A "FOXO" in sight: targeting Foxo proteins from conception to cancer

Mechano-induced cell metabolism disrupts the oxidative stress homeostasis of SAOS-2 osteosarcoma cells

There has been an increasing focus on cancer mechanobiology, determining the underlying-induced changes to unlock new avenues in the modulation of cell malignancy. Our study used LC-MS untargeted metabolomic approaches and real-time polymerase chain reaction (PCR) to characterize the molecular changes induced by a specific moderate uniaxial stretch regimen (i.e., 24 h-1 Hz, cyclic stretch 0,5% elongation) on SAOS-2 osteosarcoma cells. Differential metabolic pathway analysis revealed that the mechanical stimulation induces a downregulation of both glycolysis and the tricarboxylic acid (TCA) cycle. At the same time, the amino acid metabolism was found to be dysregulated, with the mechanical stimulation enhancing glutaminolysis and reducing the methionine cycle. Our findings showed that cell metabolism and oxidative defense are tightly intertwined in mechanically stimulated cells. On the one hand, the mechano-induced disruption of the energy cell metabolism was found correlated with an antioxidant glutathione (GSH) depletion and an accumulation of reactive oxygen species (ROS). On the other hand, we showed that a moderate stretch regimen could disrupt the cytoprotective gene transcription by altering the expression levels of manganese superoxide dismutase (SOD1), Sirtuin 1 (SIRT1), and NF-E2-related factor 2 (Nrf2) genes. Interestingly, the cyclic applied strain could induce a cytotoxic sensitization (to the doxorubicin-induced cell death), suggesting that mechanical signals are integral regulators of cell cytoprotection. Hence, focusing on the mechanosensitive system as a therapeutic approach could potentially result in more effective treatments for osteosarcoma in the future.

Innovative therapeutic strategies for cardiovascular disease

As a significant non-communicable disease, cardiovascular disease is the leading cause of death for both men and women, comprises almost twenty percent of deaths in most racial and ethnic groups, can affect greater than twenty-five million individuals worldwide over the age of twenty, and impacts global economies with far-reaching financial challenges. Multiple factors can affect the onset of cardiovascular disease that include high serum cholesterol levels, elevated blood pressure, tobacco consumption and secondhand smoke exposure, poor nutrition, physical inactivity, obesity, and concurrent diabetes mellitus. Yet, addressing any of these factors cannot completely eliminate the onset or progression of cardiovascular disorders. Novel strategies are necessary to target underlying cardiovascular disease mechanisms. The silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), a histone deacetylase, can limit cardiovascular injury, assist with stem cell development, oversee metabolic homeostasis through nicotinamide adenine dinucleotide (NAD+) pathways, foster trophic factor protection, and control cell senescence through the modulation of telomere function. Intimately tied to SIRT1 pathways are mammalian forkhead transcription factors (FoxOs) which can modulate cardiac disease to reduce oxidative stress, repair microcirculation disturbances, and reduce atherogenesis through pathways of autophagy, apoptosis, and ferroptosis. AMP activated protein kinase (AMPK) also is critical among these pathways for the oversight of cardiac cellular metabolism, insulin sensitivity, mitochondrial function, inflammation, and the susceptibility to viral infections such as severe acute respiratory syndrome coronavirus that can impact cardiovascular disease. Yet, the relationship among these pathways is both intricate and complex and requires detailed insight to successfully translate these pathways into clinical care for cardiovascular disorders.

Cognitive Impairment in Multiple Sclerosis

Almost three million individuals suffer from multiple sclerosis (MS) throughout the world, a demyelinating disease in the nervous system with increased prevalence over the last five decades, and is now being recognized as one significant etiology of cognitive loss and dementia. Presently, disease modifying therapies can limit the rate of relapse and potentially reduce brain volume loss in patients with MS, but unfortunately cannot prevent disease progression or the onset of cognitive disability. Innovative strategies are therefore required to address areas of inflammation, immune cell activation, and cell survival that involve novel pathways of programmed cell death, mammalian forkhead transcription factors (FoxOs), the mechanistic target of rapamycin (mTOR), AMP activated protein kinase (AMPK), the silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), and associated pathways with the apolipoprotein E (APOE-ε4) gene and severe acute respiratory syndrome coronavirus (SARS-CoV-2). These pathways are intertwined at multiple levels and can involve metabolic oversight with cellular metabolism dependent upon nicotinamide adenine dinucleotide (NAD+). Insight into the mechanisms of these pathways can provide new avenues of discovery for the therapeutic treatment of dementia and loss in cognition that occurs during MS.

The shared molecular mechanisms underlying aging of the brain, major depressive disorder, and Alzheimer's disease: The role of circadian rhythm disturbances

An association with circadian clock function and pathophysiology of aging, major depressive disorder (MDD), and Alzheimer's disease (AD) is well established and has been proposed as a factor in the development of these diseases. Depression and changes in circadian rhythm have been increasingly suggested as the two primary overlapping and interpenetrating changes that occur with aging. The relationship between AD and depression in late life is not completely understood and probably is complex. Patients with major depression or AD suffer from disturbed sleep/wake cycles and altered rhythms in daily activities. Although classical monoaminergic hypotheses are traditionally proposed to explain the pathophysiology of MDD, several clinical and preclinical studies have reported a strong association between circadian rhythm and mood regulation. In addition, a large body of evidence supports an association between disruption of circadian rhythm and AD. Some clock genes are dysregulated in rodent models of depression. If aging, AD, and MDD share a common biological basis in pathophysiology, common therapeutic tools could be investigated for their prevention and treatment. Nitro-oxidative stress (NOS), for example, plays a fundamental role in aging, as well as in the pathogenesis of AD and MDD and is associated with circadian clock disturbances. Thus, development of therapeutic possibilities with these NOS-related conditions is advisable. This review describes recent findings that link disrupted circadian clocks to aging, MDD, and AD and summarizes the experimental evidence that supports connections between the circadian clock and molecular pathologic factors as shared common pathophysiological mechanisms underlying aging, AD, and MDD.

Diffuse large B-cell lymphoma and red cell autoimmunity: clinical role and pathogenesis

Diffuse large B-cell lymphoma (DLBCL) is the most common form of B-cell non-Hodgkin lymphoma (B-NHL) with significant morbidity and mortality despite advancements in treatment. Lymphoma and autoimmune disease both result from breakdowns in normal cell regulatory pathways, and epidemiological studies have confirmed both that B-NHL is more likely to develop in the setting of autoimmune diseases and vice versa. Red cell immunity, as evidenced by direct antiglobulin test (DAT) positivity, has been linked to DLBCL and more recently the pathogenic causes of this association have begun to be better understood using molecular techniques. This project aimed to explore the relationship between red cell autoimmunity and DLBCL. DAT positivity was more common in DLBCL as compared to healthy controls (20.4% vs 3.7%, p=0.0005). Univariate analysis found a non-significant trend towards poorer overall survival in the DAT positive (DAT+) compared to the DAT negative (DAT-) groups (p=0.087). High throughput sequencing was used to compare mutations in DLBCL from DAT+ and DAT- patients. The most frequently mutated genes in 15 patient samples were KMT2D (n=13), MYOM2 (n=9), EP300 (n=8), SPEN (n=7), and ADAMTSL3 (n=7), which were mutated in both DAT+ and DAT- groups. BIRC3 (n=3), FOXO1 (n=3) and CARD11 (n=2) were found to be mutated only in samples from the DAT+ group. These gene mutations may be involved in disease development and progression, and potentially represent targets for future therapy. The immunoglobulin genotype IGHV4-34 is seen more frequently in DLBCL clones than in normal B cells and has intrinsic autoreactivity to self-antigens on red cells, which is largely mediated by two motifs within the first framework region (FR1); Q⁶W⁷ and A²⁴V²⁵Y.²⁶ These motifs form a hydrophobic patch which determines red cell antigen binding and are frequently mutated away from self-reactivity in normal B cells. If this does not occur this may provide constant B cell receptor signalling which encourages lymphoma development, a theory known as antigen driven lymphomagenesis. As with previous studies, IGHV4-34 was over-represented (15.6%) in our DLBCL cohort. Furthermore, of 6 IGHV4-34-expressing DLBCL samples five had unmutated hydrophobic patch mutations providing further evidence for antigen-driven lymphomagenesis. Mutation analysis of these five samples demonstrated high frequency of mutations in several genes, including CREBBP and NCOR2. Further research could explore if mutations in CREBBP and NCOR2 work in conjunction with the preserved QW and AVY motifs to promote lymphomagenesis in IGHV4-34-expressing B cells, and if so, could guide future targeted therapy.

