FoxO3 Modulates Circadian Rhythms in Neural Stem Cells.

Both FoxO transcription factors and the circadian clock act on the interface of metabolism and cell cycle regulation and are important regulators of cellular stress and stem cell homeostasis. Importantly, FoxO3 preserves the adult neural stem cell population by regulating cell cycle and cellular metabolism and has been shown to regulate circadian rhythms in the liver. However, whether FoxO3 is a regulator of circadian rhythms in neural stem cells remains unknown. Here, we show that loss of FoxO3 disrupts circadian rhythmicity in cultures of neural stem cells, an effect that is mediated via regulation of Clock transcriptional levels. Using Rev-Erbα-VNP as a reporter, we then demonstrate that loss of FoxO3 does not disrupt circadian rhythmicity at the single cell level. A meta-analysis of published data revealed dynamic co-occupancy of multiple circadian clock components within FoxO3 regulatory regions, indicating that FoxO3 is a Clock-controlled gene. Finally, we examined proliferation in the hippocampus of FoxO3-deficient mice and found that loss of FoxO3 delayed the circadian phase of hippocampal proliferation, indicating that FoxO3 regulates correct timing of NSC proliferation. Taken together, our data suggest that FoxO3 is an integral part of circadian regulation of neural stem cell homeostasis.

Hypoxia induces the dormant state in oocytes through expression of Foxo3.

In mammals, most immature oocytes remain dormant in the primordial follicles to ensure the longevity of female reproductive life. A precise understanding of mechanisms underlying the dormancy is important for reproductive biology and medicine. In this study, by comparing mouse oogenesis in vivo and in vitro, the latter of which bypasses the primordial follicle stage, we defined the gene-expression profile representing the dormant state of oocytes. Overexpression of constitutively active FOXO3 partially reproduced the dormant state in vitro. Based on further gene-expression analysis, we found that a hypoxic condition efficiently induced the dormant state in vitro. The effect of hypoxia was severely diminished by disruption of the Foxo3 gene and inhibition of hypoxia-inducible factors. Our findings provide insights into the importance of environmental conditions and their effectors for establishing the dormant state.

MiR-182 Promotes Ischemia/Reperfusion-Induced Acute Kidney Injury in Rat by Targeting FoxO3.

BACKGROUND: Renal ischemia/reperfusion (I/R) injury (RIRI) is the main cause of acute kidney injury (AKI) in patients. We investigated the role of miR-182 after renal ischemia/reperfusion (I/R) in rat to characterize the microRNA (miRNA) network activated during development and recovery from RIRI. METHODS AND RESULTS: 12 h after lethal (45 min) renal ischemia, AKI was verified by renal histology (tubular necrosis and regeneration), blood urea nitrogen level, and renal mRNA expression in Wistar rats. We found that miR-182 markedly increased after renal I/R. In cell hypoxia/reoxygenation model, we found similar upregulation of miR-182. In function gain/loss assay, we confirmed an impaired effect of miR-182 and identified Forkhead box O3 (FoxO3) as a direct downstream target of it. By using miR-182 antagomir, the I/R injury was markedly ameliorated. CONCLUSIONS: Our results demonstrate that miR-182 promotes cell apoptosis and I/R injury through directly binding to FoxO3. The present study will provide potential therapeutic targets for renal I/R-induced AKI, and open a new avenue for AKI treatment by manipulating miRNAs levels.

Astaxanthin as a Putative Geroprotector: Molecular Basis and Focus on Brain Aging.

