Overexpression of FOXO1 ameliorates the podocyte epithelial-mesenchymal transition induced by high glucose in vitro and in vivo

S100A2 activation promotes interstitial fibrosis in kidneys by FoxO1-mediated epithelial-mesenchymal transition

BACKGROUND

Renal interstitial fibrosis (RIF) is a common feature of chronic kidney diseases (CKD), with epithelial-mesenchymal transition (EMT) being one of its important mechanisms. S100A2 is a protein associated with cell proliferation and differentiation, but its specific functions and molecular mechanisms in RIF remain to be determined.

METHODS

S100A2 levels were evaluated in three mouse models, including unilateral ureteral obstruction (UUO), ischemia-reperfusion injury (IRI), and aristolochic acid nephropathy (AAN), as well as in TGF-β1- treated HK-2 cells and in kidney tissue samples. Furthermore, the role of S100A2 and its interaction with FoxO1 was investigated using RT-qPCR, immunoblotting, immunofluorescence staining, co-immunoprecipitation (Co-IP), transcriptome sequencing, and gain- or loss-of-function approaches in vitro.

RESULTS

Elevated expression levels of S100A2 were observed in three mouse models and TGF-β1-treated HK2 cells, as well as in kidney tissue samples. Following siRNA silencing of S100A2, exposure to TGF-β1 in cultured HK-2 cells suppressed EMT process and extracellular matrix (ECM) accumulation. Conversely, Overexpression of S100A2 induced EMT and ECM deposition. Notably, we identified that S100A2-mediated EMT depends on FoxO1. Immunofluorescence staining indicated that S100A2 and FoxO1 colocalized in the nucleus and cytoplasm, and their interaction was verified in Co-IP assay. S100A2 knockdown decreased TGF-β1-induced phosphorylation of FoxO1 and increased its protein expression, whereas S100A2 overexpression hampered FoxO1 activation. Furthermore, pharmacological blockade of FoxO1 rescued the induction of TGF-β1 on EMT and ECM deposition in S100A2 siRNA-treated cells.

CONCLUSION

S100A2 activation exacerbates interstitial fibrosis in kidneys by facilitating FoxO1-mediated EMT.

Integrin-linked kinase mRNA expression in circulating mononuclear cells as a biomarker of kidney and vascular damage in experimental chronic kidney disease

BACKGROUND

Traditional biomarkers of chronic kidney disease (CKD) detect the disease in its late stages and hardly predict associated vascular damage. Integrin-linked kinase (ILK) is a scaffolding protein and a serine/threonine protein kinase that plays multiple roles in several pathophysiological processes during renal damage. However, the involvement of ILK as a biomarker of CKD and its associated vascular problems remains to be fully elucidated.

METHODS

CKD was induced by an adenine-rich diet for 6 weeks in mice. We used an inducible ILK knockdown mice (cKD-ILK) model to decrease ILK expression. ILK content in mice's peripheral blood mononuclear cells (PBMCs) was determined and correlated with renal function parameters and with the expression of ILK and fibrosis and inflammation markers in renal and aortic tissues. Also, the expression of five miRNAs that target ILK was analyzed in whole blood of mice.

RESULTS

The adenine diet increased ILK expression in PBMCs, renal cortex, and aortas, and creatinine and urea nitrogen concentrations in the plasma of WT mice, while these increases were not observed in cKD-ILK mice. Furthermore, ILK content in PBMCs directly correlated with renal function parameters and with the expression of renal and vascular ILK and fibrosis and inflammation markers. Finally, the expression of the five miRNAs increased in the whole blood of adenine-fed mice, although only four correlated with plasma urea nitrogen, and of those, three were downregulated in cKD-ILK mice.

CONCLUSIONS

ILK, in circulating mononuclear cells, could be a potential biomarker of CKD and CKD-associated renal and vascular damage.

The Molecular Mechanism of Renal Tubulointerstitial Inflammation Promoting Diabetic Nephropathy

Diabetic nephropathy (DN) is a common complication affecting many diabetic patients, leading to end-stage renal disease. However, its pathogenesis still needs to be fully understood to enhance the effectiveness of treatment methods. Traditional theories are predominantly centered on glomerular injuries and need more explicit explanations of recent clinical observations suggesting that renal tubules equally contribute to renal function and that tubular lesions are early features of DN, even occurring before glomerular lesions. Although the conventional view is that DN is not an inflammatory disease, recent studies indicate that systemic and local inflammation, including tubulointerstitial inflammation, contributes to the development of DN. In patients with DN, intrinsic tubulointerstitial cells produce many proinflammatory factors, leading to medullary inflammatory cell infiltration and activation of inflammatory cells in the interstitial region. Therefore, understanding the molecular mechanism of renal tubulointerstitial inflammation contributing to DN injury is of great significance and will help further identify key factors regulating renal tubulointerstitial inflammation in the high glucose environment. This will aid in developing new targets for DN diagnosis and treatment and expanding new DN treatment methods.

