FoxO3a and disease progression

The interplay of ROS and the PI3K/Akt pathway in autophagy regulation

Autophagy causes the breakdown of damaged proteins and organelles to their constituent components. The phosphatidylinositol 3-kinase (PI3K) pathway played an important role in regulating the autophagic response of cells in response to changing reactive oxygen species (ROS) levels. The PI3K α catalytic subunit inhibits autophagy, while its β catalytic subunit promotes autophagy in response to changes in ROS levels. The downstream Akt protein acts against autophagy initiation in response to increases in ROS levels under nutrient-rich conditions. Akt acts by activating a mechanistic target of the rapamycin complex 1 (mTORC1) and by arresting autophagic gene expression. The AMP-activated protein kinase (AMPK) protein counteracts the Akt actions. mTORC1 and mTORC2 inhibit autophagy under moderate ROS levels, but under high ROS levels, mTORC2 can promote cellular senescence via autophagy. Phosphatase and tensin homolog (PTEN) protein are the negative regulators of the PI3K pathway, and it has proautophagic activities. Studies conducted on cells treated with flavonoids and ionizing radiation showed that the moderate increase in ROS levels in the flavonoid-treated groups corresponded with higher PTEN levels and lowered Akt levels leading to a higher occurrence of autophagy. In contrast, higher ROS levels evoked by ionizing radiation caused a lowering of the incidence of autophagy.

Diffuse Intrinsic Pontine Glioma (DIPG): Breakthrough and Clinical Perspective

Diffuse intrinsic pontine glioma (DIPG) mainly affects children with a median age of 6-7 years old. It accounts for 10% of all pediatric tumors. Unfortunately, DIPG has a poor prognosis, and the median survival is generally less than 16-24 months independently from the treatment received. Up to now, children with DIPG are treated with focal radiotherapy alone or in combination with antitumor agents. In the last decade, ONC201 known as dopamine receptor antagonist was uncovered, by a high throughput screening of public libraries of compounds, to be endowed with cytotoxic activity against several cancer cell lines. Efforts were made to identify the real ONC201 target, responsible for its antiproliferative effect. The hypothesized targets were the Tumor necrosis factor-Related Apoptosis-Inducing Ligand stimulation (TRAIL), two oncogenic kinases (ERK/AKT system) that target the same tumor-suppressor gene (FOXO3a), dopamine receptors (DRD2 and DRD3 subtypes) and finally the mitochondrial Caseynolitic Protease P (ClpP). ONC201 structure-activity relationship is extensively discussed in this review, together with other two classes of compounds, namely ADEPs and D9, already known for their antibiotic activity but noteworthy to be discussed and studied as potential "leads" for the development of new drugs to be used in the treatment of DIPG. In this review, a detailed and critical description of ONC201, ADEPs, and D9 pro-apoptotic activity is made, with particular attention to the specific interactions established with its targets that also are intimately described. Pubmed published patents and clinical trial reports of the last ten years were used as the bibliographic source.

Imipridone enhances vascular relaxation via FOXO1 pathway

Cardiovascular complications are a side effect of cancer therapy, potentially through reduced blood vessel function. ONC201 (TIC10) is currently used in phase 2 clinical trials to treat high-grade gliomas. TIC10 is a phosphatidylinositol 3-kinase (PI3K)/AKT/extracellular signal-regulated kinase (ERK) inhibitor that induces apoptosis via upregulation of TNF-related apoptosis-inducing ligand, which via stimulation of FOXO and death receptor could increase eNOS upregulation. This has the potential to improve vascular function through increased NO bioavailability. Our aim was to investigate the role of TIC10 on vascular function to determine if it would affect the risk of CVD. Excised abdominal aorta from White New Zealand male rabbits were cut into rings. Vessels were incubated with TIC10 and AS1842856 (FOXO1 inhibitor) followed by cumulative doses of acetylcholine (Ach) to assess vessel function. Vessels were then processed for immunohistochemistry. Incubation of blood vessels with TIC10 resulted in enhanced vasodilatory capacity. Combination treatment with the FOXO1 inhibitor and TIC10 resulted in reduced vascular function compared to control. Immunohistochemical analysis indicated a 3-fold increase in death receptor 5 (DR5) expression in the TIC10-treated blood vessels but the addition of the FOXO1 inhibitor downregulated DR5 expression. The expression of DR4 receptor was not significantly increased in the presence of TIC10; however, addition of the FOXO1 inhibitor downregulated expression. TIC10 has the capacity to improve the function of healthy vessels when stimulated with the vasodilator Ach. This highlights its therapeutic potential not only in cancer treatment without cardiovascular side effects, but also as a possible drug to treat established CVD.

Clostridium difficile toxin B-induced colonic inflammation is mediated by the FOXO3/PPM1B pathway in fetal human colon epithelial cells

Clostridium difficile (C. difficile) toxin B (TcdB) is as an inflammatory enterotoxin that accounts for manifestations of widespread healthcare-associated C. difficile infection, including colonic inflammation. The present work explored the molecular mechanism by which TcdB activates innate immunity and stimulates pro-inflammatory cytokine release. Fetal human colon epithelial cells (FHCs) were treated with recombinant TcdB protein. Cell growth inhibition and apoptosis were measured with Cell Counting Kit-8 and Annexin V-fluorescein isothiocyanate Apoptosis Detection Kit, respectively. Flow cytometry analysis was also performed. Inflammatory cytokine induction was determined with enzykeme-linked immunosorbent assay analyses. Protein expression was assessed by western blot analysis. Gene overexpression and knockdown were performed with lentiviral transduction. Real-time quantitative polymerase chain reaction was used to examine gene expression. Dual-luciferase reporter assays and chromatin immunoprecipitation were implemented to explore transcriptional regulation. Mouse colon tissues were analyzed with hematoxylin and eosin staining. The results show that TcdB-induced cell growth and apoptosis and enhanced expression of interleukin-6 and tumor necrosis factor alpha in FHCs. We identified protein phosphatase magnesium-dependent 1B (PPM1B) as the key mediator promoting the phosphorylation of nuclear factor-κB p65, which accounted for the increase in pro-inflammatory cytokines. The findings demonstrate that PPM1B expression is directly regulated by the AKT/FOXO3 signaling pathway in FHCs. We confirmed the molecular mechanism with in vivo studies using a mouse model infected with C. difficile and treated with a phosphoinositide 3-kinase/AKT signaling inhibitor. In conclusion, TcdB induces inflammation in human colon epithelial cells by regulating the AKT/FOXO3/PPM1B pathway.

Activation of forkhead box O3a by mono(2-ethylhexyl)phthalate and its role in protection against mono(2-ethylhexyl)phthalate-induced oxidative stress and apoptosis in human cardiomyocytes

Mono(2-ethylhexyl)phthalate (MEHP), the active metabolite of di(2-ethylhexyl)phthalate (DEHP), is known to exert cardiotoxicity. The aim of the present study was to investigate the role of forkhead box O3a (FOXO3a) in MEHP-induced human AC16 cardiomyocyte injuries. MEHP reduced cell viability and mitochondrial membrane potential (ΔΨm), whereas it increased lactate dehydrogenase (LDH) leakage, production of reactive oxygen species (ROS), and apoptosis in cardiomyocytes. The expression of FOXO3a and its target genes, mitochondrial superoxide dismutase (Mn-SOD) and apoptosis repressor with caspase recruitment domain (ARC), increased after MEHP exposure, but the expression of p-FOXO3a protein was decreased. Overexpression of FOXO3a decreased the production of ROS and the apoptosis rate induced by MEHP, and the expression of Mn-SOD and ARC was further increased after MEHP exposure. In contrast, knockdown of FOXO3a resulted in increased ROS production and apoptosis and suppressed the expression of Mn-SOD and ARC in the presence of MEHP. However, overexpression or knockdown of FOXO3a did not affect MEHP-induced loss of ΔΨm. In conclusion, the loss of ΔΨm and apoptosis are involved in MEHP-induced cardiomyocyte toxicity. Activation of FOXO3a defends against MEHP-induced oxidative stress and apoptosis by upregulating the expression of Mn-SOD and ARC in AC16 cardiomyocytes.

