In recent years targeted thera peutic approaches such as Imatinib or Rituximab have been developed and implemented successfully in the treatment. However, despite of these implementa tions the prognosis of adult patients remains poor indi how to order cating the need for further research in order to identify and evaluate new potential drugs targeting deregulated signaling pathways. Arylindolylmaleimides are a group of synthetic mole cules characterized by the conjunction of a maleimide compound with a bicyclic indole ring and a further aro matic structure. PDA 66 is an analogue of the arylindo lylmaleimide SB 216763 and was newly synthesized as described by Pews Davtyan et al. Both compounds possess similar structural features, but differ in their substitution pattern.

In comparison to SB 216763, in PDA 66 the indolyl group is characterized by an unprotected 2 methylindole unit, while the malei mide group is methylated. Notably, the 2,4 dichloro sub stitution pattern is replaced with 4 acetyl group. Concerning functional activity SB 216763 was shown to inhibit the enzyme activity of Glycogen Synthase Kinase 3B by 96% at a concentration of 10 uM in an ATP competitive manner leading to to manufacturers protocol. The corresponding medium was supplemented with 10% heat inactivated fetal bovine serum and 1% penicillin and streptomycin. The MOLT4 cells were cultured with medium supplemented with 20% heat inactivated fetal bovine serum. All cells were maintained at 37 C in 5% CO2. Treatment of ALL cell lines with PDA 66 Cells were seeded in 24 well plates Akt signaling antagonizing cell growth and cell cycle progression in both pathways.

However, inhibition of GSK3B led to decreased cell growth and increased apoptosis in different tumor cell lines as glioblastoma cells, gastrointestinal cancer cells, ovarian cancer cells, medullary thyroid cancer cells, pancreatic cancer cells and primary pediatric ALL cells. Joint previous analyses published by Eisenlffel et al. investigated the influence of PDA 66 in human neuronal progenitor cells and revealed an inhibitory effect on proliferation and an increased rate of apoptosis. Fur thermore, an antiproliferative impact on human lung can cer and glioblastoma cell lines was detected. In this study, we analyzed the biological effects of PDA 66 on B and T ALL cell lines and determined the influ ence on kinase activity of human recombinant GSK3B.

Our results show an inhibitory effect on the proliferation and metabolic activity of ALL cells accompanied by an in crease in apoptosis and necrosis rates. Furthermore, a minor effect on GSK3B activity could be demonstrated which was not as pronounced as caused by SB 216763. Methods Brefeldin A Inhibitors PDA 66 was synthesized at the Leibniz Institute for Ca talysis and kindly provided by the Albrecht Kossel Institute. SB 216763 was purchased from Sigma.