Identification by nano-LC-MS/MS of NT5DC2 as a protein binding to tyrosine hydroxylase: Down-regulation of NT5DC2 by siRNA increases catecholamine synthesis in PC12D cells

Low NT5DC2 expression predicts favorable prognosis and suppresses soft tissue sarcoma progression via ECM-receptor interaction pathway

BACKGROUND

Soft tissue sarcoma, a malignant tumor arising from mesenchymal tissues with poor prognosis. 5'-Nucleotidase Domain Containing 2 (NT5DC2) is a novel oncogene, and the precise involvement of NT5DC2 in soft tissue sarcoma were still undefined. Hence, our study aims to investigate NT5DC2 functions in soft tissue sarcoma progression.

METHODS

The tumor immune single-cell hub 2 (TISCH2) website, The Cancer Genome Atlas (TCGA) pan-cancer or sarcoma and Gene Expression Omnibus (GEO, GSE21122) databases were applied to visualize the NT5DC2 status in the sarcoma databases. The NT5DC2 protein expression in sarcoma tissues in our hospital was detected by using immunohistochemistry (IHC) and analyzed the associations between NT5DC2 expression and clinicopathological parameters. Real-time quantitative polymerase chain reaction (RT-qPCR), colony formation, 5-ethynyl-2'-deoxyuridine (EdU) assay, wound healing, transwell, flow cytometry and xenograft model were used to elucidate the effects of NT5DC2 downregulated by lentivirus in sarcoma cell.

RESULTS

The TISCH2 website detection found that NT5DC2 expression is enriched in malignant cells in sarcoma single-cell database. Furthermore, the TCGA-sarcoma database indicated that NT5DC2 expression correlates with metastasis, positive margin status, prognosis, and diagnostic value. Additionally, IHC staining showed that 40 % of soft tissue sarcoma patients present high expression of NT5DC2, and NT5DC2 upregulation is closely associated with poor prognosis. Functional verification analysis further revealed that downregulating NT5DC2 expression can suppress sarcoma progression through the ECM-receptor interaction pathway.

CONCLUSION

Low expression of NT5DC2 predicts a favorable prognosis in soft tissue sarcoma, and downregulated NT5DC2 expression can suppress sarcoma cell progression through the ECM-receptor interaction pathway.

Role of NT5DC2 in tyrosine hydroxylase phosphorylation based on the analysis of NT5DC2-binding proteins

The gene encoding 5'-nucleotidase domain-containing protein 2 (NT5DC2) has been associated with neuropsychiatric disorders related to the abnormality of dopamine activity in the brain. However, its physiological functions remain unclear. In this study, we analyzed the features of NT5DC2 that influence its binding with tyrosine hydroxylase (TH) and its effects on dihydroxyphenylalanine (DOPA) synthesis, using NT5DC2 overexpressed in PC12D cells by the pCMV vector. Western blot analysis revealed that the purified NT5DC2-DYKDDDDK-tag (NT5DC2-tag) protein can bind with the phosphorylated form of recombinant human TH type 1 (rhTH1), apart from the endogenous TH in PC12D cells. Proteomic analysis by mass spectrometry revealed that the purified NT5DC2-tag protein has the potential to bind to 41 proteins with multiple phosphorylation sites in PC12D cells (NT5DC2 binding proteins: positive, 391 sites/41 proteins; and negative, 85 sites/27 proteins). Overexpression of NT5DC2 in PC12D cells decreased DOPA levels in the medium. When the lysate of PC12D cells overexpressing NT5DC2 was incubated at 37 °C, the phosphorylated form of endogenous TH in PC12D cells decreased. This decrease was also detected when phosphorylated rhTH1 was incubated with purified NT5DC2-tag. Overall, our results suggest that NT5DC2 regulates DOPA synthesis by promoting the dephosphorylation of TH, similar to a phosphatase. Therefore, our study provides useful information for understanding various disorders associated with abnormalities in dopamine levels in the brain.

The gene expression landscape of the human locus coeruleus revealed by single-nucleus and spatially-resolved transcriptomics

Norepinephrine (NE) neurons in the locus coeruleus (LC) make long-range projections throughout the central nervous system, playing critical roles in arousal and mood, as well as various components of cognition including attention, learning, and memory. The LC-NE system is also implicated in multiple neurological and neuropsychiatric disorders. Importantly, LC-NE neurons are highly sensitive to degeneration in both Alzheimer's and Parkinson's disease. Despite the clinical importance of the brain region and the prominent role of LC-NE neurons in a variety of brain and behavioral functions, a detailed molecular characterization of the LC is lacking. Here, we used a combination of spatially-resolved transcriptomics and single-nucleus RNA-sequencing to characterize the molecular landscape of the LC region and the transcriptomic profile of LC-NE neurons in the human brain. We provide a freely accessible resource of these data in web-accessible and downloadable formats.