METTL3 Mediates Epithelial-Mesenchymal Transition by Modulating FOXO1 mRNA N6 -Methyladenosine-Dependent YTHDF2 Binding: A Novel Mechanism of Radiation-Induced Lung Injury

The biological roles of epithelial-mesenchymal transition (EMT) in the pathogenesis of radiation-induced lung injury (RILI) have been widely demonstrated, but the mechanisms involved have been incompletely elucidated. N6 -methyladenosine (m6 A) modification, the most abundant reversible methylation modification in eukaryotic mRNAs, plays vital roles in multiple biological processes. Whether and how m6 A modification participates in ionizing radiation (IR)-induced EMT and RILI remain unclear. Here, significantly increased m6 A levels upon IR-induced EMT are detected both in vivo and in vitro. Furthermore, upregulated methyltransferase-like 3 (METTL3) expression and downregulated α-ketoglutarate-dependent dioxygenase AlkB homolog 5 (ALKBH5) expression are detected. In addition, blocking METTL3-mediated m6 A modification suppresses IR-induced EMT both in vivo and in vitro. Mechanistically, forkhead box O1 (FOXO1) is identified as a key target of METTL3 by a methylated RNA immunoprecipitation (MeRIP) assay. FOXO1 expression is downregulated by METTL3-mediated mRNA m6 A modification in a YTH-domain family 2 (YTHDF2)-dependent manner, which subsequently activates the AKT and ERK signaling pathways. Overall, the present study shows that IR-responsive METTL3 is involved in IR-induced EMT, probably by activating the AKT and ERK signaling pathways via YTHDF2-dependent FOXO1 m6 A modification, which may be a novel mechanism involved in the occurrence and development of RILI.

CTLA4-Ig protects tacrolimus-induced oxidative stress via inhibiting the AKT/FOXO3 signaling pathway in rats

BACKGROUND/AIMS

Although the conversion from tacrolimus (TAC) to cytotoxic T-lymphocyte-associated antigen 4-immunoglobulin (CTLA4-Ig) is effective in reducing TAC-induced nephrotoxicity, it remains unclear whether CTLA4-Ig has a direct effect on TAC-induced renal injury. In this study, we evaluated the effects of CTLA4-Ig on TAC-induced renal injury in terms of oxidative stress.

METHODS

In vitro study was performed to assess the effect of CTLA4-Ig on TAC-induced cell death, reactive oxygen species (ROS), apoptosis, and the protein kinase B (AKT)/forkhead transcription factor (FOXO) 3 pathway in human kidney 2 cells. In the in vivo study, the effect of CTLA4-Ig on TAC-induced renal injury was evaluated using renal function, histopathology, markers of oxidative stress (8-hydroxy-2'-deoxyguanosine) and metabolites (4-hydroxy-2-hexenal, catalase, glutathione S-transferase, and glutathione reductase), and activation of the AKT/FOXO3 pathway with insulin-like growth factor 1 (IGF-1).

RESULTS

CTLA4-Ig significantly decreased cell death, ROS, and apoptosis caused by TAC. TAC treatment increased apoptotic cell death and apoptosis-related proteins (increased Bcl-2-associated X protein and caspase-3 and decreased Bcl-2), but it was reversed by CTLA4-Ig treatment. The activation of p-AKT and p-FOXO3 by TAC decreased with CTLA4-Ig treatment. TAC-induced renal dysfunction and oxidative marker levels were significantly improved by CTLA4-Ig in vivo. Concomitant IGF-1 treatment abolished the effects of CTLA4-Ig.

CONCLUSION

CTLA4-Ig has a direct protective effect on TAC-induced renal injury via the inhibition of AKT/FOXO3 pathway.

The Pan-Cancer Multi-Omics Landscape of FOXO Family Relevant to Clinical Outcome and Drug Resistance

The forkhead box O (FOXO) transcription factors (TFs) family are frequently mutated, deleted, or amplified in various human cancers, making them attractive candidates for therapy. However, their roles in pan-cancer remain unclear. Here, we evaluated the expression, prognostic value, mutation, methylation, and clinical features of four FOXO family genes (FOXO1, FOXO3, FOXO4, and FOXO6) in 33 types of cancers based on the Cancer Genome Atlas (TCGA) and Genotype Tissue Expression (GTEx) databases. We used a single sample gene set enrichment analysis (ssGSEA) algorithm to establish a novel index called "FOXOs score". Moreover, we investigated the association between the FOXOs score and tumor microenvironment (TME), the responses to multiple treatments, along with drug resistance. We found that the FOXO family genes participated in tumor progression and were related to the prognosis in various types of cancer. We calculated the FOXOs score and found that it was significantly correlated with multiple malignant pathways in pan-cancer, including Wnt/beta-catenin signaling, TGF-beta signaling, and hedgehog signaling. In addition, the FOXOs score was also associated with multiple immune-related characteristics. Furthermore, the FOXOs score was sensitive for predicting the efficacy of diverse treatments in multiple cancers, especially immunotherapy. In conclusion, FOXO family genes were vital in pan-cancer and were strongly correlated with the TME. A high FOXOs score indicated an excellent immune-activated TME and sensitivity to multiple treatments. Hence, the FOXOs score might potentially be used as a biomarker in patients with a tumor.

Mechanisms underlying acupuncture therapy in chronic kidney disease: A narrative overview of preclinical studies and clinical trials

Chronic kidney disease (CKD) is associated with high incidence, low awareness, and high disability rates among the population. Moreover, the disease significantly affects the physical and mental health of patients. Approximately 25% of patients with CKD develop end-stage renal disease (ESRD) within 20 years of diagnosis and have to rely on renal replacement therapy, which is associated with high mortality, heavy economic burden, and symptoms including fatigue, pain, insomnia, uremia pruritus, and restless leg syndrome. Currently, the means to delay the progress of CKD are insufficient; therefore, developing strategies for delaying CKD progression has important practical implications. In recent years, more and more people are accepting the traditional Chinese medical technique "acupuncture." Acupuncture has been shown to improve the uncomfortable symptoms of various diseases through stimulation (needling, medicinal moxibustion, infrared radiation, and acupressure) of acupoints. Its application has been known for thousands of years, and its safety and efficacy have been verified. As a convenient and inexpensive complementary therapy for CKD, acupuncture has recently been gaining interest among clinicians and scientists. Nevertheless, although clinical trials and meta-analysis findings have demonstrated the efficacy of acupuncture in reducing albuminuria, improving glomerular filtration rate, relieving symptoms, and improving the quality of life of patients with CKD, the underlying mechanisms involved are still not completely understood. Few studies explored the correlation between acupuncture and renal pathological diagnosis. The aim of this study was to conduct a literature review summarizing the currently known mechanisms by which acupuncture could delay the progress of CKD and improve symptoms in patients with ESRD. This review help provide a theoretical basis for further research regarding the influence of acupuncture on renal pathology in patients with CKD, as well as the differences between specific therapeutic mechanisms of acupuncture in different renal pathological diagnosis. The evidence in this review indicates that acupuncture may produce marked effects on blocking and reversing the critical risk factors of CKD progression (e.g., hyperglycemia, hypertension, hyperlipidemia, obesity, aging, and anemia) to improve the survival of patients with CKD via mechanisms including oxidative stress inhibition, reducing inflammatory effects, improving hemodynamics, maintaining podocyte structure, and increasing energy metabolism.

