N-acetylglucosaminyltransferase I promotes glioma cell proliferation and migration through increasing the stability of the glucose transporter GLUT1

Metabolic Signaling in Cancer Metastasis

Metastases, which are the leading cause of death in patients with cancer, have metabolic vulnerabilities. Alterations in metabolism fuel the energy and biosynthetic needs of metastases but are also needed to activate cell state switches in cells leading to invasion, migration, colonization, and outgrowth in distant organs. Specifically, metabolites can activate protein kinases as well as receptors and they are crucial substrates for posttranslational modifications on histone and nonhistone proteins. Moreover, metabolic enzymes can have moonlighting functions by acting catalytically, mainly as protein kinases, or noncatalytically through protein-protein interactions. Here, we summarize the current knowledge on metabolic signaling in cancer metastasis.

SIGNIFICANCE

Effective drugs for the prevention and treatment of metastases will have an immediate impact on patient survival. To overcome the current lack of such drugs, a better understanding of the molecular processes that are an Achilles heel in metastasizing cancer cells is needed. One emerging opportunity is the metabolic changes cancer cells need to undergo to successfully metastasize and grow in distant organs. Mechanistically, these metabolic changes not only fulfill energy and biomass demands, which are often in common between cancer and normal but fast proliferating cells, but also metabolic signaling which enables the cell state changes that are particularly important for the metastasizing cancer cells.

circ-hnRNPU inhibits NONO-mediated c-Myc transactivation and mRNA stabilization essential for glycosylation and cancer progression

BACKGROUND

Recent evidence reveals the emerging functions of circular RNA (circRNA) and protein glycosylation in cancer progression. However, the roles of circRNA in regulating glycosyltransferase expression in gastric cancer remain to be determined.

METHODS

Circular RNAs (circRNAs) were validated by Sanger sequencing. Co-immunoprecipitation, mass spectrometry, and RNA sequencing assays were applied to explore protein interaction and target genes. Gene expression regulation was observed by chromatin immunoprecipitation, RNA immunoprecipitation, dual-luciferase reporter, real-time quantitative RT-PCR, and western blot assays. Gain- and loss-of-function studies were performed to observe the impacts of circRNA and its partners on the glycosylation, growth, invasion, and metastasis of gastric cancer cells.

RESULTS

Circ-hnRNPU, an exonic circRNA derived from heterogenous nuclear ribonuclear protein U (hnRNPU), was identified to exert tumor suppressive roles in protein glycosylation and progression of gastric cancer. Mechanistically, circ-hnRNPU physically interacted with non-POU domain containing octamer binding (NONO) protein to induce its cytoplasmic retention, resulting in down-regulation of glycosyltransferases (GALNT2, GALNT6, MGAT1) and parental gene hnRNPU via repression of nuclear NONO-mediated c-Myc transactivation or cytoplasmic NONO-facilitated mRNA stability. Rescue studies indicated that circ-hnRNPU inhibited the N- and O-glycosylation, growth, invasion, and metastasis of gastric cancer cells via interacting with NONO protein. Pre-clinically, administration of lentivirus carrying circ-hnRNPU suppressed the protein glycosylation, tumorigenesis, and aggressiveness of gastric cancer xenografts. In clinical cases, low circ-hnRNPU levels and high NONO or c-Myc expression were associated with poor survival outcome of gastric cancer patients.

CONCLUSIONS

These findings indicate that circ-hnRNPU inhibits NONO-mediated c-Myc transactivation and mRNA stabilization essential for glycosylation and cancer progression.

Advances in nanotechnology for the treatment of GBM

Glioblastoma (GBM), a highly malignant glioma of the central nervous system, is the most dread and common brain tumor with a high rate of therapeutic resistance and recurrence. Currently, the clinical treatment methods are surgery, radiotherapy, and chemotherapy. However, owning to the highly invasive nature of GBM, it is difficult to completely resect them due to the unclear boundary between the edges of GBM and normal brain tissue. Traditional radiotherapy and the combination of alkylating agents and radiotherapy have significant side effects, therapeutic drugs are difficult to penetrate the blood brain barrier. Patients receiving treatment have a high postoperative recurrence rate and a median survival of less than 2 years, Less than 5% of patients live longer than 5 years. Therefore, it is urgent to achieve precise treatment through the blood brain barrier and reduce toxic and side effects. Nanotechnology exhibit great potential in this area. This article summarizes the current treatment methods and shortcomings of GBM, and summarizes the research progress in the diagnosis and treatment of GBM using nanotechnology.