Botryosphaeran, a (1 → 3)(1 → 6)-β-D-glucan, reduces tumor development and cachexia syndrome in obese male rats by increasing insulin sensitivity and FOXO3a activity

Obesity is an important risk factor in tumor development. Botryosphaeran, a (1 → 3)(1 → 6)-β-D-glucan, produced by the fungus Botryosphaeria rhodina (MAMB-05), is a high molecular mass, water-soluble exopolysaccharide. It consists of a main chain of (1 → 3)-linked β-d-glucose units, with a degree of branching of ~22% at carbon-6 with glucose and gentiobiose residues linked through β-(1 → 6)-bonds, and presents a triple helix conformation. Botryosphaeran presents anticlastogenic, antiproliferative, pro-apoptotic and anti-obesogenic activities. This study evaluated the effects of botryosphaeran on tumor development in obesity and analyzed its mechanism of action. Obesity was induced in male Wistar rats by a high-fat/high-sugar diet. After 9 weeks, rats were divided into two groups: Obese Tumor (OT) and Obese Tumor Botryosphaeran (OTB), and inoculated with 1 × 10⁷ Walker-256 tumor cells, and treatment with botryosphaeran (30 mg/kg b.w./day via gavage for 15 days) commenced. On the 11th week, biological parameters, tumor development, metabolic profile, erythrogram and protein expression were evaluated. Botryosphaeran significantly reduced tumor growth, body-weight loss and cachexia. Furthermore, botryosphaeran decreased mesenteric fat and insulin resistance, corrected macrocytic anemia, and increased Forkhead transcription factor-3a (FOXO3a) activity. Our study demonstrated the potential role of botryosphaeran in the management of cancer in tumor-bearing obese rats by increasing insulin sensitivity and FOXO3a activity.

P2Y2R contributes to the development of diabetic nephropathy by inhibiting autophagy response

OBJECTIVE

Diabetic nephropathy (DN) is one of the most common complications of diabetes and a critical risk factor for developing end-stage renal disease. Activation of purinergic receptors, including P2Y2R has been associated with the pathogenesis of renal diseases, such as polycystic kidney and glomerulonephritis. However, the role of P2Y2R and its precise mechanisms in DN remain unknown. We hypothesised that P2Y2R deficiency may play a protective role in DN by modulating the autophagy signalling pathway.

METHODS

We used a mouse model of DN by combining a treatment of high-fat diet and streptozotocin after unilateral nephrectomy in wild-type or P2Y2R knockout mice. We measured renal functional parameter in plasma, examined renal histology, and analysed expression of autophagy regulatory proteins.

RESULTS

Hyperglycaemia and ATP release were induced in wild type-DN mice and positively correlated with renal dysfunction. Conversely, P2Y2R knockout markedly attenuates albuminuria, podocyte loss, development of glomerulopathy, renal tubular injury, apoptosis and interstitial fibrosis induced by DN. These protective effects were associated with inhibition of AKT-mediated FOXO3a (forkhead box O3a) phosphorylation and induction of FOXO3a-induced autophagy gene transcription. Furthermore, inhibitory phosphorylation of ULK-1 was decreased, and the downstream Beclin-1 autophagy signalling was activated in P2Y2R deficiency. Increased SIRT-1 (sirtuin-1) and FOXO3a expression in P2Y2R deficiency also enhanced autophagy response, thereby ameliorating renal dysfunction in DN.

CONCLUSIONS

P2Y2R contributes to the pathogenesis of DN by impairing autophagy and serves as a therapeutic target for treating DN.

Artemisinin protects motoneurons against axotomy-induced apoptosis through activation of the PKA-Akt signaling pathway and promotes neural stem/progenitor cells differentiation into NeuN+ neurons

Brachial plexus axotomy is a common peripheral nerve trauma. Artemisinin, an FDA-approved antimalarial drug, has been described to possess neuroprotective properties. However, the specific mechanisms by which artemisinin protects neurons from axotomy-induced neurotoxicity remain to be elucidated. In this study, we assessed the neuroprotective effects of artemisinin on an experimental animal model of brachial plexus injury and explored the possible mechanisms involved. Artemisinin treatment restored both athletic ability and sensation of the affected upper limb, rescued motoneurons and attenuated the inflammatory response in the ventral horn of the spinal cord. Additionally, artemisinin inhibited the molecular signals of apoptosis, activated signaling pathways related to cell survival and induced NSCPs differentiation into NeuN-positive neurons. Further validation of the involved key signaling molecules, using an in vitro model of hydrogen peroxide-induced neurotoxicity, revealed that both the inhibition of PKA signaling pathway or the silencing of Akt reversed the neuroprotective action of artemisinin on motoneurons. Our results indicate that artemisinin provides neuroprotection against axotomy and hydrogen peroxide-induced neurotoxicity, an effect that might be mediated by the PKA-Akt signaling pathway.

Tumor development in rats and cancer cachexia are reduced by treatment with botryosphaeran by increasing apoptosis and improving the metabolic profile

AIMS

Cancer is a multifactorial disease characterized by an uncontrolled growth of cells that can lead to cachexia-anorexia syndrome. Botryosphaeran, a fungal (1 → 3)(1 → 6)-β-D-glucan produced by Botryosphaeria rhodina MAMB-05, has presented antimutagenic, antiproliferative, pro-apoptotic, hypoglycemic and hypocholesterolemic effects. This study evaluated the effects of botryosphaeran (30 mg/kg b.w./day) on tumor development and cachexia syndrome in Walker-256 tumor-bearing rats, and also the metabolic and hematological profiles of these animals.

MATERIALS AND METHODS

Male Wistar rats were divided into 3 groups: control (C), control tumor (CT) and control tumor botryosphaeran (CTB). On the first day, 1 × 10⁷ Walker-256 tumor cells were inoculated subcutaneously into the right flank of the CT and CTB rats, and concomitantly treatment with botryosphaeran (30 mg/kg b.w./day) started. After the 15th day of treatment, biological parameters, tumor development, cachexia, glucose and lipid profiles, hemogram and protein expression were analyzed.

KEY FINDINGS

Botryosphaeran significantly reduced tumor development (p = 0.0024) and cancer cachexia, modulated the levels of glucose, triglycerides and HDL-cholesterol, and corrected macrocytic anemia. Botryosphaeran also increased significantly the bax expression in the tumor tissue (p = 0.038) demonstrating that this (1 → 3)(1 → 6)-β-D-glucan is increasing the apoptosis of tumor cells. p53, p27, bcl-2, caspase-3 and Forkhead transcription factor 3a (FOXO3a) protein expression were similar among the groups.

SIGNIFICANCE

This study demonstrated that botryosphaeran was effective in decreasing tumor development and cachexia by direct and indirect mechanisms increasing apoptosis and improving the metabolic and hematological profiles.

FOXO3a regulates rhinovirus-induced innate immune responses in airway epithelial cells

Forkhead transcription factor class O (FOXO)3a, which plays a critical role in a wide variety of cellular processes, was also found to regulate cell-type-specific antiviral responses. Airway epithelial cells express FOXO3a and play an important role in clearing rhinovirus (RV) by mounting antiviral type I and type III interferon (IFN) responses. To elucidate the role of FOXO3a in regulating antiviral responses, we generated airway epithelial cell-specific Foxo3a knockout (Scga1b1-Foxo3a−/−) mice and a stable FOXO3a knockout human airway epithelial cell line. Compared to wild-type, Scga1b1-Foxo3a−/− mice show reduced IFN-α, IFN-β, IFN-λ2/3 in response to challenge with RV or double-stranded (ds)RNA mimic, Poly Inosinic-polycytidylic acid (Poly I:C) indicating defective dsRNA receptor signaling. RV-infected Scga1b1-Foxo3a−/− mice also show viral persistence, enhanced lung inflammation and elevated pro-inflammatory cytokine levels. FOXO3a K/O airway epithelial cells show attenuated IFN responses to RV infection and this was associated with conformational change in mitochondrial antiviral signaling protein (MAVS) but not with a reduction in the expression of dsRNA receptors under unstimulated conditions. Pretreatment with MitoTEMPO, a mitochondrial-specific antioxidant corrects MAVS conformation and restores antiviral IFN responses to subsequent RV infection in FOXO3a K/O cells. Inhibition of oxidative stress also reduces pro-inflammatory cytokine responses to RV in FOXO3a K/O cells. Together, our results indicate that FOXO3a plays a critical role in regulating antiviral responses as well as limiting pro-inflammatory cytokine expression. Based on these results, we conclude that FOXO3a contributes to optimal viral clearance and prevents excessive lung inflammation following RV infection.

