stilbenes and Neoplasms--Squamous-Cell

Cyclooxygenase-2 (COX-2) content is increased in many types of tumor cells. We have investigated the mechanism by which resveratrol, a stilbene that is pro-apoptotic in many tumor cell lines, causes apoptosis in human head and neck squamous cell carcinoma UMSCC-22B cells by a mechanism involving cellular COX-2. UMSCC-22B cells treated with resveratrol for 24 h, with or without selected inhibitors, were examined: (1) for the presence of nuclear activated ERK1/2, p53 and COX-2, (2) for evidence of apoptosis, and (3) by chromatin immunoprecipitation to demonstrate p53 binding to the p21 promoter. Stilbene-induced apoptosis was concentration-dependent, and associated with ERK1/2 activation, serine-15 p53 phosphorylation and nuclear accumulation of these proteins. These effects were blocked by inhibition of either ERK1/2 or p53 activation. Resveratrol also caused p53 binding to the p21 promoter and increased abundance of COX-2 protein in UMSCC-22B cell nuclei. Resveratrol-induced nuclear COX-2 accumulation was dependent upon ERK1/2 activation, but not p53 activation. Activation of p53 and p53-dependent apoptosis were blocked by the COX-2 inhibitor, NS398, and by transfection of cells with COX-2-siRNA. In UMSCC-22B cells, resveratrol-induced apoptosis and induction of nuclear COX-2 accumulation share dependence on the ERK1/2 signal transduction pathway. Resveratrol-inducible nuclear accumulation of COX-2 is essential for p53 activation and p53-dependent apoptosis in these cancer cells.

Topics: Apoptosis; Cell Line, Tumor; Cell Nucleus; Cyclin-Dependent Kinase Inhibitor p21; Cyclooxygenase 2; Drug Screening Assays, Antitumor; Enzyme Activation; Extracellular Signal-Regulated MAP Kinases; Head and Neck Neoplasms; Humans; MAP Kinase Signaling System; Models, Biological; Neoplasms, Squamous Cell; Nitrobenzenes; p38 Mitogen-Activated Protein Kinases; Phosphoserine; Promoter Regions, Genetic; Protein Binding; Protein Kinase Inhibitors; Resveratrol; Stilbenes; Subcellular Fractions; Sulfonamides; Tumor Suppressor Protein p53