TXNIP (VDUP-1, TBP-2): a major redox regulator commonly suppressed in cancer by epigenetic mechanisms

Vitamin D3 Upregulated Protein 1 Deficiency Promotes Azoxymethane/Dextran Sulfate Sodium-Induced Colorectal Carcinogenesis in Mice

VDUP1 acts as a tumor suppressor gene in various cancers. VDUP1 is expressed at low levels in sporadic and ulcerative-colitis-associated colorectal cancer. However, the effects of VDUP1 deficiency on CAC remain unclear. In this study, we found that VDUP1 deficiency promoted CAC development in mice. Wild-type (WT) and VDUP1 KO mice were used to investigate the role of VDUP1 in the development of azoxymethane (AOM)- and dextran sulfate sodium (DSS)-induced CAC. VDUP1 levels significantly decreased in the colonic tumor and adjacent nontumoral tissues of WT mice after AOM/DSS treatment. Moreover, AOM/DSS-treated VDUP1 KO mice exhibited a worse survival rate, disease activity index, and tumor burden than WT mice. VDUP1 deficiency significantly induced cell proliferation and anti-apoptosis in tumor tissues of VDUP1 KO mice compared to WT littermates. Additionally, mRNA levels of interleukin-6 and tumor necrosis factor-alpha and active forms of signal transducer and activator of transcription 3 and nuclear factor-kappa B p65 were significantly increased in the tumor tissues of VDUP1 KO mice. Overall, this study demonstrated that the loss of VDUP1 promoted AOM/DSS-induced colon tumorigenesis in mice, highlighting the potential of VDUP1-targeting strategies for colon cancer prevention and treatment.

TXNIP mediated by EZH2 regulated osteogenic differentiation in hBmscs and MC3T3-E1 cells through the modulation of oxidative stress and PI3K/AKT/Nrf2 pathway

BACKGROUND

Previous research has identified a significant role of Thioredoxin-interacting protein (TXNIP) in bone loss. The purpose of this investigation was to assess the role and the underlying molecular mechanisms of TXNIP in the osteogenic differentiation of human bone marrow stromal cells (hBMSCs) and pre-osteoblast MC3T3-E1 cells.

METHODS

Human bone marrow stem cells (hBMSCs) and MC3T3-E1 cells were used to induce osteogenic differentiation. The expression of genes and proteins was assessed using RT-qPCR and western blot, respectively. ChIP assay was used to validate the interaction between genes. The osteogenic differentiation ability of cells was reflected using ALP staining and detection of ALP activity. The mineralization ability of cells was assessed using ARS staining. DCFCA staining was employed to evaluate the intracellular ROS level.

RESULTS

Initially, downregulation of TXNIP and upregulation of EZH2 were observed during osteogenesis in hBMSCs and MC3T3-E1 cells. Additionally, it was discovered that EZH2 negatively regulates TXNIP expression in these cells. Furthermore, experiments indicated that the knockdown of TXNIP stimulated the activation of the PI3K/AKT/Nrf2 signaling pathway in hBMSCs and MC3T3- E1 cells, thus inhibiting the production of reactive oxygen species (ROS). Further functional experiments revealed that overexpression of TXNIP inhibited the osteogenic differentiation in hBMSCs and MC3T3-E1 cells by enhancing ROS produc-tion. On the other hand, knockdown of TXNIP promoted the osteogenic differentiation capacity of hBMSCs and MC3T3-E1 cells through the activation of the PI3K/AKT/Nrf2 pathway.

CONCLUSION

In conclusion, this study demonstrated that TXNIP expression, under the regulation of EZH2, plays a crucial role in the osteogenic differentiation of hBMSCs and MC3T3-E1 cells by regulating ROS production and the PI3K/AKT/Nrf2 pathway.

TXNIP knockdown ameliorates hepatic ischemia/reperfusion injury by inhibiting apoptosis and improving mitochondrial dysfunction via HIF-1α

This study aims to investigate whether thioredoxin-interacting protein (TXNIP) regulates cell viability, cell apoptosis and mitochondrial damage in OGD/R-induced hepatocytes and to explore its underlying mechanism. AML12 cells were cultured under oxygen-glucose deprivation/reperfusion (OGD/R) conditions. TXNIP mRNA was detected using qRT-PCR, and the TXNIP protein was analyzed using western blotting. TXNIP-targeted short hairpin RNA (sh-TXNIP) lentivirus was used to infect the AML12 cells. CCK8 and TUNEL assays were applied to detect cell viability and apoptosis, respectively. DCFH-DA probe was used to determine reactive oxygen species (ROS) release level, and JC-1 probe was used to evaluate mitochondrial membrane potential (MMP). The localization of TXNIP and HIF-1α was observed using immunofluorescence. Our results showed that TXNIP markedly increased in AML12 cells treated with OGD/R. TXNIP knockdown increased cell viability and reduced cell apoptosis under OGD/R treatment. Moreover, MMP significantly increased and ROS release decreased in cells after TXNIP knockdown under OGD/R treatment. Additionally, TXNIP knockdown markedly increased the expression of HIF-1α. HIF-1α exhibited nuclear translocation following OGD/R induction, and TXNIP knockdown further promoted it. Compared with the OGD/R + sh-TXNIP group, HIF-1α agonist ML228 inhibited cell apoptosis and ROS release, and increased MMP. However, HIF-1α inhibitor PX478 had the opposite effect. In summary, TXNIP deletion ameliorated AML12 cell injury caused by OGD/R via promoting HIF-1α expression and nuclear translocation, manifested by inhibiting cell apoptosis and alleviating mitochondrial dysfunction.

Txnip regulates the Oct4-mediated pluripotency circuitry via metabolic changes upon differentiation

Thioredoxin interacting protein (Txnip) is a stress-responsive factor regulating Trx1 for redox balance and involved in diverse cellular processes including proliferation, differentiation, apoptosis, inflammation, and metabolism. However, the biological role of Txnip function in stem cell pluripotency has yet to be investigated. Here, we reveal the novel functions of mouse Txnip in cellular reprogramming and differentiation onset by involving in glucose-mediated histone acetylation and the regulation of Oct4, which is a fundamental component of the molecular circuitry underlying pluripotency. During reprogramming or PSC differentiation process, cellular metabolic and chromatin remodeling occur in order to change its cellular fate. Txnip knockout promotes induced pluripotency but hinders initial differentiation by activating pluripotency factors and promoting glycolysis. This alteration affects the intracellular levels of acetyl-coA, a final product of enhanced glycolysis, resulting in sustained histone acetylation on active PSC gene regions. Moreover, Txnip directly interacts with Oct4, thereby repressing its activity and consequently deregulating Oct4 target gene transcriptions. Our work suggests that control of Txnip expression is crucial for cell fate transitions by modulating the entry and exit of pluripotency.

Decreased expression of TXNIP is associated with poor prognosis and immune infiltration in kidney renal clear cell carcinoma

The most prevalent and insidious type of kidney cancer is kidney clear cell carcinoma (KIRC). Thioredoxin-interacting protein (TXNIP) encodes a thioredoxin-binding protein involved in cellular energy metabolism, redox homeostasis, apoptosis induction and inflammatory responses. However, the relationship between TXNIP, immune infiltration and its prognostic value in KIRC remains unclear. Thus, the present study evaluated the potential for TXNIP as a prognostic marker in patients with KIRC. Data from The Cancer Genome Atlas were used to assess relative mRNA expression levels of TXNIP in different types of cancer. The protein expression levels of TXNIP were evaluated using the Human Protein Atlas. Enrichment analysis of genes co-expressed with TXNIP was performed to assess relevant biological processes that TXNIP may be involved in. CIBERSORT was used to predict the infiltration of 21 tumor-infiltrating immune cells (TIICs). Univariate and multivariate Cox regression analyses were used to assess the relationship between TXNIP expression and prognosis. Single-cell RNA-sequencing datasets were used to evaluate the mRNA expression levels of TXNIP in certain immune cells in KIRC. The CellMiner database was used to analyze the relationship between TXNIP mRNA expression and drug sensitivity in KIRC. The results from the present study demonstrated that TXNIP expression was significantly decreased in KIRC tissue compared with that in normal tissue, as confirmed by western blotting and reverse transcription-quantitative PCR. In addition, downregulated TXNIP expression was significantly associated with poor prognosis, a high histological grade and an advanced stage. The Cell Counting Kit-8 assay demonstrated that TXNIP overexpression significantly suppressed tumor cell proliferation. Univariate and multivariate Cox regression analyses indicated that TXNIP served as a separate prognostic factor in KIRC. Moreover, TXNIP expression was significantly correlated with the accumulation of several TIICs and its overexpression significantly downregulated the mRNA expression levels of CD25 and cytotoxic T-lymphocyte-associated protein 4, immune cell surface markers in CD4+ T lymphocytes. In conclusion, TXNIP may be used as a possible biomarker to assess unfavorable prognostic outcomes and identify immunotherapy targets in KIRC.