Colorectal cancer risk susceptibility loci in a Swedish population

To search for colorectal cancer (CRC) risk loci, Swedish samples were used for a genome-wide haplotype analysis. A logistic regression model was employed in 2663 CRC cases and 1642 controls in the discovery analysis. Three analyses were done, on all, familial-, and nonfamilial CRC samples and only results with odds ratio (OR) > 1 were analyzed. single nucleotide polymorphism (SNP) analysis did not generate any statistically significant results. Haplotype analysis suggested novel loci, on chromosome 2q36.1 (OR = 1.71, p value = 5.6924 × 10^-8 ) in all CRC samples, chromosome 1q43 (OR = 4.04 p value = 3.24 × 10^-8 ) in familial CRC samples, and two hits in nonfamilial CRC samples, chromosomes 2q36.1 (OR = 1.71 p value = 5.69 × 10^-8 ) and 3p24.3 (OR = 1.62 p value = 6.21 × 10^-9 ). Moreover, one locus on chromosome 20q13.33 was suggested in analyses of all samples, and five more novel loci were suggested on chromosomes 10q25.3, 15q,22.31, 17p11.2, 1p34.2, and 3q24. The haplotypes from the analysis of all samples were replicated in a second study of CRC cases and controls from the same part of Sweden. In summary, using haplotype analysis in Swedish CRC samples, the best hits were novel loci and the locus on chromosomes 2q36.1 and 20q13.33 suggested in the analysis of all samples were confirmed in a second cohort. The ORs were often higher than ORs from published genome-wide association study (GWAS). The study suggested it was possible that a risk locus could involve more than one gene, and that haplotypes could give information on the gene or genes possibly involved in the risk at specific locus.

Sirtuins: Potential Therapeutic Targets for Defense against Oxidative Stress in Spinal Cord Injury

Spinal cord injury (SCI) is one of the most incapacitating neurological disorders. It involves complex pathological processes that include a primary injury and a secondary injury phase, or a delayed stage, which follows the primary injury and contributes to the aggravation of the SCI pathology. Oxidative stress, a key pathophysiological event after SCI, contributes to a cascade of inflammation, excitotoxicity, neuronal and glial apoptosis, and other processes during the secondary injury phase. In recent years, increasing evidence has demonstrated that sirtuins are protective toward the pathological process of SCI through a variety of antioxidant mechanisms. Notably, strategies that modulate the expression of sirtuins exert beneficial effects in cellular and animal models of SCI. Given the significance and novelty of sirtuins, we summarize the oxidative stress processes that occur in SCI and discuss the antioxidant effects of sirtuins in SCI. We also highlight the potential of targeting sirtuins for the treatment of SCI.

Expression of FOXO transcription factors in the brain following traumatic brain injury

Traumatic brain injury (TBI) is a substantial clinical and social problem worldwide, causing high morbidity and mortality along with significant economic and medical costs. Forkhead box O transcription factors (FOXOs) have been found to play a critical role in the regulation of cell functions, such as nutrient metabolism, programmed cell death, and tumor suppression. In the central nervous system, FOXOs are reported to be pivotal regulators of learning and memory, neurite outgrowth, and axonal degeneration. However, the role of FOXOs in TBI is still unknown. Here, we investigate changes in the expression of FOXOs in the acute stage following TBI. First, we evaluated the expression of FOXO proteins in the brains of humans after TBI. A TBI model was then established in mice, and the ipsilateral cerebral cortex was collected at 3 h, 6 h, 9 h, 12 h, 24 h, and 72 h post-TBI. The dynamic expression of Foxo proteins was observed. Neuron-specific localization of Foxos was detected by double immunofluorescence staining. Following TBI, FOXO proteins in the brains of humans were significantly increased. In mice, Foxo protein levels generally peaked at 24 h. By examining co-localization with neurons, the proportion of Foxo(+) neurons was found to increase following TBI and peak at 24 h. This study reveals the time-dependent and neuron-specific expression of Foxos following TBI in mice, providing insight to enhance understanding of the role of Foxos in TBI.

L-carnitine treatment attenuates renal tubulointerstitial fibrosis induced by unilateral ureteral obstruction

BACKGROUND/AIMS

Accumulating evidence indicates that L-carnitine (LC) protects against multiorgan damage through its antioxidant properties and preservation of the mitochondria. Little information is available about the effects of LC on renal fibrosis. This study examined whether LC treatment would provide renoprotection in a rat model of unilateral ureteral obstruction (UUO) and in vitro.

METHODS

Sprague-Dawley rats that underwent UUO were treated daily with LC for 7 or 14 days. The influence of LC on renal injury caused by UUO was evaluated by histopathology, and analysis of gene expression, oxidative stress, mitochondrial function, programmed cell death, and phosphatidylinositol 3-kinase (PI3K)/ AKT/forkhead box protein O 1a (FoxO1a) signaling. In addition, H2O2-exposed human kidney cells (HK-2) were treated with LC.

RESULTS

LC treatment inhibited expression of proinflammatory and profibrotic cytokines, and was followed by a significant attenuation of tubulointerstitial inflammation and fibrosis. The increased oxidative stress caused by UUO was associated with mitochondrial dysfunction and excessive apoptosis and autophagy via PI3K/AKT/FoxO1a-dependent signaling, and this was abrogated by administration of LC. In H2O2-exposed HK-2 cells, LC decreased intracellular production of reactive oxygen species, and suppressed expression of profibrotic cytokines and reduced the number of apoptotic cells.

CONCLUSION

LC protects against the progression of tubulointerstitial fibrosis in an obstructed kidney.

Nicotinamide as a Foundation for Treating Neurodegenerative Disease and Metabolic Disorders

Neurodegenerative disorders impact more than one billion individuals worldwide and are intimately tied to metabolic disease that can affect another nine hundred individuals throughout the globe. Nicotinamide is a critical agent that may offer fruitful prospects for neurodegenerative diseases and metabolic disorders, such as diabetes mellitus. Nicotinamide protects against multiple toxic environments that include reactive oxygen species exposure, anoxia, excitotoxicity, ethanolinduced neuronal injury, amyloid (Aß) toxicity, age-related vascular disease, mitochondrial dysfunction, insulin resistance, excess lactate production, and loss of glucose homeostasis with pancreatic β-cell dysfunction. However, nicotinamide offers cellular protection in a specific concentration range, with dosing outside of this range leading to detrimental effects. The underlying biological pathways of nicotinamide that involve the silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), the mechanistic target of rapamycin (mTOR), AMP activated protein kinase (AMPK), and mammalian forkhead transcription factors (FoxOs) may offer insight for the clinical translation of nicotinamide into a safe and efficacious therapy through the modulation of oxidative stress, apoptosis, and autophagy. Nicotinamide is a highly promising target for the development of innovative strategies for neurodegenerative disorders and metabolic disease, but the benefits of this foundation depend greatly on gaining a further understanding of nicotinamide's complex biology.

Exogenous pancreatic kininogenase protects against renal fibrosis in rat model of unilateral ureteral obstruction

Tissue kallikrein has protective function against various types of injury. In this study, we investigated whether exogenous pancreatic kininogenase (PK) conferred renoprotection in a rat model of unilateral ureteral obstruction (UUO) and H₂O₂-treated HK-2 cells in vitro. SD rats were subjected to UUO surgery, then PK (7.2 U/g per day, ip) was administered for 7 or 14 days. After the treatment, rats were euthanized; the obstructed kidneys were harvested for further examination. We found that PK administration significantly attenuated interstitial inflammation and fibrosis, and downregulated the expression of proinflammatory (MCP-1, TLR-2, and OPN) and profibrotic (TGF-β1 and CTGF) cytokines in obstructed kidney. UUO-induced oxidative stress, closely associated with excessive apoptotic cell death and autophagy via PI3K/AKT/FoxO1a signaling, which were abolished by PK administration. We further showed that PK administration increased the expression of bradykinin receptors 1 and 2 (B1R and B2R) mRNA and the production of NO and cAMP in kidney tissues. Coadministration with either B1R antagonist (des-Arg9-[Leu8]-bradykinin) or B2R antagonist (icatibant) abrogated the renoprotective effects of PK, and reduced the levels of NO and cAMP in obstructed kidney. In H₂O₂-treated HK-2 cells, addition of PK (6 pg/mL) significantly decreased ROS production, regulated the expression of oxidant and antioxidant enzymes, suppressed the expression of TGF-β1 and MCP-1, and inhibited cell apoptosis. Our data demonstrate that PK treatment protects against the progression of renal fibrosis in obstructed kidneys.

