Comparison of Alzheimer disease-related gene expression in differentiated and undifferentiated NG108-15 cells

The pathogenesis of Alzheimer's disease (AD) is complicated and multifactorial, and is under the influence of genetic regulation. The NG108-15 cell line, a neuronal cell line, once differentiated exhibits neuron-like in morphology and intercellular synaptic junction formation. We, thus, hypothesize that the differentiation process may alter the expression patterns of AD-related genes in this cell line. This study primarily aimed to compare the expression patterns of five AD-related genes, namely AChE, COX-2, alpha 7 nAChR, gamma-secretase, and APR between undifferentiated and differentiated NG108-15 cells by RT-PCR techniques. The cyclic AMP analogue dibutyryl cAMP (Bt(2) cAMP) and 12-O-tetradecanoyl-phorbol 13-acetate (TPA) were used to induce neuronal differentiation. The differentiated NG108-15 cells exhibited neuron-like morphology and intercellular network formation. The level of AChE mRNA in differentiated cells was significantly greater than in undifferentiated cells at 2 and 3 day post-induction. Also, COX-2 mRNA expression in differentiated cells at day 1 post-induction was significantly greater than that in undifferentiated cells. in contrast, the expression of alpha 7 nAChR mRNA was significantly down-regulated in differentiated cells at 1 and 3 days post-induction, and the expression level of gamma-secretase mRNA was also significantly reduced in differentiated cells at 3 days post-induction. Interestingly, no significant difference of the expression of APR mRNA was detected. Our findings in this study indicate that the patterns of mRNA expression of AD related-genes in NG108-15 cells are changed after differentiation induction by Bt(2)cAMP and TPA.