Insulin-like growth factors and aging: lessons from Laron syndrome

The growth hormone (GH)-insulin-like growth factor-1 (IGF1) signaling pathway emerged in recent years as a key determinant of aging and longevity. Disruption of this network in different animal species, including flies, nematodes and mouse, was consistently associated with an extended lifespan. Epidemiological analyses have shown that patients with Laron syndrome (LS), the best-characterized disease under the umbrella of the congenital IGF1 deficiencies, seem to be protected from cancer. While aging and cancer, as a rule, are considered diametrically opposite processes, modern lines of evidence reinforce the notion that aging and cancer might, as a matter of fact, be regarded as divergent manifestations of identical biochemical and cellular underlying processes. While the effect of individual mutations on lifespan and health span is very difficult to assess, genome-wide screenings identified a number of differentially represented aging- and longevity-associated genes in patients with LS. The present review summarizes recent data that emerged from comprehensive analyses of LS patients and portrays a number of previously unrecognized targets for GH-IGF1 action. Our article sheds light on complex aging and longevity processes, with a particular emphasis on the role of the GH-IGF1 network in these mechanisms.

TXNIP loss expands Myc-dependent transcriptional programs by increasing Myc genomic binding

The c-Myc protooncogene places a demand on glucose uptake to drive glucose-dependent biosynthetic pathways. To meet this demand, c-Myc protein (Myc henceforth) drives the expression of glucose transporters, glycolytic enzymes, and represses the expression of thioredoxin interacting protein (TXNIP), which is a potent negative regulator of glucose uptake. A Mychigh/TXNIPlow gene signature is clinically significant as it correlates with poor clinical prognosis in triple-negative breast cancer (TNBC) but not in other subtypes of breast cancer, suggesting a functional relationship between Myc and TXNIP. To better understand how TXNIP contributes to the aggressive behavior of TNBC, we generated TXNIP null MDA-MB-231 (231:TKO) cells for our study. We show that TXNIP loss drives a transcriptional program that resembles those driven by Myc and increases global Myc genome occupancy. TXNIP loss allows Myc to invade the promoters and enhancers of target genes that are potentially relevant to cell transformation. Together, these findings suggest that TXNIP is a broad repressor of Myc genomic binding. The increase in Myc genomic binding in the 231:TKO cells expands the Myc-dependent transcriptome we identified in parental MDA-MB-231 cells. This expansion of Myc-dependent transcription following TXNIP loss occurs without an apparent increase in Myc's intrinsic capacity to activate transcription and without increasing Myc levels. Together, our findings suggest that TXNIP loss mimics Myc overexpression, connecting Myc genomic binding and transcriptional programs to the nutrient and progrowth signals that control TXNIP expression.

Targeting NEDDylation is a Novel Strategy to Attenuate Cisplatin-induced Nephrotoxicity

Although cisplatin remains a backbone of standard-of-care chemotherapy regimens for a variety of malignancies, its use is often associated with severe dose-limiting toxicities (DLT). Notably, 30%-40% of patients treated with cisplatin-based regimens are forced to discontinue treatment after experiencing nephrotoxicity as a DLT. New approaches that simultaneously prevent renal toxicity while improving therapeutic response have the potential to make a major clinical impact for patients with multiple forms of cancer. Here, we report that pevonedistat (MLN4924), a first-in-class NEDDylation inhibitor, alleviates nephrotoxicity and synergistically enhances the efficacy of cisplatin in head and neck squamous cell carcinoma (HNSCC) models. We demonstrate that pevonedistat protects normal kidney cells from injury while enhancing the anticancer activity of cisplatin through a thioredoxin-interacting protein (TXNIP)-mediated mechanism. Cotreatment with pevonedistat and cisplatin yielded dramatic HNSCC tumor regression and long-term animal survival in 100% of treated mice. Importantly, the combination decreased nephrotoxicity induced by cisplatin monotherapy as evidenced by the blockade of kidney injury molecule-1 (KIM-1) and TXNIP expression, a reduction in collapsed glomeruli and necrotic cast formation, and inhibition of cisplatin-mediated animal weight loss. Inhibition of NEDDylation represents a novel strategy to prevent cisplatin-induced nephrotoxicity while simultaneously enhancing its anticancer activity through a redox-mediated mechanism.

Significance

Cisplatin therapy is associated with significant nephrotoxicity, which limits its clinical use. Here we demonstrate that NEDDylation inhibition with pevonedistat is a novel approach to selectively prevent cisplatin-induced oxidative damage to the kidneys while simultaneously enhancing its anticancer efficacy. Clinical evaluation of the combination of pevonedistat and cisplatin is warranted.

Long-Term IGF1 Stimulation Leads to Cellular Senescence via Functional Interaction with the Thioredoxin-Interacting Protein, TXNIP

The growth hormone (GH)–insulin-like growth factor-1 (IGF1) signaling pathway plays a major role in orchestrating cellular interactions, metabolism, growth and aging. Studies from worms to mice showed that downregulated activity of the GH/IGF1 pathway could be beneficial for the extension of lifespan. Laron syndrome (LS) is an inherited autosomal recessive disorder caused by molecular defects of the GH receptor (GHR) gene, leading to congenital IGF1 deficiency. Life-long exposure to minute endogenous IGF1 levels in LS is associated with low stature as well as other endocrine and metabolic deficits. Epidemiological surveys reported that patients with LS have a reduced risk of developing cancer. Studies conducted on LS-derived lymphoblastoid cells led to the identification of a novel link between IGF1 and thioredoxin-interacting protein (TXNIP), a multifunctional mitochondrial protein. TXNIP is highly expressed in LS patients and plays a critical role in cellular redox regulation by thioredoxin. Given that IGF1 affects the levels of TXNIP under various stress conditions, including high glucose and oxidative stress, we hypothesized that the IGF1–TXNIP axis plays an essential role in helping maintain a physiological balance in cellular homeostasis. In this study, we show that TXNIP is vital for the cell fate choice when cells are challenged by various stress signals. Furthermore, prolonged IGF1 treatment leads to the establishment of a premature senescence phenotype characterized by a unique senescence network signature. Combined IGF1/TXNIP-induced premature senescence can be associated with a typical secretory inflammatory phenotype that is mediated by STAT3/IL-1A signaling. Finally, these mechanistic insights might help with the understanding of basic aspects of IGF1-related pathologies in the clinical setting.

Targeted Induction of Endogenous VDUP1 by Small Activating RNA Inhibits the Growth of Lung Cancer Cells

Recent studies have reported that small double-strand RNAs (dsRNAs) can activate endogenous genes via an RNA-based promoter targeting mechanism termed RNA activation (RNAa). In the present study, we showed that dsVDUP1-834, a novel small activating RNA (saRNA) targeting promoter of vitamin D₃ up-regulated protein 1 (VDUP1) gene, up-regulated expression of VDUP1 at both mRNA and protein levels in A549 lung cancer cells. We also demonstrated that dsVDUP1-834 inhibited cell proliferation in A549 lung cancer cells. Further studies showed that dsVDUP1-834 induced cell-cycle arrest by increasing p27 and p53 and decreasing cyclin A and cyclin B1. In addition, knockdown of VDUP1 abrogated dsVDUP1-834-induced up-regulation of VDUP1 gene expression and related effects. The activation of VDUP1 by dsVDUP1-834 was accompanied by an increase in dimethylation of histone 3 at lysine 4 (H3K4me2) and acetylation of histone 3 (H3ac) and a decrease in dimethylation of histone 3 at lysine 9 (H3K9me2) at the target site of VDUP1 promoter. Moreover, the enrichment of Ago2 was detected at the dsVDUP1-834 target site, and Ago2 knockdown significantly suppressed dsVDUP1-834-mediated inhibition of cell proliferation and modulation of cell-cycle regulators. Taken together, the results presented in this report demonstrate that dsVDUP1-834 induces VDUP1 gene expression by epigenetic changes, resulting in cell growth inhibition and cell-cycle arrest. Our results suggest that targeted induction of VDUP1 by dsVDUP1-834 might be a promising therapeutic strategy for the treatment of lung cancer.

3‑Bromopyruvic acid regulates glucose metabolism by targeting the c‑Myc/TXNIP axis and induces mitochondria‑mediated apoptosis in TNBC cells

Aerobic glycolysis is commonly observed in tumor cells, including triple-negative breast cancer (TNBC) cells, and the rate of aerobic glycolysis is higher in TNBC cells than in non-TNBC cells. Hexokinase 2 (HK2) is a key enzyme in the glycolytic pathway and a target of the transcription factor c-Myc, which is highly expressed in TNBC and promotes aerobic glycolysis by enhancing HK2 expression. As an inhibitor of HK2, 3-bromopyruvic acid (3-BrPA) exhibits good therapeutic efficacy in intrahepatic and extrahepatic tumors and inhibits the proliferation of human tumor cells with high expression levels of c-Myc in vivo and in vitro. In addition, 3-BrPA combines with photodynamic therapy to inhibit TNBC cell migration. Thioredoxin-interacting protein (TXNIP) competes with c-Myc to reduce glucose consumption in tumor cells to restrain cell proliferation. A comparative analysis was performed in the present study in TNBC (HCC1143) and non-TNBC (MCF-7) cell lines to explore the effect of 3-BrPA on energy metabolism in TNBC cells and to investigate the possible mechanism of action. Cell viability and apoptosis were detected through Cell Counting Kit-8 and flow cytometry assays, respectively. Expression levels of HK2, glucose transporter 1, TXNIP, c-Myc and mitochondria-regulated apoptosis pathway proteins were measured through western blotting. 3-BrPA inhibited cell proliferation, downregulated c-Myc and HK2 expression, and upregulated TXNIP expression in TNBC cells, but it doesn't have the same effect on non-TNBC cells. Furthermore, 3-BrPA induced the typical manifestations of mitochondrial-mediated apoptosis such as decreasing Bcl-2 expression and increasing Bax, Cyt-C and Caspase-3 expression. The present results suggested that 3-BrPA promoted TXNIP protein expression and reduced HK2 expression in TNBC cells by downregulating c-Myc expression, inhibiting glycolysis including suppressing lactate generation, intracellular ATP generation and HK activity, inducing mitochondrial-mediated apoptosis and eventually suppressing TNBC cell proliferation. These findings may reveal a novel therapeutic target for the clinical treatment of TNBC.