Cellular phenotypic transitions in diabetic nephropathy: An update

Diabetic nephropathy (DN) is a major cause of morbidity and mortality in diabetes and is the most common cause of end stage renal disease (ESRD). Renal fibrosis is the final pathological change in DN. It is widely believed that cellular phenotypic switching is the cause of renal fibrosis in diabetic nephropathy. Several types of kidney cells undergo activation and differentiation and become reprogrammed to express markers of mesenchymal cells or podocyte-like cells. However, the development of targeted therapy for DN has not yet been identified. Here, we discussed the pathophysiologic changes of DN and delineated the possible origins that contribute to myofibroblasts and podocytes through phenotypic transitions. We also highlight the molecular signaling pathways involved in the phenotypic transition, which would provide valuable information for the activation of phenotypic switching and designing effective therapies for DN.

A miR-9-5p/FOXO1/CPEB3 Feed-Forward Loop Drives the Progression of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide, but its regulatory mechanism remains unclear and potential clinical biomarkers are still lacking. Co-regulation of TFs and miRNAs in HCC and FFL module studies may help to identify more precise and critical driver modules in HCC development. Here, we performed a comprehensive gene expression and regulation analysis for HCC in vitro and in vivo. Transcription factor and miRNA co-regulatory networks for differentially expressed genes between tumors and adjacent tissues revealed the critical feed-forward loop (FFL) regulatory module miR-9-5p/FOXO1/CPEB3 in HCC. Gain- and loss-of-function studies demonstrated that miR-9-5p promotes HCC tumor proliferation, while FOXO1 and CPEB3 inhibit hepatocarcinoma growth. Furthermore, by luciferase reporter assay and ChIP-Seq data, CPEB3 was for the first time identified as a direct downstream target of FOXO1, negatively regulated by miR-9-5p. The miR-9-5p/FOXO1/CPEB3 FFL was associated with poor prognosis, and promoted cell growth and tumor progression of HCC in vitro and in vivo. Our study identified for the first time the existence of miR-9-5p/FOXO1/CPEB3 FFL and revealed its regulatory role in HCC progression, which may represent a new potential target for cancer therapy.

Targeting the ILK/YAP axis by LFG-500 blocks epithelial-mesenchymal transition and metastasis

Metastasis is the main cause of mortality in patients with cancer. Epithelial-mesenchymal transition (EMT), a crucial process in cancer metastasis, is an established target for antimetastatic drug development. LFG-500, a novel synthetic flavonoid, has been revealed as a potential antitumor agent owing to its various activities, including modulation of EMT in the inflammatory microenvironment. Here, using a transforming growth factor beta (TGF-β)-induced EMT models, we found that LFG-500 inhibited EMT-associated migration and invasion in human breast cancer, MCF-7, and lung adenocarcinoma, A549, cell lines, consistent with the observed downregulation of YAP activity. Further studies demonstrated that LGF-500-induced suppression of YAP activation was mediated by integrin-linked kinase (ILK), suggesting that the ILK/YAP axis might be feasible target for anti-EMT and antimetastatic treatments, which was verified by a correlation analysis with clinical data and tumor specimens. Hence, our data support the use of LGF-500 as an antimetastatic drug in cancer therapy and provide evidence that the ILK/YAP axis is a feasible biomarker of cancer progression and a promising target for repression of EMT and metastasis in cancer therapy.

STYK1/NOK Promotes Metastasis and Epithelial-Mesenchymal Transition in Non-small Cell Lung Cancer by Suppressing FoxO1 Signaling

Aims

Serine/threonine/tyrosine kinase 1 (STYK1) has been previously shown to have oncogenic properties, and emerging evidence suggests that STYK1 expression correlates with epithelial-mesenchymal transition (EMT). However, the mechanism of STYK1 involvement in oncogenesis remains unknown. The present study aimed to elucidate how STYK1 expression level relates to the metastasis, migration, invasion, and EMT in non-small cell lung cancer (NSCLC) and to determine the molecular mechanism of STYK1 effects.

Methods

Serine/threonine/tyrosine kinase 1 (STYK1) expression level and its relationship with the prognosis of NSCLC were determined using the ONCOMINE database and clinical cases. Non-small cell lung cancer cell lines with the overexpression or knockdown of STYK1 were established to determine whether STYK1 promotes cell migration, invasion, and EMT in vitro and in vivo. In addition, a constitutively active FoxO1 mutant (FoxO1AAA) was used to examine the role of FoxO1 in the STYK1-mediated upregulation of metastasis and EMT in NSCLC.

Results

Serine/threonine/tyrosine kinase 1 (STYK1) was upregulated in NSCLC tissues and cell lines, and its overexpression correlated with poor prognosis in patients with NSCLC after surgery. Enhanced expression of STYK1 potentiated the migration, invasion, and EMT in SW900 cells, thereby promoting metastasis, whereas knockdown of STYK1 inhibited these cellular phenomena in Calu-1 cells. Furthermore, STYK1 expression was positively related to the level of phosphorylated-FoxO1, whereas the constitutively active FoxO1 mutant protected against the positive effect of STYK1 overexpression on cell migration, invasion, and EMT.

