FKHRL1-mediated expression of Noxa and Bim induces apoptosis via the mitochondria in neuroblastoma cells

MicroRNA-135b mainly functions as an oncogene during tumor progression

Late diagnosis is considered one of the main reasons of high mortality rate among cancer patients that results in therapeutic failure and tumor relapse. Therefore, it is needed to evaluate the molecular mechanisms associated with tumor progression to introduce efficient markers for the early tumor detection among cancer patients. The remarkable stability of microRNAs (miRNAs) in body fluids makes them potential candidates to use as the non-invasive tumor biomarkers in cancer screening programs. MiR-135b has key roles in prognosis and survival of cancer patients by either stimulating or inhibiting cell proliferation, invasion, and angiogenesis. Therefore, in the present review we assessed the molecular biology of miR-135b during tumor progression to introduce that as a novel tumor marker in cancer patients. It has been reported that miR-135b mainly acts as an oncogene by regulation of transcription factors, signaling pathways, drug response, cellular metabolism, and autophagy. This review paves the way to suggest miR-135b as a tumor marker and therapeutic target in cancer patients following the further clinical trials and animal studies.

Forkhead box proteins as the critical regulators of cisplatin response in tumor cells

Cisplatin (CDDP) is one of the most common chemotherapy drugs used in a wide range of cancer patients; however, there is a high rate of CDDP resistance among cancer patients. Considering the side effects of cisplatin in normal tissues, it is necessary to predict the CDDP response in cancer patients. Therefore, identifying the molecular mechanisms involved in CDDP resistance can help to introduce the prognostic markers. Several molecular mechanisms such as apoptosis inhibition, drug efflux, drug detoxification, and increased DNA repair are involved in CDDP resistance. Regarding the key role of transcription factors in regulation of many cellular processes related to drug resistance, in the present review, we discussed the role of Forkhead box (FOX) protein family in CDDP response. It has been reported that FOX proteins mainly promote CDDP resistance through the regulation of DNA repair, autophagy, epithelial-mesenchymal transition (EMT), and signaling pathways. Therefore, FOX proteins can be introduced as the prognostic markers to predict CDDP response in cancer patients. In addition, considering that oncogenic role of FOX proteins, the CDDP treatment along with FOX inhibition can be used as a therapeutic strategy in cancer patients.

PLK1 as a cooperating partner for BCL2-mediated antiapoptotic program in leukemia

The deregulation of BCL2 family proteins plays a crucial role in leukemia development. Therefore, pharmacological inhibition of this family of proteins is becoming a prevalent treatment method. However, due to the emergence of primary and acquired resistance, efficacy is compromised in clinical or preclinical settings. We developed a drug sensitivity prediction model utilizing a deep tabular learning algorithm for the assessment of venetoclax sensitivity in T-cell acute lymphoblastic leukemia (T-ALL) patient samples. Through analysis of predicted venetoclax-sensitive and resistant samples, PLK1 was identified as a cooperating partner for the BCL2-mediated antiapoptotic program. This finding was substantiated by additional data obtained through phosphoproteomics and high-throughput kinase screening. Concurrent treatment using venetoclax with PLK1-specific inhibitors and PLK1 knockdown demonstrated a greater therapeutic effect on T-ALL cell lines, patient-derived xenografts, and engrafted mice compared with using each treatment separately. Mechanistically, the attenuation of PLK1 enhanced BCL2 inhibitor sensitivity through upregulation of BCL2L13 and PMAIP1 expression. Collectively, these findings underscore the dependency of T-ALL on PLK1 and postulate a plausible regulatory mechanism.

Association study to evaluate Foxo1 and Foxo3 gene polymorphisms in polycystic ovary syndrome: a preliminary case-control study and in silico analysis

BACKGROUND

Polycystic ovary syndrome (PCOS) is known as a multifactorial and multi-gene-mediated endocrine disorder among women of reproductive age. FoxO1 and FoxO3 are members of the forkhead transcriptional factors family that play a pivotal role in the function of ovaries. The current work is aimed at investigating the association between gene variants of FoxO1 and FoxO3 and the risk of PCOS in a sample of the Iranian population.

METHODS AND RESULTS

We recruited 200 women diagnosed with PCOS and 200 healthy women. Both polymerase PCR-RFLP and ARMS-PCR methods were used for genotyping. Sanger sequencing was recruited to confirm the genotyping results. The T allele of rs17592236 and the C allele of rs12585277 decreased PCOS risk by 29 and 28%, respectively. In contrast, the C allele of rs2253310 and G allele of rs2802292 increased the risk of PCOS by 1.39 and 1.63 folds, correspondingly. Bioinformatics results showed that some genes, including matrix metallopeptidase 9 (MMP-9), phosphoinositide-3-Kinase Regulatory Subunit 224 1 (PIK3R1), peroxisome proliferator-activated receptor Gamma (PPARG), and glycogen synthase 225 kinase-3 beta (GSK-3 beta) have significant interactions with FoxO1, suggesting that FoxO1 might have crucial roles in regulating different signaling pathways in ovarian cells.

CONCLUSION

We found that FoxO1 rs17592236C > T and rs12585277C > T had a protective role against PCOS, while FoxO3 rs2253310C > G and rs2802292G > T  enhanced the risk of this metabolic disorder in our population. Additional studies on larger populations with varying races are needed to confirm these findings.

When cell death goes wrong: inflammatory outcomes of failed apoptosis and mitotic cell death

Apoptosis is a regulated cellular pathway that ensures that a cell dies in a structured fashion to prevent negative consequences for the tissue or the organism. Dysfunctional apoptosis is a hallmark of numerous pathologies, and treatments for various diseases are successful based on the induction of apoptosis. Under homeostatic conditions, apoptosis is a non-inflammatory event, as the activation of caspases ensures that inflammatory pathways are disabled. However, there is an increasing understanding that under specific conditions, such as caspase inhibition, apoptosis and the apoptotic machinery can be re-wired into a process which is inflammatory. In this review we discuss how the death receptor and mitochondrial pathways of apoptosis can activate inflammation. Furthermore, we will highlight how cell death due to mitotic stress might be a special case when it comes to cell death and the induction of inflammation.

Promoting effects of calponin 3 on the growth of diffuse large B‑cell lymphoma cells

Diffuse large B‑cell lymphoma (DLBCL) is one of the most common types of lymphoma. Calponin 3 (CNN3) is a thin filament‑associated protein previously known to regulate smooth muscle contraction. Recent evidence illustrates its involvement in carcinogenesis; however, its roles in DLBCL remain unknown. CNN3 was found to be highly expressed in DLBCL specimens according to the online Gene Expression Profiling Interactive Analysis data. The aim of the present study was to investigate the roles of CNN3 in the progression of DLBCL. In vitro, the ectopic expression of CNN3 promoted the proliferation and G1/S transition of DLBCL cells, while its silencing led to opposite alterations. A similar tumor‑promoting role of CNN3 was also demonstrated by injecting nude mice with DLBCL cells over‑ or underexpressing CNN3. The results of dual‑luciferase reporter and chromatin immunoprecipitation assays revealed that forkhead box O3 (FOXO3), a known tumor suppressor in DLBCL, bound to the CNN3 promoter at ‑1955/‑1948 and ‑1190/‑1183, and suppressed the transcription of CNN3. The alterations induced by FOXO3 were partly blocked by CNN3 overexpression. On the whole, the present study demonstrates that CNN3, whose transcriptional activity is negatively regulated by FOXO3, contributes to the malignant behavior of DLBCL cells. The findings of the present study may provide novel diagnostic or therapeutic insight for DLBCL in clinical practice.

Regulation of mitochondrial function by forkhead transcription factors

Mitochondria play a central role in several important cellular processes such as energy production, apoptosis, fatty acid catabolism, calcium regulation, and cellular stress response. Multiple nuclear transcription factors have been reported for their role in the regulation of mitochondrial gene expression. More recently, the role of the forkhead family of transcription factors in various mitochondrial pathways has been reported. Among them, FOXO1, FOXO3a, FOXG1, and FOXM1 have been reported to localize to the mitochondria, of which the first two have been observed to bind to the mitochondrial D-loop. This suggests an important role for forkhead transcription factors in the direct regulation of the mitochondrial genome and function. Forkheads such as FOXO3a, FOXO1, and FOXM1 are involved in the cellular response to oxidative stress, hypoxia, and nutrient limitation. Several members of the forkhead family of transcription factors are also involved in the regulation of nuclear-encoded genes associated with the mitochondrial pathway of apoptosis, respiration, mitochondrial dynamics, and homeostasis.

