A small peptide modeled after the NRAGE repeat domain inhibits XIAP-TAB1-TAK1 signaling for NF-κB activation and apoptosis in P19 cells

NRAGE Confers Radiation Resistance in 2D and 3D Cell Culture and Poor Outcome in Patients With Esophageal Squamous Cell Carcinoma

Objective

The purpose of the study is to explore the mechanism of NRAGE enhancing radioresistance of esophageal squamous cell carcinoma (ESCC) in 2D and 3D levels.

Methods

Stably NRAGE-overexpressed ESCC cells and 3D-printing models for ESCC cells were established. Then, cellular malignancy indexes, such as cell morphology, proliferation, radioresistance, motility, apoptosis, cell cycle, and proteins of the Wnt/β-catenin pathway, were compared between radioresistant and its parental cells in 2D and 3D levels. Additionally, 44 paraffin ESCC specimens with radical radiotherapy were selected to examine NRAGE and β-catenin protein expression and analyze the clinical correlation.

Results

Experiments in 2D culture showed that morphology of the Eca109/NRAGE cells was more irregular, elongated spindle-shaped and disappeared polarity. It obtained faster growth ability, stronger resistance to irradiation, enhanced motility, reduced apoptosis ratio and cell cycle rearrangement. Moreover, Western blot results showed β-catenin, p-Gsk-3β and CyclinD1 expressions were induced, while p-β-catenin and Gsk-3β expressions decreased in Eca109/NRAGE cells. Experiments in the 3D-printing model showed Eca109/NRAGE cell-laden 3D scaffolds had the advantage on growth and spheroiding according to the brightfield observation, scanning electron microscopy and Ki-67 IHC staining, and higher expression at the β-catenin protein. Clinical analysis showed that NRAGE expression was higher in tumor tissues than in control tissues of ESCC patients from the Public DataBase. Compared with radiotherapy effective group, both NRAGE total and nuclear and β-catenin nuclear expressions were significantly upregulated from ESCC specimens in invalid group. Further analysis showed a positive and linear correlation between NRAGE nuclear and β-catenin nuclear expressions. Additionally, results from univariate and multivariate analyses revealed NRAGE nuclear expression could serve as a risk factor for ESCC patients receiving radical radiotherapy.

Conclusion

ESCC cells with NRAGE nuclear accumulation demonstrated greater radioresistance, which may be related to the activation of the Wnt/β-catenin signaling pathway. It indicated that NRAGE nuclear expression was a potential biomarker for monitoring radiotherapeutic response.

Knockdown of NRAGE induces odontogenic differentiation by activating NF-κB signaling in mouse odontoblast-like cells

PURPOSE

Neurotrophin receptor-interacting MAGE homologue (Nrage) plays an important role in bone development and the metabolism of normal skeletal structures. Our previous study showed that Nrage inhibited the odontogenic differentiation of mouse dental pulp cells. However, the potential roles and mechanism of Nrage in regulating odontogenic differentiation are unknown. The aim of this study was to investigate the molecular mechanism of Nrage in odontogenic differentiation of mouse odontoblast-like cells.

MATERIALS AND METHODS

Endogenous expression of Nrage was stably downregulated by lentivirus-mediated shRNA. Mineralized nodules formation was detected by alizarin red S staining. Dmp-1, Dspp, and ALP mRNA and protein levels were detected by qRT-PCR and western blotting, respectively. In addition, ALPase activity was detected. Confocal microscopy and co-immunoprecipitation (co-IP) were used to analyze the interactions between NRAGE and NF-κB signaling molecules. An IKK inhibitor was also used in the study.

RESULTS

NRAGE expression in odontoblasts was downregulated during mouse first maxillary molar development. Moreover, NRAGE expression was downregulated during odontogenic differentiation of odontoblast-like cells. NRAGE knockdown significantly upregulated DMP1 and DSP expression, increased ALPase activity, and promoted mineralized nodule formation. In addition, NRAGE knockdown increased the translocation of NF-κB1 to the nucleus and phosphorylation levels of p65. Co-IP results showed that NRAGE bound to IKKβ. Most importantly, the promoting effect of Nrage knockdown on odontoblastic differentiation was reduced after treatment with an IKK inhibitor.

CONCLUSIONS

Our data confirmed that NRAGE is an important regulator of odontogenic differentiation of odontoblasts by inhibiting the NF-κB signaling pathway through binding to IKKβ.

ABBREVIATIONS

Nrage: neurotrophin receptor-interacting MAGE homologue; DSP: dentin sialophospho protein; DMP-1: dentin matrix protein-1; BMP: bone morphogenetic protein; Wnt: wingless; NF-κB: nuclear factor of activated B cells; DAPI: 4',6-diamidino-2-phenylindole; KO: knockout; DPCs: dental pulp cells; AA: ascorbic acid; β-Gly: β-glycerophosphate; Dex: dexamethasone; co-IP: co-immunoprecipitation; IκB: inhibitor of NF-κB; IKK: IκB kinase.