In recent years, the scientific interest in natural compounds with geroprotective activities has grown exponentially. Among the various naturally derived molecules, astaxanthin (ASX) represents a highly promising candidate geroprotector. By virtue of the central polyene chain, ASX acts as a scavenger of free radicals in the internal membrane layer and simultaneously controls oxidation on the membrane surface. Moreover, several studies have highlighted ASX's ability to modulate numerous biological mechanisms at the cellular level, including the modulation of transcription factors and genes directly linked to longevity-related pathways. One of the main relevant evolutionarily-conserved transcription factors modulated by astaxanthin is the forkhead box O3 gene (FOXO3), which has been recognized as a critical controller of cell fate and function. Moreover, FOXO3 is one of only two genes shown to robustly affect human longevity. Due to its tropism in the brain, ASX has recently been studied as a putative neuroprotective molecule capable of delaying or preventing brain aging in different experimental models of brain damage or neurodegenerative diseases. Astaxanthin has been observed to slow down brain aging by increasing brain-derived neurotrophic factor (BDNF) levels in the brain, attenuating oxidative damage to lipids, protein, and DNA and protecting mitochondrial functions. Emerging data now suggest that ASX can modulate Nrf2, FOXO3, Sirt1, and Klotho proteins that are linked to longevity. Together, these mechanisms provide support for a role of ASX as a potential geroneuroprotector.

Akt inhibition synergizes with polycomb repressive complex 2 inhibition in the treatment of multiple myeloma.

Polycomb repressive complex 2 (PRC2) components, EZH2 and its homolog EZH1, and PI3K/Akt signaling pathway are focal points as therapeutic targets for multiple myeloma. However, the exact crosstalk between their downstream targets remains unclear. We herein elucidated some epigenetic interactions following Akt inhibition and demonstrated the efficacy of the combined inhibition of Akt and PRC2. We found that TAS-117, a potent and selective Akt inhibitor, downregulated EZH2 expression at the mRNA and protein levels via interference with the Rb-E2F pathway, while EZH1 was compensatively upregulated to maintain H3K27me3 modifications. Consistent with these results, the dual EZH2/EZH1 inhibitor, UNC1999, but not the selective EZH2 inhibitor, GSK126, synergistically enhanced TAS-117-induced cytotoxicity and provoked myeloma cell apoptosis. RNA-seq analysis revealed the activation of the FOXO signaling pathway after TAS-117 treatment. FOXO3/4 mRNA and their downstream targets were upregulated with the enhanced nuclear localization of FOXO3 protein after TAS-117 treatment. ChIP assays confirmed the direct binding of FOXO3 to EZH1 promoter, which was enhanced by TAS-117 treatment. Moreover, FOXO3 knockdown repressed EZH1 expression. Collectively, the present results reveal some molecular interactions between Akt signaling and epigenetic modulators, which emphasize the benefits of targeting PRC2 full activity and the Akt pathway as a therapeutic option for multiple myeloma.

FoxO3 regulates hepatic triglyceride metabolism via modulation of the expression of sterol regulatory-element binding protein 1c.

BACKGROUND: Excessive intrahepatic lipid accumulation is the major characteristic of nonalcoholic fatty liver disease (NAFLD). We sought to identify the mechanisms involved in hepatic triglyceride (TG) homeostasis. Forkhead box class O (FoxO) transcription factors have been shown to play an important role in hepatic metabolism. However, little is known about the effect of FoxO3 on hepatic TG metabolism. METHODS: Liver biopsy samples from patients with NALFD and liver tissues from high glucose and high sucrose (HFHS) fed mice, ob/ob mice and db/db mice were collected for protein and mRNA analysis. HepG2 cells were transfected with small interfering RNA to mediate FoxO3 knockdown, or adenovirus and plasmid to mediate FoxO3 overexpression. FoxO3-cDNA was delivered by adenovirus to the liver of C57BL/6 J male mice on a chow diet or on a high-fat diet, followed by determination of hepatic lipid metabolism. Sterol regulatory element-binding protein 1c (SREBP1c) luciferase reporter gene plasmid was co-transfected into HepG2 cells with FoxO3 overexpression plasmid. RESULTS: FoxO3 expression was increased in the livers of HFHS mice, ob/ob mice, db/db mice and patients with NAFLD. Knockdown of FoxO3 reduced whereas overexpression of FoxO3 increased cellular TG concentrations in HepG2 cells. FoxO3 gain-of-function caused hepatic TG deposition in C57BL/6 J mice on a chow diet and aggravated hepatic steatosis when fed a high-fat diet. Analysis of the transcripts established the increased expression of genes related to TG synthesis, including SREBP1c, SCD1, FAS, ACC1, GPAM and DGAT2 in mouse liver. Mechanistically, overexpression of FoxO3 stimulated the expression of SREBP1c, whereas knockdown of FoxO3 inhibited the expression of SREBP1c. Luciferase reporter assays showed that SREBP1c regulated the transcriptional activity of the SREBP1c promoter. CONCLUSIONS: FoxO3 promotes the transcriptional activity of the SREBP1c promoter, thus leading to increased TG synthesis and hepatic TG accumulation.