Effects of FOXO1 on the proliferation and cell cycle-, apoptosis- and steroidogenesis-related genes expression in sheep granulosa cells

Forkhead boxO (FOXO) transcription factors regulate diverse biological processes, including cellular metabolism, cell apoptosis, and the cell cycle. Results from several studies indicate FOXO1 regulates different granulosa cell (GC) pathways involved in proliferation, survival and differentiation. Functions and mechanisms of FOXO1 regulation of sheep GCs remain unclear. This study was conducted to analyze the function of FOXO1 in regulation of sheep GCs. In this study, the 1827 bp sheep FOXO1 coding sequence was cloned from sheep GCs. Multiple sequence alignment and phylogenetic analysis indicated that the FOXO1 protein sequence is highly homologous to FOXO1 protein sequences from other species. The results obtained from using CCK-8 assays indicated sheep GC proliferation increased when there was suppression of FOXO1 gene expression. When there was induced expression of the FOXO1 gene in sheep GCs, there was a resulting increased abundance of P21 and P27 mRNA transcript, whereas suppression of the FOXO1 gene expression had the opposite effect. Furthermore, the relative abundance in vitro of apoptosis-related protein mRNA transcripts (caspase3, caspase8, caspase9, Bax/Bcl-2) was markedly increased or decreased when there was induction or suppression of FOXO1 gene expression, respectively,(P < 0.05). Induction of FOXO1 gene expression resulted in an increase in abundance of steroidogenic protein mRNA transcripts (CYP11A1, 3β-HSD), while suppression of FOXO1 gene expresion resulted in a decrease abundance of the CYP11A1, STAR mRNA transcripts. Results from the present study indicated that FOXO1 inhibited the proliferation of sheep GCs and affected mRNA transcript abundance for proteins involved in regulation of apoptosis, the cell cycle and steroidogenesis.

Clinicopathological significance and angiogenic role of the constitutive phosphorylation of the FOXO1 transcription factor in colorectal cancer

PURPOSE

This study aimed to evaluate the clinicopathological significance of phospho-forkhead box O1 (pFOXO1) expression and its impact on the angiogenesis of colorectal cancer (CRC).

METHODS

We performed immunohistochemistry in 266 human CRC tissues for pFOXO1, and evaluated its cytoplasmic expression, regardless of its nuclear expression. We also investigated the correlation between pFOXO1 expression and clinicopathological characteristics, survival, microvessel density (MVD), and angiogenesis-related molecules in CRC.

RESULTS

pFOXO1 was expressed in the cytoplasm of 100 (37.6 %) of the 266 CRC tissues. Furthermore, pFOXO1 expression was significantly correlated with the left colon and rectum, and with vascular invasion, lymph node metastasis, distant metastasis, and higher pTNM stage. However, there was no significant correlation between pFOXO1 expression and other clinicopathological parameters. MVD was significantly higher in pFOXO1-positive tumors than in pFOXO1-negative tumors (P = 0.025). Among the angiogenesis-related molecules examined, pFOXO1 expression was significantly correlated with SIRT1 (P = 0.002) and VEGF expression (P < 0.001), but not with HIF-1α expression. pFOXO1 expression was significantly correlated with poor overall and recurrence-free survival rates (P = 0.001 and P < 0.001, respectively).

CONCLUSIONS

Taken together, our results showed that the pFOXO1 expression was significantly correlated with aggressive tumor behavior and poor survival rates. Moreover, pFOXO1 expression may affect tumor progression through SIRT1- and VEGF-induced angiogenesis.

FOXO3 gene polymorphisms influence the risk of acute lymphoblastic leukemia in Chinese children

Acute lymphoblastic leukemia (ALL) is the most frequently diagnosed cancer in children and single-nucleotide polymorphisms (SNPs) in certain genes influence risk of ALL. Although FOXO3 had been demonstrated to be involved leukemia, the role of FOXO3 polymorphisms was still not clear. In the present study, we explored the association of FOXO3 SNPs with ALL risk in Chinese children. We genotyped four polymorphisms (rs17069665 A>G, rs4945816 T>C, rs4946936 C>T, and rs9400241 A>C) of FOXO3 in 425 ALL cases and 1339 health controls. The associations were estimated by odds ratios (ORs) with their 95% confidence intervals (CIs). Further analyses were performed to explore associations of rs17069665 and rs9400241 with ALL susceptibility in terms of age, gender, immunophenotype, minimal residual disease (MRD), and other clinical characteristics. We found rs17069665 related to the increased ALL risk (OR = 1.76; 95% CI = 1.02-3.04), rs9400241 related to decreased ALL risk (OR = 0.80; 95% CI = 0.64-0.99). The effects of rs17069665 on ALL risk were more predominant in males and children < 10 years, and patients with lower rates of platelet or neutrophil. As for rs9400241, the effects were more predominant in children < 10 years, and in patients with pre B ALL, positive MRD, anemia, or hepatomegaly. In conclusion, FOXO3 gene polymorphisms influence the risk of ALL in children and might be a potential biomarker for ALL susceptibility.

FoxO1 controls the expansion of pre-B cells by regulating the expression of interleukin 7 receptor α chain and its signal pathway

Forkhead box O1 (FoxO1) has a crucial role in the early B cell development. To understand the functional importance of FoxO1 gene in the early B cell expansion, we established a FoxO1 knockdown model using 70Z/3 pre-B cell line. The FoxO1 knockdown 70Z/3 cells (70Z/3-KD cells) showed the down-regulated expression of interleukin 7 receptor α chain (IL-7Rα). Moreover, the signaling via IL-7Rα was significantly attenuated in the 70Z/3-KD cells, and this alteration was fully rescued by re-expression of FoxO1 gene. Compared to the mock cells, loss of FoxO1 reduced the growth rates in the 70Z/3-KD cells, and was fully rescued by reintroduction of FoxO1 gene. The expansion of pre-B cells (CD45R⁺CD43^- fraction) was also reduced by the knockdown of FoxO1 gene. Indeed, FoxO1 induces accumulation in the p27-mediated G0/G1 phase arrest in 70Z/3 cells. FoxO1 bound to the Il7ra locus specifically and regulate the IL-7Rα transcription. In conclusion, FoxO1 regulates the expansion of pre-B cells by regulating the expression of IL-7Rα and its signal transduction.

CTCF regulates the FoxO signaling pathway to affect the progression of prostate cancer

The present research focuses on the influence of CCCTC‐binding factor (CTCF) on prostate cancer (PC) via the regulation of the FoxO signalling pathway. A bioinformatics analysis was conducted to screen out target genes for CTCF in LNCaP cells and to enrich the relevant pathways in LNCaP cells. It was found that the FoxO pathway was enriched according to the ChIP‐seq results of CTCF. The expression of CTCF, pFoxO1a, FoxO1a, pFoxO3a and FoxO3a was tested by RT‐qPCR and Western blot. Inhibition of CTCF could lead to the up‐regulation of the FoxO signalling pathway. The rates of cell proliferation, cell invasion and apoptosis were examined by MTT assay, cell invasion assay and flow cytometry under different interference conditions. Down‐regulation of CTCF could suppress cell proliferation, cell invasion and facilitate cell apoptosis. Lastly, the effect of CTCF on tumour growth was determined in nude mice. Inhibition of CTCF regulated the FoxO signalling pathway, which retarded tumour growth in vivo. In conclusion, CTCF regulates the FoxO signalling pathway to affect the progress of PC.

Cancer Immunotherapy: Silencing Intracellular Negative Immune Regulators of Dendritic Cells

Dendritic cells (DCs) are capable of activating adaptive immune responses, or inducing immune suppression or tolerance. In the tumor microenvironment, the function of DCs is polarized into immune suppression that attenuates the effect of T cells, promoting differentiation of regulatory T cells and supporting tumor progression. Therefore, blocking negative immune regulators in DCs is considered a strategy of cancer immunotherapy. Antibodies can target molecules on the cell surface, but not intracellular molecules of DCs. The delivery of short-hairpin RNAs (shRNA) and small-interfering RNAs (siRNA) should be a strategy to silence specific intracellular targets in DCs. This review provides an overview of the known negative immune regulators of DCs. Moreover, a combination of shRNA/siRNA and DC vaccines, DNA vaccines in animal models, and clinical trials are also discussed.