Punicalagin Reversed the Hepatic Injury of Tetrachloromethane by Antioxidation and Enhancement of Autophagy

Hepatic injury is significant in the pathogenesis and development of many types of liver diseases. Punicalagin (PU) is a bioactive antioxidant polyphenol found in pomegranates. To explore its protective effect against carbon tetrachloride (CCl₄)-induced liver injury and the mechanism, Institute of Cancer Research (ICR) mice and L02 cells were used to observe the changes of serum biochemical indicators, histopathological liver structure, cell viability, antioxidative indices, and autophagy-related proteins were assessed. In ICR mice, PU ameliorated the CCl₄-induced increase of the serum aspartate aminotransferase, alanine aminotransferase, the activity of liver lactate dehydrogenase, and the damage of histopathological structure, and exhibited a hepatoprotective effect against CCl₄. PU attenuated oxidative stress by decreasing the liver malondialdehyde level and increasing the activities of liver superoxide dismutase, glutathione peroxidase, and the expression of the liver nuclear factor E2-related factor (Nrf2) protein. Furthermore, according to the vivo and vitro experiments, PU might activate autophagy through the mediation of the Akt/FOXO3a and P62/Nrf2 signaling pathway. Taken together, these results suggest that PU may protect against CCl₄-induced liver injury through the upregulation of antioxidative activities and autophagy.

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.

Iron chelation and 2-oxoglutarate-dependent dioxygenase inhibition suppress mantle cell lymphoma's cyclin D1

The patients with mantle cell lymphoma (MCL) have translocation t(11;14) associated with cyclin D1 overexpression. We observed that iron (an essential cofactor of dioxygenases including prolyl hydroxylases [PHDs]) depletion by deferoxamine blocked MCL cells' proliferation, increased expression of DNA damage marker γH2AX, induced cell cycle arrest and decreased cyclin D1 level. Treatment of MCL cell lines with dimethyloxalylglycine, which blocks dioxygenases involving PHDs by competing with their substrate 2-oxoglutarate, leads to their decreased proliferation and the decrease of cyclin D1 level. We then postulated that loss of EGLN2/PHD1 in MCL cells may lead to down-regulation of cyclin D1 by blocking the degradation of FOXO3A, a cyclin D1 suppressor. However, the CRISPR/Cas9-based loss-of-function of EGLN2/PHD1 did not affect cyclin D1 expression and the loss of FOXO3A did not restore cyclin D1 levels after iron chelation. These data suggest that expression of cyclin D1 in MCL is not controlled by ENGL2/PHD1-FOXO3A pathway and that chelation- and 2-oxoglutarate competition-mediated down-regulation of cyclin D1 in MCL cells is driven by yet unknown mechanism involving iron- and 2-oxoglutarate-dependent dioxygenases other than PHD1. These data support further exploration of the use of iron chelation and 2-oxoglutarate-dependent dioxygenase inhibitors as a novel therapy of MCL.

MeCP2 inhibits cell functionality through FoxO3a and autophagy in endothelial progenitor cells

Objectives: Autophagy is an evolutionarily conserved intracellular degradation mechanism in which cell constituents are phagocytosed to maintain cellular homeostasis. Forkhead box O 3a (FoxO3a) promotes autophagy to protect cells from environmental stress. Methylated CpG binding protein 2 (MeCP2) is a nuclear protein that binds DNA and represses transcription. However, the mechanism and interplay between FoxO3a and MeCP2 underlying endothelial progenitor cell (EPC) function are not fully understood.

Results: In EPCs, MeCP2 overexpression attenuated autophagy and cell functionality, which were reversed by the autophagy activator rapamycin or co-transfection with FoxO3a. FoxO3a promoted cell function, which was reversed by the autophagy inhibitor chloroquine. Following MeCP2 overexpression, MeCP2 was found enriched on the FoxO3a promoter, resulting in promoter hypermethylation and enhanced H3K9 histone modification in nucleosomes of the FoxO3a promoter.

Conclusions: MeCP2 attenuated cell functionality via DNA hypermethylation and histone modification of the FoxO3a promoter to inhibit FoxO3a transcription and autophagy.

Materials and Methods: EPCs were isolated from human umbilical cord blood and treated with adenoviral vectors containing interference sequences. The effects and mechanism of MeCP2 and FoxO3a were analyzed by utilizing western blotting, cell counting kit-8, transwell plates, Matrigel, matrix adhesion, transmission electron microscopy, and chromatin immunoprecipitation.

Nodal pathway activation due to Akt1 suppression is a molecular switch for prostate cancer cell epithelial-to-mesenchymal transition and metastasis

Several studies have unraveled the negative role of Akt1 in advanced cancers, including metastatic prostate cancer (mPCa). Hence, understanding the consequences of targeting Akt1 in the mPCa and identifying its downstream novel targets is essential. We studied how Akt1 deletion in PC3 and DU145 cells activates the Nodal pathway and promotes PCa epithelial-to-mesenchymal transition (EMT) and metastasis. Here we show that Akt1 loss increases Nodal expression in PCa cells accompanied by activation of FoxO1/3a, and EMT markers Snail and N-cadherin as well as loss of epithelial marker E-cadherin. Treatment with FoxO inhibitor AS1842856 abrogated the Nodal expression in Akt1 deleted PCa cells. Akt1 deficient PCa cells exhibited enhanced cell migration and invasion in vitro and lung metastasis in vivo, which were attenuated by treatment with Nodal pathway inhibitor SB505124. Interestingly, Nodal mRNA analysis from two genomic studies in cBioportal showed a positive correlation between Nodal expression and Gleason score indicating the positive role of Nodal in human mPCa. Collectively, our data demonstrate Akt1-FoxO3a-Nodal pathway as an important mediator of PCa metastasis and present Nodal as a potential target to treat mPCa patients.

Chitinase 1 regulates pulmonary fibrosis by modulating TGF-β/SMAD7 pathway via TGFBRAP1 and FOXO3

TGF-β1 is a critical mediator of tissue fibrosis in health and disease whose effects are augmented by chitinase 1 (CHIT1). However, the mechanisms that CHIT1 uses to regulate TGF-β1-mediated fibrotic responses have not been defined. Here, we demonstrate that CHIT1 enhances TGF-β1-stimulated fibrotic cellular and tissue responses and TGF-β1 signaling. Importantly, we also demonstrate that these effects are mediated by the ability of CHIT1 to inhibit TGF-β1 induction of its feedback inhibitor, SMAD7. CHIT1 also interacted with TGF-β receptor associated protein 1 (TGFBRAP1) and forkhead box O3 (FOXO3) with TGFBRAP1 playing a critical role in CHIT1 enhancement of TGF-β1 signaling and effector responses and FOXO3 playing a critical role in TGF-β1 induction of SMAD7. These pathways were disease relevant because the levels of CHIT1 were increased and inversely correlated with SMAD7 in tissues from patients with idiopathic pulmonary fibrosis or scleroderma-associated interstitial lung disease. These studies demonstrate that CHIT1 regulates TGF-β1/SMAD7 axis via TGFBRAP1 and FOXO3 and highlight the importance of these pathways in the pathogenesis of pulmonary fibrosis.

FOXO3a knockdown promotes radioresistance in nasopharyngeal carcinoma by inducing epithelial-mesenchymal transition and the Wnt/β-catenin signaling pathway

Mutations in the forkhead box O 3a (FOXO3a) gene are closely related to the progression of several types of cancers. However, few studies explore the relationship between FOXO3a and nasopharyngeal carcinoma (NPC). Our findings demonstrate that silencing FOXO3a promotes tumor radioresistance of NPC in vitro and in vivo through inducing EMT and activating Wnt/β-catenin signal pathway. These data establish that FOXO3a can be a novel and reliable NPC marker and a potential therapeutic target against NPC.

Nobiletin ameliorates hepatic ischemia and reperfusion injury through the activation of SIRT-1/FOXO3a-mediated autophagy and mitochondrial biogenesis

Hepatic ischemia and reperfusion injury are characterized by impaired autophagy, mitochondrial dysfunction, and subsequent compromise of cellular homeostasis following hepatic surgery or transplantation. Nobiletin, a natural flavonoid, is a beneficial antioxidant that possesses anti-inflammatory and anti-cancer activities. We investigated the effect of nobiletin on hepatic IR injury and described the underlying mechanisms. C57BL/6 mice were subjected to 60 min of partial hepatic ischemia, treated with nobiletin (5 mg/kg) or vehicle at the start of reperfusion, and killed at 5 h of reperfusion. Hepatic ischemia and reperfusion increased hepatocellular oxidative damage, inflammation, and cell death, but these changes were alleviated upon nobiletin treatment. Nobiletin increased the expression of proteins that control autophagy, mitochondrial dynamics, and biogenesis. Specifically, the SIRT-1/FOXO3a and PGC-1α pathways were activated by nobiletin. IR-induced AKT activation was associated with FOXO3a phosphorylation, which resulted in a significant reduction in the nuclear FOXO3a levels and potentially attenuated autophagy-regulatory gene expression. Nobiletin increased FOXO3a expression and its nuclear translocation via the inhibition of AKT. Specific inhibition of SIRT-1 abolished the protective effect of nobiletin, causing decreased FOXO3a expression, followed by autophagy induction and decreased PGC-1α expression and mitochondrial dynamics. Taken together, our data indicate that SIRT-1 directly mediates the protective effect of nobiletin against hepatic ischemia and reperfusion injury. The activation of autophagy and mitochondrial function through the SIRT-1/FOXO3a and PGC-1α pathways indicate that nobiletin could have therapeutic potential for treating hepatic ischemia and reperfusion injury.

