Smac mimetics are considered as promising cancer therapeutics, but little is yet known about how they alter gene expression. In this study we used an unbiased genome-wide expression array to investigate Smac mimetic BV6-induced gene regulation in breast cancer cell lines. Kinetic analysis revealed that BV6 alters gene expression in two waves. The first wave primarily involves NF-B- and AP-1 families of transcription factors, while the second wave largely depends on tumor necrosis factor receptor 1 (TNFR1) signaling. Interestingly, disrupting auto-/paracrine tumor necrosis factor- (TNF)/ (TNFR1) signaling by knockdown of TNFR1 strongly attenuates the BV6-induced second wave of gene expression and upregulation of many pathways including NF-B signaling, apoptosis and immune signalling, but not MAPK signaling pathways. Consistently, BV6 stimulates phosphorylation of cJun, a marker of MAPK cascade activation, irrespective of the presence or absence of the TNF blocking antibody Enbrel. We show here in a comprehensive overview that BV6-induced gene expression in breast cancer cells takes place in a time- as well as TNFR1-dependent manner.
Smac mimetic induces an early wave of gene expression via NF-κB and AP-1 and a second wave via TNFR1 signaling.
Cell line, Treatment
View SamplesTherapeutic efficacy of first-generation hypomethylating agents (HMAs) is limited in elderly acute myeloid leukemia (AML) patients. Therefore, combination strategies with targeted therapies are urgently needed. Here, we discover that priming with SGI-110 (guadecitabine), a next-generation HMA, sensitizes AML cells to ASTX660, a novel antagonist of cellular Inhibitor of Apoptosis Protein 1 and 2 (cIAP1/2) and X-linked IAP (XIAP). Importantly, SGI-110 and ASTX660 synergistically induced cell death in a panel of AML cell lines as well as in primary AML samples while largely sparing normal CD34+ human progenitor cells, underlining the translational relevance of this combination. Unbiased transcriptome analysis revealed that SGI-110 alone or in combination with ASTX660 upregulated the expression of key regulators of both extrinsic and intrinsic apoptosis signaling pathways such as TNFRSF10B (DR5), FAS and BAX. Individual knockdown of the death receptors TNFR1, DR5 and FAS significantly reduced SGI-110/ASTX660-mediated cell death, whereas blocking antibodies for TRAIL or FASLG failed to provide protection. Also, TNF-blocking antibody Enbrel had little protective effect on SGI110/ASTX660-induced cell death. Further, SGI-110 and ASTX660 acted in concert to promote cleavage of caspase-8 and BID, thereby providing a link between extrinsic and intrinsic apoptotic pathways. Consistently, sequential treatment with SGI-110 and ASTX660 triggered loss of mitochondrial membrane potential (MMP) and BAX activation, which contributes to cell death as BAX silencing significantly protected from SGI-110/ASTX660-mediated apoptosis. Together, these events culminated in activation of caspases-3/-7, nuclear fragmentation and cell death. In conclusion, SGI-110 and ASTX660 cooperatively induced apoptosis in AML cells by engaging extrinsic and intrinsic apoptosis pathways, highlighting the therapeutic potential of this combination for AML.
Next-generation hypomethylating agent SGI-110 primes acute myeloid leukemia cells to IAP antagonist by activating extrinsic and intrinsic apoptosis pathways.
Cell line
View SamplesCore binding factor (CBF) leukemias, characterized by translocations t(8;21) or inv(16)/t(16;16) targeting the core binding factor, constitute acute myeloid leukemia (AML) subgroups with favorable prognosis. However, about 40% of patients relapse, and the current classification system does not fully reflect this clinical heterogeneity. Previously, gene expression profiling (GEP) revealed two distinct CBF leukemia subgroups displaying significant outcome differences and identified apoptotic signaling, MAPKinase signaling and chemotherapy-resistance mechanisms among the most significant differentially regulated pathways. We now tested different inhibitors of the respective pathways in a cell line model (six cell lines reflecting the CBF subgroup specific gene expression alterations), and found apoptotic signaling to be differentiating between the CBF subgroup models. In accordance, primary samples from newly diagnosed CBF AML patients (n=23) also showed differential sensitivity to in vitro treatment with a Smac mimetic such as BV6, an antagonist of inhibitor of apoptosis (IAP) proteins , and ABT-737, a BCL2 inhibitor. Furthermore, GEP revealed the BV6 resistant cases to resemble the previously identified unfavorable CBF subgroup. Thus, our current findings show deregulated IAP expression and apoptotic signaling to differentiate clinically relevant CBF subgroups, which were independent of known molecular markers, thereby providing a starting point for novel therapeutic approaches.