NRAGE confers poor prognosis and promotes proliferation, invasion, and chemoresistance in gastric cancer

Neurotrophin receptor-interacting melanoma antigen-encoding protein (NRAGE) is a type II melanoma-associated antigen that plays an essential role in various processes, including cell differentiation and apoptosis. NRAGE has been shown to act as a cancer-related protein, with complex and apparently contradictory functions in a variety of cancers. In the current study, we examined the expression of NRAGE protein in 169 gastric cancer samples. NRAGE upregulation was correlated with advanced TNM stage, local invasion, and poor survival. Importantly, NRAGE could serve as an independent prognostic factor in patients with gastric cancer. We also examined the expression of NRAGE protein in GES-1 normal gastric epithelial cells and in six gastric cancer cell lines. Inhibition of NRAGE expression by transfection with small interfering RNA reduced the proliferation and invasion of MGC-803 and HGC-27 cells, as demonstrated by CCK-8 and Matrigel invasion assays. NRAGE depletion also sensitized HGC-27 and MGC-803 cells to cisplatin, as shown by CCK-8 and Annexin V/propidium iodide analyses. Western blot analysis also showed that NRAGE depletion negatively regulated Bcl-2 and p-ERK and upregulated ZO-1 and p27 expression levels. In conclusion, our results suggest that NRAGE acts as a tumor promoter in gastric cancer by facilitating cancer invasion and chemoresistance, possibly through regulation of p-ERK and Bcl-2.

XIAP Regulation by MNK Links MAPK and NFκB Signaling to Determine an Aggressive Breast Cancer Phenotype

Hyperactivation of the NFκB pathway is a distinct feature of inflammatory breast cancer (IBC), a highly proliferative and lethal disease. Gene expression studies in IBC patient tissue have linked EGFR (EGFR/HER2)-mediated MAPK signaling to NFκB hyperactivity, but the mechanism(s) by which this occurs remain unclear. Here, we report that the X-linked inhibitor of apoptosis protein (XIAP) plays a central role in linking these two pathways. XIAP overexpression correlated with poor prognoses in breast cancer patients and was frequently observed in untreated IBC patient primary tumors. XIAP drove constitutive NFκB transcriptional activity, which mediated ALDH positivity (a marker of stem-like cells), in vivo tumor growth, and an IBC expression signature in patient-derived IBC cells. Using pathway inhibitors and mathematical models, we defined a new role for the MAPK interacting (Ser/Thr)-kinase (MNK) in enhancing XIAP expression and downstream NFκB signaling. Furthermore, targeted XIAP knockdown and treatment with a MNK inhibitor decreased tumor cell migration in a dorsal skin fold window chamber murine model that allowed for intravital imaging of local tumor growth and migration. Together, our results indicate a novel role for XIAP in the molecular cross-talk between MAPK and NFκB pathways in aggressive tumor growth, which has the potential to be therapeutically exploited.Significance: Signaling by the MNK kinase is essential in inflammatory breast cancer, and it can be targeted to inhibit XIAP-NFκB signaling and the aggressive phenotype of this malignancy. Cancer Res; 78(7); 1726-38. ©2018 AACR.

The effects of short-term JNK inhibition on the survival and growth of aged sympathetic neurons

During the course of normal aging, certain populations of nerve growth factor (NGF)-responsive neurons become selectively vulnerable to cell death. Studies using dissociated neurons isolated from neonates have shown that c-Jun N-terminal kinases (JNKs) are important in regulating the survival and neurite outgrowth of NGF-responsive sympathetic neurons. Unlike neonatal neurons, adult sympathetic neurons are not dependent on NGF for their survival. Moreover, the NGF precursor, proNGF, is neurotoxic for aging but not young adult NGF-responsive neurons. Because of these age-related differences, the effects of JNK inhibition on the survival and growth of sympathetic neurons isolated from aged mice were studied. Aged neurons, as well as glia, were found to be dependent on JNK for their growth but not their survival. Conversely, proNGF neurotoxicity was JNK-dependent and mediated by the p75-interacting protein NRAGE, whereas neurite outgrowth was independent of NRAGE. These results have implications for the potential use of JNK inhibitors as therapies for ameliorating age-related neurodegenerative disease.

Complex roles of NRAGE on tumor

NRAGE, also known as Dlxin-1or MAGE-D1, is a member of type II melanoma-associated antigen (MAGE) and plays an essential role in life activities, including differentiation, apoptosis, and cell cycle. Studies increasingly found that NRAGE is closely related to the tumor events, such as tumor occurrence, invasion, and metastasis. However, complex and contradictory functions of NRAGE in different circumstances are observed, suggesting that NRAGE is unique from other MAGE gene family members. This review summarizes recent findings concerning the structure and biological functions of NRAGE, which may provide a basis for a more comprehensive understanding of and further research on NRAGE.