Nobiletin, an antioxidant found in citrus peel, may protect the liver from reperfusion injury, damage following blood flow interruption. When blood flow is restricted and then restored, as in transplant, surgery, or shock, cells are injured, largely due to damage to the cellular powerhouses, the mitochondria. Nobiletin is known to have many benefits, including anti-cancer and anti-inflammatory activities, but its mechanism of action is not well understood. Sang Won Park and Hwajin Kim, at the Gyeongsang National University School of Medicine, in Jinju, South Korea, and co-workers, investigated how nobiletin might protect the liver against interruption of blood flow. They found that nobiletin triggered cells to dismantle damaged mitochondria and produce new, functioning mitochondria, greatly reducing liver damage. These results illuminate how nobiletin works and may lead to better treatments for liver reperfusion injury.

Longevity-Associated Forkhead Box O3 (FOXO3) Single Nucleotide Polymorphisms are Associated with Type 2 Diabetes Mellitus in Chinese Elderly Women

Background

This study aimed to investigate the association of single nucleotide polymorphisms (SNPs) of Forkhead box O3 (FOXO3) gene with type 2 diabetes mellitus (T2D).

Material/Methods

A total of 843 elderly residents from east China were enrolled in this study, which included 426 patients with type 2 diabetes and 417 controls. Four SNPs were analyzed by qPCR. Genotype frequencies of the 4 SNPs in FOXO3 of the patients and controls were analyzed using logistic regression analysis. The association between each SNP and clinical indicators was analyzed by linear regression analysis.

Results

None of the 4 FOXO3 variants, rs13217795, rs2764264, rs2802292, and rs13220810, were associated with the risk of type 2 diabetes compared to controls. However, rs13217795, rs2764264, and rs2802292 were associated with lower blood glucose levels. Notably, further subgroup analysis indicated that the longevity-associated alleles of FOXO3 SNP (rs13217795, rs2764264, and rs2802292) were associated with lower blood glucose levels in women (TC versus TT, −0.724 mmol/L, P=0.005; CC versus TT, −1.093 mmol/L, P=0.03; TC versus TT, −0.801 mmol/L, P=0.002; CC versus TT, −1.212 mmol/L, P=0.001; TG versus TT, −0.754 mmol/L, P=0.004; and GG versus TT, −1.150 mmol/L, P=0.001) but not in men.

Conclusions

The results indicated that longevity-associated FOXO3 variants were correlated with lower blood glucose levels in elderly women with type 2 diabetes in east China.

Retinoids induce antagonism between FOXO3A and FOXM1 transcription factors in human oral squamous cell carcinoma (OSCC) cells

To gain a greater understanding of oral squamous cell carcinoma (OSCC) we investigated the actions of all-trans-retinoic acid (RA; a retinoid), bexarotene (a pan-RXR agonist), and forkhead box (FOX) transcription factors in human OSCC-derived cell lines. RA and bexarotene have been shown to limit several oncogenic pathways in many cell types. FOXO proteins typically are associated with tumor suppressive activities, whereas FOXM1 acts as an oncogene when overexpressed in several cancers. RA and/or bexarotene increased the transcript levels of FOXO1, FOXO3A, and TRAIL receptors; reduced the transcript levels of FOXM1, Aurora kinase B (AURKB), and vascular endothelial growth factor A (VEGFA); and decreased the proliferation of OSCC-derived cell lines. Also, RA and/or bexarotene influenced the recruitment of FOXO3A and FOXM1 to target genes. Additionally, FOXM1 depletion reduced cell proliferation, decreased transcript levels of downstream targets of FOXM1, and increased transcript levels of TRAIL receptors. Overexpression of FOXO3A decreased proliferation and increased binding of histone deacetylases (HDACs) 1 and 2 at the FOXM1, AURKB, and VEGFA promoters. This research suggests novel influences of the drugs RA and bexarotene on the expression of FOXM1 and FOXO3A in transcriptional regulatory pathways of human OSCC.

Metformin induces the AP-1 transcription factor network in normal dermal fibroblasts

Metformin is a widely-used treatment for type 2 diabetes and is reported to extend health and lifespan as a caloric restriction (CR) mimetic. Although the benefits of metformin are well documented, the impact of this compound on the function and organization of the genome in normal tissues is unclear. To explore this impact, primary human fibroblasts were treated in culture with metformin resulting in a significant decrease in cell proliferation without evidence of cell death. Furthermore, metformin induced repositioning of chromosomes 10 and 18 within the nuclear volume indicating altered genome organization. Transcriptome analyses from RNA sequencing datasets revealed that alteration in growth profiles and chromosome positioning occurred concomitantly with changes in gene expression profiles. We further identified that different concentrations of metformin induced different transcript profiles; however, significant enrichment in the activator protein 1 (AP-1) transcription factor network was common between the different treatments. Comparative analyses revealed that metformin induced divergent changes in the transcriptome than that of rapamycin, another proposed mimetic of CR. Promoter analysis and chromatin immunoprecipitation assays of genes that changed expression in response to metformin revealed enrichment of the transcriptional regulator forkhead box O3a (FOXO3a) in normal human fibroblasts, but not of the predicted serum response factor (SRF). Therefore, we have demonstrated that metformin has significant impacts on genome organization and function in normal human fibroblasts, different from those of rapamycin, with FOXO3a likely playing a role in this response.

β-hydroxybutyrate attenuates renal ischemia-reperfusion injury through its anti-pyroptotic effects

Ketone bodies including β-hydroxybutyrate (β-OHB) have been shown to protect against ischemic tissue injury when present at low concentrations. We evaluated the impact of β-OHB on renal ischemia/reperfusion injury (IRI). Mice were treated with a continuous infusion of β-OHB using an osmotic mini-pump before and after IRI. We also tested the effects of increasing endogenous serum β-OHB levels by fasting. Renal IRI was attenuated by β-OHB treatment compared to saline control, with similar results in the fasting condition. β-OHB treatment reduced the number of terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL)-positive cells and increased expression of forkhead transcription factor O3 (FOXO3), an upstream regulator of pyroptosis. Although β-OHB treatment did not impact markers of apoptosis, it decreased the expression of caspase-1 and proinflammatory cytokines, indicating that β-OHB blocked pyroptosis. In a human proximal tubular cell line exposed to hypoxia and reoxygenation, β-OHB reduced cell death in a FOXO3-dependent fashion. Histone acetylation was decreased in kidneys exposed to IRI and in proximal tubular cells exposed to hypoxia and reoxygenation, and this effect was ameliorated by β-OHB through the inactivation of histone deacetylases. In vitro, β-OHB treatment restored histone acetylation at the FOXO3 promoter. Consistent with epigenetic molecular effects, the renoprotective effects of β-OHB were still observed when the continuous infusion was stopped at the time of IRI. Thus, β-OHB attenuates renal IRI through anti-pyroptotic effects, likely mediated by an epigenetic effect on FOXO3 expression.

The Phenolic compound Kaempferol overcomes 5-fluorouracil resistance in human resistant LS174 colon cancer cells

Resistance to 5-Fluorouracil chemotherapy is a major cause of therapeutic failure in colon cancer cure. Development of combined therapies constitutes an effective strategy to inhibit cancer cells and prevent the emergence of drug resistance. For this purpose, we investigated the anti-tumoral effect of thirteen phenolic compounds, from the Tunisian quince Cydonia oblonga Miller, alone or combined to 5-FU, on the human 5-FU-resistant LS174-R colon cancer cells in comparison to parental cells. Our results showed that only Kaempferol was able to chemo-sensitize 5-FU-resistant LS174-R cells. This phenolic compound combined with 5-FU exerted synergistic inhibitory effect on cell viability. This combination enhanced the apoptosis and induced cell cycle arrest of both chemo-resistant and sensitive cells through impacting the expression levels of different cellular effectors. Kaempferol also blocked the production of reactive oxygen species (ROS) and modulated the expression of JAK/STAT3, MAPK, PI3K/AKT and NF-κB. In silico docking analysis suggested that the potent anti-tumoral effect of Kaempferol, compared to its two analogs (Kaempferol 3-O-glucoside and Kampferol 3-O-rutinoside), can be explained by the absence of glucosyl groups. Overall, our data propose Kaempferol as a potential chemotherapeutic agent to be used alone or in combination with 5-FU to overcome colon cancer drug resistance.