Deregulated apoptosis signaling in core-binding factor leukemia differentiates clinically relevant, molecular marker-independent subgroups.
Sex, Age
View SamplesApoptosis is deregulated in most, if not all, cancers, including hematological malignancies. In this study, we wanted to test whether primary acute myeloid leukemia (AML) samples are sensitive for inhibitor of apoptosis (IAP) protein antagonist treatment in vitro, and which AML subgroup might profit most from such a novel therapeutic strategy. We treated diagnostic samples of 67 adult AML patients with either cytarabine (ara-C) or IAP antagonist BV6 and correlated sensitivity with clinical, cytogenetic and molecular markers, and expression levels of selected genes involved in apoptosis. Primary AML samples showed differential sensitivity to treatment with either ara-C (40% sensitive, 17% intermediate, 43% resistant) or BV6 (51% sensitive, 21% intermediate, 28% resistant). Notably, 69% of ara-C resistant samples showed a good to fair response to IAP inhibition. Furthermore, combination treatment of ara-C with BV6 showed additive effects in most samples. Differences in sensitivity to IAP antagonist treatment correlated with significantly elevated expression levels of TNF and lower levels of XIAP in BV6 sensitive samples, as well as with NPM1 mutations. Gene expression profiling pointed to apoptosis-related pathways, which were specifically induced by IAP inhibition in sensitive samples. Thus, our results suggest IAP inhibition as a potential novel therapeutic option in AML.
Targeting inhibitor of apoptosis proteins by Smac mimetic elicits cell death in poor prognostic subgroups of chronic lymphocytic leukemia.
Sex, Age, Treatment
View SamplesInhibitor of apoptosis (IAP) proteins are expressed at high levels in CLL cells and may contribute to evasion of cell death leading to poor therapeutic outcome. Of note, prognostic unfavourable cases with e.g. non-mutated VH-status and TP53 mutation responded significantly better to BV6 than samples with unknown or favourable prognosis e.g. 13q deletion. The majority of cases with 17p deletion (10/12) and Fludarabine refractory cases were sensitive to BV6, indicating that BV6 acts independently of the p53 pathway. Importantly, BV6 dose-dependently induced cell death in 28 of 51 (54%) investigated patient samples while B cells from healthy donors were largely unaffected. BV6 also triggered cell death under survival conditions mimicking the microenvironment e.g. by adding CD40 ligand or in conditioned medium. Gene expression profiling identified cell death- and NF-kB-signaling among the top pathways regulated by BV6. This was confirmed by data showing that BV6 causes degradation of cIAP1 and cIAP2 and NF-kB pathway activation. BV6 induced cell death depended on production of reactive oxygen species, since addition of ROS scavengers significantly rescued BV6-triggerd cell death. In contrast, BV6 induced cell death independently of caspase activity, RIP1 activity or TNF-alpha, since zVAD.fmk, necrostatin-1 or TNF-alpha-blocking antibody Enbrel failed to protect against cell death. Of note, transcripts of ROS regulatory proteins were modulated by BV6. Thus, these data have important implications for developing new therapeutic strategies to overcome cell death resistance in CLL especially in poor prognostic subgroups.
Targeting inhibitor of apoptosis proteins by Smac mimetic elicits cell death in poor prognostic subgroups of chronic lymphocytic leukemia.
Sex, Age, Treatment
View SamplesSusceptibility genes for Autism Spectrum Disorder (ASD), Fragile X Syndrome (FXS), monogenetic disorders with intellectual disabilities (ID) or schizophrenia (SCZ) converge on processes related to neuronal function and differentiation. Furthermore, ASD risk genes are enriched for FMRP (Fragile X Mental Retardation Protein) targets and for genes implicated in ID. In addition, a significant co-heritability was observed between ASD and SCZ. The genetic overlap between ASD, FXS, ID and SCZ together with the symptomatic differences gives rise to the question if pathomechanisms impair the same or different regulatory patterns activated during neuronal differentiation (ND). To test this idea, we performed transcriptome analysis of in-vitro differentiation of the neuroblastoma cell line model SH-SY5Y and identified genes that were differentially expressed, dynamically regulated, and coordinately expressed. The identified genetic modules activated during ND are enriched for genetic risk factors for these four disorders. Although risk genes for the disorders significantly overlap, we observed disorder specific enrichments: ASD or FXS implicated genes were likely to be positive regulators of ND whereas ID implicated genes were related to negative regulation. ASD and SCZ genes were specifically enriched among cholesterol and fatty acid associated modules. ID genes were overrepresented among cell cycle modules. In addition, we show that ASD genes are likely to be hub genes. We hypothesize that knowledge about genetic variants of an individual combined with network and pathway context of the related genes will allow differentiating between psychiatric disorders.