Conclusion

Serine/threonine/tyrosine kinase 1 (STYK1) was upregulated in NSCLC and correlated with poor clinical outcomes. In addition, STYK1 suppressed FoxO1 functions, thereby promoting metastasis and EMT in NSCLC.

IGFBP-1 expression is reduced in human type 2 diabetic glomeruli and modulates β1-integrin/FAK signalling in human podocytes

AIMS/HYPOTHESIS

Podocyte loss or injury is one of the earliest features observed in the pathogenesis of diabetic kidney disease (DKD), which is the leading cause of end-stage renal failure worldwide. Dysfunction in the IGF axis, including in IGF binding proteins (IGFBPs), is associated with DKD, particularly in the early stages of disease progression. The aim of this study was to investigate the potential roles of IGFBPs in the development of type 2 DKD, focusing on podocytes.

METHODS

IGFBP expression was analysed in the Pima DKD cohort, alongside data from the Nephroseq database, and in ex vivo human glomeruli. Conditionally immortalised human podocytes and glomerular endothelial cells were studied in vitro, where IGFBP-1 expression was analysed using quantitative PCR and ELISAs. Cell responses to IGFBPs were investigated using migration, cell survival and adhesion assays; electrical cell-substrate impedance sensing; western blotting; and high-content automated imaging.

RESULTS

Data from the Pima DKD cohort and from the Nephroseq database demonstrated a significant reduction in glomerular IGFBP-1 in the early stages of human type 2 DKD. In the glomerulus, IGFBP-1 was predominantly expressed in podocytes and controlled by phosphoinositide 3-kinase (PI3K)-forkhead box O1 (FoxO1) activity. In vitro, IGFBP-1 signalled to podocytes via β1-integrins, resulting in increased phosphorylation of focal-adhesion kinase (FAK), increasing podocyte motility, adhesion, electrical resistance across the adhesive cell layer and cell viability.

CONCLUSIONS/INTERPRETATION

This work identifies a novel role for IGFBP-1 in the regulation of podocyte function and that the glomerular expression of IGFBP-1 is reduced in the early stages of type 2 DKD, via reduced FoxO1 activity. Thus, we hypothesise that strategies to maintain glomerular IGFBP-1 levels may be beneficial in maintaining podocyte function early in DKD.

Exploring the mechanisms underlying the therapeutic effect of Salvia miltiorrhiza in diabetic nephropathy using network pharmacology and molecular docking

The mechanisms underlying the therapeutic effect of Salvia miltiorrhiza (SM) on diabetic nephropathy (DN) were examined using a systematic network pharmacology approach and molecular docking. The Traditional Chinese Medicine Systems Pharmacology (TCMSP) database was used to screen active ingredients of SM. Targets were obtained using the SwissTargetPrediction and TCMSP databases. Proteins related to DN were retrieved from the GeneCards and DisGeNET databases. A protein–protein interaction (PPI) network was constructed using common SM/DN targets in the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database. The Metascape platform was used for Gene Ontology (GO) function analysis, and the Cytoscape plug-in ClueGO was used for Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Molecular docking was performed using iGEMDOCK and AutoDock Vina software. Pymol and LigPlos were used for network mapping. Sixty-six active ingredients and 189 targets of SM were found. Sixty-four targets overlapped with DN-related proteins. The PPI network revealed that AKT serine/threonine kinase 1 (AKT1), VEGFA, interleukin 6 (IL6), TNF, mitogen-activated protein kinase 1 (MAPK1), tumor protein p53 (TP53), epidermal growth factor receptor (EGFR), signal transducer and activator of transcription 3 (STAT3), mitogen-activated protein kinase 14 (MAPK14), and JUN were the ten most relevant targets. GO and KEGG analyses revealed that the common targets of DN and SM were mainly involved in advanced glycation end-products, oxidative stress, inflammatory response, and immune regulation. Molecular docking revealed that potential DN-related targets, including tumor necrosis factor (TNF), NOS2, and AKT1, more stably bound with salvianolic acid B than with tanshinone IIA. In conclusion, the present study revealed the active components and potential molecular therapeutic mechanisms of SM in DN and provides a reference for the wide application of SM in clinically managing DN.

Improving the Dysregulation of FoxO1 Activity Is a Potential Therapy for Alleviating Diabetic Kidney Disease

A substantial proportion of patients with diabetes will develop kidney disease. Diabetic kidney disease (DKD) is one of the most serious complications in diabetic patients and the leading cause of end-stage kidney disease worldwide. Although some mechanisms have been revealed to contribute to the understanding of the pathogenesis of DKD and some drugs currently in use have been shown to be beneficial, prevention and management of DKD remain tricky and challenging. FoxO1 transcriptional factor is a crucial regulator of cellular homeostasis and posttranslational modification is a major mechanism to alter FoxO1 activity. There is increasing evidence that FoxO1 is involved in the regulation of various cellular processes such as stress resistance, autophagy, cell cycle arrest, and apoptosis, thereby playing an important role in the pathogenesis of DKD. Improving the dysregulation of FoxO1 activity by natural compounds, synthetic drugs, or manipulation of gene expression may attenuate renal cell injury and kidney lesion in the cells cultured under a high-glucose environment and in diabetic animal models. The available data imply that FoxO1 may be a potential clinical target for the prevention and treatment of DKD.