Redoxisome and diabetic retinopathy: Pathophysiology and therapeutic interventions

Diabetic retinopathy (DR) is a chronic microvascular complication of diabetes mellitus (DM). It is a worldwide growing epidemic disease considered to be the leading cause of vision-loss and blindness in people with DM. Redox reactions occurring at the extra- and intracellular levels are essential for the maintenance of cellular homeostasis. Dysregulation of redox homeostasis are implicated in the onset and development of DR. Thioredoxin1 (TRX1) and Thioredoxin2 (TRX2) are cytoplasmic and mitochondrially localized antioxidant proteins ubiquitously expressed in various cells and control cellular reactive oxygen species (ROS) by reducing the disulfides into thiol groups. Thioredoxin-interacting protein (TXNIP) binds to TRX system and inhibits the active reduced form of TRX through disulfide exchange reaction. Recent studies indicate the association of TRX/TXNIP with redox signal transduction pathways including activation of Nod-like receptor pyrin domain containing protein-3 (NLRP3) inflammasome, apoptosis, autophagy/mitophagy, epigenetic modifications in a redox-dependent manner. Thus, it is important to gain a more in-depth understanding about the cellular and molecular mechanisms that links redoxisome and ER/Mitochondrial dysfunction to drive the progression of DR. The purpose of this review is to provide a mechanistic understanding of the complex molecular mechanisms and pathophysiological roles associated with redoxisome, the TRX/TXNIP redox signaling complex under oxidative stress in the development of DR. Also, the molecular targets of FDA approved drugs and clinical trials in addition to effective antioxidant strategies for the treatment of diabetic retinopathy are reviewed.

Thioredoxin-Interacting Protein in Cancer and Diabetes

Significance: Thioredoxin-interacting protein (Txnip) is an α-arrestin protein that acts as a cancer suppressor. Txnip is simultaneously a critical regulator of energy metabolism. Other alpha-arrestin proteins also play key roles in cell biology and cancer. Recent Advances: Txnip expression is regulated by multilayered mechanisms, including transcriptional regulation, microRNA, messenger RNA (mRNA) stabilization, and protein degradation. The Txnip-based connection between cancer and metabolism has been widely recognized. Meanwhile, new aspects are proposed for the mechanism of action of Txnip, including the regulation of RNA expression and autophagy. Arrestin domain containing 3 (ARRDC3), another α-arrestin protein, regulates endocytosis and signaling, whereas ARRDC1 and ARRDC4 regulate extracellular vesicle formation. Critical Issues: The mechanism of action of Txnip is yet to be elucidated. The regulation of intracellular protein trafficking by arrestin family proteins has opened an emerging field of biology and medical research, which needs to be examined further. Future Directions: A fundamental understanding of the mechanism of action of Txnip and other arrestin family members needs to be explored in the future to combat diseases such as cancer and diabetes. Antioxid. Redox Signal. 36, 1001-1022.

Thiol-Based Antioxidants and the Epithelial/Mesenchymal Transition in Cancer

Significance: The epithelial/mesenchymal transition (EMT) is commonly associated with tumor metastasis. Oxidative and nitrosative stress is maintained in cancer cells and is involved in the EMT. Cancer cells are endowed with high levels of enzymatic and nonenzymatic antioxidants, which counteract the effects of oxidative and nitrosative stress. Thiol-based antioxidant systems such as the thioredoxin/thioredoxin reductase (Trx/TrxR) and glutathione/glutaredoxin (GSH/Grx) are continually active in cancer cells, while the thioredoxin-interacting protein (Txnip), the negative regulator of the Trx/TrxR system, is downregulated. Recent Advances: Trx/TrxR and GSH/Grx systems play a major role in maintaining EMT signaling and cancer cell progression. Critical Issues: Enhanced stress conditions stimulated in cancer cells inhibit EMT signaling. The elevated expression levels of the Trx/TrxR and GSH/Grx systems in these cells provide the antioxidant protection necessary to guarantee the occurrence of the EMT. Future Directions: Elevation of the intracellular reactive oxygen species and nitric oxide concentrations in cancer cells has been viewed as a promising strategy for elimination of these cells. The development of inhibitors of GSH synthesis and of the Trx/TrxR system together with genetic-based strategies to enhance Txnip levels may provide the necessary means to achieve this goal. Antioxid. Redox Signal. 36, 1037-1050.

α-Arrestins and Their Functions: From Yeast to Human Health

α-Arrestins, also called arrestin-related trafficking adaptors (ARTs), constitute a large family of proteins conserved from yeast to humans. Despite their evolutionary precedence over their extensively studied relatives of the β-arrestin family, α-arrestins have been discovered relatively recently, and thus their properties are mostly unexplored. The predominant function of α-arrestins is the selective identification of membrane proteins for ubiquitination and degradation, which is an important element in maintaining membrane protein homeostasis as well as global cellular metabolisms. Among members of the arrestin clan, only α-arrestins possess PY motifs that allow canonical binding to WW domains of Rsp5/NEDD4 ubiquitin ligases and the subsequent ubiquitination of membrane proteins leading to their vacuolar/lysosomal degradation. The molecular mechanisms of the selective substrate’s targeting, function, and regulation of α-arrestins in response to different stimuli remain incompletely understood. Several functions of α-arrestins in animal models have been recently characterized, including redox homeostasis regulation, innate immune response regulation, and tumor suppression. However, the molecular mechanisms of α-arrestin regulation and substrate interactions are mainly based on observations from the yeast Saccharomyces cerevisiae model. Nonetheless, α-arrestins have been implicated in health disorders such as diabetes, cardiovascular diseases, neurodegenerative disorders, and tumor progression, placing them in the group of potential therapeutic targets.

N-WASP Attenuates Cell Proliferation and Migration through ERK2-Dependent Enhanced Expression of TXNIP

Simple Summary

Neural Wiskott–Aldrich Syndrome Protein (N-WASP) regulates actin cytoskeleton remodeling and can, it has been suggested, suppress several cancers. In this study, HSC-5 cells, a mammalian cell line with reduced N-WASP expression, were used to generate control cells and HSC-5 cells with increased N-WASP expression that is comparable to that of normal keratinocytes. The two cell lines were used to elucidate the regulation of cell proliferation and migration by N-WASP. Our findings suggest that N-WASP increases ERK2-dependent phosphorylation of FOXO1 and increases TXNIP expression, which reduces cell proliferation and migration. This study is the first to propose an antiproliferative role of N-WASP, which is mediated via ERK2, and it suggests new avenues for cancer therapeutic research and treatment.

Abstract

Neural Wiskott–Aldrich Syndrome Protein (N-WASP) regulates actin cytoskeleton remodeling. It has been known that reduced N-WASP expression in breast and colorectal cancers is associated with poor prognosis. Here, we found reduced N-WASP expression in squamous cell carcinoma (SCC) patient samples. The SCC cell line HSC-5 with reduced N-WASP expression was used to generate HSC-5^CN (control) and HSC-5^NW (N-WASP overexpression) cells. HSC-5^NW cells had reduced cell proliferation and migration compared to HSC-5^CN cells. HSC-5^NW cells had increased phospho-ERK2 (extracellular signal-regulated kinase 2), phosphorylated Forkhead box protein class O1 (FOXO1) and reduced nuclear FOXO1 staining compared to HSC-5^CN cells. Proteasome inhibition stabilized total FOXO1, however, not nuclear staining, suggesting that FOXO1 could be degraded in the cytoplasm. Inhibition of ERK2 enhanced nuclear FOXO1 levels and restored cell proliferation and migration of HSC-5^NW to those of HSC-5^CN cells, suggesting that ERK2 regulates FOXO1 activity. The expression of thioredoxin-interacting protein (TXNIP), a FOXO1 target that inhibits thioredoxin and glucose uptake, was higher in HSC-5^NW cells than in HSC-5^CN cells. Knockdown of TXNIP in HSC-5^NW cells restored cell proliferation and migration to those of HSC-5^CN cells. Thus, we propose that N-WASP regulates cell proliferation and migration via an N-WASP-ERK2-FOXO1-TXNIP pathway.