Sirt3 suppresses calcium oxalate-induced renal tubular epithelial cell injury via modification of FoxO3a-mediated autophagy

High oxalic acid and calcium oxalate (CaOx)-induced renal tubular epithelial cell (TEC) injury plays a key role in nephrolithiasis. However, the mechanism remains unknown. Gene array analysis of the mice nephrolithiasis model indicated significant downregulation of sirtuin 3 (Sirt3) and activation of mitogen-activated protein kinase (MAPK) pathway. Kidney biopsy tissues of renal calculi patients also showed decreased Sirt3 expression. Silencing Sirt3 exacerbated oxidative stress and TEC death under CaOx stimulation. Restoring Sirt3 expression by overexpression or enhancing its activity protected renal function and reduced TEC death both in vitro and in vivo. Inhibiting the MAPK pathway resulted in upregulation of Sirt3 expression, preservation of renal function and decreased cell death both in vitro and in vivo. Furthermore, Sirt3 could upregulate FoxO3a activity post-translationally via deacetylation, dephosphorylation and deubiquitination. FoxO3a was found to interact with the promoter region of LC3B and to increase its expression, enhancing TEC autophagy and suppressing cell apoptosis and necrosis. Taken together, our results indicate that the MAPK/Sirt3/FoxO3a pathway modulates renal TEC death and autophagy in TEC injury.

Expression of the Forkhead box transcription factor Foxo3a in human periapical granulomas

It has been reported that Forkhead box transcription factor class O3a (Foxo3a) is expressed in rheumatoid arthritis, a chronic inflammatory condition accompanied by bone resorption, and plays a role in its pathology. However, it has remained unclear whether Foxo3a is involved in the pathogenesis of periapical granulomas. The present study was performed to compare the expression of Foxo3a in periapical granulomas and healthy gingival tissues. Samples were obtained surgically from patients, and subjected to hematoxylin-eosin staining for histopathologic diagnosis. Two-color immunofluorescence staining was also performed using antibodies against Foxo3a and markers for three types of inflammatory cells: neutrophils, T lymphocytes, and B lymphocytes. This revealed that Foxo3a was expressed in all three cell types in periapical granulomas but not in healthy gingival tissues. Foxo3a was expressed in 82.1%, 78.3%, and 77.5% of neutrophils, T lymphocytes, and B lymphocytes, respectively, and statistical analysis using the Kruskal-Wallis test followed by the Steel-Dwass test showed no significant difference of Foxo3a expression among the three cell types. Our results suggest that Foxo3a transcription factors may be involved in the pathogenesis of periapical granulomas.

Up-Regulation of miR-21, miR-25, miR-93, and miR-106b in Gastric Cancer

BACKGROUND

Differential expression profile of microRNAs (miRNAs) could be a diagnosis signature for monitoring gastric cancer (GC) progression. In this study, we focus on the comparison of expression levels of miR-21, miR-25, miR-93, miR-106b, and miR-375 during the sequential pattern of GC development, including normal gastric, gastric dysplasia, and GC sample.

METHODS

We used SYBR Green-based quantitative-PCR to quantify miRNAs expression.

RESULTS

Our analysis revealed the increased expression levels of miR-21 (p = 0.034), miR-25 (p = 0.0003), miR-93 (p = 0.0406), and miR-106b (p = 0.023) in GC samples. In addition, GC patients with positive lymph node metastasis showed the up-regulation of miR-25, miR-93, and miR-106b (p < 0.05).

CONCLUSION

Our findings suggested that the expression of miR-21, miR-25, miR-93, and miR-106b altered in GC, and some of them may be further investigated as biomarkers for GC early detection and prognosis prediction.

The Dominant Role of Forkhead Box Proteins in Cancer

Forkhead box (FOX) proteins are multifaceted transcription factors that are significantly implicated in cancer, with various critical roles in biological processes. Herein, we provide an overview of several key members of the FOXA, FOXC, FOXM1, FOXO and FOXP subfamilies. Important pathophysiological processes of FOX transcription factors at multiple levels in a context-dependent manner are discussed. We also specifically summarize some major aspects of FOX transcription factors in association with cancer research such as drug resistance, tumor growth, genomic alterations or drivers of initiation. Finally, we suggest that targeting FOX proteins may be a potential therapeutic strategy to combat cancer.

PI3k/AKT signaling pathway: Erythropoiesis and beyond

Erythropoiesis is a multi-step process that involves the differentiation of hematopoietic stem cells into mature red blood cells (RBCs). This process is regulated by several signaling pathways, transcription factors and microRNAs (miRNAs). Many studies have shown that dysregulation of this process can lead to hematologic disorders. PI3K/AKT is one of the most important pathways that control many cellular processes including, cell division, autophagy, survival, and differentiation. In this review, we focus on the role of PI3K/AKT pathway in erythropoiesis and discuss the function of some of the most important genes, transcription factors, and miRNAs that regulate different stages of erythropoiesis which play roles in differentiation and maturation of RBCs, prevention of apoptosis, and autophagy induction. Understanding the role of the PI3K pathway in erythropoiesis may provide new insights into diagnosing erythrocyte disorders.

MicroRNA-30c-5p inhibits NLRP3 inflammasome-mediated endothelial cell pyroptosis through FOXO3 down-regulation in atherosclerosis

Atherosclerosis is a chronic inflammatory disease involved in endothelial dysfunction. Pyroptosis is a pro-inflammatory form of cell death and plays pivotal roles in atherosclerosis. MicroRNAs (miRNAs) are implicated in atherosclerosis, however the mechanisms that underlie miR-30c-5p is required for endothelial cell pyroptosis remain elusive. In the present study, we probed the interaction of miR-30c-5p with forkhead box O3 (FOXO3) and investigated the effect of miR-30c-5p and FOXO3 on NLRP3 inflammasome and endothelial cell pyroptosis. Introduction of oxidized low density lipoprotein (ox-LDL) dose-dependently increased lactate dehydrogenase (LDH) release as well as pyroptosis in human aortic endothelial cells (HAECs). On the basis of ox-LDL treatment, we found the expression of miR-30c-5p was impaired and enrichment of miR-30c-5p protected HAECs from ox-LDL-induced pyroptosis. Moreover, addition of miR-30c-5p inhibited ox-LDL-activated NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, which was associated with HEACs pyroptosis. Nevertheless, miR-30c-5p failed to show efficacy of Toll-like receptor (TLR) signaling of NLRP3 inflammasome activation. Intriguingly, FOXO3 was suggested to be targeted by miR-30c-5p and addition of miR-30c-5p blocked FOXO3 expression, whereas miR-30c-5p depletion showed opposite effects. Furthermore, silencing of FOXO3 inhibited NLRP3-mediated pyroptosis and reversed anti-miR-30c-5p-induced activation of NLRP3 inflammasome and pyroptosis in HEACs with ox-LDL treatment. Our finding suggested that miR-30c-5p might play essential role in NLRP3 inflammasome-modulated cell pyroptosis by targeting FOXO3 in HAECs, providing a novel therapeutic avenue for atherosclerosis treatment.

FGF21 protects human umbilical vein endothelial cells against high glucose-induced apoptosis via PI3K/Akt/Fox3a signaling pathway

AIMS

Diabetic macroangiopathy is the main cause of morbidity and mortality in patients with diabetes. Endothelial cell injury is a pathological precondition for diabetic macroangiopathy. Fibroblast growth factor 21 (FGF21) is a key metabolic regulator which has recently been suggested to protect cardiac myocytes and vascular cells against oxidative stress-induced injury in vitro and vivo. In this study, we aimed to investigate the protective capacity of FGF21 in human umbilical vein endothelial cells (HUVECs) against high glucose (HG)-induced apoptosis via phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt)/FoxO3a pathway.

METHODS

The cell viability was examined by CCK-8 assay, Intracellular ROS levels were measured by the detection of the fluorescent product formed by the oxidation of DCFH-DA, Apoptosis was analyzed using Hoechst 33258 nuclear staining and Flow Cytometry Analysis (FCA), the expression of protein were detected by Western blot.