MyoD- and FoxO3-mediated hotspot interaction orchestrates super-enhancer activity during myogenic differentiation.

Super-enhancers (SEs) are cis-regulatory elements enriching lineage specific key transcription factors (TFs) to form hotspots. A paucity of identification and functional dissection promoted us to investigate SEs during myoblast differentiation. ChIP-seq analysis of histone marks leads to the uncovering of SEs which remodel progressively during the course of differentiation. Further analyses of TF ChIP-seq enable the definition of SE hotspots co-bound by the master TF, MyoD and other TFs, among which we perform in-depth dissection for MyoD/FoxO3 interaction in driving the hotspots formation and SE activation. Furthermore, using Myogenin as a model locus, we elucidate the hierarchical and complex interactions among hotspots during the differentiation, demonstrating SE function is propelled by the physical and functional cooperation among hotspots. Finally, we show MyoD and FoxO3 are key in orchestrating the Myogenin hotspots interaction and activation. Altogether our results identify muscle-specific SEs and provide mechanistic insights into the functionality of SE.

FOXO3 Transcription Factor Is Essential for Protecting Hematopoietic Stem and Progenitor Cells from Oxidative DNA Damage.

Accumulation of damaged DNA in hematopoietic stem cells (HSC) is associated with chromosomal abnormalities, genomic instability, and HSC aging and might promote hematological malignancies with age. Despite this, the regulatory pathways implicated in the HSC DNA damage response have not been fully elucidated. One of the sources of DNA damage is reactive oxygen species (ROS) generated by both exogenous and endogenous insults. Balancing ROS levels in HSC requires FOXO3, which is an essential transcription factor for HSC maintenance implicated in HSC aging. Elevated ROS levels result in defective Foxo3-/- HSC cycling, among many other deficiencies. Here, we show that loss of FOXO3 leads to the accumulation of DNA damage in primitive hematopoietic stem and progenitor cells (HSPC), associated specifically with reduced expression of genes implicated in the repair of oxidative DNA damage. We provide further evidence that Foxo3-/- HSPC are defective in DNA damage repair. Specifically, we show that the base excision repair pathway, the main pathway utilized for the repair of oxidative DNA damage, is compromised in Foxo3-/- primitive hematopoietic cells. Treating mice in vivo with N-acetylcysteine reduces ROS levels, rescues HSC cycling defects, and partially mitigates HSPC DNA damage. These results indicate that DNA damage accrued as a result of elevated ROS in Foxo3-/- mutant HSPC is at least partially reversible. Collectively, our findings suggest that FOXO3 serves as a protector of HSC genomic stability and health.

Foxo3 circular RNA promotes cardiac senescence by modulating multiple factors associated with stress and senescence responses.

AIMS: Circular RNAs are a subclass of non-coding RNAs detected within mammalian cells. This study was designed to test the roles of a circular RNA circ-Foxo3 in senescence using in vitro and in vivo approaches. METHODS AND RESULTS: Using the approaches of molecular and cellular biology, we show that a circular RNA generated from a member of the forkhead family of transcription factors, Foxo3, namely circ-Foxo3, was highly expressed in heart samples of aged patients and mice, which was correlated with markers of cellular senescence. Doxorubicin-induced cardiomyopathy was aggravated by ectopic expression of circ-Foxo3 but was relieved by silencing endogenous circ-Foxo3. We also found that silencing circ-Foxo3 inhibited senescence of mouse embryonic fibroblasts and that ectopic expression of circ-Foxo3 induced senescence. We found that circ-Foxo3 was mainly distributed in the cytoplasm, where it interacted with the anti-senescent protein ID-1 and the transcription factor E2F1, as well as the anti-stress proteins FAK and HIF1α. CONCLUSION: We conclude that ID-1, E2F1, FAK, and HIF1α interact with circ-Foxo3 and are retained in the cytoplasm and could no longer exert their anti-senescent and anti-stress roles, resulting in increased cellular senescence.