TXNIP: A Double-Edged Sword in Disease and Therapeutic Outlook

Thioredoxin-interacting protein (TXNIP) was originally named vitamin D₃ upregulated protein-1 (VDUP1) because of its ability to bind to thioredoxin (TRX) and inhibit TRX function and expression. TXNIP is an alpha-arrestin protein that is essential for redox homeostasis in the human body. TXNIP may act as a double-edged sword in the cell. The balance of TXNIP is crucial. A study has shown that TXNIP can travel between diverse intracellular locations and bind to different proteins to play different roles under oxidative stress. The primary function of TXNIP is to induce apoptosis or pyroptosis under oxidative stress. TXNIP also inhibits proliferation and migration in cancer cells, although TXNIP levels decrease, and function diminishes in various cancers. In this review, we summarized the main structure, binding proteins, pathways, and the role of TXNIP in diseases, aiming to explore the double-edged sword role of TXNIP, and expect it to be helpful for future treatment using TXNIP as a therapeutic target.

HIF-1α-Mediated miR-623 Regulates Apoptosis and Inflammatory Responses of Nucleus Pulposus Induced by Oxidative Stress via Targeting TXNIP

Excessive apoptosis and inflammatory responses of nucleus pulposus (NP) cells induced by oxidative stress contribute to intervertebral disc degeneration (IVDD). Though some microRNAs are associated with IVDD, the specific microRNA that can mediate apoptotic and inflammatory responses of NP cells induced by oxidative stress synchronously still needs further identification. Here, we find that microRNA-623 (miR-623) is downregulated in IVDD and its expression is regulated by hypoxia-inducible factor-1α (HIF-1α) under oxidative stress conditions. Mechanistically, HIF-1α is observed to promote miR-623 expression by directly binding to its promoter region (-1,994/-1,987 bp). Functionally, miR-623 is found to work as an intermediator in alleviating apoptosis and inflammatory responses of NP cells induced by oxidative stress via regulating thioredoxin-interacting protein (TXNIP) expression by directly targeting its 3'-untranslated region (3'-UTR). Thus, on elucidating the expression and functional mechanisms of miR-623, our study suggests that miR-623 can be a valuable therapeutic target for treating oxidative stress-induced IVDD.

A Comparison of Doxorubicin-Resistant Colon Cancer LoVo and Leukemia HL60 Cells: Common Features, Different Underlying Mechanisms

Chemoresistance causes cancer relapse and metastasis, thus remaining the major obstacle to cancer therapy. While some light has been shed on the underlying mechanisms, it is clear that chemoresistance is a multifaceted problem strictly interconnected with the high heterogeneity of neoplastic cells. We utilized two different human cell lines, i.e., LoVo colon cancer and promyelocytic leukemia HL60 cells sensitive and resistant to doxorubicin (DXR), largely used as a chemotherapeutic and frequently leading to chemoresistance. LoVo and HL60 resistant cells accumulate less reactive oxygen species by differently modulating the levels of some pro- and antioxidant proteins. Moreover, the content of intracellular magnesium, known to contribute to protect cells from oxidative stress, is increased in DXR-resistant LoVo through the upregulation of MagT1 and in DXR-resistant HL60 because of the overexpression of TRPM7. In addition, while no major differences in mitochondrial mass are observed in resistant HL60 and LoVo cells, fragmented mitochondria due to increased fission and decreased fusion are detected only in resistant LoVo cells. We conclude that DXR-resistant cells evolve adaptive mechanisms to survive DXR cytotoxicity by activating different molecular pathways.

The α-arrestin family of ubiquitin ligase adaptors links metabolism with selective endocytosis

The regulation of nutrient uptake into cells is important, as it allows to either increase biomass for cell growth or to preserve homoeostasis. A key strategy to adjust cellular nutrient uptake is the reconfiguration of the nutrient transporter repertoire at the plasma membrane by the addition of nutrient transporters through the secretory pathway and by their endocytic removal. In this review, we focus on the mechanisms that regulate selective nutrient transporter endocytosis, which is mediated by the α-arrestin protein family. In the budding yeast Saccharomyces cerevisiae, 14 different α-arrestins (also named arrestin-related trafficking adaptors, ARTs) function as adaptors for the ubiquitin ligase Rsp5. They instruct Rsp5 to ubiquitinate subsets of nutrient transporters to orchestrate their endocytosis. The ART proteins are under multilevel control of the major nutrient sensing systems, including amino acid sensing by the general amino acid control and target of rapamycin pathways, and energy sensing by 5'-adenosine-monophosphate-dependent kinase. The function of the six human α-arrestins is comparably under-characterised. Here, we summarise the current knowledge about the function, regulation and substrates of yeast ARTs and human α-arrestins, and highlight emerging communalities and general principles.

Pharmacological activation of pyruvate kinase M2 reprograms glycolysis leading to TXNIP depletion and AMPK activation in breast cancer cells

Background

Aerobic glycolysis, discovered by Otto Warburg, is a hallmark of cancer metabolism even though not yet fully understood. The low activity of the cancerous pyruvate kinase isozyme (M2) is thought to play an important role by facilitating the conversion of glycolytic intermediates to other anabolic pathways to support tumors’ high proliferation rate.

Methods

Five breast cancer cell lines representing different molecular subtypes were used in this study where real time measurements of cellular bioenergetics and immunoblotting analysis of energy- and nutrient-sensing pathways were employed to investigate the potential effects of PKM2 allosteric activator (DASA-58) in glucose rewiring.

Results

In this study, we show that DASA-58 can induce pyruvate kinase activity in breast cancer cells without affecting the overall cell survival. The drug is also able to reduce TXNIP levels (an intracellular glucose sensor) probably through depletion of upstream glycolytic metabolites and independent of AMPK and ER signaling. AMPK shows an induction in phosphorylation (T172) in response to treatment an effect that can be potentiated by combining DASA-58 with other metabolic inhibitors.

Conclusions

Altogether, the multifaceted metabolic reprogramming induced by DASA-58 in breast cancer cells increases their susceptibility to other therapeutics suggesting the suitability of the intracellular glucose sensor TXNIP as a marker of PK activity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40170-021-00239-8.

TXNIP induced by MondoA, rather than ChREBP, suppresses cervical cancer cell proliferation, migration and invasion

Evidence has indicated the associations between thioredoxin-interacting protein (TXNIP) and cancers. However, the role of TXNIP in cervical cancer remains unclear. Hence, this study aims to investigate the role of TXNIP in regulating cervical cancer cell proliferation, migration and invasion. TXNIP expression can be regulated by either MondoA or ChREBP in a cell- or tissue- dependent manner. Thus, we also explored whether TXNIP expression in cervical cancer can be regulated by MondoA or ChREBP. Our results showed that TXNIP expression was decreased in cervical cancer cells (HeLa, SiHa, CaSki, MS751, C-33A). Furthermore, TXNIP overexpression inhibited cell proliferation, migration and invasion in HeLa cells, whereas TXNIP silencing exerted the opposite effect in C-33A cells. Moreover, TXNIP expression could be induced by MondoA, rather than ChREBP in HeLa cells. Additionally, MondoA overexpression inhibited cell proliferation, migration and invasion through upregulating TXNIP in HeLa cells. In summary, TXNIP induced by MondoA, rather than ChREBP, suppresses cervical cancer cell proliferation, migration and invasion. Our findings provide new ideas for the prevention and treatment of cervical cancer.

CircECE1 activates energy metabolism in osteosarcoma by stabilizing c-Myc

Background

Osteosarcoma (OS) is the most common malignant bone tumor and has a poor prognosis. The potential involvement of circular RNAs (circRNAs) in OS progression remains unexplored.

Here, we report that CircECE1, a circular RNA derived from human ECE1, plays a critical role in energy metabolism in OS.

Methods

The RIP chip sequence assay was performed to confirm CircECE1, through overexpression or knockdown of CircECE1 to verify its function in 143B and U2OS. RNA immunoprecipitation and immunoprecipitation were used to verify CircECE1’s regulation of protein c-Myc and co- immunoprecipitation was used to verified the competitive binding relationship between CircECE1 and SPOP. The influence of CircECE1 on energy metabolism was evaluated by seahorse experiment, western blot, and immunohistochemistry.

Results

We found that CircECE1 is highly expressed in OS tissues and cells and that CircECE1 knockdown suppresses tumor proliferation and metastasis both in vitro and in vivo. Further, CircECE1 significantly promotes glucose metabolism in OS cells in vitro and in vivo. Mechanistically, CircECE1 interacts with c-Myc to prevent speckle-type POZ-mediated c-Myc ubiquitination and degradation. C-Myc inhibits thioredoxin binding protein (TXNIP) transcription and subsequently activates the Warburg effect.

Conclusions

CircECE1 regulates the Warburg effect through the c-Myc/TXNIP axis. CircECE1 mediated signal transduction plays a important role in OS process and energy metabolism. These findings may identify novel targets for OS molecular therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12943-020-01269-4.