The Molecular Quality and Mitochondrial Activity of Porcine Cumulus-Oocyte Complexes Are Affected by Their Exposure to Three Endocrine-Active Compounds under 3D In Vitro Maturation Conditions

Thus far, the potential short- and long-term detrimental effects of a variety of environmental chemicals designated as endocrine-active compounds (EACs) have been found to interfere with histo- and anatomo-physiological functions of the reproductive system in humans and wildlife species. For those reasons, this study sought to examine whether selected EACs, which encompass the fungicide vinclozolin (Vnz), the androgenic anabolic steroid nandrolone (Ndn) and the immunosuppressant cyclosporin A (CsA), affect the developmental competence and molecular quality (MQ) of porcine cumulus–oocyte complexes (COCs) subjected to in vitro maturation (IVM) under 3D culture conditions. The COCs underwent 3D-IVM in the presence of Vnz, Ndn or CsA for 48 h. To explore whether the selected EACs induce internucleosomal DNA fragmentation in cumulus cells (CCs), TUNEL-assisted detection of late apoptotic cells was performed. Additionally, for the detailed evaluation of pro- and antiapoptotic pathways in COCs, apoptosis proteome profiler arrays were used. To determine changes in intracellular metabolism in COCs, comprehensive assessments of mitochondrial ultrastructure and activity were carried out. Moreover, the relative abundances (RAs) of mRNAs transcribed from genes that are involved in scavenging reactive oxygen species (ROS), such as SIRT3 and FOXO3, and intramitochondrial bioenergetic balance, such as ATP synthase subunit (ATP5A1), were ascertained. Finally, to investigate the extent of progression of oocyte maturation, the intraooplasmic levels of cAMP and the RAs of mRNA transcripts encoding regulatory and biocatalytic subunits of a heterodimeric meiosis-promoting factor, termed cyclin B1 (CCNB1) and cyclin-dependent kinase 1 (CDC2), were also estimated. The obtained results provide, for the first time, strong evidence that both Vnz and Ndn decrease the developmental competence of oocytes and stimulate apoptosis processes in CCs. The present study is also the first to highlight that Vnz accelerates the maturation process in immature oocytes due to both increased ROS production and the augmented RA of the CCNB1 gene. Furthermore, Vnz was proven to trigger proapoptotic events in CCs by prompting the activity of the FOXO3 transcription factor, which regulates the mitochondrial apoptosis pathway. In turn, Ndn was shown to inhibit oocyte maturation by inducing molecular events that ultimately lead to an increase in the intraooplasmic cAMP concentration. However, due to the simultaneous enhancement of the expression of TNF-β and HSP27 proteins in CCs, Ndn might be responsible for the onset of their neoplastic transformation. Finally, our current investigation is the first to clearly demonstrate that although CsA did not interfere with the nuclear and cytoplasmic maturation of oocytes, by inducing mitophagy in CCs, it disrupted oocyte metabolism, consequently attenuating the parameters related to the MQ of COCs. Summing up, Vnz, Ndn and CsA reduced not only the processes of growth and IVM but also the MQ of porcine COCs, which might make them unsuitable for assisted reproductive technologies (ARTs) such as in vitro fertilization by either gamete co-incubation or intracytoplasmic sperm injection (ICSI) and cloning by somatic cell nuclear transfer (SCNT).

3D bioprinted, vascularized neuroblastoma tumor environment in fluidic chip devices for precision medicine drug testing

Neuroblastoma is an extracranial solid tumor which develops in early childhood and still has a poor prognosis. One strategy to increase cure rates is the identification of patient-specific drug responses in tissue models that mimic the interaction between patient cancer cells and tumor environment. We therefore developed a perfused and micro-vascularized tumor-environment model that is directly bioprinted into custom-manufactured fluidic chips. A gelatin-methacrylate/fibrin-based matrix containing multiple cell types mimics the tumor-microenvironment that promotes spontaneous micro-vessel formation by embedded endothelial cells. We demonstrate that both, adipocyte- and iPSC-derived mesenchymal stem cells can guide this process. Bioprinted channels are coated with endothelial cells post printing to form a dense vessel - tissue barrier. The tissue model thereby mimics structure and function of human soft tissue with endothelial cell-coated larger vessels for perfusion and micro-vessel networks within the hydrogel-matrix. Patient-derived neuroblastoma spheroids are added to the matrix during the printing process and grown for more than two weeks. We demonstrate that micro-vessels are attracted by and grow into tumor spheroids and that neuroblastoma cells invade the tumor-environment as soon as the spheroids disrupt. In summary, we describe the first bioprinted, micro-vascularized neuroblastoma - tumor-environment model directly printed into fluidic chips and a novel medium-throughput biofabrication platform suitable for studying tumor angiogenesis and metastasis in precision medicine approaches in future.

Cell Signaling Pathways That Promote Radioresistance of Cancer Cells

Radiation therapy (RT) is a standard treatment for solid tumors and about 50% of patients with cancer, including pediatric cancer, receive RT. While RT has significantly improved the overall survival and quality of life of cancer patients, its efficacy has still been markedly limited by radioresistance in a significant number of cancer patients (intrinsic or acquired), resulting in failure of the RT control of the disease. Radiation eradicates cancer cells mainly by causing DNA damage. However, radiation also concomitantly activates multiple prosurvival signaling pathways, which include those mediated by ATM, ATR, AKT, ERK, and NF-κB that promote DNA damage checkpoint activation/DNA repair, autophagy induction, and/or inhibition of apoptosis. Furthermore, emerging data support the role of YAP signaling in promoting the intrinsic radioresistance of cancer cells, which occurs through its activation of the transcription of many essential genes that support cell survival, DNA repair, proliferation, and the stemness of cancer stem cells. Together, these signaling pathways protect cancer cells by reducing the magnitude of radiation-induced cytotoxicity and promoting radioresistance. Thus, targeting these prosurvival signaling pathways could potentially improve the radiosensitivity of cancer cells. In this review, we summarize the contribution of these pathways to the radioresistance of cancer cells.

Anti-inflammatory and Pro-apoptotic Effects of 18beta-Glycyrrhetinic Acid In Vitro and In Vivo Models of Rheumatoid Arthritis

18β-Glycyrrhetinic acid (18β-GA), an active component from Glycyrrhiza glabra L. root (licorice), has been demonstrated to be able to protect against inflammatory response and reduce methotrexate (MTX)-derived toxicity. This study was therefore designed to test the therapeutic possibility of 18β-GA on rheumatoid arthritis (RA) and to explore the underlying mechanism. LPS or TNF-α-induced inflammatory cell models and collagen-induced arthritis (CIA) animal models were applied in this study. Real-time quantitative PCR (RT-qPCR) was used to measure the mRNA levels of various cytokines and FOXO family members. The protein levels of molecules in the MAPK/NF-κB signaling pathway were analyzed using western blot. The cell proliferation assay and colony-forming assay were used to test the influence of 18β-GA on cell viability. The cell apoptosis assay and cell cycle assay were performed to detect the effect of 18β-GA on cell proliferative capacity by using flow cytometry. Hematoxylin and eosin (H&E) staining was performed to evaluate pathological changes after drug administration. The enzyme-linked immunosorbent assay (ELISA) was carried out for the detection of cytokines in serum. In vitro, we found that 18β-GA decreased the mRNA levels of IL-1β, IL-6, and COX-2 by inhibiting the MAPK/NF-κB signaling pathway in MH7A and RAW264.7 cell lines. Moreover, 18β-GA was able to suppress cell viability, trigger cell apoptosis, and G1 phase cell cycle arrest in our in vitro studies. 18β-GA dramatically enhanced the mRNA level of FOXO3 in both TNF-α- and LPS-induced inflammation models in vitro. Interestingly, after analyzing GEO datasets, we found that the FOXO3 gene was significantly decreased in the RA synovial tissue as compared to healthy donors in multiple microarray studies. In vivo, 18β-GA exhibited a promising therapeutic effect in a collagen-induced arthritis mouse model by alleviating joint pathological changes and declining serum levels of TNF-α, IL-1β, and IL-6. Finally, we observed that 18β-GA administration could mitigate liver damage caused by collagen or MTX. Collectively, the current study demonstrates for the first time that 18β-GA can inhibit inflammation and proliferation of synovial cells, and the underlying mechanism may be associated with its inhibition of MAPK/NF-κB signaling and promotion of FOXO3 signaling. Therefore, 18β-GA is expected to be a new drug candidate for RA therapy.