X-linked inhibitor of apoptosis protein mediates tumor cell resistance to antibody-dependent cellular cytotoxicity

Inflammatory breast cancer (IBC) is the deadliest, distinct subtype of breast cancer. High expression of epidermal growth factor receptors [EGFR or human epidermal growth factor receptor 2 (HER2)] in IBC tumors has prompted trials of anti-EGFR/HER2 monoclonal antibodies to inhibit oncogenic signaling; however, de novo and acquired therapeutic resistance is common. Another critical function of these antibodies is to mediate antibody-dependent cellular cytotoxicity (ADCC), which enables immune effector cells to engage tumors and deliver granzymes, activating executioner caspases. We hypothesized that high expression of anti-apoptotic molecules in tumors would render them resistant to ADCC. Herein, we demonstrate that the most potent caspase inhibitor, X-linked inhibitor of apoptosis protein (XIAP), overexpressed in IBC, drives resistance to ADCC mediated by cetuximab (anti-EGFR) and trastuzumab (anti-HER2). Overexpression of XIAP in parental IBC cell lines enhances resistance to ADCC; conversely, targeted downregulation of XIAP in ADCC-resistant IBC cells renders them sensitive. As hypothesized, this ADCC resistance is in part a result of the ability of XIAP to inhibit caspase activity; however, we also unexpectedly found that resistance was dependent on XIAP-mediated, caspase-independent suppression of reactive oxygen species (ROS) accumulation, which otherwise occurs during ADCC. Transcriptome analysis supported these observations by revealing modulation of genes involved in immunosuppression and oxidative stress response in XIAP-overexpressing, ADCC-resistant cells. We conclude that XIAP is a critical modulator of ADCC responsiveness, operating through both caspase-dependent and -independent mechanisms. These results suggest that strategies targeting the effects of XIAP on caspase activation and ROS suppression have the potential to enhance the activity of monoclonal antibody-based immunotherapy.

Identification of novel NRAGE involved in the radioresistance of esophageal cancer cells

Radiotherapy (RT) is one main method for the treatment of esophageal squamous cell carcinoma (ESCC), and the radioresistance is the predominant cause of patients with local recurrence. The previous results of gene microarray and subsequent verification showed that NRAGE might be involved in radiation resistance of ESCC cells. In this study, we reestablished human esophageal carcinoma radioresistant cell lines TE13R120 and ECA109R60 with gradient dose irradiation as previously reported, respectively. NRAGE expression was high in TE13R120 and ECA109R60 cells and was correlative with ionizing radiation (IR) resistance in clinic. However, the radiosensitivity of TE13R120 cells had a remarkable increase detected by colony formation assays after siRNA against NRAGE (siNRG) transfection into TE13R120 cells. Compared with TE13 cells, an increasing number of TE13R120 cells with NRAGE overexpression in S phase and a lower ratio in G2/M were observed by flow cytometry method (FCM). Intriguingly, the above changes were partially reversed in TE13R120 cells treated with siNRG. More importantly, the ectopic subcellular localization of NRAGE mediated nuclear translocation of β-catenin which may be one reason of IR resistance of esophageal carcinoma cell. These data indicate that NRAGE extremely may be a pivotal factor involved in Wnt/β-catenin signal pathway, mediating nuclear translocation of β-catenin and then facilitating the formation of radioresistance of ESCC.

Effects of neurotrophin receptor-mediated MAGE homology on proliferation and odontoblastic differentiation of mouse dental pulp cells

OBJECTIVES

This study aimed to investigate effects of neurotrophin receptor-mediated melanoma antigen-encoding gene homology (NRAGE) on proliferation and odontoblastic differentiation of mouse dental pulp cells (mDPCs).

MATERIALS AND METHODS

Mouse dental pulp cells were infected with recombinant lentivirus to stably knockdown expression of NRAGE, and biological effects of NRAGE on the cells were detected. Proliferation and odontoblastic differentiation of mDPCs were observed. Simultaneously, mRNA and protein levels of NRAGE and nuclear factor-κB (NF-κB) protein expression were detected. Immunofluorescence assay was used to detect expression and location of NRAGE and NF-κB.

RESULTS

NRAGE mRNA and protein levels reduced significantly after mDPC odontoblastic induction. Knockdown of NRAGE inhibited the proliferation of mDPCs. However, knockdown of NRAGE enhanced their odontoblastic differentiation with up-regulated ALPase activity. It also promoted mineral nodule formation as well as mRNA and protein expressions of ALP, DSPP and DMP1. Protein levels of NF-κB/p50 significantly increased, whereas NF-κB/p105 protein expression decreased in the mDPC/shNRG group. Immunofluorescence revealed that relocation of NF-κB was similar to that of NRAGE during odontoblastic induction, in which NF-κB translocated from the cytoplasm to the nucleus.