4sc-202 and Ink-128 cooperate to reverse the epithelial to mesenchymal transition in OSCC

Treatment of oral squamous cell carcinoma remains a challenge due to a high incidence of treatment resistance, which is followed by tumor recrudescence and metastasis to the lymph nodes. Thus, it is important to explore novel inhibitors of OSCC. Here, we aimed to identify drugs that may cooperate with histone deacetylase inhibitors to reverse the EMT, inhibit EMT and cell migration and invasion, and contribute to therapeutic efficacy. We found that treatment with 4sc-202 potently reversed the EMT and thereby inhibited cell migration and invasion in vitro, in part by inducing expression of the FoxO1 tumor-suppressor gene. Furthermore, 4sc-202 also synergized with Ink-128 to inhibit tumor migration and invasion in vitro. Mechanistically, 4sc-202 induced FoxO1 expression, whereas Ink-128 promoted nuclear translocation of FoxO1. Our findings indicated that FoxO1 might reverse the EMT by interacting with Twist1 in OSCC. In conclusion, we identified an effective combination therapy involving class I histone deacetylase and mammalian target of rapamycin complex 1/2 inhibition that effectively blocked the EMT of tumor cells by upregulating FoxO1 expression to inhibit Twist1 transcription. These data have implications for developing new targets for early diagnosis and treatment of OSCC.

Astragaloside IV protects against podocyte apoptosis by inhibiting oxidative stress via activating PPARγ-Klotho-FoxO1 axis in diabetic nephropathy

AIMS

Podocyte apoptosis plays an important role in the pathogenesis of diabetic nephropathy (DN). Astragaloside IV (AS-IV) has been shown to protect against podocyte apoptosis. Here we aim to investigate the mechanism responsible for the protective effects of AS-IV.

MAIN METHODS

Diabetic db/db mice and high glucose (HG)-cultured podocytes were treated with AS-IV. Renal function and histopathological changes were measured to evaluate the therapeutic effects of AS-IV against DN. Adenovirus-mediated Klotho overexpression, Klotho siRNA, and PPARγ inhibitor were applied in vitro to investigate the potential mechanism. The expression levels of mRNA and proteins were analyzed by qRT-PCR, western blot or immunofluorescence. Intracellular ROS and mitochondrial superoxide were detected by DHE and MitoSOx Red, respectively. Cell apoptosis was evaluated by TUNEL staining and flow cytometry.

KEY FINDINGS

AS-IV improved renal function and ameliorated podocyte injury in db/db mice accompanied with enhanced Klotho expression in glomerular podocytes. In vitro, AS-IV inhibited HG-induced podocyte apoptosis and restored HG-inhibited Klotho expression, whereas Klotho knockdown abrogated the anti-apoptosis action of AS-IV. Further study showed that adenovirus-mediated Klotho overexpression enhanced Forkhead transcription factor O1 (FoxO1)-dependent antioxidant activity and attenuated HG-evoked oxidative stress and apoptosis. AS-IV prevented HG-induced FoxO1 inhibition and oxidative stress, whereas Klotho knockdown reversed these effects. Cotreatment with PPARγ inhibitor T0070907 abolished AS-IV-induced Klotho expression and anti-apoptosis action.

SIGNIFICANCE

These data suggested that AS-IV attenuated podocyte apoptosis presumably by inhibiting oxidative stress via activating PPARγ-Klotho-FoxO1 signaling pathway, thereby ameliorating DN. This study provided new insights into the molecular mechanisms of AS-IV against DN.

FOXO transcription factor family in cancer and metastasis

Forkhead box O (FOXO) transcription factors regulate diverse biological processes, affecting development, metabolism, stem cell maintenance and longevity. They have also been increasingly recognised as tumour suppressors through their ability to regulate genes essential for cell proliferation, cell death, senescence, angiogenesis, cell migration and metastasis. Mechanistically, FOXO proteins serve as key connection points to allow diverse proliferative, nutrient and stress signals to converge and integrate with distinct gene networks to control cell fate, metabolism and cancer development. In consequence, deregulation of FOXO expression and function can promote genetic disorders, metabolic diseases, deregulated ageing and cancer. Metastasis is the process by which cancer cells spread from the primary tumour often via the bloodstream or the lymphatic system and is the major cause of cancer death. The regulation and deregulation of FOXO transcription factors occur predominantly at the post-transcriptional and post-translational levels mediated by regulatory non-coding RNAs, their interactions with other protein partners and co-factors and a combination of post-translational modifications (PTMs), including phosphorylation, acetylation, methylation and ubiquitination. This review discusses the role and regulation of FOXO proteins in tumour initiation and progression, with a particular emphasis on cancer metastasis. An understanding of how signalling networks integrate with the FOXO transcription factors to modulate their developmental, metabolic and tumour-suppressive functions in normal tissues and in cancer will offer a new perspective on tumorigenesis and metastasis, and open up therapeutic opportunities for malignant diseases.

Protective effect of silencing Stat1 on high glucose-induced podocytes injury via Forkhead transcription factor O1-regulated the oxidative stress response

Background

Podocyte plays an important role in maintaining the integrity and function of the glomerular filtration barrier. Various studies reported that forkhead transcription factor (Fox) O1 played a key role in anti-oxidative signaling. This study aimed to investigate the role of Stat1 in high glucose (HG) -induced podocyte injury.

Methods

Under normal glucose, hypertonic and HG stimulated podocyte conditions, cell counting kit-8 (CCK-8) assay, flow cytometry and western blot and quantitative real-time polymerase chain reaction (qRT-PCR) were respectively carried out to determine cell viability, apoptosis, reactive oxygen species (ROS) production and related genes expressions. We then respectively used silent Stat1, simultaneous silencing Stat1 and FoxO1 and over-expression of FoxO1, to observe whether they/it could reverse the damage of podocytes induced by HG.

