UCN‐01 alters phosphorylation of Akt and GSK3β and induces apoptosis in six independent human neuroblastoma cell lines

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Abstract
In this study we evaluated UCN‐01, a small molecule that inhibits protein kinases by interacting with the ATP‐binding site, as a potential anti‐cancer agent for neuroblastoma. UCN‐01 was effective at inducing apoptosis in six neuroblastoma cell lines with diverse cellular and genetic phenotypes. 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT), terminal deoxynucleotidyl transferase‐mediated dUTP nick‐end‐labeling (TUNEL) assays, detection of active caspase‐3 and cleaved poly ADP‐ribose polymerase (PARP) confirmed that UCN‐01 induced apoptosis. Cell cycle analysis determined that the UCN‐01 treated cells accumulated in S phase by 16 h. Unlike vinblastine and docetaxel that increased survivin expression, UCN‐01 treatment did not increase X‐linked inhibitor of apoptosis protein (XIAP) and survivin levels. Analysis of specific phosphoepitopes on chk1/2, Akt, and GSK3β following UCN‐01 treatment determined that there was no significant change in phospho‐chk1/2. However, there was decreased immunoreactivity at Ser473 and Thr308 of Akt and Ser9 of GSK3β by 4 h indicating that the Akt survival pathway and downstream signalling was compromised. Thus, UCN‐01 was effective at inducing apoptosis in neuroblastoma cell lines.