FOXO3a-dependent Parkin regulates the development of gastric cancer by targeting ATP-binding cassette transporter E1

Gastric cancer (GC) is one of the most common malignant tumors in China and the third leading cause of cancer-related death. Parkin has been shown to be a tumor suppressor in a variety of malignancies, including GC. However, the mechanism of Parkin in GC remains unclear. In this study, the low expression of Parkin in GC cells and patient tumor tissues was observed, and Parkin inhibited proliferation and migration of GC cells. Additionally, doxorubicin (DOX) upregulated the expression of Parkin and promoted its anticancer effect. Forkhead box O3 (FOXO3a) is a crucial transcription factor that involves in the regulation of cancer cell proliferation, apoptosis, and metabolism. Here, we found that FOXO3a inhibits cell proliferation, migration, and promotes apoptosis in GC by regulating Parkin expression at the transcriptional level. In addition, Parkin inhibited cell proliferation, migration, and promoted apoptosis by inhibiting ATP-binding box protein E1 (ABCE1) expression. In summary, our results demonstrated a new regulatory axis of FOXO3a-Parkin-ABCE1 that modulated GC cell proliferation, migration, and apoptosis, and it can serve as a potential therapeutic target in GC.

Serum COX-2 and FOXO3a in patients with rheumatoid arthritis and correlation with disease activity

Expression levels of serum cyclooxygenase (COX)-2 and forkhead box O3a (FOXO3a) in patients with rheumatoid arthritis (RA) and the correlation with disease activity were investigated. Sixty patients with RA admitted to the People's Hospital of Guangxi Zhuang Autonomous Region (study group; 28 active patients and 32 remissive patients), and further 30 healthy subjects undergoing physical examinations during the same period (control group) were enrolled in this study. RT-qPCR and enzyme-linked immunosorbent assay (ELISA) were used to detect the expression levels of COX-2 and FOXO3a in serum. According to DAS28 score, the patients were divided into active and remissive patients, between whom the expression levels were compared. Receiver operating characteristic (ROC) curves were plotted to analyze the diagnostic values of COX-2 and FOXO3a for disease activity. Pearson's correlation coefficient was used to analyze the correlation of the two markers with erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and DAS28 score. The expression levels of COX-2 and FOXO3a in active and remissive patients were significantly higher than those in the control group (both P<0.05), and those in active patients were significantly higher than those in remissive patients (both P<0.05). The areas under the ROC curves (AUCs) of COX-2 and FOXO3a were 0.748 and 0.802, respectively, suggesting that the two markers have high diagnostic value. The expression levels of COX-2 and FOXO3a were positively correlated with ESR, CRP, and DAS28 score of active and remissive patients (both P<0.05). In conclusion, the expression levels of COX-2 and FOXO3a in patients with RA are upregulated, thus, the two markers may be involved in the development and progression of the disease. The expression levels of COX-2 and FOXO3a are related to the disease activity of RA, and therefore can be used as diagnostic indicators for the disease activity.

Bim, Puma and Noxa upregulation by Naftopidil sensitizes ovarian cancer to the BH3-mimetic ABT-737 and the MEK inhibitor Trametinib

Ovarian cancer represents the first cause of mortality from gynecologic malignancies due to frequent chemoresistance occurrence. Increasing the [BH3-only Bim, Puma, Noxa proapoptotic]/[Bcl-xL, Mcl-1 antiapoptotic] proteins ratio was proven to efficiently kill ovarian carcinoma cells and development of new molecules to imbalance Bcl-2 member equilibrium are strongly required. Drug repurposing constitutes an innovative approach to rapidly develop therapeutic strategies through exploitation of established drugs already approved for the treatment of noncancerous diseases. This strategy allowed a renewed interest for Naftopidil, an α1-adrenergic receptor antagonist commercialized in Japan for benign prostatic hyperplasia. Naftopidil was reported to decrease the incidence of prostate cancer and its derivative was described to increase BH3-only protein expression in some cancer models. Based on these arguments, we evaluated the effects of Naftopidil on ovarian carcinoma and showed that Naftopidil reduced cell growth and increased the expression of the BH3-only proteins Bim, Puma and Noxa. This effect was independent of α1-adrenergic receptors blocking and involved ATF4 or JNK pathway depending on cellular context. Finally, Naftopidil-induced BH3-only members sensitized our models to ABT-737 and Trametinib treatments, in vitro as well as ex vivo, in patient-derived organoid models.

Targeting ERK-Hippo Interplay in Cancer Therapy

Extracellular signal-regulated kinase (ERK) is a part of the mitogen-activated protein kinase (MAPK) signaling pathway which allows the transduction of various cellular signals to final effectors and regulation of elementary cellular processes. Deregulation of the MAPK signaling occurs under many pathological conditions including neurodegenerative disorders, metabolic syndromes and cancers. Targeted inhibition of individual kinases of the MAPK signaling pathway using synthetic compounds represents a promising way to effective anti-cancer therapy. Cross-talk of the MAPK signaling pathway with other proteins and signaling pathways have a crucial impact on clinical outcomes of targeted therapies and plays important role during development of drug resistance in cancers. We discuss cross-talk of the MAPK/ERK signaling pathway with other signaling pathways, in particular interplay with the Hippo/MST pathway. We demonstrate the mechanism of cell death induction shared between MAPK/ERK and Hippo/MST signaling pathways and discuss the potential of combination targeting of these pathways in the development of more effective anti-cancer therapies.

Mitochondrial Protection by PARP Inhibition

Inhibitors of the nuclear DNA damage sensor and signalling enzyme poly(ADP-ribose) polymerase (PARP) have recently been introduced in the therapy of cancers deficient in double-strand DNA break repair systems, and ongoing clinical trials aim to extend their use from other forms of cancer non-responsive to conventional treatments. Additionally, PARP inhibitors were suggested to be repurposed for oxidative stress-associated non-oncological diseases resulting in a devastating outcome, or requiring acute treatment. Their well-documented mitochondria- and cytoprotective effects form the basis of PARP inhibitors’ therapeutic use for non-oncological diseases, yet can limit their efficacy in the treatment of cancers. A better understanding of the processes involved in their protective effects may improve the PARP inhibitors’ therapeutic potential in the non-oncological indications. To this end, we endeavoured to summarise the basic features regarding mitochondrial structure and function, review the major PARP activation-induced cellular processes leading to mitochondrial damage, and discuss the role of PARP inhibition-mediated mitochondrial protection in several oxidative stress-associated diseases.

Repaglinide Silences the FOXO3/Lumican Axis and Represses the Associated Metastatic Potential of Neuronal Cancer Cells

The transcription factor FOXO3 is associated with poor outcome in high-stage neuroblastoma (NB), as it facilitates chemoprotection and tumor angiogenesis. In other tumor entities, FOXO3 stimulates metastasis formation, one of the biggest challenges in the treatment of aggressive NB. However, the impact of FOXO3 on the metastatic potential of neuronal tumor cells remains largely unknown. In the present study, we uncover the small leucine-rich proteoglycan family member lumican (LUM) as a FOXO3-regulated gene that stimulates cellular migration in NB. By a drug-library screen we identified the small molecular weight compound repaglinide (RPG) as a putative FOXO3 inhibitor. Here, we verify that RPG binds to the FOXO3-DNA-binding-domain (DBD) and thereby silences the transcriptional activity of FOXO3. Consistent with the concept that the FOXO3/LUM axis enhances the migratory capacity of aggressive NB cells, we demonstrate that stable knockdown of LUM abrogates the FOXO3-mediated increase in cellular migration. Importantly, FOXO3 inhibition by RPG represses the binding of FOXO3 to the LUM promoter, inhibits FOXO3-mediated LUM RNA and protein expression, and efficiently abrogates FOXO3-triggered cellular “wound healing” as well as spheroid-based 3D-migration. Thus, silencing the FOXO3/LUM axis by the FDA-approved compound RPG represents a promising strategy for novel therapeutic interventions in NB and other FOXO3-dependent tumors.