Mitochondria and FOXO3 in stem cell homeostasis, a window into hematopoietic stem cell fate determination.

The production of all blood cells from hematopoietic stem cells (HSC) is highly sensitive to reactive oxygen species (ROS). Cumulating evidence suggests that mitochondria are critical for HSC fate determination. FOXO are known regulators of anti-oxidant response and key to the maintenance of HSC. Recent works indicate that FOXO3 is implicated in the control of mitochondrial function beyond regulating levels of ROS in HSC. Here we review these findings and discuss implications for homeostatic blood formation and stem cell fate determination.

FoxO3 inactivation promotes human cholangiocarcinoma tumorigenesis and chemoresistance through Keap1-Nrf2 signaling.

UNLABELLED: FoxO transcription factors have been reported to play pivotal roles in tumorigenesis and drug resistance. The mechanisms underlying the tumor suppression function of FoxOs in human cancers remain largely unknown. Aberrant expression and activation of Nrf2 often correlate with chemoresistance and poor prognosis. Here, we report that FoxO3 directs the basal transcription of Kelch-like ECH-associated protein 1 (Keap1), an adaptor protein that bridges Nrf2 to Cul3 for degradation. FoxO3 depletion resulted in Keap1 down-regulation, thereby activating Nrf2 signaling. We further demonstrated that inhibition of the FoxO3-Keap1 axis accounts for Nrf2 induction and activation induced by constitutively active AKT signaling or tumor necrosis factor α treatment. Unlike previous findings, FoxO3 silencing led to decreased reactive oxygen species production, therefore protecting cells from oxidative stress-induced killing in an Nrf2-dependent manner. Importantly, FoxO3 deficiency strongly potentiated tumor formation in nude mice and rendered cholangiocarcinoma xenografts resistant to cisplatin-induced cell death by activating Nrf2. Additionally, we found that clinical cholangiocarcinoma samples displayed FoxO3-Keap1 down-regulation and Nrf2 hyperactivation, underscoring the essential roles of these proteins in cholangiocarcinoma development. CONCLUSION: Our results unravel a unique mechanism underlying the tumor suppressor function of FoxO3 through constraining Nrf2 signaling. (Hepatology 2016;63:1914-1927).

Serum Glucocorticoid-Regulated Kinase 1 Blocks CKD-Induced Muscle Wasting Via Inactivation of FoxO3a and Smad2/3.

Muscle proteolysis in CKD is stimulated when the ubiquitin-proteasome system is activated. Serum glucocorticoid-regulated kinase 1 (SGK-1) is involved in skeletal muscle homeostasis, but the role of this protein in CKD-induced muscle wasting is unknown. We found that, compared with muscles from healthy controls, muscles from patients and mice with CKD express low levels of SGK-1. In mice, SGK-1-knockout (SGK-1-KO) induced muscle loss that correlated with increased expression of ubiquitin E3 ligases known to facilitate protein degradation by the ubiquitin-proteasome, and CKD substantially aggravated this response. SGK-1-KO also altered the phosphorylation levels of transcription factors FoxO3a and Smad2/3. In C2C12 muscle cells, expression of dominant negative FoxO3a or knockdown of Smad2/3 suppressed the upregulation of E3 ligases induced by loss of SGK-1. Additionally, SGK-1 overexpression increased the level of phosphorylated N-myc downstream-regulated gene 1 protein, which directly interacted with and suppressed the phosphorylation of Smad2/3. Overexpression of SGK-1 in wild-type mice with CKD had similar effects on the phosphorylation of FoxO3a and Smad2/3 and prevented CKD-induced muscle atrophy. Finally, mechanical stretch of C2C12 muscle cells or treadmill running of wild-type mice with CKD stimulated SGK-1 production, and treadmill running inhibited proteolysis in muscle. These protective responses were absent in SGK-1-KO mice. Thus, SGK-1 could be a mechanical sensor that mediates exercise-induced improvement in muscle wasting stimulated by CKD.

