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: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:ALK mutations occur in 10% of primary neuroblastoma and represent a major target for precision treatment. In combination with MYCN amplification, ALK mutations infer an ultra-high-risk phenotype with very poor prognosis. To anticipate to future precision drugging, a deeper understanding of the molecular consequences of constitutive ALK signaling and its relationship to MYCN activity in this aggressive pediatric tumor, will be essential to understand treatment responses and failure as well as to ensure improved design of drugging combinations. We show that mutant ALK downregulates the HMG-box transcription factor 1 (HBP1) through the PI3K-AKT-FOXO3a signaling axis. Interestingly, we also demonstrate that HBP1 is under control of MYCN, through negative regulation of the miR-17~92 cluster. Moreover, modulation of HBP1 in neuroblastoma negatively affect MYCN activity, including alleviating MYCN/PRC2 controlled gene repression. Combined targeting of PI3K and MYCN signaling induced strong synergistic blocking of tumor growth, thus offering potential for targeted therapeutic interventions.
Project description:ALK mutations occur in 10% of primary neuroblastoma and represent a major target for precision treatment. In combination with MYCN amplification, ALK mutations infer an ultra-high-risk phenotype with very poor prognosis. To anticipate to future precision drugging, a deeper understanding of the molecular consequences of constitutive ALK signaling and its relationship to MYCN activity in this aggressive pediatric tumor, will be essential to understand treatment responses and failure as well as to ensure improved design of drugging combinations. We show that mutant ALK downregulates the HMG-box transcription factor 1 (HBP1) through the PI3K-AKT-FOXO3a signaling axis. Interestingly, we also demonstrate that HBP1 is under control of MYCN, through negative regulation of the miR-17~92 cluster. Moreover, modulation of HBP1 in neuroblastoma negatively affect MYCN activity, including alleviating MYCN/PRC2 controlled gene repression. Combined targeting of PI3K and MYCN signaling induced strong synergistic blocking of tumor growth, thus offering potential for targeted therapeutic interventions.
Project description:Self-renewing tumor initiating cells that are capable of differentiation and responsible for tumor growth have been isolated from cancers and cell lines. If such minor populations are associated with tumor progression, understanding molecular pathways that are required for viability and maintenance of these populations will allow to target these pathways to eradicate tumors that are resistant to existing therapies. In this study we enriched for prostate cancer progenitors (Pr. CPM-CM-"M-BM-^@M-BM-^Ys) expressing cell surface markers CD44/CD133/alpha 2 beta 1 integrin in non-adherent serum-free growth conditions maintained as spheres. Cells grown in these conditions have increased in vivo clonogenic and in vivo tumorigenic potential. microarray analysis of cells grown in sphere conditions compared with long term monolayer culture conditions revealed preferential activation of PI3K/AKT pathway in prostate cancer progenitors. PI3K p110 alpha and beta protein levels were high in sphere condition cultured cells, and PTEN knockdown lead to an increase in Pr.CPM-CM-"M-BM-^@M-BM-^Ys, and to increased clonogenic and tumorigenic potential. Inhibition of Akt1 phosphorylation target FoxO3a lead to inhibition of tumorigenic capacity in vivo for prostate cancer cells. Inhibition of PI3K activity by PI3K inhibitor NVP-BEZ235 lead to a selective inhibition of Pr.CPM-CM-"M-BM-^@M-BM-^Ys, nuclear localization of FoxO3a and increase in GADD45a in prostate cancer cells. Taken together our data strongly suggest that PTEN and PI3K/Akt pathways are critical for prostate cancer stem-like cell maintenance and targeting the PI3K signaling by selective inhibitors may give an incredible advancement in prostate cancer treatment. Experiment Overall Design: sphere and monolayer cultures from two different prostate cancer cell lines