Modulating FOXO3 transcriptional activity by small, DBD-binding molecules

FOXO transcription factors are critical regulators of cell homeostasis and steer cell death, differentiation and longevity in mammalian cells. By combined pharmacophore-modeling-based in silico and fluorescence polarization-based screening we identified small molecules that physically interact with the DNA-binding domain (DBD) of FOXO3 and modulate the FOXO3 transcriptional program in human cells. The mode of interaction between compounds and the FOXO3-DBD was assessed via NMR spectroscopy and docking studies. We demonstrate that compounds S9 and its oxalate salt S9OX interfere with FOXO3 target promoter binding, gene transcription and modulate the physiologic program activated by FOXO3 in cancer cells. These small molecules prove the druggability of the FOXO-DBD and provide a structural basis for modulating these important homeostasis regulators in normal and malignant cells.

Up-regulation of PGC-1α in neurons protects against experimental autoimmune encephalomyelitis

Reactive oxygen species (ROS) generation and mitochondrial dysfunction are related to neuron loss in multiple sclerosis (MS). Although peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) appears to play a key role in modulating levels of mitochondrial ROS, antioxidants, and uncoupling proteins (UCPs), and PGC-1α expression is reduced in the neocortex of patients with MS, it is unclear what its role is in neurons and in the manifestation of clinical symptoms of MS. Here, we show in wild-type (WT) experimental autoimmune encephalomyelitis (EAE) mice that PGC-1α is decreased 13 d after EAE induction followed by a steady decline up to 20 d. These changes were accompanied by parallel alterations in levels of superoxide dismutase 2, peroxiredoxin 3, thioredoxin 2, UCP4, and UCP5. In transgenic (TG) mice with neuron-specific overexpression of PGC-1α (PGC-1α^f/fEno2-Cre), clinical symptoms after EAE induction were delayed and less severe than in WT mice. The degrees of apoptotic neuron loss and demyelination were also less severe in PGC-1α-TG mice. Overexpression of PGC-1α in neuronal neuroblastoma spinal cord 34 cells subjected to EAE inflammatory conditions showed similar results to those obtained in vivo. RNA sequencing analysis showed that apoptotic processes were significantly enriched in the top 10 significant gene ontology (GO) terms of differentially expressed genes, and the apoptotic pathway was significantly enriched in Kyoto Encyclopedia of Genes and Genomes pathway analysis. Our findings indicate that up-regulation of neuronal PGC-1α protected neurons from apoptosis in EAE. Manipulating PGC-1α levels in MS may help stave off this devastating disease.-Dang, C., Han, B., Li, Q., Han, R., Hao, J. Up-regulation of PGC-1α in neurons protects against experimental autoimmune encephalomyelitis.

Perfluorooctane sulfonate induces apoptosis via activation of FoxO3a and upregulation of proapoptotic Bcl-2 proteins in PC12 cells

Perfluorooctane sulfonate (PFOS), a kind of organic pollutant widely found in the environment and biota, could alter normal brain development and produce cognitive dysfunction. For the past years, the neurotoxic effects of PFOS have been shown. Recent studies have proven that PFOS can induce neuronal apoptosis and cause neurotoxicity, but the regulatory proteins referred to the process have not been clarified. In this study, PC12 cells were used to investigate the changes of the expression of apoptosis-related proteins, forkhead box O3 (FoxO3a) and pro-apoptotic Bcl-2 proteins. We detected that the levels of cleaved caspase-3 and cleaved PARP were up-regulated obviously in PFOS-treated PC12 cells by using Western blotting, and that the apoptotic rate of PC12 cells was increased significantly by using flow cytometry, verifying that PFOS could induce neuronal apoptosis. Western blot analysis and immunofluorescence revealed obvious up-regulation of the expression of FoxO3a and proapoptotic Bcl-2 proteins. In addition, knockdown of FoxO3a gene inhibited Bim expression and apoptosis. According to the data, we believe that FoxO3a may play a crucial role in PFOS-induced neurotoxicity.

A drug library screen identifies Carbenoxolone as novel FOXO inhibitor that overcomes FOXO3-mediated chemoprotection in high-stage neuroblastoma

The transcription factor FOXO3 has been associated in different tumor entities with hallmarks of cancer, including metastasis, tumor angiogenesis, maintenance of tumor-initiating stem cells, and drug resistance. In neuroblastoma (NB), we recently demonstrated that nuclear FOXO3 promotes tumor angiogenesis in vivo and chemoresistance in vitro. Hence, inhibiting the transcriptional activity of FOXO3 is a promising therapeutic strategy. However, as no FOXO3 inhibitor is clinically available to date, we used a medium-throughput fluorescence polarization assay (FPA) screening in a drug-repositioning approach to identify compounds that bind to the FOXO3-DNA-binding-domain (DBD). Carbenoxolone (CBX), a glycyrrhetinic acid derivative, was identified as a potential FOXO3-inhibitory compound that binds to the FOXO3-DBD with a binding affinity of 19 µM. Specific interaction of CBX with the FOXO3-DBD was validated by fluorescence-based electrophoretic mobility shift assay (FAM-EMSA). CBX inhibits the transcriptional activity of FOXO3 target genes, as determined by chromatin immunoprecipitation (ChIP), DEPP-, and BIM promoter reporter assays, and real-time RT-PCR analyses. In high-stage NB cells with functional TP53, FOXO3 triggers the expression of SESN3, which increases chemoprotection and cell survival. Importantly, FOXO3 inhibition by CBX treatment at pharmacologically relevant concentrations efficiently repressed FOXO3-mediated SESN3 expression and clonogenic survival and sensitized high-stage NB cells to chemotherapy in a 2D and 3D culture model. Thus, CBX might be a promising novel candidate for the treatment of therapy-resistant high-stage NB and other "FOXO-resistant" cancers.

FOXO3a from the Nucleus to the Mitochondria: A Round Trip in Cellular Stress Response

Cellular stress response is a universal mechanism that ensures the survival or negative selection of cells in challenging conditions. The transcription factor Forkhead box protein O3 (FOXO3a) is a core regulator of cellular homeostasis, stress response, and longevity since it can modulate a variety of stress responses upon nutrient shortage, oxidative stress, hypoxia, heat shock, and DNA damage. FOXO3a activity is regulated by post-translational modifications that drive its shuttling between different cellular compartments, thereby determining its inactivation (cytoplasm) or activation (nucleus and mitochondria). Depending on the stress stimulus and subcellular context, activated FOXO3a can induce specific sets of nuclear genes, including cell cycle inhibitors, pro-apoptotic genes, reactive oxygen species (ROS) scavengers, autophagy effectors, gluconeogenic enzymes, and others. On the other hand, upon glucose restriction, 5′-AMP-activated protein kinase (AMPK) and mitogen activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) -dependent FOXO3a mitochondrial translocation allows the transcription of oxidative phosphorylation (OXPHOS) genes, restoring cellular ATP levels, while in cancer cells, mitochondrial FOXO3a mediates survival upon genotoxic stress induced by chemotherapy. Interestingly, these target genes and their related pathways are diverse and sometimes antagonistic, suggesting that FOXO3a is an adaptable player in the dynamic homeostasis of normal and stressed cells. In this review, we describe the multiple roles of FOXO3a in cellular stress response, with a focus on both its nuclear and mitochondrial functions.