[The role of FOXO3a-Bim signaling in triptolide induced bladder cancer T24 cells apoptosis].

Objective: To investigate the role of FOXO3a-Bim signaling in triptolide induced bladder cancer T24 cells apoptosis. Methods: T24 cells were used and divided into control group, triptolide group(50 nmol/L), MK2206 group(50 nmol/L triptolide+ 5 µmol/L MK2206), FOXO3a-siRNA group(50 nmol/L triptolide+ 100 nmol/L FOXO3a-siRNA), Bim-siRNA group (50 nmol/L triptolide+ 100 nmol/L Bim-siRNA). MTT assay was used to analyze the cells growth inhibition.Annexin V/PI staining was implemented to detect cell apoptosis rate, the expression of p-Akt, Akt, p-FOXO3a, FOXO3a, Bim, Bax.Cleaved-caspase 3 was analyzed by Western blot. Results: After treatment with triptolide 25, 50, 100, 250 nmol/L, the cell growth inhibition rates at 24 hours(17%±9%, 24%±5%, 43%±8%, 61%±8%), 48 hours (20%±7%, 34%±6%, 56%±7%, 74%±5%) and 72 hours(32%±8%, 41%±7%, 69%±7%, 84%±3%) were significantly higher than control group respectively.The IC(50) at 24, 48, 72 hours were (113±10), (91±8), (68±5) nmol/L; the cell apoptosis rates at 24 hours (10%±4%, 15%±5%, 29%±8%, 46%±8%), 48 hours (16%±5%, 24%±6%, 40%±7%, 55%±9%) and 72 hours (27%±4%, 38%±5%, 50%±9%, 65%±8%) were significantly increased (P<0.05). Western blot showed that triptolide reduced the expression of p-Akt, p-FOXO3a and increased the expression of Bim, Bax, cleaved-caspase 3.The cell inhibition rate in Triptolide group (30%±8%) was significantly higher than that in the control group (P<0.05) and the rates in MK2206 group (54% ±6%), FOXO3a-siRNA group (18%±7%) and Bim-siRNA group (11%±6%) were also higher than the control group.Compared with the triptolide group, the inhibition rate in MK2206 group was significantly increased, but decreased in FOXO3a-siRNA group and Bim-siRNA group(P<0.05). Conclusion: Triptolide induces T24 cells apoptosis through FOXO3a-Bim signaling pathway.

Mitochondrial FOXO3a is involved in amyloid ß peptide-induced mitochondrial dysfunction.

Mitochondrial dysfunction is a hallmark of amyloid ß peptide (Aß)-induced neuronal toxicity in Alzheimer's disease (AD). However, the precise mechanism(s) of Aß-induced mitochondrial dysfunction has not been fully understood. There is evidence that Forkhead box O3a (FOXO3a) is normally present in neuronal mitochondria. Using HT22 murine hippocampal neuronal cells and primary hippocampal neurons, the present study investigated whether mitochondrial FOXO3a was involved in mitochondrial dysfunction induced by Aß. It was found that Aß induced dephosphorylation and mitochondrial translocation of FOXO3a. In addition, Aß enhanced association of FOXO3a with mitochondrial DNA (mtDNA), causing a decrease in the expression of cytochrome c oxidase subunit 1 (COX1) and the activity of COX. In addition, Aß-induced mitochondrial dysfunction, indicated by the decrease in 3- (4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) conversion, mitochondrial adenosine triphosphate (ATP) production and COX activity, could be suppressed by knockdown of FOXO3a (FOXO3a-KD). These results provide new insights into the mechanism underlying Aß-induced neurotoxicity and open up new therapeutic perspectives for AD.

FOXO Transcription Factors Are Required for Normal Somatotrope Function and Growth.