Thioredoxin Interacting Protein (TXNIP) Is Differentially Expressed in Human Tumor Samples but Is Absent in Human Tumor Cell Line Xenografts: Implications for Its Use as an Immunosurveillance Marker

Simple Summary

The metabolic protein TXNIP plays a crucial role in various cellular processes. Abnormal TXNIP levels are notable, e.g., in type II diabetes, cardiovascular diseases, and tumors. Using immunohistochemical staining for TXNIP in different tumor entities, we give new insights of TXNIP expression on the protein level. In human tumors, staining intensity inversely correlated with aggressiveness of the tumor entity. In contrast, human tumor cell lines grown in mice (xenografts), consistently revealed no staining. Hence, loss of TXNIP suggests a critical role for the development of tumors in xenografts. Furthermore, we investigated TXNIP staining of immunocompetent cells in the proximity of the xenograft tumor tissue. Our findings demonstrate that TXNIP downregulation is a common feature in human tumor xenograft models. Subsequently, TXNIP expression might be used to monitor the functional state of tumor-infiltrating leukocytes in tissue sections and may help to predict response to modern immune therapy.

Abstract

Thioredoxin interacting protein (TXNIP) is a metabolic protein critically involved in redox homeostasis and has been proposed as a tumor suppressor gene in a variety of malignancies. Accordingly, TXNIP is downregulated in breast, bladder, and gastric cancer and in tumor transplant models TXNIP overexpression inhibits growth and metastasis. As TXNIP protein expression has only been investigated in few malignancies, we employed immunohistochemical detection in a large multi-tumor tissue microarray consisting of 2,824 samples from 94 different tumor entities. In general, TXNIP protein was present only in a small proportion of primary tumor samples and in these cases was differently expressed depending on tumor stage and subtype (e.g., renal cell carcinoma, thyroid cancer, breast cancer, and ductal pancreatic cancer). Further, TXNIP protein expression was determined in primary mouse xenograft tumors derived from human cancer cell lines and was immunohistochemically absent in all xenograft tumors investigated. Intriguingly, TXNIP expression became gradually lower in the proximity of the primary tumor tissue and was absent in leukocytes directly adjacent to tumor tissue. In conclusion, these findings suggest that TXNIP downregulation is as a common feature in human tumor xenograft models and that intra-tumoral leukocytes down-regulate TXNIP. Hence TXNIP expression might be used to monitor the functional state of tumor-infiltrating leukocytes in tissue sections.

The Thioredoxin-Interacting Protein TXNIP Is a Putative Tumour Suppressor in Cutaneous T-Cell Lymphoma

BACKGROUND

The thioredoxin-interacting protein (TXNIP) is involved in cellular metabolism and cell proliferation, and recently, deficient expression of TXNIP has been associated with progression and poor outcome for cancer patients.

OBJECTIVES

To assess TXNIP expression and function in malignant T cells from cutaneous T-cell lymphoma (CTCL).

METHODS

CTCL-derived malignant (MyLa2059, PB2B) and non-malignant (MyLa1850) cell lines were analysed by Western blotting and qPCR for TXNIP expression. Subsequently, the malignant CTCL cell lines were treated with GSK126 - an inhibitor of enhancer of zeste homolog 2 (EZH2) methyltransferase activity or assessed by bisulphite sequencing for TXNIP promoter methylation. Methylation was also assessed with the demethylating agent 5-azacytidine (5AZA). Finally, TXNIP was overexpressed in the malignant PB2B cell line via plasmid transduction, and the effect of TXNIP was further analysed by flow cytometry.

RESULTS

We report on low expression of TXNIP protein in all cell lines representing different subtypes and stages of CTCL when compared to non-malignant T cells. Epigenetic silencing and other mechanisms were involved in the repression of TXNIP whereas forced expression of TXNIP strongly inhibited proliferation of malignant T cells.

CONCLUSIONS

Epigenetic silencing and other as yet unknown mechanisms repress TXNIP expression in malignant T cells. As forced expression of TXNIP inhibits malignant proliferation, we propose that TXNIP is a putative tumour suppressor in CTCL.

Vitamin D in Triple-Negative and BRCA1-Deficient Breast Cancer-Implications for Pathogenesis and Therapy

Several studies show that triple-negative breast cancer (TNBC) patients have the lowest vitamin D concentration among all breast cancer types, suggesting that this vitamin may induce a protective effect against TNBC. This effect of the active metabolite of vitamin D, 1α,25-dihydroxyvitamin D3 (1,25(OH)2D), can be attributed to its potential to modulate proliferation, differentiation, apoptosis, inflammation, angiogenesis, invasion and metastasis and is supported by many in vitro and animal studies, but its exact mechanism is poorly known. In a fraction of TNBCs that harbor mutations that cause the loss of function of the DNA repair-associated breast cancer type 1 susceptibility (BRCA1) gene, 1,25(OH)2D may induce protective effects by activating its receptor and inactivating cathepsin L-mediated degradation of tumor protein P53 binding protein 1 (TP53BP1), preventing deficiency in DNA double-strand break repair and contributing to genome stability. Similar effects can be induced by the interaction of 1,25(OH)2D with proteins of the growth arrest and DNA damage-inducible 45 (GADD45) family. Further studies on TNBC cell lines with exact molecular characteristics and clinical trials with well-defined cases are needed to determine the mechanism of action of vitamin D in TNBC to assess its preventive and therapeutic potential.

Rivaroxaban ameliorates angiotensin II-induced cardiac remodeling by attenuating TXNIP/Trx2 interaction in KKAy mice

As an anticoagulant, Rivaroxaban has recently been reported to be protective in cardiac injury. Based on those previous research results, we detected the roles of Rivaroxaban in Angiotensin II (AngII)-induced cardiac remodeling with KKAy mice and unraveled the underlying mechanisms. Rivaroxaban inhibited cardiac fibrosis and hypertrophy in AngII-infused KKAy mice. In addition, it also inhibited mitochondrial dysfunction. Noteworthily, Rivaroxaban altered the expression of many genes associated with mitochondrial function. Rivaroxaban inhibited the expression of thioredoxin binding protein (TXNIP) as well as the activation of apoptosis stimulating kinase 1 (ASK1). In H9c2 cells treated with AngII and high glucose, Rivaroxaban inhibited TXNIP/thioredoxin2 (Trx2) interaction. Moreover, TXNIP knockout abolished AngII-induced cardiac fibrosis and hypertrophy. Thus, Rivaroxaban ameliorates AngII-induced cardiac remodeling via the suppression of TXNIP signaling in KKAy mice, providing novel mechanism underlying the protective roles of Rivaroxaban against cardiac damage.

Oxidative Stress in Canine Histiocytic Sarcoma Cells Induced by an Infection with Canine Distemper Virus Led to a Dysregulation of HIF-1α Downstream Pathway Resulting in a Reduced Expression of VEGF-B in vitro

Histiocytic sarcomas represent malignant tumors which require new treatment strategies. Canine distemper virus (CDV) is a promising candidate due to its oncolytic features reported in a canine histiocytic sarcoma cell line (DH82 cells). Interestingly, the underlying mechanism might include a dysregulation of angiogenesis. Based on these findings, the aim of the present study was to investigate the impact of a persistent CDV-infection on oxidative stress mediated changes in the expression of hypoxia-inducible factor (HIF)-1α and its angiogenic downstream pathway in DH82 cells in vitro. Microarray data analysis, immunofluorescence for 8-hydroxyguanosine, superoxide dismutase 2 and catalase, and flow cytometry for oxidative burst displayed an increased oxidative stress in persistently CDV-infected DH82 cells (DH82Ond pi) compared to controls. The HIF-1α expression in DH82Ond pi increased, as demonstrated by Western blot, and showed an unexpected, often sub-membranous distribution, as shown by immunofluorescence and immunoelectron microscopy. Furthermore, microarray data analysis and immunofluorescence confirmed a reduced expression of VEGF-B in DH82Ond pi compared to controls. In summary, these results suggest a reduced activation of the HIF-1α angiogenic downstream pathway in DH82Ond pi cells in vitro, most likely due to an excessive, unusually localized, and non-functional expression of HIF-1α triggered by a CDV-induced increased oxidative stress.

miR-20b and miR-451a Are Involved in Gastric Carcinogenesis through the PI3K/AKT/mTOR Signaling Pathway: Data from Gastric Cancer Patients, Cell Lines and Ins-Gas Mouse Model

Gastric cancer (GC) is one of the most common and lethal gastrointestinal malignancies worldwide. Many studies have shown that development of GC and other malignancies is mainly driven by alterations of cellular signaling pathways. MicroRNAs (miRNAs) are small noncoding molecules that function as tumor-suppressors or oncogenes, playing an essential role in a variety of fundamental biological processes. In order to understand the functional relevance of miRNA dysregulation, studies analyzing their target genes are of major importance. Here, we chose to analyze two miRNAs, miR-20b and miR-451a, shown to be deregulated in many different malignancies, including GC. Deregulated expression of miR-20b and miR-451a was determined in GC cell lines and the INS-GAS mouse model. Using Western Blot and luciferase reporter assay we determined that miR-20b directly regulates expression of PTEN and TXNIP, and miR-451a: CAV1 and TSC1. Loss-of-function experiments revealed that down-regulation of miR-20b and up-regulation of miR-451a expression exhibits an anti-tumor effect in vitro (miR-20b: reduced viability, colony formation, increased apoptosis rate, and miR-451a: reduced colony forming ability). To summarize, the present study identified that expression of miR-20b and miR-451a are deregulated in vitro and in vivo and have a tumor suppressive role in GC through regulation of the PI3K/AKT/mTOR signaling pathway.