BH3 mimetic ABT-263 enhances the anticancer effects of apigenin in tumor cells with activating EGFR mutation

Background

Mutated epidermal growth factor receptor (EGFR) is one of the most successful targets in cancer targeted therapy. While this treatment has benefited many patients with an activating EGFR mutation (EGFRm), almost all those who initially benefited will eventually develop acquired drug resistance (ADR) after a certain period of time. New therapeutic strategies need to be explored to treat EGFRm tumors and overcome or minimize this recurring ADR.

Results

Our data showed that apigenin alone has only mild inhibitory effects on EGFRm tumor cells. By drug screening, we found that ABT-263 can significantly enhance the antitumor activities of apigenin in tumor cells harbouring an activating EGFR mutation and AZD9291-resistant H1975 cells. Mechanistically, apigenin upregulated the expression of Noxa in EGFRm tumor cells by targeting the AKT-FoxO3a pathway, thereby synergizing with ABT-263 to suppress tumor cell growth and proliferation in vitro and in vivo.

Conclusions

Our study provides a rationale for the clinical application of the combination treatment of apigenin and BH3 mimetics in the treatment of EGFRm tumors.

Electronic supplementary material

The online version of this article (10.1186/s13578-019-0322-y) contains supplementary material, which is available to authorized users.

Roles of forkhead box O (FoxO) transcription factors in neurodegenerative diseases: A panoramic view

Neurodegenerative diseases (NDDs), which are among the most important aging-related diseases, are typically characterized by neuronal damage and a progressive impairment in neurological function during aging. Few effective therapeutic targets for NDDs have been revealed; thus, an understanding of the pathogenesis of NDDs is important. Forkhead box O (FoxO) transcription factors have been implicated in the mechanisms regulating aging and longevity. The functions of FoxOs are regulated by diverse post-translational modifications (e.g., phosphorylation, acetylation, ubiquitination, methylation and glycosylation). FoxOs exert both detrimental and protective effects on NDDs. Therefore, an understanding of the precise function of FoxOs in NDDs will be helpful for developing appropriate treatment strategies. In this review, we first introduce the post-translational modifications of FoxOs. Next, the regulation of FoxO expression and post-translational modifications in the central nervous system (CNS) is described. Afterwards, we analyze and address the important roles of FoxOs in NDDs. Finally, novel potential directions of future FoxO research in NDDs are discussed. This review recapitulates essential facts and questions about the promise of FoxOs in treating NDDs, and it will likely be important for the design of further basic studies and to realize the potential for FoxOs as therapeutic targets in NDDs.

Transcriptional activation of SIRT6 via FKHRL1/FOXO3a inhibits the Warburg effect in glioblastoma cells

Glioblastoma (GBM) is the most aggressive and malignant form of brain tumors. However, its molecular mechanisms of tumorigenesis and cancer development remains to elucidate. Here, we reported FKHRL1, also called as FOXO3a, was an anti-cancer factor that inhibited the Warburg effect in GBM. Clinical data analysis revealed that FKHRL1 expression was positively correlated with the prognosis of patients with GBM. FKHRL1 silencing promoted glycolysis and cell growth of HEB gliocytes. Besides, FKHRL1 expression was tightly correlated with the expression of SIRT6 and a cluster of glycolytic genes that controlling the Warburg effect in glioma samples. Interestingly, the expression of SIRT6 was reduced after FKHRL1 knockdown, while its expression was upregulated when FKHRL1 was overexpressed in human U251 GBM cell line. In addition, SIRT6 restoration recovered the upregulated aerobic glycolysis induced by FKHRL1 knockdown. Meanwhile, SIRT6 knockdown also rescued the decrease of glucose metabolism induced by FKHRL1 overexpression. Luciferase assay and chromatin immunoprecipitation (ChIP) assay revealed that FKHRL1 bound to the promoter region of SIRT6 and enhanced its expression. Both in vitro and in vivo experiments further confirmed that FKHRL1-SIRT6 axis played a pivotal role in cell metabolism and tumor growth. Our results indicate that FKHRL1-SIRT6 axis regulates cell metabolism and may provide clues for GBM treatment.

miR-374a Inhibitor Enhances Etoposide-Induced Cytotoxicity Against Glioma Cells Through Upregulation of FOXO1

Glioma is a commonly diagnosed brain tumor that shows high mortality rate. Despite the great advancement of cancer therapy in recent years, chemotherapy is still an important approach for treatment of glioma. However, long-term chemotherapy usually causes serious side effects or complications. It is desirable to take strategies to enhance the efficacy of current chemotherapy. In the present study, we observed obvious upregulation of miR-374a in glioma cells. More importantly, we found that knockdown of miR-374a was able to enhance the etoposide-induced cytotoxicity against glioma cells. Mechanically, we demonstrated that FOXO1 was the target of miR-374a in glioma. Treatment with miR-374a inhibitor induced overexpression of FOXO1, and thus promoted the expression of Bim and Noxa. Since Bim and Noxa act as key proapoptotic proteins in mitochondrial apoptosis, miR-374a inhibitor was able to enhance the etoposide-induced apoptosis pathway in glioma.

Increased Foxo3a Nuclear Translocation and Activity is an Early Neuronal Response to βγ-Secretase-Mediated Processing of the Amyloid-β Protein Precursor: Utility of an AβPP-GAL4 Reporter Assay

Sequential cleavage of the amyloid-β protein precursor (AβPP) by BACE1 (β-secretase) followed by theγ-secretase complex, is strongly implicated in Alzheimer's disease (AD) but the initial cellular responses to these cleavage events are not fully defined. β-secretase-mediated AβPP processing yields an extracellular domain (sAβPPβ) and a C-terminal fragment of AβPP of 99 amino acids (C99). Subsequent cleavage by γ-secretase produces amyloid-β (Aβ) and an AβPP intracellular domain (AICD). A cellular screen based on the generation of AICD from an AβPP-Gal4 fusion protein was adapted by introducing familial AD (FAD) mutations into the AβPP sequence and linking the assay to Gal4-UAS driven luciferase and GFP expression, to identify responses immediately downstream of AβPP processing in neurons with a focus on the transcription factor Foxo3a which has been implicated in neurodegeneration. The K670N/M671L, E682K, E693G, and V717I FAD mutations and the A673T protective mutation, were introduced into the AβPP sequence by site directed mutagenesis. When expressed in mouse cortical neurons, AβPP-Gal4-UAS driven luciferase and GFP expression was substantially reduced by γ-secretase inhibitors, lowered by β-secretase inhibitors, and enhanced by α-secretase inhibitors suggesting that AICD is a product of the βγ-secretase pathway. AβPP-Gal4-UAS driven GFP expression was exploited to identify individual neurons undergoing amyloidogenic AβPP processing, revealing increased nuclear localization of Foxo3a and enhanced Foxo3a-mediated transcription downstream of AICD production. Foxo3a translocation was not driven by AICD directly but correlated with reduced Akt phosphorylation. Collectively this suggests that βγ-secretase-mediated AβPP processing couples to Foxo3a which could be an early neuronal signaling response in AD.

The established and the predicted roles of dynein light chain in the regulation of mitochondrial apoptosis

The mitochondrial pathway of apoptosis is regulated by the interplay between the members of Bcl-2 family. Within this family, BH3-only proteins are the sensors of apoptotic stimuli and can trigger apoptosis either by inhibiting the anti-apoptotic Bcl-2-family proteins or by directly activating the effectors Bax and Bak. An expanding body of research suggests that a number of non-Bcl-2 proteins can also interact with Bcl-2 proteins and contribute to the decision of cell fate. Dynein light chain (LC8, DYNLL or DLC), a hub protein and a dimerizing engine has been proposed to regulate the pro-apoptotic activity of two BH3-only proteins, Bim and Bmf. Our recent work has provided insight into the mechanisms through which DLC1 (DYNLL1) modulates Bim activity. Here we discuss the present day understanding of Bim-DLC interaction and endeavor to evaluate this interaction in the light of information from studies of DLC with other binding partners.