Understanding the molecular mechanisms underlying pituitary organogenesis and function is essential for improving therapeutics and molecular diagnoses for hypopituitarism. We previously found that deletion of the forkhead factor, Foxo1, in the pituitary gland early in development delays somatotrope differentiation. While these mice grow normally, they have reduced growth hormone expression and free serum insulin-like growth factor-1 (IGF1) levels, suggesting a defect in somatotrope function. FOXO factors show functional redundancy in other tissues, so we deleted both Foxo1 and its closely related family member, Foxo3, from the primordial pituitary. We find that this results in a significant reduction in growth. Consistent with this, male and female mice in which both genes have been deleted in the pituitary gland (dKO) exhibit reduced pituitary growth hormone expression and serum IGF1 levels. Expression of the somatotrope differentiation factor, Neurod4, is reduced in these mice. This suggests a mechanism underlying proper somatotrope function is the regulation of Neurod4 expression by FOXO factors. Additionally, dKO mice have reduced Lhb expression and females also have reduced Fshb and Prl expression. These studies reveal FOXO transcription factors as important regulators of pituitary gland function.

Knockdown of long noncoding RNA growth arrest-specific transcript 5 regulates forkhead box O3 to inhibit lipopolysaccharide-induced human bronchial epithelial cell pyroptosis.

Pyroptosis is a novel proinflammatory programmed cell death process. This study was designed to investigate the functional mechanisms of long noncoding RNA growth arrest-specific transcript 5 (lncRNA GAS5) on lipopolysaccharide (LPS)-induced human bronchial epithelial cell (HBEC) pyroptosis. LPS was used to induce pyroptosis in HBECs, followed by the detection of the expression of GAS5, forkhead box O3 (FOXO3), and nuclear factor E2-related factor 2/heme oxygenase 1 (Nrf2/HO-1) signaling pathway-related factors. Cell viability was evaluated using CCK-8 assay, lactate dehydrogenase (LDH) release was assessed by LDH assay kit and caspase-1 activity by flow cytometry. Furthermore, expression of NOD-like receptor family pyrin domain containing 3 and pyroptosis-related proteins was evaluated using Western blot analysis, while enzyme-linked immunosorbent assay was used to determine the levels of inflammatory factors. The interaction between GAS5 and FOXO3 was confirmed using bioinformatic prediction, RNA immunoprecipitation assay, RNA pull-down, and dual-luciferase reporter gene assay. Treatment of HBECs with LPS upregulated the expression of GAS5 and FOXO3, resulting in the inactivation of the Nrf2/HO-1 signaling pathway. On the other hand, inhibition of both GAS5 and FOXO3 promoted cell viability, reduced LDH release, pyroptosis, and inflammatory response in LPS-induced HBECs. Furthermore, FOXO3 could interact with GAS5, while FOXO3 overexpression reversed the inhibitory effect of GAS5 knockdown on cell pyroptosis. Thus, mechanistically, inhibition of FOXO3 activates the Nrf2/HO-1 pathway to suppress LPS-induced pyroptosis in HBECs. This study revealed that GAS5 knockdown attenuates FOXO3 expression thereby activating the Nrf2/HO-1 pathway to inhibit LPS-induced pyroptosis in HBECs. These findings may contribute to identifying novel targets that inhibit pyroptosis in HBECs.

Inhibition of EZH2 ameliorates hyperoxaluria-induced kidney injury through the JNK/FoxO3a pathway.

