Project description:To explore the underlying molecular mechanisms of FOXO3A-regulated AML cell function To determine the impact of FOXO3A deficiency on AML cells, we generated knock-out (KO) cells of FOXO3A using small guide RNAs (sgRNAs)
Project description:Neuroblastoma is a pediatric tumor of the peripheral sympathetic nervous system with a highly variable prognosis. Activation of the 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. Further, 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.
Project description:Neuroblastoma is a pediatric tumor of the peripheral sympathetic nervous system with a highly variable prognosis. Activation of the 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. Further, 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. Affymetrix U133 Plus 2.0 profiling of SY5Y-TetR-FOXO3A cells treated with doxycycline and/or the PI3K/mTOR inhibitor PI-103. Each condition profiled in triplicate.
Project description:c-Jun N-terminal kinase (JNK) plays a pivotal role in the regulation of cancer cell apoptosis. Previous studies have revealed that forkhead transcription factor (Foxo3a) is a critical effector of JNK-mediated tumor suppression. However, it is not clear whether caveolin-1 (CAV1) mediated JNK/Foxo3a pathway is involved in cancer cell apoptosis. We found that cordycepin upregulates CAV1 expression, which was accompanied by JNK phosphorylation (p-JNK), which induced Foxo3a translocation into the nucleus, resulting in the upregulation of levels of Bax protein. Furthermore, we found that CAV1 overexpression upregulated p-JNK, whereas siRNA mediated inhibition of CAV1 downregulated p-JNK, and that JNK inhibition by SP600125, a specific JNK inhibitor, significantly increased Foxo3a phosphorylation (p-Foxo3a), which attenuated Foxo3a translocation into the nucleus, indicating caveolin-1 mediated JNK’s regulation of Foxo3a. siRNA mediated inhibition of Foxo3a downregulated levels of Bax protein, attenuated A549 cell apoptosis, indicating that CAV1 mediated JNK/Foxo3a pathway induce the apoptosis of A549 lung cancer cells. Taken, together, these results indicate that cordycepin promotes CAV1 upregulation to enhance JNK/Foxo3a signaling pathway activation to induce apoptosis in lung cancer cells and support the potential of cordycepin as a therapeutic agent for lung cancer.
Project description:Persistence of memory CD4+ T cells in ECs was coupled with the inactivation of FOXO3a transcriptional activities, which we have previously identified as a critical regulator of TCM survival. Indeed, expression levels of transcriptional targets of FOXO3a, endowed with pro-apoptotic and anti-proliferative functions, were lower in TCM and TEM from ECs as compared to ST individuals. Silencing the transcriptionally active form of FOXO3a by siRNA rescued TCM and TEM of STs from Fas-mediated apoptosis. Moreover the expression of FOXO3a dominant negative form (FOXO3a Nt) rescued the long-term survival of TCM from STs as these cells persisted as long as those derived from ECs. Overall, these studies indicate that FOXO3a activation is an important mediator of the shortened survival and heighteined turnover of TCM and TEM in chronic HIV infection. Targeting this pathway may provide a strategy to preserve memory T cell numbers in HIV infection. Keywords: comparative gene profile, cell-type comparison