Results

High glucose attenuated cell survival and promoted cell apoptosis in MPC-5 cells at the same time, and it was also observed to promote the protein expression of Stat1 and the FoxO1 expression inhibition. Silencing Stat1 could reverse HG-induced podocytes injury. Specifically, siStat1 increased cell viability, inhibited cell apoptosis and attenuated ROS level in a high-glucose environment. Cleaved caspase-3 and pro-apoptosis protein Bax was significantly down-regulated, and anti-apoptosis protein Bcl-2 was up-regulated by siStat1. The antioxidant genes Catalase, MnSOD, NQO1 and HO1 were up-regulated by siStat1. We found that silencing FoxO1 reversed the protective effect of siStat1 on the HG-induced podocytes injury.

Conclusions

Silencing Stat1 could reverse the effects of high glucose-triggered low cell viability, cell apoptosis and ROS release and the functions of Stat1 might be involved in FoxO1 mediated-oxidative stress in nucleus.

Atrasentan alleviates high glucose-induced podocyte injury by the microRNA-21/forkhead box O1 axis

Diabetic nephropathy (DN) is the most common complication of diabetes mellitus. Atrasentan (Atr) has potential therapeutic values for DN. MicroRNAs (miRNAs) function as vital regulators in the pathophysiology of kidney diseases including DN. Our present study aimed to further explore whether Atr could alleviate kidney injury by regulating microRNA-21(miR-21)/forkhead box O1 (FOXO1) in DN mouse models and cell models. Blood glucose concentration and ACR ratio were determined by matching commercial kits. MiR-21 and FOXO1 mRNA level was measured by RT-qPCR assay. Protein levels of FOXO1, LC3Ⅰ, LC3Ⅱ and p62 were measured by western blot assay. Cell apoptotic index was examined by flow cytometry. The interaction of miR-21 and FOXO1 was tested by bioinformatics analysis, luciferase assay and RIP assay. We found that Atr alleviated kidney injury by inhibiting miR-21 expression and promoting autophagy in DN mice. Moreover, miR-21 loss suppressed apoptosis and induced autophagy in high glucose (HG)-treated podocytes. And, Atr inhibited cell apoptosis and improved cell autophagic activity by downregulating miR-21 in HG-cultured podocytes. Moreover, FOXO1 was identified as a target of miR-21. MiR-21 exerted its pro-apoptosis and anti-autophagy effects by targeting FOXO1 in HG-cultured podocytes. Atr enhanced FOXO1 expression by downregulating miR-21 in HG-cultured podocytes. We concluded that Atr mitigated kidney injury in DN mice and alleviated HG-mediated apoptosis increase and autophagy inhibition in podocytes by regulating miR-21/FOXO1 axis, further elucidating the molecular basis by which Atr hampered DN progression.

Polydatin inhibits hepatocellular carcinoma via the AKT/STAT3-FOXO1 signaling pathway

Polydatin, extracted from Polygonum cuspidatum, is known for its anti-platelet aggregation and anti-inflammatory effects. However, studies on the association of polydatin with cancer are limited, particularly with regards to epithelial-mesenchymal transition (EMT)-associated migration and invasion of cancer cells. The purpose of the present study was to reveal the potential anticancer effects of polydatin on hepatocellular carcinoma (HCC) cells, particularly its effects on EMT. MTT assay was used to determine cell viability. Migration and invasion were evaluated through wound healing and transwell assays. Colony formation efficiency assay was conducted to detect proliferation. Flow cytometric analyses of apoptosis and cell cycle progression were performed following cells staining with Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) and PI alone, respectively. Western blotting was used to investigate relevant molecular mechanisms. The results indicated that polydatin inhibited proliferation via G₂/M arrest, suppressed migration and invasion of HCC cells, and promoted their apoptosis. In addition, phosphorylated (p)-protein kinase B (AKT), p-Janus kinase 1 and p-signal transducer and activator of transcription 3 (STAT3) levels were decreased as polydatin concentrations increased, and forkhead box protein O1 (FOXO1) expression was upregulated. Furthermore, the expression levels of various markers of EMT were reversed following treatment with polydatin. In conclusion, the present study validated that polydatin may inhibit proliferation via G₂/M arrest, and suppressed EMT-associated migration and invasion of HCC cells. The results also suggested that polydatin may promote HCC cell apoptosis by blocking the AKT/STAT3-FOXO1 signaling pathway.

FOXO1 Overexpression Attenuates Tubulointerstitial Fibrosis and Apoptosis in Diabetic Kidneys by Ameliorating Oxidative Injury via TXNIP-TRX

Objective

The generation of hyperglycemia-induced reactive oxygen species (ROS) is a key event in diabetic nephropathy (DN) development. Since forkhead box class O1 (FOXO1) is associated with oxidative stress and shows a positive effect on DN, its role on renal function and the underlying mechanism is still unclear.

Methods

We examined the role of FOXO1 in vivo (in a transgenic diabetic mouse model overexpressing Foxo1) and in vitro (in human HK-2 cells with FOXO1 knockin (KI) and knockout (KO) cultured under high glucose).

Results

Renal proximal tubular cells of kidney biopsies from patients with DN showed tubulointerstitial fibrosis and apoptosis. Accordingly, these proximal tubular injuries were accompanied by the increase of ROS generation in diabetic mice. Tissue-specific Foxo1 overexpression in transgenic mice had a protective effect on the renal function and partially reversed tubular injuries by attenuating the diabetes-induced increase in TXNIP and decrease in the TRX levels. FOXO1 knockin and knockout HK-2 cells were constructed to identify the associations between FoxO1 and TXNIP-TRX using CRISPR/CAS9. Similarly, the effects of FOXO1 KI and KO under high glucose were significantly modulated by the treatment of TRX inhibitor PX-12 and TXNIP small interfering RNA. In addition, TXNIP and TXN were identified as the direct FOXO1 transcriptional targets by chromatin immunoprecipitation.