AIMS: Enhancer of zeste homolog 2 (EZH2), a histone H3 lysine 27 methyltransferase, has been shown to play a role in kidney diseases. However, its role in hyperoxaluria-induced renal tubular epithelial cells (TECs) injury remains unclear. MATERIALS AND METHODS: A hyperoxaluria rat model was established by providing 0.5% ammonium chloride and drinking water containing 1% ethylene glycol. TECs were exposed to oxalate stress. The 3-DZNeP, a selective EZH2 inhibitor, was administered in vivo and in vitro. Cell viability, ROS production, and apoptosis ratio were evaluated. Crystal deposition was detected by Von Kossa staining and kidney tissue injury was detected by HE staining and TUNEL. EZH2, H3K27me3, cleaved-caspase3, IL-6, and MCP-1 were examined by western blot or immunohistochemistry. KEY FINDINGS: Inhibition of EZH2 by 3-DZNeP significantly attenuated hyperoxaluria-induced oxidative and inflammatory injury and CaOx crystal deposition in vivo. Similarly, inhibition of EZH2 using 3-DZNeP or shRNA restored cell viability, suppressed LDH release and the production of intracellular ROS in vitro. Furthermore, the MAPK signaling pathway and FoxO3a levels were activated or elevated in TECs exposed to oxalate. EZH2 inhibition using 3-DZNeP blocked these effects. CC90003 (ERK inhibitor) or SB203580 (p38 inhibitor) did not significantly affect the expression of FoxO3a in TECs treated with 3-DZNeP and oxalate; only SP600125 (JNK inhibitor) significantly decreased FoxO3a expression. SIGNIFICANCE: EZH2 inhibition protects against oxalate-induced TECs injury and reduces CaOx crystal deposition in the kidney may by modulating the JNK/FoxO3a pathway; EZH2 may be a promising therapeutic target in TECs injury.

FOXO3 is targeted by miR-223-3p and promotes osteogenic differentiation of bone marrow mesenchymal stem cells by enhancing autophagy.

Mesenchymal stem cells (MSCs) are a promising regenerative medicine. The roles of miRNAs in osteogenic differentiation of bone marrow MSCs (BM-MSCs) remained less reported. Forkhead Box O3 (FOXO3) and alkaline phosphatase (ALP) levels in the BM-MSCs were measured on 3, 7, and 14 days after osteogenic differentiation. After transfection of FOXO3 overexpression plasmids or siFOXO3 into BM-MSCs, factors related to osteogenic differentiation or cell autophagy were determined. Besides, 3-methyladenine or rapamycin, as well as miR-223-3p mimic or inhibitor were applied to further determine the effect of FOXO3 in BM-MSCs. FOXO3 and ALP levels were increased in a time-dependent manner with osteogenic differentiation, supported by Alizarin Red Staining. Furthermore, up-regulated FOXO3 increased levels of ALP and factors related to osteogenic differentiation by increasing levels of autophagy-related factors. FOXO3, targeted by miR-223-3p, reversed the effects of miR-223-3p on factors related to BM-MSC autophagy and osteogenic differentiation. Down-regulated miR-223-3p expression promoted osteogenic differentiation of BM-MSCs by enhancing autophagy via targeting FOXO3, suggesting the potential of miR-223-3p as a therapeutic target for enhancing bone functions.

FOXO3a-driven miRNA signatures suppresses VEGF-A/NRP1 signaling and breast cancer metastasis.

Metastasis remains the major obstacle to improved survival for breast cancer patients. Downregulation of FOXO3a transcription factor in breast cancer is causally associated with the development of metastasis through poorly understood mechanisms. Here, we report that FOXO3a is functionally related to the inhibition of VEGF-A/NRP1 signaling and to the consequent suppression of breast cancer metastasis. We show that FOXO3a directly induces miR-29b-2 and miR-338 expression. Ectopic expression of miR-29b-2/miR-338 significantly suppresses EMT, migration/invasion, and in vivo metastasis of breast cancer. Moreover, we demonstrate that miR-29b-2 directly targets VEGF-A while miR-338 directly targets NRP1, and show that regulation of miR-29b-2 and miR-338 mediates the ability of FOXO3a to suppress VEGF-A/NRP1 signaling and breast cancer metastasis. Clinically, our results show that the FOXO3a-miR-29b-2/miR-338-VEGF-A/NRP1 axis is dysregulated and plays a critical role in disease progression in breast cancer. Collectively, our findings propose that FOXO3a functions as a metastasis suppressor, and define a novel signaling axis of FOXO3a-miRNA-VEGF-A/NRP1 in breast cancer, which might be potential therapeutic targets for breast cancer.