Project description:Self-renewing tumor initiating cells that are capable of differentiation and responsible for tumor growth have been isolated from cancers and cell lines. If such minor populations are associated with tumor progression, understanding molecular pathways that are required for viability and maintenance of these populations will allow to target these pathways to eradicate tumors that are resistant to existing therapies. In this study we enriched for prostate cancer progenitors (Pr. CP’s) expressing cell surface markers CD44/CD133/alpha 2 beta 1 integrin in non-adherent serum-free growth conditions maintained as spheres. Cells grown in these conditions have increased in vivo clonogenic and in vivo tumorigenic potential. microarray analysis of cells grown in sphere conditions compared with long term monolayer culture conditions revealed preferential activation of PI3K/AKT pathway in prostate cancer progenitors. PI3K p110 alpha and beta protein levels were high in sphere condition cultured cells, and PTEN knockdown lead to an increase in Pr.CP’s, and to increased clonogenic and tumorigenic potential. Inhibition of Akt1 phosphorylation target FoxO3a lead to inhibition of tumorigenic capacity in vivo for prostate cancer cells. Inhibition of PI3K activity by PI3K inhibitor NVP-BEZ235 lead to a selective inhibition of Pr.CP’s, nuclear localization of FoxO3a and increase in GADD45a in prostate cancer cells. Taken together our data strongly suggest that PTEN and PI3K/Akt pathways are critical for prostate cancer stem-like cell maintenance and targeting the PI3K signaling by selective inhibitors may give an incredible advancement in prostate cancer treatment. Keywords: multiple tissues
Project description:Dysregulation of PI3K/Akt signaling is a dominant feature in basal-like or triple-negative breast cancers (TNBC). However, the mechanisms regulating this pathway are largely unknown in this subset of aggressive tumors. Here we demonstrate that the transcription factor SOX4 is a key regulator of PI3K signaling in TNBC. Genomic and proteomic analyses coupled with mechanistic studies identified TGFBR2 as a direct transcriptional target of SOX4 and demonstrated that TGFBR2 is required to mediate SOX4-dependent PI3K signaling. We further report that SOX4 and the SWI/SNF ATPase SMARCA4, which are uniformly overexpressed in basal-like tumors, form a previously unreported complex that is required to maintain an open chromatin conformation at the TGFBR2 regulatory regions in order to mediate TGFBR2 expression and PI3K signaling. Collectively, our findings delineate the mechanism by which SOX4 and SMARCA4 cooperatively regulate PI3K/Akt signaling and suggest that this complex may play an essential role in TNBC genesis and/or progression.
Project description:Dysregulation of PI3K/Akt signaling is a dominant feature in basal-like or triple-negative breast cancers (TNBC). However, the mechanisms regulating this pathway are largely unknown in this subset of aggressive tumors. Here we demonstrate that the transcription factor SOX4 is a key regulator of PI3K signaling in TNBC. Genomic and proteomic analyses coupled with mechanistic studies identified TGFBR2 as a direct transcriptional target of SOX4 and demonstrated that TGFBR2 is required to mediate SOX4-dependent PI3K signaling. We further report that SOX4 and the SWI/SNF ATPase SMARCA4, which are uniformly overexpressed in basal-like tumors, form a previously unreported complex that is required to maintain an open chromatin conformation at the TGFBR2 regulatory regions in order to mediate TGFBR2 expression and PI3K signaling. Collectively, our findings delineate the mechanism by which SOX4 and SMARCA4 cooperatively regulate PI3K/Akt signaling and suggest that this complex may play an essential role in TNBC genesis and/or progression. Kinase enrichment proteomic analysis was performed using HCC1143 breast cancer cells treated with a control siRNA pool or a pool targeting SOX4 in biological triplicate to evaluate the effects on the functional kinome.
Project description:Strong activation of the oncogenic Wnt/beta-catenin pathway is a main mechanism of resistance to FOXO3a-induced apoptosis promoted by PI3K and AKT inhibitors in colorectal cancer (CRC). Reducing Wnt/beta-catenin activity would sensitize colorectal tumors to these inhibitors. However, no Wnt/beta-catenin signaling inhibitor has proven clinical potential yet. Recently, inhibitors that block tankyrases were shown to reduce colon cancer cell proliferation by decreasing nuclear beta-catenin. We aim to identify determinants of response to these novel Wnt-inhibitors. Therefore, we treated in vivo three different patient-derived xenograft models (PDX; P2, P5 and P30) growing subcutaneously in NOD SCID mice with the novel tankyrase inhibitor NVP-TNKS656.
Project description:Dataset containing multiple Hyptis and Artemisia spp. used for the discovery of natural products inhibiting aberrant signaling, namely MAPK/ERK and PI3K/AKT, in melanoma