Dependence of p53-deficient cells on the DHX9 DExH-box helicase

DHX9 is a DExH-box helicase family member with key regulatory roles in a broad range of cellular processes. It participates at multiple levels of gene regulation, including DNA replication, transcription, translation, RNA transport, and microRNA processing. It has been implicated in tumorigenesis and recent evidence suggests that it may be a promising chemotherapeutic target. Previous studies have determined that DHX9 suppression elicits an apoptotic or senescence response by activating p53 signaling. Here, we show that DHX9 inhibition can also have deleterious effects in cells lacking functional p53. Loss of DHX9 led to increased cell death in p53-deficient mouse lymphomas and HCT116 human colon cancer cells, and G0/G1 cell cycle arrest in p53-deficient mouse embryonic fibroblasts. Analysis of mRNA levels for p53 transcriptional targets showed that a subset of p53 targets in the p53-null lymphomas and HCT116 cells were activated despite the absence of functional p53. This implies an alternative pathway of DHX9-mediated activation of cell death and cell cycle arrest in p53-deficient cells and supports the feasibility of targeting DHX9 in p53-deficient tumors.

The tubulin inhibitor MG-2477 induces autophagy-regulated cell death, ROS accumulation and activation of FOXO3 in neuroblastoma

Neuroblastoma is the most frequent extra-cranial solid tumor in children with still high mortality in stage M. Here we studied the tubulin-inhibitor MG-2477 as a possible therapeutic agent for neuroblastoma therapy and uncovered that MG-2477 induces death in neuroblastoma cells independent of PKB-activation status and stage. MG-2477 triggers within 30 minutes extensive autophagosome-formation that finally leads to cell death associated with mitotic catastrophe. Autophagy is critical for MG-2477-induced death and is regulated by the BH3-only protein PMAIP1/NOXA which sequesters the anti-apoptotic BCL2-protein BCLXL and thereby displaces and activates the autophagy-regulator BECN1/beclin1. Knockdown of NOXA or overexpression of its pro-survival binding partners MCL1 and BCLXL counteracts MG-2477-induced cell death. MG-2477 also rapidly induces the repression of the anti-apoptotic protein Survivin, which promotes autophagy and cell death. We further observed the accumulation of reactive oxygen species (ROS) that triggers autophagy induction suggesting a change of the PI3 kinase-III/BECN1 complex and activates the transcription factor FOXO3, which contributes to final cell death induction. The combined data suggest that MG-2477 induces a sequential process of ROS-accumulation, autophagy and FOXO3-activation that leads to cell death in neuroblastoma cells.

The Study of Apoptosis-inducing Effects of Three Pre-apoptotic Factors by Gallic Acid, Using Simulation Analysis and the Comet Assay Technique on the Prostatic Cancer Cell Line PC3

BACKGROUND

In this study, we demonstrated the effects of the Gallic Acid (GA) molecule on the prostate cancer cells line PC3 using the comet assay (Alkaline electrophoresis) technique and its effects on some important apoptotic factors including BAD (Bcl-2-Associated Death promoter), BAK (Bcl-2 homologous Antagonist/Killer), and BIM (Bcl-2-like protein 11) via simulation analysis by using the Auto Dock and Gromacs software.

METHODS

Following the MTT assay on the PC3 cells, and determining IC50, we used three concentrations of GA to around IC50 to treat PC3 cells. 100 comet pictures were obtained by alkaline electrophoresis and have been analysed with the CASP version 1.2.2 software; all the results were thereafter analysed by the SPSS version 21 statistical software.

RESULTS

The IC50 value for GA was determined to be 35 μM. The ratio of tail to head in alkaline electrophoresis for the three concentrations below the IC50 of GA in 25, 30, and 35 μM were measured as 24.7 (2.7), 44.5 (1.8), and 57.3 (1.3) percent, respectively. The results of the preapoptotic factors (BAD, BAK, and BIM) in the performed simulation in the absence and presence of GA showed that the GA protein causes the structural instability in the BAD protein, and the effect of GA can be explained by the creation of hydrogen bonds with proteins.

CONCLUSION

GA is a polyphenol compound in plants that can suppress cell growth and induce apoptosis in PC3 cells in prostate cancer in the range of IC50 concentrations. The apoptotic properties of GA induce pre-apoptotic factors.

FOXO3-mediated chemo-protection in high-stage neuroblastoma depends on wild-type TP53 and SESN3

Forkhead box O class transcription factors are homeostasis regulators that control cell death, longevity and therapy-resistance. In neuroblastoma (NB), nuclear FOXO3 correlates with stage M disease and poor prognosis. To analyze whether FOXO3 contributes to drug-resistance in this childhood cancer, we investigated how different high-stage-derived NB cells respond to the activation of an ectopic FOXO3 allele. We found endogenous FOXO3 mostly localized to the nucleus—upon activation of an ectopic, 4OHT-activated FOXO3(A3)ER fusion protein two of the cell lines underwent apoptosis, whereas in the others FOXO3-activation even increased survival during drug-treatment. In the latter cell type, FOXO3 did not induce the BH3-only protein BCL2L11/BIM due to impaired binding of FOXO3 to the BIM-promoter, but still activated other FOXO3 targets. It was shown before that FOXO3 and TP53 physically interact with each other at two different regions—the TP53-N-terminus binds to the FOXO3-DNA binding domain (DBD) and the FOXO3-C-terminus interacts with the TP53-DBD. Interestingly, cell lines that undergo FOXO3-induced cell death carry homozygous point mutations in the TP53-DBD near the structural hotspot-mutation-site R175H, which abrogated FOXO3–TP53 interaction. In contrast, in FOXO3-death-resistant cells no point mutations in the TP53-DBD were found—in these cells FOXO3–TP53 complexes are formed and FOXO3-binding to the BIM-promoter, but not the induction of the detoxifying protein SESN3, were prevented, which in turn increased chemo-protection in this type of high-stage-derived NB cells. Our combined data suggest that FOXO3 steps in as a death inducer in case of TP53-mutation, whereas functional TP53 alters FOXO3-target-promoter-recognition, which prevents death induction by FOXO3 and instead increases chemo-protection and survival of NB cells. This novel mechanism may explain the low incidence of TP53 mutation in high-stage NB at diagnosis and suggests FOXO3 as a therapeutic target for this childhood malignancy.

C10ORF10/DEPP-mediated ROS accumulation is a critical modulator of FOXO3-induced autophagy

Background

Neuroblastoma is the most common solid tumor in childhood and develops from undifferentiated progenitor cells of the sympathetic nervous system. In neuronal tumor cells DNA-damaging chemotherapeutic agents activate the transcription factor FOXO3 which regulates the formation of reactive oxygen species (ROS) and cell death as well as a longevity program associated with therapy resistance.

We demonstrated before that C10ORF10/DEPP, a transcriptional target of FOXO3, localizes to peroxisomes and mitochondria and impairs cellular ROS detoxification. In the present study, we investigated the impact of FOXO3 and DEPP on the regulation of autophagy. Autophagy serves to reduce oxidative damage as it triggers a self-degradative process for the removal of aggregated or misfolded proteins and damaged organelles.

Methods

The effect of FOXO3 and DEPP on autophagy induction was analyzed using live cell fluorescence microscopy and immunoblot analyses of SH-EP cells transfected with a plasmid for EYFP-LC3 and with siRNAs specific for LC3, respectively. ROS steady-state levels were measured with reduced MitoTrackerRed CM-H2XROS. Cellular apoptosis was analyzed by flow cytometry and the caspase 3/7 assay.

Results

We report for the first time that DEPP induces ROS accumulation and thereby mediates the formation of autophagosomes as inhibition of ROS formation by N-acetyl-cysteine completely blocks autophagy. We further demonstrate that H₂O₂-treatment triggers autophagy-induction by FOXO3-mediated DEPP expression. Importantly, knockdown of DEPP was sufficient to efficiently inhibit autophagy-induction under different stress conditions such as serum starvation and genotoxic stress, suggesting that DEPP expression is critical for the initiation of autophagy in neuroblastoma. FOXO3-triggered autophagy partially protects neuroblastoma cells from cell death. Consistent with this concept, we demonstrate that inhibition of autophagy by LC3-knockdown significantly increased etoposide- and doxorubicin-induced apoptosis. These results were also confirmed by the use of the autophagy-inhibitor chloroquine that significantly enhanced the chemotherapeutic effect of etoposide and doxorubicin in neuronal tumor cells.

