Differentiation Intensifies the Susceptibility of Pheochromocytoma Cells to Antisense Oligodeoxynucleotide-Dependent Suppression of Acetylcholinesterase Activity

To investigate the effect of neuronal differentiation on the capacity of antisense oligonucleotides (AS-ODNs) to suppress the production of acetylcholinesterase (AChE) in rat pheochromocytoma cells, we tested seven 3‵-phosphorothioated AS-ODNs targeted to ACHEmRNA and two control ODNs. Three different administration protocols were used: oligonucleotides were added at 1 μM for 24 hours to nondifferentiated PC12 cells, together with nerve growth factor (NGF) or 24 hours following NGF-induced cholinergic differentiation. The content of free thiol groups in lysed cells was measured to evaluate cell number, therefore, survival, and the rate of acetylthiocholine hydrolysis was the measure of AChE activity. Among nondifferentiated cells, over 95% survived treatment with 8 of 9 of the ODNs. Moreover, two AS-ODN suppressed AChE activity in nondifferentiated PC12 cells by 16%-20% as compared with 10% suppression by control ODNs (p ≤ 0.01). When added concurrently with NGF, one other AS-ODN suppressed AChE activity ...