Gastric cancer metastasis-related NT5DC2 indicates unfavorable prognosis of patients

PURPOSE

Approximately 80 to 90% of patients with gastric cancer (GC) eventually develop into metastatic GC nowadays,because GC is difficult to be diagnosed at an early stage. GC patients with metastases typically have a poor prognosis. It is necessary to explore a potential prognostic marker in metastatic GC.

METHODS

All GC data were obtained from The Cancer Genome Atlas and Gene Expression Omnibus databases. The metastasis-related candidate gene and its role in GC were analyzed by comprehensive analysis.

RESULTS

Totally 1049 metastasis-related genes were identified in GC. Univariate Cox regression analysis screened the top 10 genes (PDHX, SLC43A1, CSAG2, NT5DC2, CSAG1, FMN1, MED1, HIVEP2, FNDC3A, and PPP1R2) that were closely correlated with prognosis of GC patients. Among which, NT5DC2 was screened as the target gene for subsequent study. The NT5DC2 expression were increased in primary GC and metastatic GC samples. Moreover, GC patients with high NT5DC2 expression exhibited shorter overall survival and post progression survival, and the NT5DC2 was metastatic GC patients' independent prognostic factor. Totally 29 pathways were activated in metastatic GC samples with high NT5DC2 expression. Four immune cells' infiltration were significantly different between NT5DC2 high and low expressed metastatic GC patients. NT5DC2 showed significantly negative correlations with 6 types of immune cells' critical marker genes and 5 types of immune cell infiltration. The 10 immune checkpoint expressions were decreased in high NTDC2 expression metastatic GC patients.

CONCLUSIONS

NT5DC2 plays a prognostic role in metastatic GC. GC patients with high NT5DC2 expression indicates unfavorable prognosis.

Cascade-Responsive 2-DG Nanocapsules Encapsulate aV-siCPT1C Conjugates to Inhibit Glioblastoma through Multiple Inhibition of Energy Metabolism

Aerobic glycolysis is the primary energy supply mode for glioblastoma (GBM) cells to maintain growth and proliferation. However, due to the metabolic reprogramming of tumor cells, GBM can still produce energy through fatty acid oxidation (FAO) and amino acid metabolism after blocking this metabolic pathway. In addition, GBM can provide a steady stream of nutrients through high-density neovascularization, which puts the block energy metabolism therapy for glioma in the situation of "internal and external problems". Herein, based on the abundant reactive oxygen species (ROS) and glutathione (GSH) in the tumor microenvironment and cytoplasm, we successfully designed and developed a cascade-responsive 2-DG nanocapsule delivery system. This nanocapsule contains a conjugate of anti-VEGFR2 monoclonal antibody (aV) and CPT1C siRNA (siCPT1C) linked by a disulfide cross-linker (aV-siCPT1C). The surface of this nanocapsule (2-DG/aV-siCPT1C NC) is loaded with the glycolysis inhibitor 2-DG, and it utilizes GLUT1, which is highly expressed on the blood-brain barrier (BBB) and GBM cells, to effectively penetrate the BBB and target GBM. The nanocapsule realizes multidrug codelivery, jointly blocks glycolysis and FAO of GBM, and reduces angiogenesis. Meanwhile, it also solves the problems of low delivery efficiency of mAb in the central nervous system (CNS) and easy degradation of siRNA. In general, this drug joint delivery strategy could open up a new avenue for the treatment of GBM.

Recent Applications of Nano-Liquid Chromatography in Food Safety and Environmental Monitoring: A Review

In recent years, a trend toward instrument miniaturization has led to the development of new and sophisticated analytical systems, such as nano-liquid chromatography (nano-LC), which has enabled improvements of sensitivity, as well as chromatographic resolution. The growing interest in nano-LC methodology has resulted in a variety of innovative and promising applications. In this article, we review the applications of nano-LC separation methods coupled with mass spectrometry in the analysis of food and environmental samples. An assessment of sample preparation methods and analytical performance are provided, along with comparison to other, more established analytical techniques. Three main groups of compounds that are crucial for food safety assessment are considered in this review: pharmaceuticals (including antibiotics), pesticides, and mycotoxins. Recent practical applications of the nano-LC method in the determination of these compounds are discussed. Furthermore, we also focus on methods for the determination of various environmental contaminants using nano-LC methods. Future perspectives for the development of nano-LC methods are discussed.