RESULTS

Results show that pretreating HUVECs with FGF21 before exposure to HG increases cell viability, while decreasing apoptosis and the generation of reactive oxygen species. Western blot analysis shows that HG reduces the phosphorylation of Akt and FoxO3a, and induces nuclear localization of FoxO3a. The effects were significantly reversed by FGF21 pre-treatment. Furthermore, the protective effects of FGF21 were prevented by PI3K/Akt inhibitor LY294002.

CONCLUSIONS

Our data demonstrates that FGF21 protects HUVECs from HG-induced oxidative stress and apoptosis via the activation of PI3K/Akt/FoxO3a signaling pathway.

Metabolic Regulation of Angiogenesis in Diabetes and Aging

Impaired angiogenesis and endothelial dysfunction are hallmarks of diabetes and aging. Clinical efforts at promoting angiogenesis have largely focused on growth factor pathways, with mixed results. Recently, a new repertoire of endothelial intracellular molecules critical to endothelial metabolism has emerged as playing an important role in regulating angiogenesis. This review thus focuses on the emerging importance and therapeutic potential of these proteins and of endothelial bioenergetics in diabetes and aging.

Non-Coding RNAs and Resistance to Anticancer Drugs in Gastrointestinal Tumors

Non-coding RNAs are important regulators of gene expression and transcription. It is well established that impaired non-coding RNA expression especially the one of long non-coding RNAs and microRNAs is involved in a number of pathological conditions including cancer. Non-coding RNAs are responsible for the development of resistance to anticancer treatments as they regulate drug resistance-related genes, affect intracellular drug concentrations, induce alternative signaling pathways, alter drug efficiency via blocking cell cycle regulation, and DNA damage response. Furthermore, they can prevent therapeutic-induced cell death and promote epithelial-mesenchymal transition (EMT) and elicit non-cell autonomous mechanisms of resistance. In this review, we summarize the role of non-coding RNAs for different mechanisms resulting in drug resistance (e.g., drug transport, drug metabolism, cell cycle regulation, regulation of apoptotic pathways, cancer stem cells, and EMT) in the context of gastrointestinal cancers.

Up-Regulation of miR-21, miR-25, miR-93, and miR-106b in Gastric Cancer

Background:

Differential expression profile of microRNAs (miRNAs) could be a diagnosis signature for monitoring gastric cancer (GC) progression. In this study, we focus on the comparison of expression levels of miR-21, miR-25, miR-93, miR-106b, and miR-375 during the sequential pattern of GC development, including normal gastric, gastric dysplasia, and GC sample.

Methods:

We used SYBR Green-based quantitative-PCR to quantify miRNAs expression.

Results:

Our analysis revealed the increased expression levels of miR-21 (p = 0.034), miR-25 (p = 0.0003), miR-93 (p = 0.0406), and miR-106b (p = 0.023) in GC samples. In addition, GC patients with positive lymph node metastasis showed the up-regulation of miR-25, miR-93, and miR-106b (p < 0.05).

Conclusion:

Our findings suggested that the expression of miR-21, miR-25, miR-93, and miR-106b altered in GC, and some of them may be further investigated as biomarkers for GC early detection and prognosis prediction.

Insulin signaling pathway protects neuronal cell lines by Sirt3 mediated IRS2 activation

Cellular stress like ER and oxidative stress are the principle causative agents of various proteinopathies. Multifunctional protein PARK7/DJ-1 provides protection against cellular stress. Recently, insulin/IGF also has emerged as a neuro-protective molecule. However, it is not known whether DJ-1 and insulin/IGF complement each other for cellular protection in response to stress. In this study, we show for the first time, that in human and mouse neuronal cell lines, down regulation of DJ-1 for 48 h leads to compensatory upregulation of insulin/IGF signaling (IIS) pathway genes, namely, insulin receptor, insulin receptor substrate, and Akt under normal physiological conditions as well as in cellular stress conditions. Moreover, upon exogenous supply of insulin there is a marked increase in the IIS components both at gene and protein levels leading to down regulation and inactivation of GSK3β. By immunoprecipitation, it was observed that Sirt3 mediated deacetylation and activation of FoxO3a could not occur under DJ-1 downregulation. Transient DJ-1 downregulation also led to Akt mediated increased phosphorylation and nuclear exclusion of FoxO3a. When DJ-1 was downregulated increased interaction of Sirt3 with IRS2 was observed leading to its activation resulting in IIS upregulation. Thus, transient downregulation of DJ-1 leads to stimulation of IIS pathway by Sirt3 mediated IRS2 activation. Consequently, antiapoptotic program is triggered in neuronal cells via Akt-GSK3β-FoxO3a axis. © 2018 BioFactors, 44(3):224-236, 2018.

New Insights into Protein Kinase B/Akt Signaling: Role of Localized Akt Activation and Compartment-Specific Target Proteins for the Cellular Radiation Response

Genetic alterations driving aberrant activation of the survival kinase Protein Kinase B (Akt) are observed with high frequency during malignant transformation and cancer progression. Oncogenic gene mutations coding for the upstream regulators or Akt, e.g., growth factor receptors, RAS and phosphatidylinositol-3-kinase (PI3K), or for one of the three Akt isoforms as well as loss of the tumor suppressor Phosphatase and Tensin Homolog on Chromosome Ten (PTEN) lead to constitutive activation of Akt. By activating Akt, these genetic alterations not only promote growth, proliferation and malignant behavior of cancer cells by phosphorylation of various downstream signaling molecules and signaling nodes but can also contribute to chemo- and radioresistance in many types of tumors. Here we review current knowledge on the mechanisms dictating Akt’s activation and target selection including the involvement of miRNAs and with focus on compartmentalization of the signaling network. Moreover, we discuss recent advances in the cross-talk with DNA damage response highlighting nuclear Akt target proteins with potential involvement in the regulation of DNA double strand break repair.

Dihydromyricetin protects against liver ischemia/reperfusion induced apoptosis via activation of FOXO3a-mediated autophagy

Liver ischemia and reperfusion (I/R) injury is characterized by defective liver autophagy accompanied by alterations to the endogenous defense system. Dihydromyricetin (DHM) is a natural flavonoid that demonstrates a wide range of physiological functions, and has been implicated as a regulator of autophagy. This study investigates the protective effects of DHM pretreatment on liver injury caused by ischemia/reperfusion (I/R) and elucidates the potential mechanism of DHM-mediated protection. Mice were subjected to 60 minutes of ischemia followed by 5 hours of reperfusion. DHM (100 mg/kg bw/day) or the vehicle was administered daily by gavage 7 days before ischemia and immediately before reperfusion. In this study, DHM markedly decreased serum aminotransferase activity and inhibited liver I/R -stimulated apoptosis. Moreover, DHM exerted hepatoprotective effects by upregulating mRNA levels of various essential autophagy-related genes including ATG5, ATG12, BECN1, and LC3. Autophagy inhibitor chloroquine or Atg5 knockdown blocked DHM -mediated elevation in liver function. Specifically, DHM significantly increased FOXO3a expression, and enhanced FOXO3a nuclear translocation and Ser588 phosphorylation modification. Importantly, the inhibition of FOXO3a with FOXO3a-siRNA in mice decreased DHM-induced autophagy-related genes and diminished the protective effects of DHM against liver I/R injury. In summary, these findings identify DHM as a novel hepatoprotective small molecule by elevating FOXO3a expression and nuclear translocation, stimulating autophagy-related genes and suppressing liver I/R-induced apoptosis, suggesting FOXO3a may have therapeutic value in liver cell protection in liver I/R injury.

FoxO3a confers cetuximab resistance in RAS wild-type metastatic colorectal cancer through c-Myc

Resistance to epidermal growth factor receptor (EGFR) targeted monoclonal antibody therapy represents a clinical challenge in patients suffered from RAS wild-type (WT) metastatic colorectal cancer (mCRC). However, the molecular mechanisms and key factors conferring this resistance are largely unknown. Forkhead transcription factors of the O class 3a (FoxO3a), an important regulator of cell survival, has been reported with dual functions in tumor recently. In this study, we found that FoxO3a was highly expressed in cetuximab resistant CRC tissues compared with cetuximab sensitive tissues. We therefore further analyzed its function in induced cetuximab resistant RAS-WT CRC cells (Caco2-CR) and intrinsic resistant cells with BRAF mutation (HT29). We found that FoxO3a was significantly up-regulated in Caco2-CR as well as in cetuximab treated HT29 cells. Knockdown of FoxO3a could sensitize these cells to cetuximab treatment with reduced cell proliferation and migration ability. Further, biochemical experiments demonstrated that FoxO3a directly bind to c-Myc promoter and activated the transcription of the c-Myc gene, thus participated in regulating of c-Myc downstream genes, including ACO2, LARS2, MRPL12 and PKM2 in these resistant cells. Moreover, knockdown of c-Myc elevated cell apoptosis to cetuximab treatment and suppressed cell proliferation and migration ability consistently. Altogether, our study indicates that FoxO3a might be a key regulator in cetuximab resistance through up-regulating c-Myc in colorectal cancer targeted therapy.