Conclusion

Targeting FOXO3/DEPP-triggered autophagy is a promising strategy to sensitize neuroblastoma cells to chemotherapy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-017-0661-4) contains supplementary material, which is available to authorized users.

Deletion of the BH3-only protein Noxa alters electrographic seizures but does not protect against hippocampal damage after status epilepticus in mice

Several members of the Bcl-2 gene family are dysregulated in human temporal lobe epilepsy and animal studies show that genetic deletion of some of these proteins influence electrographic seizure responses to chemoconvulsants and associated brain damage. The BH3-only proteins form a subgroup comprising direct activators of Bax–Bak that are potently proapoptotic and a number of weaker proapoptotic BH3-only proteins that act as sensitizers by neutralization of antiapoptotic Bcl-2 family members. Noxa was originally characterized as a weaker proapoptotic, ‘sensitizer' BH3-only protein, although recent evidence suggests it too may be potently proapoptotic. Expression of Noxa is under p53 control, a known seizure-activated pathway, although Noxa has been linked to energetic stress and autophagy. Here we characterized the response of Noxa to prolonged seizures and the phenotype of mice lacking Noxa. Status epilepticus induced by intra-amygdala kainic acid caused a rapid increase in expression of noxa in the damaged CA3 subfield of the hippocampus but not undamaged CA1 region. In vivo upregulation of noxa was reduced by pifithrin-α, suggesting transcription may be partly p53-dependent. Mice lacking noxa developed less severe electrographic seizures during status epilepticus in the model but, surprisingly, displayed equivalent hippocampal damage to wild-type animals. The present findings indicate Noxa does not serve as a proapoptotic BH3-only protein during seizure-induced neuronal death in vivo. This study extends the comprehensive phenotyping of seizure and damage responses in mice lacking specific Bcl-2 gene family members and provides further evidence that these proteins may serve roles beyond control of cell death in the brain.

Nuclear FOXO3 predicts adverse clinical outcome and promotes tumor angiogenesis in neuroblastoma

Neuroblastoma is the most frequent, extracranial solid tumor in children with still poor prognosis in stage IV disease. In this study, we analyzed FOXO3-phosphorylation and cellular localization in tumor biopsies and determined the function of this homeostasis regulator in vitro and in vivo. FOXO3-phosphorylation at threonine-32 (T32) and nuclear localization in biopsies significantly correlated with stage IV disease. DNA-damaging drugs induced nuclear accumulation of FOXO3, which was associated with elevated T32-phosphorylation in stage IV-derived neuroblastoma cells, thereby reflecting the in situ results. In contrast, hypoxic conditions repressed PKB-activity and caused dephosphorylation of FOXO3 in both, stroma-like SH-EP and high-stage-derived STA-NB15 cells. The activation of an ectopically-expressed FOXO3 in these cells reduced viability at normoxia, but promoted growth at hypoxic conditions and elevated VEGF-C-expression. In chorioallantoic membrane (CAM) assays STA-NB15 tumors with ectopic FOXO3 showed increased micro-vessel formation and, when xenografted into nude mice, a gene-dosage-dependent effect of FOXO3 in high-stage STA-NB15 cells became evident: low-level activation increased tumor-vascularization, whereas hyper-activation repressed tumor growth.The combined data suggest that, depending on the mode and intensity of activation, cellular FOXO3 acts as a homeostasis regulator promoting tumor growth at hypoxic conditions and tumor angiogenesis in high-stage neuroblastoma.

Induction of autophagy by ARHI (DIRAS3) alters fundamental metabolic pathways in ovarian cancer models

BACKGROUND

Autophagy is a bulk catabolic process that modulates tumorigenesis, therapeutic resistance, and dormancy. The tumor suppressor ARHI (DIRAS3) is a potent inducer of autophagy and its expression results in necroptotic cell death in vitro and tumor dormancy in vivo. ARHI is down-regulated or lost in over 60 % of primary ovarian tumors yet is dramatically up-regulated in metastatic disease. The metabolic changes that occur during ARHI induction and their role in modulating death and dormancy are unknown.

METHODS

We employed Nuclear Magnetic Resonance (NMR)-based metabolomic strategies to characterize changes in key metabolic pathways in both cell culture and xenograft models of ARHI expression and autophagy. These pathways were further interrogated by cell-based immunofluorescence imaging, tracer uptake studies, targeted metabolic inhibition, and in vivo PET/CT imaging.

RESULTS

Induction of ARHI in cell culture models resulted in an autophagy-dependent increase in lactate production along with increased glucose uptake and enhanced sensitivity to glycolytic inhibitors. Increased uptake of glutamine was also dependent on autophagy and dramatically sensitized cultured ARHI-expressing ovarian cancer cell lines to glutaminase inhibition. Induction of ARHI resulted in a reduction in mitochondrial respiration, decreased mitochondrial membrane potential, and decreased Tom20 staining suggesting an ARHI-dependent loss of mitochondrial function. ARHI induction in mouse xenograft models resulted in an increase in free amino acids, a transient increase in [¹⁸F]-FDG uptake, and significantly altered choline metabolism.

CONCLUSIONS

ARHI expression has previously been shown to trigger autophagy-associated necroptosis in cell culture. In this study, we have demonstrated that ARHI expression results in decreased cellular ATP/ADP, increased oxidative stress, and decreased mitochondrial function. While this bioenergetic shock is consistent with programmed necrosis, our data indicates that the accompanying up-regulation of glycolysis and glutaminolysis is autophagy-dependent and serves to support cell viability rather than facilitate necroptotic cell death. While the mechanistic basis for metabolic up-regulation following ARHI induction is unknown, our preliminary data suggest that decreased mitochondrial function and increased metabolic demand may play a role. These alterations in fundamental metabolic pathways during autophagy-associated necroptosis may provide the basis for new therapeutic strategies for the treatment of dormant ovarian tumors.

Forkhead transcription factors: new considerations for alzheimer's disease and dementia

Life expectancy of individuals in both developed and undeveloped nations continues to rise at an unprecedented rate. Coupled to this increase in longevity for individuals is the rise in the incidence of chronic neurodegenerative disorders that includes Alzheimer's disease (AD). Currently, almost ten percent of the population over the age of 65 suffers from AD, a disorder that is presently without definitive therapy to prevent the onset or progression of cognitive loss. Yet, it is estimated that AD will continue to significantly increase throughout the world to impact millions of individuals and foster the escalation of healthcare costs. One potential target for the development of novel strategies against AD and other cognitive disorders involves the mammalian forkhead transcription factors of the O class (FoxOs). FoxOs are present in "cognitive centers" of the brain to include the hippocampus, the amygdala, and the nucleus accumbens and may be required for memory formation and consolidation. FoxOs play a critical role in determining survival of multiple cell types in the nervous system, drive pathways of apoptosis and autophagy, and control stem cell proliferation and differentiation. FoxOs also interface with multiple cellular pathways that include growth factors, Wnt signaling, Wnt1 inducible signaling pathway protein 1 (WISP1), and silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1) that ultimately may control FoxOs and determine the fate and function of cells in the nervous system that control memory and cognition. Future work that can further elucidate the complex relationship FoxOs hold over cell fate and cognitive function could yield exciting prospects for the treatment of a number of neurodegenerative disorders including AD.

Altered FoxO3 expression and apoptosis in granulosa cells of women with polycystic ovary syndrome

PURPOSE

To determine the level of apoptosis, and alteration of FoxO3 (forkhead box O3 transcription factor) expression and phosphorylation in human granulosa cells amongst polycystic ovary syndrome (PCOS) patients and control group.

METHODS

We recruited infertile women with PCOS (n = 14) and compared them with infertile women due to tubal blockage or male factor infertility (n = 14, controls). GnRH agonist and gonadotropins were used for ovarian stimulation. Follicular fluids from large follicles (>16 mm) were pooled and granulosa cells (GCs) were isolated using cell strainer methodology. Apoptosis of purified GCs was measured by flow cytometry using Annexin V and propidium iodide. Quantitative real-time PCR and western blotting were performed to assess alteration of FoxO3 expression and phosphorylation in GCs.

