NF-κB Controls Resistance of Human Salivary Gland (HSG) Cells to Apoptosis in an in Vitro Model of Sjogren’s Syndrome

Aim: To elucidate the anti-apoptotic properties of nuclear factor kappa light-chain-enhancer of activated B cells (NF-κB) and feedback regulation of NF-κB by nuclear factor of kappa light-chain-enhancer of activated B-cells inhibitor alpha (IκBα). Methods: We developed an in vitro model of Sjogren’s syndrome by transfecting human salivary gland (HSG) and acinar cells (NS-SV-AC) with a plasmid-encoding IκBαM (pCMV-IκBαM), a degradation-resistant IκBα (nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha)-mutant, and examined TNF-induced apoptosis and anti-apoptotic properties of NF-κB. Apoptosis and induction of pro-apoptotic and anti-apoptotic genes were investigated by cDNA arrays, RT-PCR, electrophoretic mobility shift assays, and western blot. Results: In the presence of NF-κB inhibitors, TNF-induced apoptosis was markedly increased in both salivary gland and acinar cells. Increased caspase-3 activity was present in both HSG and NS-SV-AC cells. IκBαM-transfected salivary gland cells were more sensitive to TNF-induced apoptosis than IκBαM-transfected acinar cells. Transcription of pro-apoptotic genes was confirmed in both HSG and NS-SV-AC cells that were transfected with IκBαM. Results from caspase-3 activity assay confirmed previous experiments showing an apoptotic role for NF-κB. Conclusion: Data from gene expression arrays suggest that different mechanisms may operate during TNF-induced apoptosis in salivary gland ductal and acinar cells. Corresponding author.