SIRT3 inhibits prostate cancer metastasis through regulation of FOXO3A by suppressing Wnt/β-catenin pathway

SIRT3, a mitochondrial NAD⁺-dependent deacetylase, has been reported to restrain prostate cancer growth both in vitro and in vivo, however, its role in metastatic prostate cancer has not been revealed. In this study, we reported that SIRT3 inhibited the epithelial-mesenchymal transition (EMT) and migration of prostatic cancer cells in vitro and their metastasis in vivo. Consistently, based on analyses of tissue microarray and microarray datasets, lower SIRT3 expression level was correlated with higher prostate cancer Gleason scores, and SIRT3 expression were significantly decreased in metastatic tissues compared with prostate tumor tissues. Mechanistically, SIRT3 promoted FOXO3A expression by attenuating Wnt/β-catenin pathway, thereby inhibiting EMT and migration of prostate cancer cells. Indeed, SIRT3's inhibitory effect on EMT and migration of prostate cancer cells can be rescued after applying Wnt/β-catenin pathway activator LiCl, or boosted by wnt inhibitor XAV939. Together, this study revealed a novel mechanism for prostate cancer metastasis that involves SIRT3/ Wnt/β-catenin/ FOXO3A signaling to modulate EMT and cell migration.

Homeostatic interplay between FoxO proteins and ER proteostasis in cancer and other diseases

Cancer cells are exposed to adverse conditions within the tumor microenvironment that challenge cells to adapt and survive. Several of these homeostatic perturbations insults alter the normal function of the endoplasmic reticulum (ER), resulting in the accumulation of misfolded proteins. ER stress triggers a conserved signaling pathway known as the unfolded protein response (UPR) to cope with the stress or trigger apoptosis of damaged cells. The UPR has been described as a major driver in the acquisition of malignant characteristics that ultimately lead to cancer progression. Although, several reports describe the relevance of the UPR in tumor growth, the possible crosstalk with other cancer-related pathways is starting to be elucidated. The Forkhead Box O (FoxO) subfamily of proteins has a major role in cancer progression, where chromosomal translocations and deregulated signaling lead to loss-of-function of FoxO proteins, contributing to tumor progression. Here we discuss the homeostatic connection between the UPR and FoxO proteins and its possible implications to tumor progression and the acquisition of several hallmarks of cancer. In addition, studies linking a crosstalk between the UPR and FoxO proteins in other diseases, including neurodegeneration and metabolic disorders is provided.

Amelioration of streptozotocin‑induced pancreatic β cell damage by morin: Involvement of the AMPK‑FOXO3‑catalase signaling pathway

Pancreatic β cells are sensitive to oxidative stress, which is one of the predominant causes of cell damage and the emergence of diabetes. The identification of effective therapeutic strategies to protect pancreatic cells from oxidative stress has increased interest in the screening of antioxidants from natural products. The present study aimed to investigate the protective effects of morin against streptozotocin (STZ)‑induced cell damage in a rat insulinoma cell line (RINm5F pancreatic β cells) and to identify the underlying mechanisms. The results indicated that morin inhibited the increase in intracellular reactive oxygen species, attenuated the activity of poly (ADP‑ribose) polymerase, restored intracellular nicotinamide adenine dinucleotide levels and reduced the apoptotic cell death of STZ‑treated pancreatic β cells. Treatment with morin significantly upregulated catalase in pancreatic β cells, and ameliorated the STZ‑induced loss of catalase at the genetic, protein and enzymatic level. In further experiments, morin induced the phosphorylation of 5' adenosine monophosphate‑activated protein kinase (AMPK), which subsequently promoted the translocation of forkhead box O3 (FOXO3) to the nucleus. Specific small interfering RNAs (siRNAs) against AMPK and FOXO3 suppressed morin‑induced catalase expression. Furthermore, catalase‑specific siRNA abolished the protective effects of morin against STZ‑stimulated cell death. Taken together, these results indicated that morin protected RINm5F cells from STZ‑induced cell damage by triggering the phosphorylation of AMPK, thus resulting in subsequent activation of FOXO3 and induction of catalase.

Effect of Sirtuin 1 inhibition on matrix metalloproteinase 2 and Forkhead box O3a expression in breast cancer cells

Breast cancer is the most common invasive cancer in women worldwide. Sirtuin 1 (SIRT1) has recently been shown to have implications in regulating cancer cell growth and apoptosis. SIRT1 regulates Forkhead box O3a (FOXO3a) by both inhibiting FOXO3-induced apoptosis and potentiating the ability of FOXO3a to resist oxidative stress. Matrix metalloproteinase 2 (MMP2) participates in tumor invasion and metastasis by degrading extracellular matrix. SIRT1 up regulates MMP2 expression by its deacetylation activity. This study aimed to investigate the expression of SIRT1, FOXO3a and MMP2 in breast tissues of women with breast cancer. In addition, the effect of SIRT1 inhibition on both FOXO3a and MMP2 expression in breast cancer (MCF-7) cells was assessed. The expression levels of SIRT1, FOXO3a and MMP2 in the breast tissues were determined by real-time PCR in 60 patients with malignant tumor and in 24 patients with benign tumors. After SIRT1 inhibition, protein levels of SIRT1 and FOXO3a were assessed by Western Blot and levels of MMP2 by ELISA in MCF-7 cells. The expression levels of SIRT1, FOXO3a and MMP2 were significantly higher in breast cancer tissues compared to in benign breast tumor and adjacent normal tissues. SIRT1, MMP2 and FOXO3a expression were associated directly with each other. SIRT1 inhibition suppresses MMP2 and FOXO3a expression compared to control MCF7. Sirtinol (SIRT1 inhibitor) effectively induced inhibition of MMP2 and FOXO3a expression in MCF-7 cells, indicating the promising therapeutic strategy of targeting SIRT1 for breast cancer.

The use of natural compounds for the targeting and chemoprevention of ovarian cancer

Among gynaecological cancers, ovarian cancer represents the leading cause of death in women. Current treatment for ovarian cancer entails surgery followed by combined chemotherapy with platinum and taxane, which are associated, particularly cisplatin, with severe side effects. While this treatment approach appears to be initially effective in a high number of patients, nearly 70% of them suffer a relapse within a few months after initial treatment. Therefore, more effective and better-tolerated treatment options are clearly needed. In recent years, several natural compounds (such as curcumin, epigallocatechin 3-gallate (EGCG), resveratrol, sulforaphane and Withaferin-A), characterized by long-term safety and negligible and/or inexistent side effects, have been proposed as possible adjuvants of traditional chemotherapy. Indeed, several in vitro and in vivo studies have shown that phytocompounds can effectively inhibit tumor cell proliferation, stimulate autophagy, induce apoptosis, and specifically target ovarian cancer stem cells (CSCs), which are generally considered to be responsible for tumor recurrence in several types of cancer. Here we review current literature on the role of natural products in ovarian cancer chemoprevention, highlighting their effects particularly on the regulation of inflammation, autophagy, proliferation and apoptosis, chemotherapy resistance, and ovarian CSC growth.

MicroRNA-25 contributes to cisplatin resistance in gastric cancer cells by inhibiting forkhead box O3a

Gastric cancer (GC) is a common type of malignancy worldwide, and chemotherapeutic resistance accounts for the majority of the failures in clinical treatment. MicroRNAs (miRs) are a class of small non-coding RNAs, which serve essential roles in GC. The present study aimed to investigate the potential role of miR-25 in the cisplatin sensitivity of GC cells. The expression level of miR-25 was significantly upregulated in the cisplatin-resistant GC cell line SGC-7901/DDP compared with the SGC-7901 parental cell line. Overexpression of miR-25 significantly enhanced cell cycle progression and decreased the sensitivity of SGC-7901 cells to cisplatin, whereas inhibition of miR-25 in the SGC-7901/DDP cisplatin-resistant cells resulted in cell cycle arrest at the G₀/G₁ phase and significantly increased drug sensitivity. Furthermore, the tumor suppressor forkhead box O3a (FOXO3a) was identified as a direct target gene of miR-25 by luciferase assay and western blot analysis, and was shown to mediate the drug-resistance phenotype of GC cells. These findings suggest that upregulation of miR-25 is important for GC cells to establish a cisplatin-resistant phenotype via a FOXO3a-dependent mechanism. Therefore, targeting miR-25 may be a promising therapeutic approach to treat patients with cisplatin-resistant GC.