Targeting endothelial thioredoxin-interacting protein (TXNIP) protects from metabolic disorder-related impairment of vascular function and post-ischemic revascularisation

INTRODUCTION

Although thioredoxin-interacting protein (TXNIP) is involved in a variety of biological functions, the contribution of endothelial TXNIP has not been well-defined in regards to endothelial and vascular function or in post-ischemic revascularisation. We postulated that inhibition of endothelial TXNIP with siRNA or in a Cre-LoxP system could be involved in protection from high fat, high protein, low carbohydrate (HFHPLC) diet-induced oxidative stress and endothelial dysfunction, leading to vascular damage and impaired revascularisation in vivo.

METHODS AND RESULTS

To investigate the role of endothelial TXNIP, the TXNIP gene was deleted in endothelial cells using anti-TXNIP siRNA treatment or the Cre-LoxP system. Murine models were fed a HFHPLC diet, known to induce metabolic disorders. Endothelial TXNIP targeting resulted in protection against metabolic disorder-related endothelial oxidative stress and endothelial dysfunction. This protective effect mitigates media cell loss induced by metabolic disorders and hampered metabolic disorder-related vascular dysfunction assessed by aortic reactivity and distensibility. In aortic ring cultures, metabolic disorders impaired vessel sprouting and this alteration was alleviated by deletion of endothelial TXNIP. When subjected to ischemia, mice fed a HFHPLC diet exhibited defective post-ischemic angiogenesis and impaired blood flow recovery in hind limb ischemia. However, reducing endothelial TXNIP rescued metabolic disorder-related impairment of ischemia-induced revascularisation.

CONCLUSION

Collectively, these results show that targeting endothelial TXNIP in metabolic disorders is essential to maintaining endothelial function, vascular function and improving ischemia-induced revascularisation, making TXNIP a potential therapeutic target for therapy of vascular complications related to metabolic disorders.

Decreased expression of TXNIP predicts poor prognosis in patients with clear cell renal cell carcinoma

Accumulating evidence has demonstrated that thioredoxin interacting protein (TXNIP) is abnormally expressed in a variety of malignant tumors and functions as a tumor suppressor. However, the association between TXNIP and clear cell renal cell carcinoma (CCRCC) has not yet been fully elucidated. The aim of the present study was to evaluate the role of TXNIP in CCRCC using The Cancer Genome Atlas (TCGA) database. The RNA sequencing data and corresponding clinical data were collected from TCGA database. The association between TXNIP and patient clinicopathological characteristics was analyzed using analysis of variance and logistic regression. The Kaplan-Meier method and Cox proportional hazards model were used to assess the association between TXNIP and overall survival. Gene Set Enrichment Analysis (GSEA) was used to explore the associated signaling pathways. TXNIP expression was identified to be decreased in CCRCC tissues compared with normal tissues. The decreased expression of TXNIP in CCRCC was significantly associated with clinical stage [OR=0.509 for III vs. I (P=0.002); OR=0.527 for IV vs. I (P=0.012)], T stage [OR=0.552 for T3 vs. T1 (P=0.002)] and grade [OR=0.261 for G4 vs. G1 (P=0.027)]. Kaplan-Meier survival analysis indicated that cases of CCRCC with low TXNIP expression were associated with poorer prognoses compared with those with a high expression level (P=0.002). Univariate and multivariate Cox analyses indicated that TXNIP was an independent prognostic factor in CCRCC. GSEA revealed that 6 pathways exhibited significant differential enrichment in the TXNIP high-expression phenotype, including the WNT signaling pathway, the mitogen-activated protein kinase (MAPK) signaling pathway, the phosphatidylinositol signaling system, the transforming growth factor-β (TGF-β) signaling pathway, autophagy and the Janus kinase (JAK)-STAT signaling pathway. Taken together, the results of the present study indicate that TXNIP expression may be a potential prognostic marker for patients with CCRCC. In addition, the WNT signaling pathway, MAPK signaling pathway, phosphatidylinositol signaling system, TGF-β signaling pathway, autophagy and the JAK-STAT signaling pathway may be the crucial pathways regulated by TXNIP in CCRCC.

Tumor necrosis factor induces rapid down-regulation of TXNIP in human T cells

In addition to antigen-driven signals, T cells need co-stimulatory signals for robust activation. Several receptors, including members of the tumor necrosis factor receptor superfamily (TNFRSF), can deliver co-stimulatory signals to T cells. Thioredoxin interacting protein (TXNIP) is an important inhibitor of glucose uptake and cell proliferation, but it is unknown how TXNIP is regulated in T cells. The aim of this study was to determine expression levels and regulation of TXNIP in human T cells. We found that naïve T cells express high levels of TXNIP and that treatment of blood samples with TNF results in rapid down-regulation of TXNIP in the T cells. TNF-induced TXNIP down-regulation correlated with increased glucose uptake. Furthermore, we found that density gradient centrifugation (DGC) induced down-regulation of TXNIP. We demonstrate that DGC induced TNF production that paralleled the TXNIP down-regulation. Treatment of blood with toll-like receptor (TLR) ligands induced TNF production and TXNIP down-regulation, suggesting that damage-associated molecular patterns (DAMPs), such as endogenous TLR ligands, released during DGC play a role in DGC-induced TXNIP down-regulation. Finally, we demonstrate that TNF-induced TXNIP down-regulation is dependent on caspase activity and is caused by caspase-mediated cleavage of TXNIP.

Jagged1-mediated myeloid Notch1 signaling activates HSF1/Snail and controls NLRP3 inflammasome activation in liver inflammatory injury

Notch signaling plays important roles in the regulation of immune cell functioning during the inflammatory response. Activation of the innate immune signaling receptor NLRP3 promotes inflammation in injured tissue. However, it remains unknown whether Jagged1 (JAG1)-mediated myeloid Notch1 signaling regulates NLRP3 function in acute liver injury. Here, we report that myeloid Notch1 signaling regulates the NLRP3-driven inflammatory response in ischemia/reperfusion (IR)-induced liver injury. In a mouse model of liver IR injury, Notch1-proficient (Notch1^FL/FL) mice receiving recombinant JAG1 showed a reduction in IR-induced liver injury and increased Notch intracellular domain (NICD) and heat shock transcription factor 1 (HSF1) expression, whereas myeloid-specific Notch1 knockout (Notch1^M-KO) aggravated hepatocellular damage even with concomitant JAG1 treatment. Compared to JAG1-treated Notch1^FL/FL controls, Notch1^M-KO mice showed diminished HSF1 and Snail activity but augmented NLRP3/caspase-1 activity in ischemic liver. The disruption of HSF1 reduced Snail activation and enhanced NLRP3 activation, while the adoptive transfer of HSF1-expressing macrophages to Notch1^M-KO mice augmented Snail activation and mitigated IR-triggered liver inflammation. Moreover, the knockdown of Snail in JAG1-treated Notch1^FL/FL livers worsened hepatocellular functioning, reduced TRX1 expression and increased TXNIP/NLRP3 expression. Ablation of myeloid Notch1 or Snail increased ASK1 activation and hepatocellular apoptosis, whereas the activation of Snail increased TRX1 expression and reduced TXNIP, NLRP3/caspase-1, and ROS production. Our findings demonstrated that JAG1-mediated myeloid Notch1 signaling promotes HSF1 and Snail activation, which in turn inhibits NLRP3 function and hepatocellular apoptosis leading to the alleviation of IR-induced liver injury. Hence, the Notch1/HSF1/Snail signaling axis represents a novel regulator of and a potential therapeutic target for liver inflammatory injury.

UHRF1 promotes renal cell carcinoma progression through epigenetic regulation of TXNIP

UHRF1 is an important epigenetic regulator that belongs to the UHRF family. Overexpression of UHRF1 has been found in many kinds of tumors and its overexpression is associated with poor prognosis and short survival in certain cancer types. However, its function in renal cell carcinoma (RCC) is not clear. Here we report that RCC tumor tissues had obviously higher UHRF1 expression than normal renal tissues. Downregulation of UHRF1 by siRNA or shRNA in RCC cell lines resulted in decreased cell viability, inhibited cell migration and invasion, and increased apoptosis. UHRF1 knockdown RCC xenografts also resulted in obviously inhibited tumor growth in vivo. After downregulation of UHRF1 in RCC cells, the expression of TXNIP was upregulated. In addition, after UHRF1 and TXNIP were simultaneously downregulated, cell viability and cell invasion increased, whereas cell apoptosis decreased compared with UHRF1 single downregulated cells. We also showed that UHRF1 could recruit HDAC1 to the TXNIP promoter and mediate the deacetylation of histone H3K9, resulting in the inhibition of TXNIP expression. Our results confirm that UHRF1 has oncogenic function in RCC and UHRF1 may promote tumor progression through epigenetic regulation of TXNIP. UHRF1 might be used as a therapeutic target for RCC treatment.

Clinical Significance of the Thioredoxin System and Thioredoxin-Domain-Containing Protein Family in Hepatocellular Carcinoma

BACKGROUND

Oxidative stress occurs due to the excessive generation of cellular reactive oxygen species and antioxidant system dysfunction. The thioredoxin (TXN) system and TXN-domain-containing protein (TXNDC) family form networks maintaining the cellular reducing environment. Recently, the importance of these genes in the tumor environment has been emphasized.