FOXO1 overexpression and loss of pSerine256-FOXO1 expression predicts clinical outcome in esophageal adenocarcinomas

The function of Forkhead box O 1 (FOXO1) and pSerine256-FOXO1 immunostaining in esophageal cancer is unclear. To clarify the prognostic role of nuclear FOXO1 and cytoplasmic pSerine256-FOXO1 immunostaining, a tissue microarray containing more than 600 esophageal cancers was analyzed. In non-neoplastic esophageal mucosae, FOXO1 expression was detectable in low and pSerine256-FOXO1 expression in high intensities. Increased FOXO1 and decreased pSerine256-FOXO1 expression were linked to advanced tumor stage and high UICC stage in esophageal adenocarcinomas (EACs) (tumor stage: p = 0.0209 and p < 0.0001; UICC stage: p = 0.0201 and p < 0.0001) and squamous cell carcinomas (ESCCs) (tumor stage: p = 0.0003 and p = 0.0016; UICC stage: p = 0.0026 and p = 0.0326). Additionally, overexpression of FOXO1 and loss of pSerine256-FOXO1 expression predicted shortened survival of patients with EACs (p = 0.0003 and p = 0.0133) but were unrelated to outcome in patients with ESCCs (p = 0.7785 and p = 0.8426). In summary, our study shows that overexpression of nuclear FOXO1 and loss of cytoplasmic pSerine256-FOXO1 expression are associated with poor prognosis in patients with EACs. Thus, evaluation of FOXO1 and pSerine256-FOXO1 protein expression - either alone or in combination with other markers - might be useful for prediction of clinical outcome in patients with EAC.

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.

Novel Treatment Strategies for the Nervous System: Circadian Clock Genes, Non-coding RNAs, and Forkhead Transcription Factors

BACKGROUND

With the global increase in lifespan expectancy, neurodegenerative disorders continue to affect an ever-increasing number of individuals throughout the world. New treatment strategies for neurodegenerative diseases are desperately required given the lack of current treatment modalities.

METHODS

Here, we examine novel strategies for neurodegenerative disorders that include circadian clock genes, non-coding Ribonucleic Acids (RNAs), and the mammalian forkhead transcription factors of the O class (FoxOs).

RESULTS

Circadian clock genes, non-coding RNAs, and FoxOs offer exciting prospects to potentially limit or remove the significant disability and death associated with neurodegenerative disorders. Each of these pathways has an intimate relationship with the programmed death pathways of autophagy and apoptosis and share a common link to the silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1) and the mechanistic target of rapamycin (mTOR). Circadian clock genes are necessary to modulate autophagy, limit cognitive loss, and prevent neuronal injury. Non-coding RNAs can control neuronal stem cell development and neuronal differentiation and offer protection against vascular disease such as atherosclerosis. FoxOs provide exciting prospects to block neuronal apoptotic death and to activate pathways of autophagy to remove toxic accumulations in neurons that can lead to neurodegenerative disorders.

CONCLUSION

Continued work with circadian clock genes, non-coding RNAs, and FoxOs can offer new prospects and hope for the development of vital strategies for the treatment of neurodegenerative diseases. These innovative investigative avenues have the potential to significantly limit disability and death from these devastating disorders.

Molecular Signature of Tumors with Monoallelic 13q14 Deletion: a Case Series of Spindle Cell Lipoma and Genetically-Related Tumors Demonstrating a Link Between FOXO1 Status and p38 MAPK Pathway

Spindle cell/pleomorphic lipomas (SCLs), cellular angiofibromas (CAFs) and mammary-type myofibroblastomas (MFBs) are rare benign mesenchymal tumors with monoallelic 13q14 deletion. They are predicted to have a common pathogenic mechanism due to shared similar histological and immunohistochemical features; however, pathological consequences of monoallelic 13q14 deletion remain unknown. We previously reported a CAF case with monoallelic 13q14 deletion in which the tumor expressed decreased levels of FOXO1 and RB1, both of which were encoded in 13q14, and increased reactive oxygen species (ROS) levels. We further demonstrated the activation of p38 mitogen-activated protein kinase (p38 MAPK) pathway induced by oxidative stress. We hypothesized that SCLs, CAFs and MFBs would share common molecular signatures involving FOXO1, ROS and p38 MAPK and that their expression patterns were different from those tumors without monoallelic 13q14 deletion such as solitary fibrous tumors (SFTs). We compared the expression levels of FOXO1, RB1, ROS markers and several signal transduction factors between SCLs and SFTs. SCLs expressed decreased levels of FOXO1 and RB1, whereas SFTs showed no change. Both tumor types exhibited increased markers of ROS; however, nuclear localization of phosphorylated p38 was significantly more frequent in SCLs than that in SFTs, suggesting p38 MAPK activation by oxidative stress. SFTs showed lower p38 MAPK activity and higher β-catenin expression, implying that oxidative stress was caused by increased cellular proliferation stress. Finally, CAFs and MFBs showed changes similar to those observed in SCLs. Overall, tumors with monoallelic 13q14 deletion showed shared molecular signatures that might be associated with pathogenesis.

Nutritional biomarkers: Current view and future perspectives

There is a poor relationship between nutrient intake and existing nutritional biomarkers due to variety of factors affecting their sensitivity and specificity. To explore the impact of nutrients at molecular level and devising a sensitive biomarker, proteomics is a central technology with sirtuins as one of the most promising nutritional biomarker. Sirtuins (seven mammalian sirtuins reported so far) have been reported to perform protein deacetylases and ADP-ribosyltransferases activity. It is distributed in different cellular compartments thereby controlling several metabolic processes. Sirtuins are oxidized nicotinamide adenine dinucleotide dependent, which implicates a direct effect of the metabolic state of the cell on its activity. Calorie restriction upregulates the mammalian sirtuin protein levels in variety of tissues and organs where it acts upon both histone and nonhistone substrates. Sirtuin senses nutrient availability and impacts gluconeogenesis, glycolysis, and insulin sensitivity. It deacetylates and inhibits the nuclear receptor that activates fat synthesis and adipogenesis in the body, leading to fat loss and bringing favorable cellular and health changes. Sirtuins mediates intracellular response that promotes cell survival, DNA damage repair thereby increasing the cell longitivity. The activation of sirtuins brings a wide spectrum of other health benefits and its activity levels are indicative of nutritional status as well as disease progression in cancer, inflammation, obesity, cardiovascular diseases, and viral infections. There are several foods that activate sirtuin activity and offer significant health benefits by their consumption.

Transcriptional hallmarks of cancer cell lines reveal an emerging role of branched chain amino acid catabolism

A comparative analysis between cancer cell lines and healthy dividing cells was performed using data (289 microarrays and 50 RNA-seq samples) from 100 different cancer cell lines and 6 types of healthy stem cells. The analysis revealed two large-scale transcriptional events that characterize cancer cell lines. The first event was a large-scale up-regulation pattern associated to epithelial-mesenchymal transition, putatively driven by the interplay of the SP1 transcription factor and the canonical Wnt signaling pathway; the second event was the failure to overexpress a diverse set of genes coding membrane and extracellular proteins. This failure is putatively caused by a lack of activity of the AP-1 complex. It was also shown that the epithelial-mesenchymal transition was associated with the up-regulation of 5 enzymes involved in the degradation of branched chain amino acids. The suitability of silencing one of this enzymes (branched chain amino acid transaminase 2; BCAT2) with therapeutic effects was tested experimentally on the breast cancer cell line MCF-7 and primary cell culture of breast tumor (BCC), leading to lower cell proliferation. The silencing of BCAT2 did not have any significant effect on ASM and MCF10A cells, which were used as models of healthy dividing cells.

Role of Forkhead Box Class O proteins in cancer progression and metastasis

It is now widely accepted that several gene alterations including transcription factors are critically involved in cancer progression and metastasis. Forkhead Box Class O proteins (FoxOs) including FoxO1/FKHR, FoxO3/FKHRL1, FoxO4/AFX and FoxO6 transcription factors are known to play key roles in proliferation, apoptosis, metastasis, cell metabolism, aging and cancer biology through their phosphorylation, ubiquitination, acetylation and methylation. Though FoxOs are proved to be mainly regulated by upstream phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3 K)/Akt signaling pathway, the role of FoxOs in cancer progression and metastasis still remains unclear so far. Thus, with previous experimental evidences, the present review discussed the role of FoxOs in association with metastasis related molecules including cannabinoid receptor 1 (CNR1), Cdc25A/Cdk2, Src, serum and glucocorticoid inducible kinases (SGKs), CXCR4, E-cadherin, annexin A8 (ANXA8), Zinc finger E-box-binding homeobox 2 (ZEB2), human epidermal growth factor receptor 2 (HER2) and mRNAs such as miR-182, miR-135b, miR-499-5p, miR-1274a, miR-150, miR-34b/c and miR-622, subsequently analyzed the molecular mechanism of some natural compounds targeting FoxOs and finally suggested future research directions in cancer progression and metastasis.