CONCLUSION

NRAGE is a potent regulator of proliferation and odontoblastic differentiation of mDPCs, which might be via the NF-κB signalling pathway.

The F-box protein FBXO7 positively regulates bone morphogenetic protein-mediated signaling through Lys-63-specific ubiquitination of neurotrophin receptor-interacting MAGE (NRAGE)

Parkinson's disease (PD) is characterized by progressive midbrain dopaminergic neuron degeneration and the formation of intracellular protein aggregates, referred to as Lewy bodies. F-box only protein 7 (FBXO7) gene mutations are closely associated with progression of the autosomal recessive form of familial PD. FBXO7 encodes a component of Skp1, cullin, F-box ubiquitin ligase complexes; however, its cellular targets, including substrates and regulators, are not yet clarified. To identify potential substrates of FBXO7, we performed a yeast two-hybrid screen of a human fetal brain library and identified neurotrophin receptor-interacting MAGE protein (NRAGE) as a novel FBXO7-binding partner. We found that FBXO7 interacts with NRAGE and mediates Lys-63-linked poly-ubiquitination of NRAGE in mammalian cells. FBXO7 overexpression accelerates formation of NRAGE-TAK1-TAB1 complexes, whereas FBXO7 knockdown correspondingly decreases complex formation. In addition, BMP4 stimulation enhances NRAGE ubiquitination through FBXO7 and facilitates endogenous NRAGE-TAK1-TAB1 complex formation. Furthermore, FBXO7 positively regulates formation of the BMP receptor-NRAGE-TAK1-TAB1 complex, and up-regulates NF-κB activity. Taken together, our results suggest that FBXO7 affects BMP4-mediated signaling through proteasome-independent ubiquitination of NRAGE and augments formation of downstream signaling components.

Maged1 co-interacting with CREB through a hexapeptide repeat domain regulates learning and memory in mice

Maged1 is a member of the type II melanoma antigen (MAGE) family of proteins, which is highly conserved in the brain between mouse and human. Recently, Maged1 has been reported to be involved in depression and impaired sexual behavior. However, the role of Maged1 in learning and memory remains unknown. The aim of the present study was therefore to investigate whether Maged1 deficiency can impair learning and memory formation. By behavioral tests and electrophysiological recording, we observed that 5-6-month-old Maged1 knockout mice displayed the reduced basal synaptic transmission, pronounced hippocampal dysfunction, impaired spatial learning, and a deficit in long-term potentiation induction. Data from immunohistochemical and Western blot showed the reduced dendritic spine density and the number of synapses in the hippocampus of the Maged1 knockout mice, and Maged1 deficiency prevented the interaction of Maged1 with cAMP response element-binding protein (CREB). Furthermore, by chromatin immunoprecipitation and luciferase assay, we observed the downregulated activity of CREB and the suppressed CREB-dependent transcription after deficiency of Maged1, which lead to the decreased levels of brain-derived neurotrophic factor. Taken together, our results provide the evidence that Maged1 is involved in synaptic transmission and hippocampus-dependent learning and memory formation.

Ror2-Src signaling in metastasis of mouse melanoma cells is inhibited by NRAGE

The receptor tyrosine kinase (RTK) Ror2 plays important roles in developmental morphogenesis and mediates the filopodia formation in Wnt5a-induced cell migration. However, the function of Ror2 in noncanonical Wnt signaling resulting in cancer metastasis is largely unknown. Here, we show that Ror2 expression is higher in the highly metastatic murine B16-BL6 melanoma cells than in the low metastatic variant B16 cells. Overexpression of Ror2 increases the metastasis ability of B16 cells, and knockdown of Ror2 reduces the migration ability of B16-BL6 cells. Furthermore, the inhibition of Src kinase activity is critical for the Ror2-mediated cell migration upon Wnt5a treatment. The C-terminus of Ror2, which is deleted in brachydactyly type B (BDB), is essential for the mutual interaction with the SH1 domain of Src. Intriguingly, the Neurotrophin receptor-interacting MAGE homologue (NRAGE), which, as we previously reported, can remodel the cellular skeleton and inhibit cell-cell adhesion and metastasis of melanoma and pancreatic cancer, sharply blocks the interaction between Src and Ror2 and inhibits Ror2-mediated B16 cell migration by decreasing the activity of Src and focal adhesion kinase (FAK). Our data show that Ror2 is a potential factor in the tumorigenesis and metastasis in a Src-dependent manner that is negatively regulated by NRAGE.