AIM

To investigate the clinical significance of TXNs and TXNDC family members in HCC.

METHODS

Genomic data from 367 hepatocellular carcinoma (HCC) patients who underwent hepatic resections were analyzed to determine genetic alterations in mRNA and protein levels between patients and healthy controls. In addition, functional enrichment and survival analyses were performed.

RESULTS

HCC patients were shown to have enhanced expression of TXN, TXNRD1, and TXNDC7/9/14 mRNA and protein compared with controls. In accordance with the survival analyses, strong associations were found that patients with TXN, TXNRD1, and TXNDC1/7/9 alterations were proven to have poor prognosis in overall survival. Moreover, gene set enrichment analysis and network analyses revealed that positive correlations were found in mRNA expression of TXN, TXNRD1, and TXNDC7/9 genes with upregulation of the tumor-promoting genes, specifically mTORC1, E2F targets, and Myc targets. On the other hand, elevated expressions of TXNIP and TXNDC11 genes were correlated with suppression of the above tumor-promoting genes.

CONCLUSIONS

TXN system and TXNDC family gene panel obtained from the resected tissue of the HCC patients could be used to predict survival prognosis of HCC, and these genes could be considered as potential therapeutic targets for improving HCC survival.

Loss of KDM6A characterizes a poor prognostic subtype of human pancreatic cancer and potentiates HDAC inhibitor lethality

Although genomic analysis have recently discovered the malignant subtype of human pancreatic ductal adenocarcinoma (PDAC) characterized by frequent mutations of histone demethylase KDM6A, the biological and molecular roles still remain obscure. We herein elucidated the clinical and biological impacts of KDM6A deficiency on human PDAC and identified the therapeutic potential by pathological and molecular evaluation. Immunohistochemical analysis suggested that loss of KDM6A in cancerous tissues was an independent prognostic factor for both recurrence-free and overall survival in the 103 tumor specimens surgically resected from patients with PDAC. We established KDM6A knocked out cells by using the CRISPR/Cas9 system and KDM6A-expressed cells by doxycycline-inducible system from each two human PDAC cell lines, respectively. KDM6A knockout enhanced aggressive traits of human PDAC cell lines, whereas KDM6A overexpression suppressed them. Microarray analysis revealed reduced expression of 22 genes including five well-known tumor suppressors, such as CDKN1A, and ChIP-PCR analysis displayed depleted enrichment of histone H3 lysine 27 acetylation (H3K27ac) at the promoter regions of the five candidates. The epigenetic alterations were induced by the impaired recruitment of histone acetyltransferase p300, which cooperatively interacted with KDM6A. Consistent with these results, the KDM6A knockout cells demonstrated higher vulnerability to histone deacetylase (HDAC) inhibitors through the reactivation of CDKN1A in vitro and in vivo than the KDM6A wild-type. In conclusion, KDM6A exhibited essential roles in human PDAC as a tumor suppressor and KDM6A deficiency could be a promising biomarker for unfavorable outcome in PDAC patients and a potential surrogate marker for response to HDAC inhibitors.

Thioredoxin-interacting protein is an independent risk stratifier for breast ductal carcinoma in situ

Current clinicopathological parameters are useful predictors of breast ductal carcinoma in situ behavior, but they are insufficient to define high-risk patients for disease progression precisely. Thioredoxin-interacting protein (TXNIP) is a key player of oxidative stress. This study aims to evaluate the role of TXNIP as a predictor of ductal carcinoma in situ progression. Tissue microarrays from 776 pure ductal carcinoma in situ and 239 mixed ductal carcinoma in situ and invasive tumors were constructed. All patients were treated at a single institution with a long-term follow-up and TXNIP expression was assessed using immunohistochemistry. TXNIP expression was investigated in terms of associations with clinicopathological and molecular features and patient outcome. Loss/reduced cytoplasmic expression of TXNIP was associated with features of aggressiveness including high nuclear grade (p = 1.6 × 10^-5), presence of comedo necrosis (p = 0.001), and estrogen receptor negative (ER-)/HER2- ductal carcinoma in situ (p = 4.6 × 10^-5). Univariate analysis showed an inverse association between TXNIP expression and outcome in terms of shorter local recurrence-free survival (p = 0.009). Multivariable analyses showed that independent predictors of ductal carcinoma in situ recurrence were low TXNIP expression (p = 0.005, HR = 0.51, and 95% CI: 0.32-0.81), larger ductal carcinoma in situ size, and high nuclear grade. TXNIP functions as a tumor suppressor gene with loss of its expression associated with ductal carcinoma in situ recurrence. TXNIP can be used as a potentially useful marker in prognostic stratification of ductal carcinoma in situ for management decisions.

Activation of pro-survival metabolic networks by 1,25(OH)2D3 does not hamper the sensitivity of breast cancer cells to chemotherapeutics

BACKGROUND

We have previously identified 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], the bioactive form of vitamin D3, as a potent regulator of energy-utilization and nutrient-sensing pathways in prostate cancer cells. In the current study, we investigated the effects of 1,25(OH)2D3 on breast cancer (BCa) cell metabolism using cell lines representing distinct molecular subtypes, luminal (MCF-7 and T-47D), and triple-negative BCa (MDA-MB-231, MDA-MB-468, and HCC-1143).

METHODS

1,25(OH)2D3's effect on BCa cell metabolism was evaluated by employing a combination of real-time measurements of glycolysis/oxygen consumption rates using a biosensor chip system, GC/MS-based metabolomics, gene expression analysis, and assessment of overall energy levels. The influence of treatment on energy-related signaling molecules was investigated by immunoblotting.

RESULTS

We show that 1,25(OH)2D3 significantly induces the expression and activity of the pentose phosphate pathway enzyme glucose-6-phosphate dehydrogenase (G6PD) in all BCa cell lines, however differentially influences glycolytic and respiratory rates in the same cells. Although 1,25(OH)2D3 treatment was found to induce seemingly anti-oxidant responses in MCF-7 cells, such as increased intracellular serine levels, and reduce the expression of its putative target gene thioredoxin-interacting protein (TXNIP), intracellular reactive oxygen species levels were found to be elevated. Serine accumulation in 1,25(OH)2D3-treated cells was not found to hamper the efficacy of chemotherapeutics, including 5-fluorouracil. Detailed analyses of the nature of TXNIP's regulation by 1,25(OH)2D3 included genetic and pharmacological inhibition of signaling molecules and metabolic enzymes including AMP-activated protein kinase and G6PD, as well as by studying the ITCH (E3 ubiquitin ligase)-TXNIP interaction. While these investigations demonstrated minimal involvement of such pathways in the observed non-canonical regulation of TXNIP, inhibition of estrogen receptor (ER) signaling by tamoxifen mirrored the reduction of TXNIP levels by 1,25(OH)2D3, demonstrating that the latter's negative regulation of ER expression is a potential mechanism of TXNIP modulation.

CONCLUSIONS

Altogether, we propose that regulation of energy metabolism contributes to 1,25(OH)2D3's anti-cancer effects and that combining 1,25(OH)2D3 with drugs targeting metabolic networks in tumor cells may lead to synergistic effects.

Adenine derivatives invert high glucose-induced thioredoxin-interacting protein overexpression

Overexpression of thioredoxin-interacting protein (TXNIP) is associated with reduced insulin sensitivity and β-cell apoptosis. We have previously shown that W2476 inhibited high glucose-induced TXNIP expression at both mRNA and protein levels in INS-1E cells. In this study, we describe structural modification and optimization of W2476 leading to three more active derivatives, 8d, 8g, and 9h, capable of suppressing TXNIP expression in BG73 and INS-1E cells, increasing insulin production, and reducing high glucose-induced apoptosis in INS-1E cells.

BET Bromodomain inhibition promotes De-repression of TXNIP and activation of ASK1-MAPK pathway in acute myeloid leukemia

Background

Targeted therapy has always been the focus in developing therapeutic approaches in cancer, especially in the treatment of acute myeloid leukemia (AML). A new small molecular inhibitor, JQ1, targeting BRD4, which recognizes the acetylated lysine residues, has been shown to induce cell cycle arrest in different cancers by inhibiting MYC oncogene. However, the downstream signaling of MYC inhibition induced by BET inhibitor is not well understood.

Methods

In this study, we explored the more mechanisms of JQ1-induced cell death in acute myeloid lukemia and downstream signaling of JQ1.

Results

We found that JQ1 is able to reactivate the tumor suppressor gene, TXNIP, and induces apoptosis through the ASK1-MAPK pathway. Further studies confirmed that MYC could repress the expression of TXNIP through the miR-17-92 cluster.

Conclusions

These findings provide novel insight on how BET inhibitor can induce apoptosis in AML, and further support the development of BET inhibitors as a promising therapeutic strategy against AML.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4661-6) contains supplementary material, which is available to authorized users.