Transcriptomic signatures of neuronal differentiation and their association with risk genes for autism spectrum and related neuropsychiatric disorders.
Sex, Specimen part, Cell line
View SamplesThe number of long-term survivors of high-risk neuroblastoma remains discouraging, with 10-year survival as low as 20%, despite decades of considerable international efforts to improve outcome. Major obstacles remain and include managing resistance to induction therapy, which causes tumor progression and early death in high-risk patients, and managing chemotherapy-resistant relapses, which can occur years after the initial diagnosis. Identifying and validating novel therapeutic targets is essential to improve treatment. Delineating and deciphering specific functions of single histone deacetylases in neuroblastoma may support development of targeted acetylome-modifying therapeutics for patients with molecularly defined high-risk neuroblastoma profiles. We show here that HDAC11 depletion in MYCN-driven neuroblastoma cell lines strongly induces cell death, mostly mediated by apoptotic programs. Genes necessary for mitotic cell cycle progression and cell division were most prominently enriched in at least two of three time points in whole-genome expression data combined from two cell systems, and all nine genes in these functional categories were strongly repressed, including CENPA, KIF14, KIF23 and RACGAP1. Enforced expression of one selected candidate, RACGAP1, partially rescued the induction of apoptosis caused by HDAC11 depletion. High-level expression of all nine genes in primary neuroblastomas signicantly correlated with unfavorable overall and event-free survival in patients, suggesting a role in mediating the more aggressive biological and clinical phenotype of these tumors. Our study identied a group of cell cycle-promoting genes regulated by HDAC11, being both predictors of unfavorable patient outcome and essential for tumor cell viability. The data indicates a signicant role of HDAC11 for mitotic cell cycle progression and survival of MYCN-amplified neuroblastoma cells, and suggests that HDAC11 could be a valuable drug target.
Neuroblastoma cells depend on HDAC11 for mitotic cell cycle progression and survival.
Cell line, Time
View SamplesFloodings already have a nearly 60% share in the worldwide damage to crops provoked by natural disasters. Climate change will cause plants to be even more frequently exposed to oxygen limiting conditions (hypoxia) in the near future due to heavy precipitation and concomitant waterlogging or flooding events in large areas of the world. Although the homeostatic regulation of adaptive responses to low oxygen stress in plants is well described, it remained unknown by which initial trigger the molecular response to low-oxygen stress is activated. Here, we show that a hypoxia-induced decline of the ATP level of the cell reduces LONG-CHAIN ACYL-COA SYNTHETASE (LACS) activity, which leads to a shift in the composition of the acyl-CoA pool. High oleoyl-CoA levels release the transcription factor RELATED TO APETALA 2.12 (RAP2.12) from its interaction partner ACYL-COA BINDING PROTEIN (ACBP) at the plasma membrane to induce low oxygen-specific gene expression. We show that different acyl-CoAs provoke unique molecular responses revealing a novel role as cellular signalling component also in plants. In terms of hypoxia signalling, dynamic acyl-CoA levels integrate the cellular energy status into the oxygen signalling cascade with ACBP and RAP2.12 being the central hub. The conserved nature of the ACBP:RAP2.12 module in crops and the novel mechanistic understanding of how low-oxygen stress responses are initiated by oleoyl-CoA in plants provide useful leads for enhancing future food security. Overall design: 1 control and 3 treatments with different forms of acyl-CoA in triplicate biological replicates
Low-oxygen response is triggered by an ATP-dependent shift in oleoyl-CoA in <i>Arabidopsis</i>.
Specimen part, Treatment, Subject
View SamplesThe role of different proteins, Always Early (Aly), Spermatocyte Arrest (Sa), Ubi-p63E (Magn) on the gene expression in spermatocyte differentation was assessed by microarray
The polyubiquitin gene Ubi-p63E is essential for male meiotic cell cycle progression and germ cell differentiation in Drosophila.
Specimen part
View SamplesTranscriptome analysis of LDBM cells stimulated with IL-5
IL-5 triggers a cooperative cytokine network that promotes eosinophil precursor maturation.
Specimen part
View Samples