FOXO Signaling Pathways as Therapeutic Targets in Cancer

Many transcription factors play a key role in cellular differentiation and the delineation of cell phenotype. Transcription factors are regulated by phosphorylation, ubiquitination, acetylation/deacetylation and interactions between two or more proteins controlling multiple signaling pathways. These pathways regulate different physiological processes and pathological events, such as cancer and other diseases. The Forkhead box O (FOXO) is one subfamily of the fork head transcription factor family with important roles in cell fate decisions and this subfamily is also suggested to play a pivotal functional role as a tumor suppressor in a wide range of cancers. During apoptosis, FOXOs are involved in mitochondria-dependent and -independent processes triggering the expression of death receptor ligands like Fas ligand, TNF apoptosis ligand and Bcl‑X_L, bNIP3, Bim from Bcl-2 family members. Different types of growth factors like insulin play a vital role in the regulation of FOXOs. The most important pathway interacting with FOXO in different types of cancers is the PI3K/AKT pathway. Some other important pathways such as the Ras-MEK-ERK, IKK and AMPK pathways are also associated with FOXOs in tumorigenesis. Therapeutically targeting the FOXO signaling pathway(s) could lead to the discovery and development of efficacious agents against some cancers, but this requires an enhanced understanding and knowledge of FOXO transcription factors and their regulation and functioning. This review focused on the current understanding of cell biology of FOXO transcription factors which relates to their potential role as targets for the treatment and prevention of human cancers. We also discuss drugs which are currently being used for cancer treatment along with their target pathways and also point out some potential drawbacks of those drugs, which further signifies the need for development of new drug strategies in the field of cancer treatment.

Forkhead Transcription Factors: Formulating a FOXO Target for Cognitive Loss

BACKGROUND

With almost 47 million individuals worldwide suffering from some aspect of dementia, it is clear that cognitive loss impacts a significant proportion of the global population. Unfortunately, definitive treatments to resolve or prevent the onset of cognitive loss are limited. In most cases such care is currently non-existent prompting the need for novel treatment strategies.

METHODS

Mammalian forkhead transcription factors of the O class (FoxO) are one such avenue of investigation that offer an exciting potential to bring new treatments forward for disorders that involve cognitive loss. Here we examine the background, structure, expression, and function of FoxO transcription factors and their role in cognitive loss, programmed cell death in the nervous system with apoptosis and autophagy, and areas to target FoxOs for dementia and specific disorders such as Alzheimer's disease.

RESULTS

FoxO proteins work in concert with a number of other cell survival pathways that involve growth factors, such as erythropoietin and neurotrophins, silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), Wnt1 inducible signaling pathway protein 1 (WISP1), Wnt signaling, and cancer-related pathways. FoxO transcription factors oversee proinflammatory pathways, affect nervous system amyloid (Aβ) production and toxicity, lead to mitochondrial dysfunction, foster neuronal apoptotic cell death, and accelerate the progression of degenerative disease. However, under some scenarios such as those involving autophagy, FoxOs also can offer protection in the nervous system and reduce toxic intracellular protein accumulations and potentially limit Aβ toxicity.

CONCLUSION

Given the ability of FoxOs to not only promote apoptotic cell death in the nervous system, but also through the induction of autophagy offer protection against degenerative disease that can lead to dementia, a fine balance in the activity of FoxOs may be required to target cognitive loss in individuals. Future work should yield exciting new prospects for FoxO proteins as new targets to treat the onset and progression of cognitive loss and dementia.

Disease onset and aging in the world of circular RNAs

Circular ribonucleic acids (circRNAs) are non-coding RNAs of approximately 100 nucleotides in length with thousands of members in mammalian cells. The presence of circRNAs is believed to be even greater than that of messenger RNAs. Identification of circRNAs occurred approximately 37 years ago with the subsequent demonstration that covalent bonds are necessary for the unique circular structure of these ribonucleic acids. However, present understanding of the complex biological role of circRNAs remains limited and requires further elucidation. CircRNAs may impact aging, multiple disorders, function as biomarkers, and are able to regulate gene expression by acting as effective microRNA (miRNA) sponges. New work suggests that circRNAs are vital for the modulation of cellular senescence and programmed cell death pathways such as apoptosis. These non-coding RNAs can control cell cycle progression, cellular proliferation, and cellular survival impacting disorders linked to aging, cardiovascular disease, and atherosclerosis through pathways that involve cyclin-dependent kinase 2 (CDK2), cyclin-dependent kinase inhibitor 1 (p21), and mammalian forkhead transcription factors. In addition, circRNAs can oversee cellular metabolism and disorders such as diabetes mellitus through the regulation of insulin signaling as well as limit tumor progression through Wnt signaling and β-catenin pathways. Further understanding of the biology of circRNAs offers great promise for the targeting of novel strategies against a wide spectrum of disease entities.

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.

dFoxO promotes Wingless signaling in Drosophila

The Wnt/β-catenin signaling is an evolutionarily conserved pathway that regulates a wide range of physiological functions, including embryogenesis, organ maintenance, cell proliferation and cell fate decision. Dysregulation of Wnt/β-catenin signaling has been implicated in various cancers, but its role in cell death has not yet been fully elucidated. Here we show that activation of Wg signaling induces cell death in Drosophila eyes and wings, which depends on dFoxO, a transcription factor known to be involved in cell death. In addition, dFoxO is required for ectopic and endogenous Wg signaling to regulate wing patterning. Moreover, dFoxO is necessary for activated Wg signaling-induced target genes expression. Furthermore, Arm is reciprocally required for dFoxO-induced cell death. Finally, dFoxO physically interacts with Arm both in vitro and in vivo. Thus, we have characterized a previously unknown role of dFoxO in promoting Wg signaling, and that a dFoxO-Arm complex is likely involved in their mutual functions, e.g. cell death.

Inhibition of FOXO1 by small interfering RNA enhances proliferation and inhibits apoptosis of papillary thyroid carcinoma cells via Akt/FOXO1/Bim pathway

Forkhead box protein O1 (FOXO1) is a multifunctional transcription factor of the forkhead family. It may function as a tumor suppressor through its ability to regulate cellular events, including cell proliferation, apoptosis, and cell cycle control. As reported, FOXO1 is downregulated in papillary thyroid carcinoma (PTC). However, the function of FOXO1 in human PTC remains unclear. In this study, we investigated the function and underlying regulatory mechanisms of FOXO1 in PTC cells. PTC cell lines K1 and TPC1 were transiently transfected with FOXO1 small interfering RNA (siRNA) and negative control RNA. Successful transfection was confirmed by RT-qPCR and Western blot analysis. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cell proliferation assays, colony formation assays, apoptosis, and cell cycle assays were used to explore the potential function of FOXO1 in the PTC cell lines. We found that downregulation of FOXO1 promoted cellular proliferation, enhanced clonogenesis, and inhibited cellular apoptosis. However, the cell cycle was not markedly affected by FOXO1 siRNA. Furthermore, Bim, a downstream target of the Akt/FOXO1 signaling pathway, was downregulated at both mRNA and protein levels in cells transfected with FOXO1 siRNA. Collectively, these results indicate that FOXO1 may play an important role in inhibiting PTC development by regulating cellular proliferation, growth, and apoptosis. FOXO1 expression is a potentially useful biomarker for human PTC. Moreover, tumorigenesis of PTC may be associated with repression of the Akt/FOXO1/Bim signaling pathway.