Induction of Thioredoxin-Interacting Protein by a Histone Deacetylase Inhibitor, Entinostat, Is Associated with DNA Damage and Apoptosis in Esophageal Adenocarcinoma

In 2017, an estimated 17,000 individuals were diagnosed with esophageal adenocarcinoma (EAC), and less than 20% will survive 5 years. Positron emission tomography avidity is indicative of high glucose utilization and is nearly universal in EAC. TXNIP blocks glucose uptake and exhibits proapoptotic functions. Higher expression in EAC has been associated with improved disease-specific survival, lack of lymph node involvement, reduced perineural invasion, and increased tumor differentiation. We hypothesized that TXNIP may act as a tumor suppressor that sensitizes EAC cells to standard chemotherapeutics. EAC cell lines and a Barrett epithelial cell line were used. qRT-PCR, immunoblot, and immunofluorescence techniques evaluated gene expression. TXNIP was stably overexpressed or knocked down using lentiviral RNA transduction techniques. Murine xenograft methods examined growth following overexpression of TXNIP. Apoptosis and DNA damage were measured by annexin V and γH2AX assays. Activation of the intrinsic apoptosis was quantitated with green fluorescence protein-caspase 3 reporter assay. In cultured cells and an esophageal tissue array, TXNIP expression was higher in Barrett epithelia and normal tissue compared with EAC. Constitutive overexpression of TXNIP decreased proliferation, clonogenicity, and tumor xenograft growth. TXNIP overexpression increased, whereas knockdown abrogated, DNA damage and apoptosis following cisplatin treatment. An HDAC inhibitor, entinostat (currently in clinical trials), upregulated TXNIP and synergistically increased cisplatin-mediated DNA damage and apoptosis. TXNIP is a tumor suppressor that is downregulated in EACC. Its reexpression dramatically sensitizes these cells to cisplatin. Our findings support phase I/II evaluation of "priming" strategies to enhance the efficacy of conventional chemotherapeutics in EAC. Mol Cancer Ther; 17(9); 2013-23. ©2018 AACR.

The Function of Thioredoxin-Binding Protein-2 (TBP-2) in Different Diseases

Thioredoxin-binding protein-2 (TBP-2) has an important role in the redox system, but it plays a different role in many different diseases (e.g., various cancers, diabetes mellitus (DM), cardiovascular disease, and cataracts) by influencing cell proliferation, differentiation, apoptosis, autophagy, and metabolism. Distinct transcription factors (TFs) stimulated by different factors combine with binding sites or proteins to upregulate or downregulate TBP-2 expression, in order to respond to the change in the internal environment. Most research disclosed that the main function of TBP-2 is associating with thioredoxin (Trx) to inhibit the antioxidant capacity of Trx. Furthermore, the TBP-2 located in tissues, whether normal or abnormal, has the ability to cause the dysfunctioning of cells and even death through different pathways, such as shortening the cell cycle and inducing apoptosis or autophagy. Through these studies, we found that TBP-2 promoted the development of diseases which are involved in inflammatory and oxidative damage. To a certain extent, we believe that there is some hidden connection between the biological functions which TBP-2 participates in and some distinct diseases. This review presents only a summary of the roles that TBP-2 plays in cancer, DM, cataracts, and so on, as well as its universal mechanisms. Further investigations are needed for the cell signaling pathways of the effects caused by TBP-2. A greater understanding of the mechanisms of TBP-2 could produce potential new targets for the treatment of diseases, including cancer and diabetes, cardiovascular disease, and cataracts.

TXNIP in Metabolic Regulation: Physiological Role and Therapeutic Outlook

Background & Objective:

Thioredoxin-interacting protein (TXNIP) also known as thioredoxin binding protein-2 is a ubiquitously expressed protein that interacts and negatively regulates expression and function of Thioredoxin (TXN). Over the last few years, TXNIP has attracted considerable attention due to its wide-ranging functions impacting several aspects of energy metabolism. TXNIP acts as an important regulator of glucose and lipid metabolism through pleiotropic actions including regulation of β-cell function, hepatic glucose production, peripheral glucose uptake, adipogenesis, and substrate utilization. Overexpression of TXNIP in animal models has been shown to induce apoptosis of pancreatic β-cells, reduce insulin sensitivity in peripheral tissues like skeletal muscle and adipose, and decrease energy expenditure. On the contrary, TXNIP deficient animals are protected from diet induced insulin resistance and type 2 diabetes.

Summary:

Consequently, targeting TXNIP is thought to offer novel therapeutic opportunity and TXNIP inhibitors have the potential to become a powerful therapeutic tool for the treatment of diabetes mellitus. Here we summarize the current state of our understanding of TXNIP biology, highlight its role in metabolic regulation and raise critical questions that could help future research to exploit TXNIP as a therapeutic target.

Fisetin administration improves LPS-induced acute otitis media in mouse in vivo

Acute otitis media is one of the most common infectious diseases worldwide in spite of the widespread vaccination. The present study was conducted to explore the effects of fisetin on mouse acute otitis media models. The animal models were established by lipopolysaccharide (LPS) injection into the middle ear of mice via the tympanic membrane. Fisetin was administered to mice for ten days through intragastric administration immediate after LPS application. Hematoxylin and eosin (H&E) staining was performed and the pro-inflammatory cytokines, including interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), IL-6 and VEGF, were measured through enzyme-linked immunosorbent assay (ELISA) method and RT-qPCR analysis. Toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) signaling pathway was detected by immunoblotting assays. Reactive oxygen species (ROS) generated levels were determined through assessment of anti-oxidants, and TXNIP/MAPKs signaling pathways were explored to reveal the possible molecular mechanism for acute otitis media progression and the function of fisetin. Fisetin reduced mucosal thickness caused by LPS. In fisetin-treated animals, pro-inflammatory cytokine release was downregulated accompanied with TLR4/NF-κB inactivation. ROS production was significantly decreased in comparison to the LPS-treated group. The TXNIP/MAPKs signaling pathway was inactivated for fisetin treatment in LPS-induced mice with acute otitis media. The above results indicated that fisetin improved acute otitis media through inflammation and ROS suppression via inactivating TLR4/NF-κB and TXNIP/MAPKs signaling pathways.

Expression of TXNIP in Cancer Cells and Regulation by 1,25(OH)₂D₃: Is It Really the Vitamin D₃ Upregulated Protein?

Thioredoxin-interacting protein (TXNIP) was originally identified in HL-60 cells as the vitamin D₃ upregulated protein 1, and is now known to be involved in diverse cellular processes, such as maintenance of glucose homeostasis, redox balance, and apoptosis. Besides the initial characterization, little is known about if and how 1,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃] induces TXNIP expression. We therefore screened multiple cancerous cell lines of different tissue origins, and observed induction, repression, or no change in TXNIP expression in response to 1,25(OH)₂D₃. In-depth analyses on HL-60 cells revealed a rapid and transient increase in TXNIP mRNA levels by 1,25(OH)₂D₃ (3-24 h), followed by a clear reduction at later time points. Furthermore, a strong induction in protein levels was observed only after 96 h of 1,25(OH)₂D₃ treatment. Induction of TXNIP expression by 1,25(OH)₂D₃ was found to be dependent on the availability of glucose in the culture medium, as well as the presence of a functional glucose transport system, indicating an inter-dependence of 1,25(OH)₂D₃ actions and glucose-sensing mechanisms. Moreover, the inhibition of de novo protein synthesis by cycloheximide reduced TXNIP half-life in 24 h, but not in 96 h-1,25(OH)₂D₃-treated HL-60 cells, demonstrating a possible influence of 1,25(OH)₂D₃ on TXNIP stability in long-term treatment.

Thioredoxin-1 protects against androgen receptor-induced redox vulnerability in castration-resistant prostate cancer

Androgen deprivation (AD) therapy failure leads to terminal and incurable castration-resistant prostate cancer (CRPC). We show that the redox-protective protein thioredoxin-1 (TRX1) increases with prostate cancer progression and in androgen-deprived CRPC cells, suggesting that CRPC possesses an enhanced dependency on TRX1. TRX1 inhibition via shRNA or a phase I-approved inhibitor, PX-12 (untested in prostate cancer), impedes the growth of CRPC cells to a greater extent than their androgen-dependent counterparts. TRX1 inhibition elevates reactive oxygen species (ROS), p53 levels and cell death in androgen-deprived CRPC cells. Unexpectedly, TRX1 inhibition also elevates androgen receptor (AR) levels under AD, and AR depletion mitigates both TRX1 inhibition-mediated ROS production and cell death, suggesting that AD-resistant AR expression in CRPC induces redox vulnerability. In vivo TRX1 inhibition via shRNA or PX-12 reverses the castration-resistant phenotype of CRPC cells, significantly inhibiting tumor formation under systemic AD. Thus, TRX1 is an actionable CRPC therapeutic target through its protection against AR-induced redox stress.

Vitamin D as a Novel Regulator of Tumor Metabolism: Insights on Potential Mechanisms and Implications for Anti-Cancer Therapy

1,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃], the bioactive form of vitamin D, has been shown to possess significant anti-tumor potential. While most studies so far have focused on the ability of this molecule to influence the proliferation and apoptosis of cancer cells, more recent data indicate that 1,25(OH)₂D₃ also impacts energy utilization in tumor cells. In this article, we summarize and review the evidence that demonstrates the targeting of metabolic aberrations in cancers by 1,25(OH)₂D₃, and highlight potential mechanisms through which these effects may be executed. We shed light on the ability of this molecule to regulate metabolism-related tumor suppressors and oncogenes, energy- and nutrient-sensing pathways, as well as cell death and survival mechanisms such as autophagy.