Trichostatin A attenuates oxidative stress-mediated myocardial injury through the FoxO3a signaling pathway

Trichostatin A (TSA), a histone deacetylase inhibitor, is widely used as an anticancer drug. Recently, TSA has been shown to exert a protective effect on ischemia/reperfusion (I/R) injury; however, the underlying mechanisms remain unclear. Forkhead box O3a (FoxO3a), a unique FoxO family member, has been shown to attenuate myocardial injury by increasing resistance to oxidative stress in mice. The present study aimed to investigate whether TSA exerts its cardioprotective effects through the FoxO3a signaling pathway. For this purpose, healthy male Wistar rats were pre-treated with TSA for 5 days before they were subjected to ligation/relaxation of the left anterior descending branch of the coronary artery and to 30 min of ischemia, followed by 24 h of reperfusion. The activities of creatine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST) and superoxide diamutase (SOD), as well as the malondialdehyde (MDA) levels were examined. The H9c2 rat myocardial cell line was cultured in 10% FBS-containing DMEM for 24 h. The cells were incubated with/without TSA (50 nmol/l) for 1 h and then incubated with/without H₂O₂ (400 µM) for 2 h. Reactive oxygen species (ROS) and mitochondrial membrane potential (Δψm) were measured by probe staining in the H9c2 cells. The expression of FoxO3a, mitochondrial SOD2 and catalase was quantified by western blot analysis. The levels of H3 and H4 acetylation of the FoxO3a promoter region were examined by chromatin immunoprecipitation assay. TSA significantly reduced the myocardial infarct size and the activities of serum LDH, AST and CK in the rats. TSA also decreased the levels of MDA and increased the activities of SOD in the myocardial tissue of the rats. Consistent with the reduced injury to the TSA-treated rats, TSA significantly reduced the H₂O₂-induced levels of ROS and increased Δψm. In addition, TSA increased the expression of FoxO3a, SOD2 and catalase, which may be related to increasing the level of H4 acetylation of the FoxO3a promoter region. Our results thus revealed that TSA protected the myocardium from oxidative stress-mediated damage by increasing H4 acetylation of the FoxO3a promoter region, and the expression of FoxO3a, SOD2 and catalase.

Cowden syndrome-associated germline succinate dehydrogenase complex subunit D (SDHD) variants cause PTEN-mediated down-regulation of autophagy in thyroid cancer cells

Thyroid cancer is a major component cancer of Cowden syndrome (CS), a disorder typically associated with germline mutations in PTEN. Germline variants in succinate dehydrogenase genes (SDHx) co-occurring with PTEN germline mutations confer a 2-fold increased prevalence (OR 2.7) of thyroid cancer compared to PTEN-associated CS but 50% decreased prevalence (OR 0.54) of thyroid cancer compared to SDHx-associated CS. We have previously shown that CS-associated SDHD variants G12S and H50R induce PTEN oxidation and nuclear accumulation in thyroid cancer. Our current study shows that SDHD-G12S and -H50R variants cause down-regulation of autophagy, demonstrating a role for SDHD in autophagy-associated pathogenesis of differentiated thyroid cancer. These findings could explain the increased prevalence of thyroid cancer in CS patients with SDHx germline mutations compared to those with PTEN mutations alone. Importantly, we demonstrate the dependence of this process on functional wild-type PTEN with reversal of decreased autophagy after PTEN knockdown. The latter could explain the clinically observed decrease in thyroid cancer prevalence in patients with co-existent PTEN mutations and SDHx variants. We also show that SDHD-G12S/H50R promotes mono-ubiquitination of PTEN, causing its translocation into the nucleus, upregulation of AKT and consequent phosphorylation of FOXO3a. Furthermore, SDHD-G12S/H50R-mediated increase in acetylation of FOXO3a further enhances AKT-associated phosphorylation of FOXO3a. This combination of phosphorylation and acetylation of FOXO3a results in its nuclear export for degradation and consequent down-regulation of FOXO3a-target autophagy-related gene (ATG) expression. Overall, our study reveals a novel mechanism of crosstalk amongst SDHD, PTEN and autophagy pathways and their potential roles in thyroid carcinogenesis.

Anticarcinogenic effects of water extract of sporoderm-broken spores of Ganoderma lucidum on colorectal cancer in vitro and in vivo

Ganoderma lucidum (G. lucidum) polysaccharides (GLPs) have been used as traditional Chinese medicine for cancer prevention for many years. However, the mechanism by which GLP exerts its chemopreventive activities remains elusive. In addition, it is unclear whether sporoderm-broken spores of G. lucidum water extract (BSGLWE), which contains mainly GLPs, has anticancer effects on colorectal cancer. The present study investigated the anticancer effects and potential mechanisms of BSGLWE on colorectal cancer in vivo and in vitro. Our results showed that BSGLWE significantly inhibited colorectal cancer HCT116 cell viability in a time- and dose-dependent manner. Flow cytometry analysis indicated that BSGLWE disrupted cell cycle progression at G2/M phase via downregulation of cyclin B1 and cyclin A2, and upregulation of P21 at mRNA levels. Moreover, BSGLWE induced apoptosis by decreasing Bcl-2 and survivin at mRNA levels, and reduced Bcl-2, PARP, pro-caspase-3 and pro-caspase-9 at protein levels. Furthermore, BSGLWE suppressed tumor growth in vivo by regulating the expression of genes and proteins associated with cell cycle and apoptosis, which was further confirmed by a reduction of Ki67, PCNA, and Bcl-2 expression as determined by immunohistochemistry staining. NSAID activated gene-1 (NAG-1), a pro-apoptotic gene, was significantly upregulated in vivo and in vitro upon BSGLWE treatment at both mRNA and protein levels. In addition, the relative amounts of secreted NAG-1 in cell culture medium or serum of nude mice were all upregulated upon BSGLWE treatments, suggesting a role of NAG-1 in BSGLWE-induced anticolorectal cancer activity. This is the first study to show that BSGLWE inhibits colorectal cancer carcinogenesis through regulating genes responsible for cell proliferation, cell cycle and apoptosis cascades. These findings indicate that BSGLWE possesses chemopreventive potential in colorectal cancer which may serve as a promising anticancer agent for clinical applications.

A novel cytoprotective peptide protects mesenchymal stem cells against mitochondrial dysfunction and apoptosis induced by starvation via Nrf2/Sirt3/FoxO3a pathway

Background

Mesenchymal stem cell (MSC) has been widely explored in the past decade as a cell-based treatment for various diseases. However, poor survival of adaptively transferred MSCs limits their clinical therapeutic potentials, which is largely ascribed to the nutrient starvation. In this study, we determined whether a novel kidney protective peptide CHBP could protect MSCs against starvation and invested the underlying mechanisms.

Methods

MSCs were subjected to serum deprivation and CHBP of graded concentrations was administered. Cell viability and apoptosis were detected by CCK-8, Annexin V/PI assay and Hoechst staining. ROS generation, mitochondrial membrane potential indicated by JC-1 and mitochondrial mass were measured by flow cytometry. The location of cytochrome c within cells was observed under fluorescence microscopy. Expressions of Nrf2, Sirt3, and FoxO3a were analyzed by western blot. In addition, preconditioning MSCs with CHBP was applied to test the possible protection against starvation. Finally, the effect of CHBP on the differentiation and self-renewal capacity of MSCs was also examined.

Results

CHBP improved cell viability and suppressed apoptosis in a dose dependent manner. Starvation resulted in the mitochondrial dysfunction and treatment of CHBP could alleviate mitochondrial stress by diminishing oxidative injury of ROS, restoring mitochondrial membrane potential and maintaining mitochondrial membrane integrity. Importantly, Nrf2/Sirt3/FoxO3a pathway was activated by CHBP and Sirt3 knockdown partially abolished the protection of CHBP. Moreover, MSCs pretreated with CHBP were more resistant to starvation. Under normal condition, CHBP exerted little effects on the differential and self-renewal capacity of MSCs.

Conclusions

The present study demonstrated the efficient protection of CHBP upon MSCs against starvation-induced mitochondrial dysfunction and apoptosis and indicated possible involvement of Nrf2/Sirt3/FoxO3a pathway in the protective effect.