Erythropoietin and diabetes mellitus

Erythropoietin (EPO) is a 30.4 kDa growth factor and cytokine that governs cell proliferation, immune modulation, metabolic homeostasis, vascular function, and cytoprotection. EPO is under investigation for the treatment of variety of diseases, but appears especially suited for the treatment of disorders of metabolism that include diabetes mellitus (DM). DM and the complications of this disease impact a significant portion of the global population leading to disability and death with currently limited therapeutic options. In addition to its utility for the treatment of anemia, EPO can improve cardiac function, reduce fatigue, and improve cognition in patients with DM as well as regulate cellular energy metabolism, obesity, tissue repair and regeneration, apoptosis, and autophagy in experimental models of DM. Yet, EPO can have adverse effects that involve the vasculature system and unchecked cellular proliferation. Critical to the cytoprotective capacity and the potential for a positive clinical outcome with EPO are the control of signal transduction pathways that include protein kinase B, the mechanistic target of rapamycin, Wnt signaling, mammalian forkhead transcription factors of the O class, silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae), and AMP activated protein kinase. Therapeutic strategies that can specifically target and control EPO and its signaling pathways hold great promise for the development of new and effective clinical treatments for DM and the complications of this disorder.

Cellular angiofibroma in women: a review of the literature

Cellular Angiofibroma (CA) represents a quite recently described mesenchymal tumour that occurs in both genders, in particular in the vulvo-vaginal region in women and in the inguino-scrotal area in men. The first description of this tumour dates from Nucci et al. article in 1997; since then, the literature reports different reviews and case report of this tumour in both genders, but no article specifically addressing CA treatment and follow-up in women. In this review we collected all 79 published female CA cases, analyzing the clinical, pathological and immunohistochemical features of the tumour.

CA affects women mostly during the fifth decade of life, it is generally a small and asymptomatic mass that mainly arises in the vulvo-vaginal region, although there are reported pelvic and extra-pelvic cases. The treatment requires a simple local excision due to an extremely low ability to recurrent locally and no chance to metastasize. Throughout the immunohistochemical and pathological findings it is also easily possible a differential diagnosis from the other soft tissue tumours which affect the vulvo-vaginal area, such as spindle cell lipoma, solitary fibrous tumour, angiomyofibroblastoma and aggressive angiomyxoma.

MiR-135 post-transcriptionally regulates FOXO1 expression and promotes cell proliferation in human malignant melanoma cells

Malignant melanoma is the deadliest form of all skin cancers. Recently, microRNAs (miRNAs) are small, non-coding RNAs that regulate gene expression by targeted repression of transcription and translation and play essential roles during cancer development. Our study showed that miR-135a is upregulated in malignant melanoma tissues and cell lines by using Real-time PCR assay. Enforced expression of miR-135a in malignant melanoma cells promotes cell proliferation, tumorigenicity, and cell cycle progression, whereas inhibition of miR-135a reverses the function. Additionally, we demonstrated FOXO1 is a direct target of miR-135a and transcriptionally down-regulated by miR-135a. Ectopic expression of miR-135a led to downregulation of the FOXO1 protein, resulting in upregulation of Cyclin D1, and downregulation of P21(Cip1) and P27(Kip1) through AKT pathway. Our findings suggested that miR-135a represents a potential onco-miRNA and plays an important role in malignant melanoma progression by suppressing FOXO1 expression.

The role of microRNA-1274a in the tumorigenesis of gastric cancer: accelerating cancer cell proliferation and migration via directly targeting FOXO4

MicroRNAs (miRNAs) are a series of 18-25 nucleotides length non-coding RNAs, which play critical roles in tumorigenesis. Previous study has shown that microRNA-1274a (miR-1274a) is upregulated in human gastric cancer. However, its role in gastric cancer progression remains poorly understood. Therefore, the current study was aimed to examine the effect of miR-1274a on gastric cancer cells. We found that miR-1274a was overexpressed in gastric cancer tissues or gastric cancer cells including HGC27, MGC803, AGS, and SGC-7901 by qRT-PCR analysis. Transfection of miR-1274a markedly promoted gastric cancer cells proliferation and migration as well as induced epithelial-mesenchymal transition (EMT) of cancer cells. Our further examination identified FOXO4 as a target of miR-1274a, which did not influence FOXO4 mRNA expression but significantly inhibited FOXO4 protein expression. Moreover, miR-1274a overexpression activated PI3K/Akt signaling and upregulated cyclin D1, MMP-2 and MMP-9 expressions. With tumor xenografts in mice models, we also showed that miR-1274a promoted tumorigenesis of gastric cancer in vivo. In all, our study demonstrated that miR-1274a prompted gastric cancer cells growth and migration through dampening FOXO4 expression thus provided a potential target for human gastric cancer therapy.

Polymorphisms in microRNA target sites of forkhead box O genes are associated with hepatocellular carcinoma

The forkhead box O (FOXO) transcription factors play important roles in various cancer development including Hepatocellular Carcinoma (HCC). In this study we conducted a hospital-based case control study including 1049 cases (HCC patients) and 1052 controls (non-tumor patients) to examine whether single nucleotide polymorphisms (SNPs) within microRNA (miRNA) target sites of FOXO genes confer HCC susceptibility. A total of three miRNA target site SNPs in the 3’ untranslated regions (UTR) of FOXO1 (rs17592236), FOXO3 (rs4946936) and FOXO4 (rs4503258) were analyzed. No statistically significant differences were found in genotype distribution for rs17592236, rs4946936, and rs4503258 between the HCC patient group and the tumor-free control group using single factor chi-square analysis (P>0.05). However, multivariate logistic regression analysis showed that the CT/TT genotype in rs17592236 was significantly associated with decreased risk of HCC development (P = 0.010, OR = 0.699, 95% CI: 0.526–0.927) as compared to the CC genotype in rs17592236. Additionally, a genetic interaction was found between rs17592236 and rs4503258 (P = 0.003, OR = 0.755, 95% CI: 0.628–0.908). Functional dual luciferase reporter assays verified that the rs17592236 SNP was a target site of human miRNA miR-137. Together, these results indicate that the rs17592236 polymorphism is associated with decreasing of HCC hereditary susceptibility likely through modulating the binding affinity of miR-137 to the 3’UTR in FOXO1 messenger RNA (mRNA). Further knowledge obtained from this study may provide important evidence for the prevention and targeted therapy of HCC.

Forkhead Transcription Factor FOXO1 Inhibits Angiogenesis in Gastric Cancer in Relation to SIRT1

Purpose

We previously reported that forkhead transcription factors of the O class 1 (FOXO1) expression in gastric cancer (GC) was associated with angiogenesis-related molecules. However, there is little experimental evidence for the direct role of FOXO1 in GC. In the present study, we investigated the effect of FOXO1 on the tumorigenesis and angiogenesis in GC and its relationship with SIRT1.

Materials and Methods

Stable GC cell lines (SNU-638 and SNU-601) infected with a lentivirus containing FOXO1 shRNA were established for animal studies as well as cell culture experiments. We used xenograft tumors in nude mice to evaluate the effect of FOXO1 silencing on tumor growth and angiogenesis. In addition, we examined the association between FOXO1 and SIRT1 by immunohistochemical tissue array analysis of 471 human GC specimens and Western blot analysis of xenografted tumor tissues.

Results

In cell culture, FOXO1 silencing enhanced hypoxia inducible factor-1α (HIF-1α) expression and GC cell growth under hypoxic conditions, but not under normoxic conditions. The xenograft study showed that FOXO1 downregulation enhanced tumor growth, microvessel areas, HIF-1α activation and vascular endothelial growth factor (VEGF) expression. In addition, inactivated FOXO1 expression was associated with SIRT1 expression in human GC tissues and xenograft tumor tissues.

Conclusion

Our results indicate that FOXO1 inhibits GC growth and angiogenesis under hypoxic conditions via inactivation of the HIF-1α–VEGF pathway, possibly in association with SIRT1. Thus, development of treatment modalities aiming at this pathway might be useful for treating GC.

FOXO3a modulates WNT/β-catenin signaling and suppresses epithelial-to-mesenchymal transition in prostate cancer cells

Emerging evidence has revealed a negative correlation between Forkhead box-O (FOXO) expression and prostate cancer grade and spread, indicating its role as a suppressor of prostate cancer metastasis. However, there is still incomplete understanding about the role of FOXO transcription factors in prostate cancer progression. In this investigation, we demonstrate that FOXO3a significantly inhibits the expression β-catenin in prostate cancer cells. The mechanism of inhibiting β-catenin expression involves the FOXO3a-mediated transactivated microRNA-34b/c, which consequently suppressed β-catenin mRNA expression by targeting the untranslated regions (UTRs) of β-catenin. Additionally, FOXO3a can directly bind to β-catenin, and competes with TCF for interaction with β-catenin, thereby inhibiting β-catenin/TCF transcriptional activity and reducing the expression of β-catenin target genes. Furthermore, prostate cancer cells expressing FOXO3a shRNAs display mesenchymal characteristics, including enhanced cell migration and differential regulation of the EMT markers, whereas knockdown of β-catenin results in reversal of shFOXO3a-mediated EMT phenotypic changes. Collectively, these observations demonstrated that FOXO3a inhibits malignant phenotypes that are dependent on β-catenin-dependent modulation of EMT-related genes, and provided fresh insight into the mechanisms by which a FOXO3a-miR-34b/c axis restrains canonical β-catenin signaling cascades in prostate cancer cell.