Investigating cytosolic 5'-nucleotidase II family genes as candidates for neuropsychiatric disorders in Drosophila (114/150 chr)

Cytosolic 5'-nucleotidases II (cNT5-II) are an evolutionary conserved family of 5'-nucleotidases that catalyze the intracellular hydrolysis of nucleotides. In humans, the family is encoded by five genes, namely NT5C2, NT5DC1, NT5DC2, NT5DC3, and NT5DC4. While very little is known about the role of these genes in the nervous system, several of them have been associated with neuropsychiatric disorders. Here, we tested whether manipulating neuronal expression of cNT5-II orthologues affects neuropsychiatric disorders-related phenotypes in the model organism Drosophila melanogaster. We investigated the brain expression of Drosophila orthologues of cNT5-II family (dNT5A-CG2277, dNT5B-CG32549, and dNT5C-CG1814) using quantitative real-time polymerase chain reaction (qRT-PCR). Using the UAS/Gal4 system, we also manipulated the expression of these genes specifically in neurons. The knockdown was subjected to neuropsychiatric disorder-relevant behavioral assays, namely light-off jump reflex habituation and locomotor activity, and sleep was measured. In addition, neuromuscular junction synaptic morphology was assessed. We found that dNT5A, dNT5B, and dNT5C were all expressed in the brain. dNT5C was particularly enriched in the brain, especially at pharate and adult stages. Pan-neuronal knockdown of dNT5A and dNT5C showed impaired habituation learning. Knockdown of each of the genes also consistently led to mildly reduced activity and/or increased sleep. None of the knockdown models displayed significant alterations in synaptic morphology. In conclusion, in addition to genetic associations with psychiatric disorders in humans, altered expression of cNT5-II genes in the Drosophila nervous system plays a role in disease-relevant behaviors.

NT5DC2 knockdown inhibits colorectal carcinoma progression by repressing metastasis, angiogenesis and tumor-associated macrophage recruitment: A mechanism involving VEGF signaling

Colorectal cancer (CRC) is one of the most commonly diagnosed tumors among human worldwide. Angiogenesis and tumor-associated macrophage (TAM) recruitment are closely associated with CRC development. Nevertheless, the mechanisms revealing CRC progression are still not fully understood. 5'-Nucleotidase domain containing 2 (NT5DC2), a member of the NT5DC family, modulates various cellular events to mediate tumor growth, and thus serves as a disgnostic biomarker. Here, we explored the potential of NT5DC2 on tumor progression in CRC. We first found that NT5DC2 expression was significantly up-regulated in CRC tissues and cell lines. CRC patients with higher NT5DC2 expression showed poor overall survival. Furthermore, CRC cell lines stably transfected with shNT5DC2 lentivirus plasmids exhibited markedly reduced cell proliferation, migration and invasion compared with the negative control group. Hypoxia inducible factor-1α (HIF-1α) and vascular endothelial growth factor A (VEGF-A) expression levels were remarkably reduced in CRC cells with NT5DC2 deletion, along with evidently reduced tube formation in the HUVECs cultured in the collected conditional medium. The expression levels of CC chemokine ligand 2 (CCL2) and its receptor CCR2 were found to be greatly down-regulated in CRC cells transfected with shNT5DC2. Moreover, NT5DC2 knockdown markedly suppressed the activation of protein kinase-B/nuclear transcription factor κB (AKT/NF-κB) signaling in CRC cells. Furthermore, we found that NT5DC2 deletion obviously reduced the TAM recruitments through suppressing CCL2/CCR2 and AKT/NF-κB signaling pathways. Intriguingly, our in vitro experiments demonstrated that VEGF reduction was necessary for shNT5DC2-inhibited cell proliferation, migration, invasion, angiogenesis and TAM recruitment. In vivo studies also confirmed that NT5DC2 knockdown effectively reduced the tumor growth and VEGF expression in a xonegraft mouse model with CRC. Lung metastasis of CRC cells was also hindered by NT5DC2 deletion in vivo. Collectively, our results indicated a previously unrecognized NT5DC2/VEGF/CCL2 axis involved in CRC development and metastasis.

NT5DC2 suppression restrains progression towards metastasis of non-small-cell lung cancer through regulation p53 signaling