RESULTS

There were higher percentages of early and late apoptosis in GCs of PCOS patients than in the control group. FoxO3 mRNA level and total FoxO3 protein were significantly higher in PCOS group than in the control group. The ratio of p-FoxO3/total FoxO3 decreased significantly in PCOS than in the control group. It was inferred that unphosphorylated (active form) FoxO3 was higher in GCs of PCOS patients. Apoptosis was significantly and positively correlated with the total FoxO3 and negatively correlated with the p-FoxO3 protein levels in PCOS patients.

CONCLUSIONS

Activation and overexpression of FoxO3 in granulosa cells of PCOS women correlated with higher apoptosis levels in these cells suggesting that FoxO3 may be a candidate for the higher apoptosis in granulosa cells from women with PCOS.

Dihydroartemisinin and its derivative induce apoptosis in acute myeloid leukemia through Noxa-mediated pathway requiring iron and endoperoxide moiety

Anti-apoptotic protein Mcl-1 plays an important role in protecting cell from death in acute myeloid leukemia (AML). The apoptosis blocking activity of Mcl-1 is inhibited by BH3-only protein Noxa. We found that dihydroartemisinin (DHA) and its derivative X-11 are potent apoptosis inducers in AML cells and act through a Noxa-mediate pathway; X-11 is four-fold more active than DHA. DHA and X-11-induced apoptosis is associated with induction of Noxa; apoptosis is blocked by silencing Noxa. DHA and X-11 induce Noxa expression by upregulating the transcription factor FOXO3a in a reactive oxygen species-mediated pathway. Interfering with the integrity of the endoperoxide moiety of DHA and X-11, as well as chelating intracellular iron with deferoxamine, diminish apoptosis and Noxa induction. AML cells expressing Bcl-xL, or with overexpression of Bcl-2, have decreased sensitivity to DHA and X-11-induced apoptosis which could be overcome by addition of Bcl-2/Bcl-xL inhibitor ABT-737. DHA and X-11 represent a new group of AML cells-apoptosis inducing compounds which work through Noxa up-regulation utilizing the specific endoperoxide moiety and intracellular iron.

Serine 574 phosphorylation alters transcriptional programming of FOXO3 by selectively enhancing apoptotic gene expression

Forkhead box O3 (FOXO3) is a multispecific transcription factor that is responsible for multiple and conflicting transcriptional programs such as cell survival and apoptosis. The protein is heavily post-translationally modified and there is considerable evidence that post-transcriptional modifications (PTMs) regulate protein stability and nuclear-cytosolic translocation. Much less is known about how FOXO3 PTMs determine the specificity of its transcriptional program. In this study we demonstrate that exposure of hepatocytes to ethanol or exposure of macrophages to lipopolysaccharide (LPS) induces the c-Jun N-terminal kinase (JNK)-dependent phosphorylation of FOXO3 at serine-574. Chromatin immunoprecipitation (ChIP), mRNA and protein measurements demonstrate that p-574-FOXO3 selectively binds to promoters of pro-apoptotic genes but not to other well-described FOXO3 targets. Both unphosphorylated and p-574-FOXO3 bound to the B-cell lymphoma 2 (Bcl-2) promoter, but the unphosphorylated form was a transcriptional activator, whereas p-574-FOXO3 was a transcriptional repressor. The combination of increased TRAIL (TNF-related apoptosis-inducing ligand) and decreased Bcl-2 was both necessary and sufficient to induce apoptosis. LPS treatment of a human monocyte cell line (THP-1) induced FOXO3 S-574 phosphorylation and apoptosis. LPS-induced apoptosis was prevented by knockdown of FOXO3. It was restored by overexpressing wild-type FOXO3 but not by overexpressing a nonphosphorylatable S-574A FOXO3. Expression of an S-574D phosphomimetic form of FOXO3 induced apoptosis even in the absence of LPS. A similar result was obtained with mouse peritoneal macrophages where LPS treatment increased TRAIL, decreased Bcl-2 and induced apoptosis in wild-type but not FOXO3(-/-) cells. This work thus demonstrates that S-574 phosphorylation generates a specifically apoptotic form of FOXO3 with decreased transcriptional activity for other well-described FOXO3 functions.

Regulation of Bim in Health and Disease

The BH3-only Bim protein is a major determinant for initiating the intrinsic apoptotic pathway under both physiological and pathophysiological conditions. Tight regulation of its expression and activity at the transcriptional, translational and post-translational levels together with the induction of alternatively spliced isoforms with different pro-apoptotic potential, ensure timely activation of Bim. Under physiological conditions, Bim is essential for shaping immune responses where its absence promotes autoimmunity, while too early Bim induction eliminates cytotoxic T cells prematurely, resulting in chronic inflammation and tumor progression. Enhanced Bim induction in neurons causes neurodegenerative disorders including Alzheimer's, Parkinson's and Huntington's diseases. Moreover, type I diabetes is promoted by genetically predisposed elevation of Bim in β-cells. On the contrary, cancer cells have developed mechanisms that suppress Bim expression necessary for tumor progression and metastasis. This review focuses on the intricate network regulating Bim activity and its involvement in physiological and pathophysiological processes.

Evaluation of NF-κB subunit expression and signaling pathway activation demonstrates that p52 expression confers better outcome in germinal center B-cell-like diffuse large B-cell lymphoma in association with CD30 and BCL2 functions

Nuclear factor-κB (NF-κB) is a transcription factor with a well-described oncogenic role. Study for each of five NF-κB pathway subunits was only reported on small cohorts in diffuse large B-cell lymphoma (DLBCL). In this large cohort (n=533) of patients with de novo DLBCL, we evaluated the protein expression frequency, gene expression signature, and clinical implication for each of these five NF-κB subunits. Expression of p50, p52, p65, RELB, and c-Rel was 34%, 12%, 20%, 14%, and 23%, whereas p50/p65, p50/c-Rel, and p52/RELB expression was 11%, 11%, and 3%, respectively. NF-κB subunits were expressed in both germinal center B-cell-like (GCB) and activated B-cell-like (ABC) DLBCL, but p50 and p50/c-Rel were associated with ABC-DLBCL. p52, RELB, and p52/RELB expressions were associated with CD30 expression. p52 expression was negatively associated with BCL2 (B-cell lymphoma 2) expression and BCL2 rearrangement. Although p52 expression was associated with better progression-free survival (PFS) (P=0.0170), singular expression of the remaining NF-κB subunits alone did not show significant prognostic impact in the overall DLBCL cohort. Expression of p52/RELB was associated with better overall survival (OS) and PFS (P=0.0307 and P=0.0247). When cases were stratified into GCB- and ABC-DLBCL, p52 or p52/RELB dimer expression status was associated with better OS and PFS (P=0.0134 and P=0.0124) only within the GCB subtype. However, multivariate analysis did not show p52 expression to be an independent prognostic factor. Beneficial effect of p52 in GCB-DLBC appears to be its positive correlation with CD30 and negative correlation with BCL2 expression. Gene expression profiling (GEP) showed that p52(+) GCB-DLBCL was distinct from p52(-) GCB-DLBCL. Collectively, our data suggest that DLBCL patients with p52 expression might not benefit from therapy targeting the NF-κB pathway.

FoxO proteins in the nervous system

Acute as well as chronic disorders of the nervous system lead to significant morbidity and mortality for millions of individuals globally. Given the ability to govern stem cell proliferation and differentiated cell survival, mammalian forkhead transcription factors of the forkhead box class O (FoxO) are increasingly being identified as potential targets for disorders of the nervous system, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and auditory neuronal disease. FoxO proteins are present throughout the body, but they are selectively expressed in the nervous system and have diverse biological functions. The forkhead O class transcription factors interface with an array of signal transduction pathways that include protein kinase B (Akt), serum- and glucocorticoid-inducible protein kinase (SgK), IκB kinase (IKK), silent mating type information regulation 2 homolog 1 (S. cerevisiae) (SIRT1), growth factors, and Wnt signaling that can determine the activity and integrity of FoxO proteins. Ultimately, there exists a complex interplay between FoxO proteins and their signal transduction pathways that can significantly impact programmed cell death pathways of apoptosis and autophagy as well as the development of clinical strategies for the treatment of neurodegenerative disorders.