Induction of Heat Shock Protein 70 Inhibits NF-kappa-B in Squamous Cell Carcinoma

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Abstract
To determine the relationship between heat shock proteins (HSPs) and the proinflammatory, anti-apoptosis mediator NF-kappa-B in squamous cell carcinoma. CA-9-22 cells were exposed to heat stress to induce the production of HSPs. Immunoblot and reporter gene experiments determined the inducibility of HSP production and the activation of cytokine-induced NF-kappa-B. Immunoblot experiments determined the presence of the inhibitor-kappa-B-alpha (IkappaB alpha). CA-9-22 cells can be induced by heat stress to produce HSPs at 100-fold above baseline levels. The induction of HSPs prevents the activation and nuclear translocation of NF-kappa-B despite stimulation with IL-1beta and TNF-alpha. Constitutive activation of NF-kappa-B is prevented by HSP induction through an increase in IkappaB alpha synthesis. The induction of HSP70 alters the inflammatory milieu associated with squamous cell carcinoma progression through the inhibition of NF-kappa-B and may ultimately promote apoptosis in head and neck carcinoma.