Non-small cell lung cancer (NSCLC) is a leading cause of tumor mortality worldwide. Nevertheless, the molecular mechanisms revealing NSCLC progression are still unclear. 5'-Nucleotidase domain containing 2 (NT5DC2), as a member of the NT5DC family, contains a haloacid dehalogenase motif localized in the N-terminus of these proteins. NT5DC2 plays an essential role in cancer development. The purpose of the study was to explore NT5DC2's role in tumorigenesis and its potential mechanisms in NSCLC. Our findings showed that NT5DC2 expression was significantly up-regulated in clinical NSCLC tissues compared to the paired non-tumor tissues. Functionally, NT5DC2 knockdown in A549 and H1299 cells markedly reduced cell proliferation, migration and invasion. On the contrary, NT5DC2 over-expression promoted NSCLC cell proliferative, migrative and invasive capacities. Additionally, NT5DC2 down-regulation significantly induced the G2 cell cycle arrest and apoptosis in NSCLC cells. Mechanistically, p53 might be a target of NT5DC2. The expression of p53 was highly induced in NSCLC cells with NT5DC2 knockdown, and opposite result was detected when NT5DC2 was over-expressed. Importantly, we found that NT5DC2 knockdown-restrained cell proliferation and -induced apoptosis was almost abrogated by p53 down-regulation in NSCLC cells, demonstrating that NT5DC2-regulated cell proliferation and apoptotic cell death in NSCLC was p53-dependent. Finally, we confirmed that reducing NT5DC2 could inhibit NSCLC tumorigenesis and hepatic metastasis in vivo. Collectively, these results suggested that NT5DC2 may be a potential driver of NSCLC, providing a new therapeutic target for the clinical treatment of NSCLC.

NT5DC2 affects the phosphorylation of tyrosine hydroxylase regulating its catalytic activity

5'-Nucleotidase domain-containing protein 2 (NT5DC2) has been revealed by genome-wide association studies (GWAS) as a gene implicated in neuropsychiatric disorders related to the abnormality of dopamine (DA) activity in the brain. Based on its amino acid sequence, NT5DC2 is assumed to be a member of the family of haloacid dehalogenase-type phosphatases; although there is no information about its function and structural conformation. We recently reported that NT5DC2 binds to tyrosine hydroxylase (TH) and that the down-regulation of NT5DC2 tended to increase DA synthesis. In this study, we investigated whether NT5DC2 could regulate the catalytic activity of TH, which converts tyrosine to DOPA, because the phosphorylation level of TH, controlled by protein kinases and phosphatases, is well known to regulate its catalytic activity. The down-regulation of NT5DC2 by siRNA increased mainly DOPA synthesis by TH in PC12D cells, although this down-regulation tended to increase the conversion of DOPA to DA by aromatic L-amino acid decarboxylase. The increased DOPA synthesis should be attributed to the catalytic activity of TH controlled by its phosphorylation, because Western blot analysis revealed that the down-regulation of NT5DC2 tended to increase the level of TH phosphorylated at its Ser residues, but not that of the TH protein. Moreover, the induction of kinase activity by forskolin markedly potentiated the phosphorylation of TH at its Ser40 in PC12D cells having down-regulated NT5DC2. Immunocytochemical analysis of PC12D cells demonstrated that NT5DC2, TH protein, and TH phosphorylated at its Ser40 were predominantly localized in the cytoplasm and that the localization of NT5DC2 and TH proteins partially overlapped. Collectively, our results indicate that NT5DC2 could work to inhibit the DOPA synthesis by decreasing the phosphorylation of TH at its Ser40. We propose that NT5DC2 might decrease this phosphorylation of TH by promoting dephosphorylation or by inhibiting kinase activity.

NT5DC2 promotes tumor cell proliferation by stabilizing EGFR in hepatocellular carcinoma

Most hepatocellular carcinoma (HCC) patients are diagnosed at an advanced stage; however, the effect of systemic therapy on advanced HCC remains undetermined. Therefore, new treatment targets must be identified. We analyzed Gene Expression Omnibus datasets from two HCC patient cohorts and found that NT5DC2 was associated with vascular invasion and poor survival. In two hepatoma cell lines, NT5DC2 overexpression promoted HCC cell proliferation and clone formation in vitro and promoted tumor growth in vivo. Coimmunoprecipitation assays and liquid chromatography with tandem mass spectrometry analysis revealed that NT5DC2 bound directly to epidermal growth factor receptor (EGFR). NT5DC2 upregulated EGFR expression by downregulating EGFR ubiquitination and preventing its degradation via the ubiquitin-proteasome pathway but did not upregulate its transcription. EGFR upregulation activated downstream signal transduction, which played a critical role in the protumor effects of NT5DC2. Erlotinib, a small-molecule inhibitor of EGFR, blocked the effect of NT5DC2 in promoting HCC cell proliferation. In a cohort of 79 patients who underwent curative resection for HCC, NT5DC2 expression in the tumors was associated with larger tumors and microvascular invasion. NT5DC2 expression was also independently associated with recurrence-free survival. The present study demonstrated for the first time that NT5DC2 promotes tumor cell proliferation in HCC and may serve as a potential molecular target for treating HCC. EGFR blockage could be used to treat selected patients with NT5DC2 upregulation.