FoxO Transcription Factors and Regenerative Pathways in Diabetes Mellitus

Mammalian forkhead transcription factors of the O class (FoxO) are exciting targets under consideration for the development of new clinical entities to treat metabolic disorders and diabetes mellitus (DM). DM, a disorder that currently affects greater than 350 million individuals globally, can become a devastating disease that leads to cellular injury through oxidative stress pathways and affects multiple systems of the body. FoxO proteins can regulate insulin signaling, gluconeogenesis, insulin resistance, immune cell migration, and cell senescence. FoxO proteins also control cell fate through oxidative stress and pathways of autophagy and apoptosis that either lead to tissue regeneration or cell demise. Furthermore, FoxO signaling can be dependent upon signal transduction pathways that include silent mating type information regulation 2 homolog 1 (S. cerevisiae) (SIRT1), Wnt, and Wnt1 inducible signaling pathway protein 1 (WISP1). Cellular metabolic pathways driven by FoxO proteins are complex, can lead to variable clinical outcomes, and require in-depth analysis of the epigenetic and post-translation protein modifications that drive FoxO protein activation and degradation.

Programming apoptosis and autophagy with novel approaches for diabetes mellitus

According to the World Health Organization, diabetes mellitus (DM) in the year 2030 will be ranked the seventh leading cause of death in the world. DM impacts all systems of the body with oxidant stress controlling cell fate through endoplasmic reticulum stress, mitochondrial dysfunction, alterations in uncoupling proteins, and the induction of apoptosis and autophagy. Multiple treatment approaches are being entertained for DM with Wnt1 inducible signaling pathway protein 1 (WISP1), mechanistic target of rapamycin (mTOR), and silent mating type information regulation 2 homolog) 1 (S. cerevisiae) (SIRT1) generating significant interest as target pathways that can address maintenance of glucose homeostasis as well as prevention of cellular pathology by controlling insulin resistance, stem cell proliferation, and the programmed cell death pathways of apoptosis and autophagy. WISP1, mTOR, and SIRT1 can rely upon similar pathways such as AMP activated protein kinase as well as govern cellular metabolism through cytokines such as EPO and oral hypoglycemics such as metformin. Yet, these pathways require precise biological control to exclude potentially detrimental clinical outcomes. Further elucidation of the ability to translate the roles of WISP1, mTOR, and SIRT1 into effective clinical avenues offers compelling prospects for new therapies against DM that can benefit hundreds of millions of individuals throughout the globe.

Cutting through the complexities of mTOR for the treatment of stroke

On a global basis, at least 15 million individuals suffer some form of a stroke every year. Of these individuals, approximately 800,000 of these cerebrovascular events occur in the United States (US) alone. The incidence of stroke in the US has declined from the third leading cause of death to the fourth, a result that can be attributed to multiple factors that include improved vascular disease management, reduced tobacco use, and more rapid time to treatment in patients that are clinically appropriate to receive recombinant tissue plasminogen activator. However, treatment strategies for the majority of stroke patients are extremely limited and represent a critical void for care. A number of new therapeutic considerations for stroke are under consideration, but it is the mammalian target of rapamycin (mTOR) that is receiving intense focus as a potential new target for cerebrovascular disease. As part of the phosphoinositide 3-kinase (PI 3-K) and protein kinase B (Akt) cascade, mTOR is an essential component of mTOR Complex 1 (mTORC1) and mTOR Complex 2 (mTORC2) to govern cell death involving apoptosis, autophagy, and necroptosis, cellular metabolism, and gene transcription. Vital for the consideration of new therapeutic strategies for stroke is the ability to understand how the intricate and complex pathways of mTOR signaling sometimes lead to disparate clinical outcomes.

Evidence for an association between increased oxidative stress and derangement of FOXO1 signaling in tumorigenesis of a cellular angiofibroma with monoallelic 13q14: a case report

Cellular angiofibroma (CAF) is a rare soft tissue tumor characterized by random arrangement of spindle tumor cells in the stroma with short collagen bundles and thick- and hyalinized small vessels. CAFs share histological characteristics with spindle cell lipomas and mammary type myofibroblastomas. Because these tumors harbor monoallelic 13q14, common genetic and molecular mechanism for tumorigenesis is presumed. In this study, we reported a case of CAF in a 69-year-old man with monoallelic 13q14. Immunohistochemical analysis revealed that FOXO1, which is located in chromosome 13q14, was not expressed in the tumor. We also detected oxidative stress markers and found p38 MAPK activation, which is often induced by cellular stressors such as reactive oxygen species (ROS). Because FOXO1 induces the expression of genes encoding enzymes that generate antioxidants, oxidative stress induced by loss of FOXO1 expression may be common among CAFs, spindle cell lipomas, and mammary type myofibroblastomas.

Icariin protects against intestinal ischemia-reperfusion injury

BACKGROUND

This study investigated the role of Sirtuin 1 (SIRT1)/forkhead box O3 (FOXO3) pathway, and a possible protective function for Icariin (ICA), in intestinal ischemia-reperfusion (I/R) injury and hypoxia-reoxygenation (H/R) injury.

MATERIALS AND METHODS

Male Sprague-Dawley rats were pretreated with different doses of ICA (30 and 60 mg/kg) or olive oil as control 1 h before intestinal I/R. Caco-2 cells were pretreated with different concentrations of ICA (25, 50, and 100 μg/mL) and then subjected to H/R-induced injury.

RESULTS

The in vivo results demonstrated that ICA pretreatment significantly improved I/R-induced tissue damage and decreased serum tumor necrosis factor α and interleukin-6 levels. Changes of manganese superoxide dismutase, Bcl-2, and Bim were also reversed by ICA, and apoptosis was reduced. Importantly, the protective effects of ICA were positively associated with SIRT1 activation. Increased SIRT1 expression, as well as decreased acetylated FOXO3 expression, was observed in Caco-2 cells pretreated with ICA. Additionally, the protective effects of ICA were abrogated in the presence of SIRT1 inhibitor nicotinamide. This suggests that ICA exerts a protective effect upon H/R injury through activation of SIRT1/FOXO3 signaling pathway. Accordingly, the SIRT1 activator resveratrol achieved a similar protective effect as ICA on H/R injury, whereas cellular damage resulting from H/R was exacerbated by SIRT1 knockdown and nicotinamide.

CONCLUSIONS

SIRT1, activated by ICA, protects intestinal epithelial cells from I/R injury by inducing FOXO3 deacetylation both in vivo and in vitro These findings suggest that the SIRT1/FOXO3 pathway can be a target for therapeutic approaches intended to minimize injury resulting from intestinal dysfunction.

Genetic polymorphisms at SIRT1 and FOXO1 are associated with carotid atherosclerosis in the SAPHIR cohort

Background

SIRT1 and FOXO1 interact with each other in multiple pathways regulating aging, metabolism and resistance to oxidative stress and control different pathways involved in atherosclerotic process. It is not known, if genetic polymorphisms (SNPs) at the SIRT1 and FOXO1 have an influence on carotid atherosclerosis.

Methods

Intima-media thickness (IMT) was measured on the common and internal carotid arteries. Morphological alterations of the carotid arteries and size of these alterations were included in the B-score grading on a five point scale. Eleven SNPs at SIRT1 and FOXO1 gene loci were genotyped in the SAPHIR cohort (n = 1742). The association of each SNP with common carotid IMT, internal carotid IMT and B-score was analyzed using linear regression models.

