mk-2206 and Neuroblastoma

Neuroblastoma is a pediatric tumor of the peripheral sympathetic nervous system with a highly variable prognosis. Activation of the phosphoinositide 3-kinase (PI3K)/AKT pathway in neuroblastoma is correlated with poor patient prognosis, but the precise downstream effectors mediating this effect have not been determined. Here we identify the forkhead transcription factor FOXO3a as a key target of the PI3K/AKT pathway in neuroblastoma. FOXO3a expression was elevated in low-stage neuroblastoma tumors and normal embryonal neuroblasts, but reduced in late-stage neuroblastoma. Inactivation of FOXO3a by AKT was essential for neuroblastoma cell survival. Treatment of neuroblastoma cells with the dual PI3K/mTOR inhibitor PI-103 activated FOXO3a and triggered apoptosis. This effect was rescued by FOXO3a silencing. Conversely, apoptosis induced by PI-103 or the AKT inhibitor MK-2206 was potentiated by FOXO3a overexpression. Furthermore, levels of total or phosphorylated FOXO3a correlated closely with apoptotic sensitivity to MK-2206. In clinical specimens, there was an inverse relationship between gene expression signatures regulated by PI3K signaling and FOXO3a transcriptional activity. Moreover, high PI3K activity and low FOXO3a activity were each associated with an extremely poor prognosis. Our work indicates that expression of FOXO3a and its targets offer useful prognostic markers as well as biomarkers for PI3K/AKT inhibitor efficacy in neuroblastoma.

Topics: Apoptosis; Cell Line, Tumor; Forkhead Box Protein O3; Forkhead Transcription Factors; Furans; Heterocyclic Compounds, 3-Ring; Humans; Neuroblastoma; Neurons; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Phosphorylation; Prognosis; Proto-Oncogene Proteins c-akt; Pyridines; Pyrimidines; Signal Transduction; Survival Rate

Activation of Akt is a marker of decreased event-free or overall survival in neuroblastoma patients. MK-2206, a novel allosteric Akt inhibitor, is now tested in clinical trials in adult cancers. In this study, effect of MK-2206 on tumor growth and murine survival, alone or in combination, with etoposide or rapamycin was evaluated.. The anticell proliferation effect of MK-2206 was tested in eight neuroblastoma cell lines by MTS assay. Caspase-3/7 activity, cell-cycle analysis, and reactive oxygen species (ROS) production were determined. Effect of MK-2206 combined with etoposide or rapamycin was evaluated in vitro and in vivo. Akt phosphorylation was measured by Western blotting in neuroblastoma cells and tumors.. In vitro, MK-2206 treatment inhibited neuroblastoma cell proliferation, which was accompanied by a cell line selective G(1) arrest of cell cycle or production of ROS. A synergistic effect between MK-2206 and etoposide was detected in four tested neuroblastoma cell lines via caspase-dependent apoptosis, whereas increased inhibition of cell growth induced by combination of MK-2206 and rapamycin was mediated by ROS production. In vivo, MK-2206 alone decreased tumor growth and increased murine survival at dose that inhibited Akt phosphorylation in tumors. MK-2206, in combination with etoposide or rapamycin, caused a significant decrease in tumor growth and increase of murine survival compared with MK-2206 alone.. Akt inhibition by MK-2206 increased the efficacy of etoposide or rapamycin. Our study supports future clinical evaluation of MK-2206 in combination with conventional cytotoxic therapy or with rapamycin in high-risk neuroblastoma patients.

Topics: Allosteric Regulation; Animals; Antineoplastic Combined Chemotherapy Protocols; Cell Line, Tumor; Cell Proliferation; Drug Synergism; Etoposide; Female; Heterocyclic Compounds, 3-Ring; Humans; Inhibitory Concentration 50; Mice; Mice, Nude; Neuroblastoma; Phosphorylation; Protein Processing, Post-Translational; Proto-Oncogene Proteins c-akt; Reactive Oxygen Species; Sirolimus; Tumor Burden; Xenograft Model Antitumor Assays