Conclusion

The regulatory role of FOXO1/TXNIP-TRX activation in DN can protect against the high glucose-induced renal proximal tubular cell injury by attenuating cellular ROS production. Modulating the FOXO1/TXNIP-TRX pathway may be a new therapeutic target in DN.

Chronic kidney disease induced by an adenine rich diet upregulates integrin linked kinase (ILK) and its depletion prevents the disease progression

Kidney fibrosis is one of the main pathological findings of progressive chronic kidney disease (CKD) although the pathogenesis of renal scar formation remains incompletely explained. Integrin-linked kinase (ILK), a major scaffold protein between the extracellular matrix (ECM) and intracellular signaling pathways, is involved in several pathophysiological processes during renal damage. However, ILK contribution in the CKD progress remains to be fully elucidated. In the present work, we studied 1) the renal functional and structural consequences of CKD genesis and progression when ILK is depleted and 2) the potential of ILK depletion as a therapeutic approach to delay CKD progression. We induced an experimental CKD model, based on an adenine-supplemented diet on adult wild-type (WT) and ILK-depleted mice, with a tubulointerstitial damage profile resembling that is observed in human CKD. The adenine diet induced in WT mice a progressive increase in plasma creatinine and urea concentrations. In the renal cortex it was also observed tubular damage, interstitial fibrosis and progressive increased ECM components, pro-inflammatory and chemo-attractant cytokines, EMT markers and TGF-β1 expressions. These observations were highly correlated to a simultaneous increase of ILK expression and activity. In adenine-fed transgenic ILK-depleted mice, all these changes were prevented. Additionally, we evaluated the potential role of ILK depletion to be applied after the disease induction, as an effective approach to interventions in human CKD subjects. In this scenario, two weeks after the establishment of adenine-induced CKD, ILK was abrogated in WT mice and stabilized renal damage, avoiding CKD progression. We propose ILK to be a potential target to delay renal disease progression.

Role of the mTOR‑FOXO1 pathway in obesity‑associated renal tubulointerstitial inflammation

Since obesity is largely responsible for the growing incidence of renal tubulointerstitial inflammation, exploration into the mechanisms of obesity‑associated tubulointerstitial inflammation is essential. Studies have demonstrated that mammalian target of rapamycin (mTOR) is a crucial molecule in the pathogenesis of renal inflammation, including regulating the expression of inflammatory factors. The purpose of the present study was to further elucidate the role of mTOR in obesity‑associated tubulointerstitial inflammation. In the clinical study, obese and healthy subjects were recruited for physical examination, as well as the collection of blood and urine samples. Further study was performed on a high fat diet (HFD)‑induced obese rat model and a cultured human renal tubular epithelial cell line (HK‑2). The clinical study demonstrated that the participants with obesity had increased serum lipids, creatinine (Cr), urinary albumin to creatinine ratio (UACR) and urinary neutrophil gelatinase‑associated lipocalin (u‑NGAL). Moreover, the level of urinary monocyte chemoattractant protein‑1 (u‑MCP‑1) was increased in the participants with obesity, and it was positively correlated with free fatty acid (FFA), UACR and u‑NGAL. In the in vivo study, the results indicated that the levels of serum lipids, Cr and blood urea nitrogen (BUN), as well as 24 h urine protein and u‑NGAL, were significantly increased in the HFD‑fed obese rats. In addition, the infiltration of CD68+ cells into the renal interstitial area and the release of interleukin‑1β (IL‑1β) was observed in the kidneys of obese rats. Meanwhile, the supernatant from HK‑2 cells treated with palmitic acid stimulated THP‑1 monocyte migration. The upregulation of MCP‑1, phosphorylated forkhead boxO1 (p‑FOXO1), and phosphorylated mTOR (p‑mTOR) was observed in vivo and in vitro. However, inhibition of mTOR was able to alleviate the above effects. Overall, these results demonstrated that activated mTOR induced FOXO1 phosphorylation, which mediates renal MCP‑1 release, causes tubulointerstitial inflammation and ultimately leads to pathological renal changes and dysfunction. However, inhibition of mTOR may play a renoprotective role during the progression of obesity‑associated tubulointerstitial inflammation.

Silence of IGFBP7 suppresses apoptosis and epithelial mesenchymal transformation of high glucose induced-podocytes

Insulin-like growth factor-binding protein 7 (IGFBP7) has been identified as a secreted protein associated with a number of cellular processes. However, the specific regulatory mechanisms of IGFBP7 on podocytes of diabetic nephropathy (DN) are yet to be elucidated. In the present study, podocytes were identified initially via an immunofluorescence assay using an anti-synaptopodin antibody. It was subsequently demonstrated that glucose promoted podocyte proliferation in a time- and dose-dependent manner via MTT assay. In addition, IGFBP7 expression was silenced in podocytes via siRNA, the effects of which were evaluated using western blotting and reverse transcription-quantitative polymerase chain reaction. It was demonstrated that silencing IGFBP7 inhibited apoptosis and epithelial mesenchymal transformation (EMT) of podocytes mediated by high glucose (HG). Transforming growth factor (TGF)-β1/mothers against decapentaplegic homolog (Smad) signaling was associated with proliferation, apoptotic activities and EMT. Therefore, the expression levels of TGF-β1/Smad pathway were detected, and it was observed that silencing IGFBP7 suppressed the TGF-β1/Smad pathway in podocytes induced by HG. These findings suggested that IGFBP7 may serve as a potential therapeutic target for DN.

Liraglutide ameliorates early renal injury by the activation of renal FoxO1 in a type 2 diabetic kidney disease rat model

AIMS

The aim of this study was to investigate the effects of liraglutide on renal injury and the renal expression of FoxO1 in type 2 diabetic rats.

