206 (Feb 2004) ISSN: 1368-8375 [Print] England
• PMID: 14693245 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Enzyme Inhibitors
• FASLG protein, human
• Fas Ligand Protein
• I-kappa B Proteins
• Ligands
• Membrane Glycoproteins
• NF-kappa B
• NFKBIA protein, human
• Neoplasm Proteins
• fas Receptor
• NF-KappaB Inhibitor alpha
• Okadaic Acid

Topics

• Carcinoma, Squamous Cell (metabolism)
• Enzyme Inhibitors (pharmacology)
• Fas Ligand Protein
• Gene Expression Regulation, Neoplastic (drug effects)
• Humans
• I-kappa B Proteins (metabolism)
• Ligands
• Membrane Glycoproteins (drug effects, metabolism)
• NF-KappaB Inhibitor alpha
• NF-kappa B (drug effects, metabolism)
• Neoplasm Proteins (metabolism)
• Okadaic Acid (pharmacology)
• Promoter Regions, Genetic
• Reverse Transcriptase Polymerase Chain Reaction
• Tongue Neoplasms (metabolism)
• Transfection
• Tumor Cells, Cultured
• fas Receptor (drug effects, genetics, metabolism)