Results

A significant association was found between common carotid IMT and two SNPs at FOXO1 - rs10507486, rs2297627 (beta = -0.00168, p = 0.0007 and beta = -0.00144, p = 0.0008 respectively) and at least a trend for rs12413112 at SIRT1 (beta = 0.00177, p = 0.0157) using an additive model adjusting for age and sex. Additional adjustment for traditional cardiovascular risk factors and markers (BMI, smoking status, hypertension, total cholesterol, HDL-cholesterol, hsCRP) even improved the strength of this association (p = 0.0037 for SIRT1 and p = 0.0002 for both SNPs at FOXO1). Analysis for internal carotis IMT and B-score did not reveal any significant association. One haplotype in FOXO1 showed a moderate effect on common carotid IMT and B-score in comparison to the reference haplotype of this gene. Several SNPs within SIRT1 showed differential effects for men and women with higher effect sizes for women: rs3740051 on all three investigated phenotypes (interaction p-value < 0.0069); rs2236319 on common and internal carotid IMT (interaction p-value < 0.0083), rs10823108, rs2273773 on common carotid IMT and rs1467568 on B-score (interaction p-value = 0.0007). The latter was significant in women only (beta_women = 0.111, p_women = 0.00008; beta_men = -0.009, p_men = 0.6464).

Conclusions

This study demonstrated associations of genetic variations at the SIRT1 and FOXO1 loci with carotid atherosclerosis and highlighted the need for further investigation by functional studies.

Suppression of FOXO1 is responsible for a growth regulatory repressive transcriptional sub-signature of EWS-FLI1 in Ewing sarcoma

The Ewing sarcoma (ES) EWS-FLI1 chimeric oncoprotein is a prototypic aberrant ETS transcription factor with activating and repressive regulatory functions. We report that EWS-FLI1-repressed promoters are enriched in forkhead box (FOX) recognition motifs, and identify FOXO1 as a EWS-FLI1-suppressed regulator orchestrating a major subset of EWS-FLI1-repressed genes. In addition to FOXO1 regulation by direct promoter binding of EWS-FLI1, its subcellular localization and activity is regulated by cyclin-dependent kinase 2- and AKT-mediated phosphorylation downstream of EWS-FLI1. Restoration of nuclear FOXO1 expression in ES cells impaired proliferation and significantly reduced clonogenicity. Gene-expression profiling revealed a significant overlap between EWS-FLI1-repressed and FOXO1-activated genes. As a proof of principle for a potential therapeutic application of our findings, the treatment of ES cell lines with methylseleninic acid (MSA) reactivated endogenous FOXO1 in the presence of EWS-FLI1 in a dose- and time-dependent manner and induced massive cell death dependent on FOXO1. In an orthotopic xenograft mouse model, MSA increased FOXO1 expression in the tumor paralleled by a significant decrease in ES tumor growth. FOXO1 reactivation by small molecules may therefore serve as a promising strategy for a future ES-specific therapy.

FoxO3a nuclear localization and its association with β-catenin and Smads in IFN-α-treated hepatocellular carcinoma cell lines

Interferon-α2b (IFN-α2b) reduces proliferation and increases apoptosis in hepatocellular carcinoma cells by decreasing β-catenin/TCF4/Smads interaction. Forkhead box O-class 3a (FoxO3a) participates in proliferation and apoptosis and interacts with β-catenin and Smads. FoxO3a is inhibited by Akt, IκB kinase β (IKKβ), and extracellular-signal-regulated kinase (Erk), which promote FoxO3a sequestration in the cytosol, and accumulates in the nucleus upon phosphorylation by c-Jun N-terminal kinase (JNK) and p38 mitogen-activated kinase (p38 MAPK). We analyzed FoxO3a subcellular localization, the participating kinases, FoxO3a/β-catenin/Smads association, and FoxO3a target gene expression in IFN-α2b-stimulated HepG2/C3A and Huh7 cells. Total FoxO3a and Akt-phosphorylated FoxO3a levels decreased in the cytosol, whereas total FoxO3a levels increased in the nucleus upon IFN-α2b stimulus. IFN-α2b reduced Akt, IKKβ, and Erk activation, and increased JNK and p38 MAPK activation. p38 MAPK inhibition blocked IFN-α2b-induced FoxO3a nuclear localization. IFN-α2b enhanced FoxO3a association with β-catenin and Smad2/3/7. Two-step coimmunoprecipitation experiments suggest that these proteins coexist in the same complex. The expression of several FoxO3a target genes increased with IFN-α2b. FoxO3a knockdown prevented the induction of these genes, suggesting that FoxO3a acts as mediator of IFN-α2b action. Results suggest a β-catenin/Smads switch from TCF4 to FoxO3a. Such events would contribute to the IFN-α2b-mediated effects on cellular proliferation and apoptosis. These results demonstrate new mechanisms for IFN-α action, showing the importance of its application in antitumorigenic therapies.

Metformin mitigates apoptosis in ischemic myocardium

BACKGROUND

Epidemiologic data has shown that metformin confers a survival advantage in patients with cardiovascular disease. Although the underlying cardioprotective mechanism is unclear, it appears to be independent of metformin's insulin-sensitizing effect. The purpose of this study was to evaluate the effect of metformin on the apoptosis pathway in the ischemic and nonischemic cardiac tissue in a swine model of metabolic syndrome.

MATERIALS AND METHODS

Ossabaw miniswine were fed either a regular diet (Ossabaw control, n = 8), a high-cholesterol diet (Ossabaw high cholesterol, n = 8), or a high-cholesterol diet supplemented with metformin (Ossabaw high-cholesterol metformin, n = 8). After 9 wk, all animals underwent placement of an ameroid constrictor to the left circumflex coronary artery to induce chronic ischemia. Seven weeks after ameroid placement, animals underwent cardiac harvest.

RESULTS

In the chronically ischemic myocardium, metformin significantly upregulates prosurvival proteins: extracellular signal-regulated kinases, nuclear factor κB, phosphorylated endothelial nitric oxide synthase, and P38. Metformin also significantly inhibits or downregulates proapoptosis proteins: FOXO3 and caspase 3. Metformin decreased the percent apoptotic cells in the ischemic and nonischemic myocardium. There was no difference in arteriolar density, capillary density, intramyocardial fibrosis, or collagen deposition in the ischemic or nonischemic myocardium.

CONCLUSIONS

Metformin selectively alters the apoptosis pathway by inhibiting FOXO3 and decreasing the active form of caspase 3, cleaved caspase 3. Metformin also upregulates mitogen-activated kinase proteins p38 and extracellular signal-regulated protein kinases 1 and 2, which are considered cardioprotective during ischemic preconditioning. Perhaps, the altered activation of the apoptosis pathway in ischemic myocardium is one mechanism by which metformin is cardioprotective.

Critical physiological and pathological functions of Forkhead Box O tumor suppressors

The Forkhead box, subclass O (FOXO) proteins are critical transcription factors, ubiquitously expressed in the human body. These proteins are characterized by a remarkable functional diversity, being involved in cell cycle arrest, apoptosis, oxidative detoxification, DNA damage repair, stem cell maintenance, cell differentiation, cell metabolism, angiogenesis, cardiac development, aging and others. In addition, FOXO have critical implications in both normal and cancer stem cell biology. New strategies to modulate FOXO expression and activity may now be developed since the discovery of novel FOXO regulators and non-coding RNAs (such as microRNAs) targeting FOXO transcription factors. This review focuses on physiological and pathological functions of FOXO proteins and on their action as fine regulators of cell fate and context-dependent cell decisions. A better understanding of the structure and critical functions of FOXO transcription factors and tumor suppressors may contribute to the development of novel therapies for cancer and other diseases.

Mutation of Foxo3 causes adult onset auditory neuropathy and alters cochlear synapse architecture in mice

Auditory neuropathy is a form of hearing loss in which cochlear inner hair cells fail to correctly encode or transmit acoustic information to the brain. Few genes have been implicated in the adult-onset form of this disease. Here we show that mice lacking the transcription factor Foxo3 have adult onset hearing loss with the hallmark characteristics of auditory neuropathy, namely, elevated auditory thresholds combined with normal outer hair cell function. Using histological techniques, we demonstrate that Foxo3-dependent hearing loss is not due to a loss of cochlear hair cells or spiral ganglion neurons, both of which normally express Foxo3. Moreover, Foxo3-knock-out (KO) inner hair cells do not display reductions in numbers of synapses. Instead, we find that there are subtle structural changes in and surrounding inner hair cells. Confocal microscopy in conjunction with 3D modeling and quantitative analysis show that synaptic localization is altered in Foxo3-KO mice and Myo7a immunoreactivity is reduced. TEM demonstrates apparent afferent degeneration. Strikingly, acoustic stimulation promotes Foxo3 nuclear localization in vivo, implying a connection between cochlear activity and synaptic function maintenance. Together, these findings support a new role for the canonical damage response factor Foxo3 in contributing to the maintenance of auditory synaptic transmission.