METHODS

Type 2 diabetic rats model was induced by a high-sugar and high-fat diet and intraperitoneal injection of low-dose Streptozotocin (STZ) (30 mg/kg). Five weeks after STZ injection, diabetic rats were randomly treated with or without subcutaneous injection of liraglutide (0.2 mg/kg/12 h) for eight weeks. Diabetes-related physical and biochemical indicators, renal histopathological and ultrastructural changes, the expression of renal transforming growth factor beta-1 (TGF-β1), fibronectin (FN), type IV collagen (Col IV), protein kinase B (Akt), forkhead box protein O1 (FoxO1) and manganese superoxide dismutase (MnSOD) were measured.

RESULTS

Rats in DN group showed a significant increase in fasting blood glucose, HbA1c, kidney to body weight index, serum creatinine (Scr), blood urea nitrogen (BUN), urinary albumin excretion, mesangial matrix index, glomerular basement membrane (GBM) thickening, podocyte foot process fusion, the mRNA and protein levels of renal TGF-β1, FN and Col IV and a dramatic decrease in the mRNA and protein levels of renal MnSOD, all of which were significantly ameliorated by liraglutide. In addition, liraglutide also increased the expression of FoxO1 mRNA and reduced renal phosphorylation levels of Akt and FoxO1 protein.

CONCLUSIONS

These results suggest that liraglutide may exert a renoprotective effect by a FoxO1-mediated upregulation of renal MnSOD expression in the early DKD.

Forkhead box O proteins: Crucial regulators of cancer EMT

The epithelial-mesenchymal transition (EMT) is an acknowledged cellular transition process in which epithelial cells acquire mesenchymal-like properties that endow cancer cells with increased migratory and invasive behavior. Forkhead box O (FOXO) proteins have been shown to orchestrate multiple EMT-associated pathways and EMT-related transcription factors (EMT-TFs), thereby modulating the EMT process. The focus of the current review is to evaluate the latest research progress regarding the roles of FOXO proteins in cancer EMT. First, a brief overview of the EMT process in cancer and a general background on the FOXO family are provided. Next, we present the interactions between FOXO proteins and multiple EMT-associated pathways during malignancy development. Finally, we propose several novel potential directions for future research. Collectively, the information compiled herein should serve as a comprehensive repository of information on this topic and should aid in the design of additional studies and the future development of FOXO proteins as therapeutic targets.

FOXO1/3: Potential suppressors of fibrosis

Fibrosis is a universally age-related disease that involves nearly all organs. It is typically initiated by organic injury and eventually results in organ failure. There are still few effective therapeutic strategy targets for fibrogenesis. Forkhead box proteins O1 and O3 (FOXO1/3) have been shown to have favorable inhibitory effects on fibroblast activation and subsequent extracellular matrix production and can ameliorate fibrosis levels in numerous organs, including the heart, liver, lung, and kidney; they are therefore promising targets for anti-fibrosis therapy. Moreover, we can develop appropriate strategies to make the best use of FOXO1/3's anti-fibrosis properties. The information reviewed here should be significant for understanding the roles of FOXO1/3 in fibrosis and should contribute to the design of further studies related to FOXO1/3 and the fibrotic response and shed light on a potential treatment for fibrosis.

SIRT1 rs10823108 and FOXO1 rs17446614 responsible for genetic susceptibility to diabetic nephropathy

SIRT1 and FOXO1 play an important role in the pathogenesis of diabetic nephropathy (DN). However, the association between genetic polymorphisms and susceptibility to type 2 DN (T2DN) has not been explored. In this study, a total of 1066 patients with type 2 diabetes mellitus (T2DM) (413 without and 653 with DN) were enrolled. The genotypes of three htSNPs (rs3818292, rs4746720, rs10823108) within SIRT1 and two htSNPs (rs2721068, rs17446614) in FOXO1 were determined by PCR-RFLP. HbA1C, LDL, HDL, TC, and TG levels were also examined. SIRT1 rs10823108 AA genotype was significantly associated with a decreased risk of DN (OR = 0.60, 95%CI: 0.38–0.97), while GA genotype (OR = 1.77, 95%CI: 1.33–2.35) and AA genotype (OR = 2.32, 95%CI: 1.25–4.34) of FOXO1 rs17446614 was associated with an increased T2DN risk. The interactions among rs1744 6614, BMI and duration of diabetes (OR: 2.63, 95%CI: 1.23–4.31) were also observed. Subsequent haplotype analysis revealed that two haplotype defined by AC (OR: 1.50, 95%CI: 1.15–1.94) and AT (OR: 1.79, 95%CI: 1.06–2.80) within FOXO1 gene may increase the risk of T2DN. In conclusion, genetic variant rs10823108 in SIRT1 and variant rs17446614 in FoxO1 may contribute to the risk of DN in T2DM patients.

Knocking down TCF8 inhibits high glucose- and angiotensin II-induced epithelial to mesenchymal transition in podocytes

Epithelial to mesenchymal transition (EMT) is a physiological phenomenon in mammalian embryogenesis by which epithelial cells become mesenchymal stem cells. Studies have indicated that an inappropriate EMT plays a key role in a variety of pathogenic processes such as embryonic development and tumor metastasis. Moreover, recent studies have indicated EMT also plays an important role in renal fibrosis. In the current study, glucose and angiotensin II promoted EMT in podocytes as well as changes in the cellular morphology of podocytes. A high concentration of glucose and angiotensin II also promoted podocyte movement and migration. Moreover, a high concentration of glucose and angiotensin II promoted TCF8 expression. Inhibiting TCF8 expression with siRNA reversed EMT in podocytes in the presence of a high concentration of glucose and angiotensin. Inhibiting TCF8 expression also reversed changes in cellular morphology and podocyte movement and migration. Therefore, glucose and angiotensin II may promote EMT in podocytes via TCF8.