Glycan-Lectin Interactions as Novel Immunosuppression Drivers in Glioblastoma

Despite diagnostic and therapeutic improvements, glioblastoma (GB) remains one of the most threatening brain tumor in adults, underlining the urgent need of new therapeutic targets. Lectins are glycan-binding proteins that regulate several biological processes through the recognition of specific sugar motifs. Lectins and their ligands are found on immune cells, endothelial cells and, also, tumor cells, pointing out a strong correlation among immunity, tumor microenvironment and vascularization. In GB, altered glycans and lectins contribute to tumor progression and immune evasion, shaping the tumor-immune landscape promoting immunosuppressive cell subsets, such as myeloid-derived suppressor cells (MDSCs) and M2-macrophages, and affecting immunoeffector populations, such as CD8⁺ T cells and dendritic cells (DCs). Here, we discuss the latest knowledge on the immune cells, immune related lectin receptors (C-type lectins, Siglecs, galectins) and changes in glycosylation that are involved in immunosuppressive mechanisms in GB, highlighting their interest as possible novel therapeutical targets.

MicroRNA miR-331-3p suppresses osteosarcoma progression via the Bcl-2/Bax and Wnt/β-Catenin signaling pathways and the epithelial-mesenchymal transition by targeting N-acetylglucosaminyltransferase I (MGAT1)

Osteosarcoma (OS) is a high-grade malignant disease that is a prevalent primary malignant sarcoma of the bone. The purpose of this investigation was to therefore elucidate the association between miR-331-3p and OS development and to identify a potential underlying mechanism. Key genes involved in OS were selected using GSE65071 dataset from the Gene Expression Omnibus (GEO) database and Gene Expression Profiling Interactive Analysis (GEPIA). Reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blotting were conducted to detect miR-331-3p, MGAT1, the epithelial-mesenchymal transition (EMT), Bcl-2/Bax and Wnt/β-Catenin signaling pathways related proteins. Dual-luciferase reporter assay and TargetScan were used for validating interaction between MGAT1 mRNA and miR-331-3p. Biological effects of miR-331-3p and MGAT1 on OS cells were detected employing MTT, Transwell, wound healing and flow cytometry, respectively. MiR-331-3p was under-expressed in OS, and up-regulation or inhibition of its expression could significantly inhibit or promote the malignant phenotypes of OS cells. Furthermore, we found that MGAT1, a target of miR-331-3p, had elevated expression in OS. Interestingly, MGAT1 could partially alleviate the effect of miR-331-3p in vitro. Collectively, miR-331-3p acts as an critical tumor suppressor through inhibiting MGAT1, results in suppressed Wnt/β-Catenin pathway and decreased proliferation of OS cells; leads to increased apoptosis via Bcl-2/Bax pathway and inhibited migration and invasion ability via the EMT.

Critical Determinants in ER-Golgi Trafficking of Enzymes Involved in Glycosylation

All living cells generate structurally complex and compositionally diverse spectra of glycans and glycoconjugates, critical for organismal evolution, development, functioning, defense, and survival. Glycosyltransferases (GTs) catalyze the glycosylation reaction between activated sugar and acceptor substrate to synthesize a wide variety of glycans. GTs are distributed among more than 130 gene families and are involved in metabolic processes, signal pathways, cell wall polysaccharide biosynthesis, cell development, and growth. Glycosylation mainly takes place in the endoplasmic reticulum (ER) and Golgi, where GTs and glycosidases involved in this process are distributed to different locations of these compartments and sequentially add or cleave various sugars to synthesize the final products of glycosylation. Therefore, delivery of these enzymes to the proper locations, the glycosylation sites, in the cell is essential and involves numerous secretory pathway components. This review presents the current state of knowledge about the mechanisms of protein trafficking between ER and Golgi. It describes what is known about the primary components of protein sorting machinery and trafficking, which are recognition sites on the proteins that are important for their interaction with the critical components of this machinery.

Clinical Value of TXNDC12 Combined With IDH and 1p19q as Biomarkers for Prognosis of Glioma

Background: Glioma is the primary malignant tumor of the central nervous system and presents high mortality and disability rates under existing treatment measures. Thioredoxin domain-containing 12 (TXNDC12) has been shown to play an important role in various malignant tumors. Therefore, we explored the clinicopathological characteristics of TXNDC12 in glioma to bring to light new ideas in its treatment.

Methods: We obtained data packages related to TXNDC12 expression status in gliomas from public databases. We analyzed glioma TXNDC12 expression and patient survival status and validated the above results using glioma specimens from our institution. Next, we analyzed the value of TXNDC12 in combination with 1p19q and isocitrate dehydrogenase (IDH) on the prognosis of glioma by regression model and receiver operating characteristic curve (ROC). Finally, we explored the function of related genes by GO analysis and KEGG analysis.

Results: Compared with normal brain tissue, the expression of TXNDC12 in glioma cells, regarding both mRNA and protein levels, was significantly upregulated. The survival time of patients with high-expression of TXNDC12 in glioma cells was shortened. In the World Health Organization pathological classification, IDH status, 1p19q status, and IDH combined with 1p19q subgroups, the expression of TXNDC12 increased with the deterioration of the above indicators. Tumor local immune analysis showed that the immune cell infiltration in TXNDC12 high-expressing glioma tissue increased, the tumor purity was reduced. GO and KEGG analyses indicated that TXNDC12 may be involved in the malignant prognosis of glioma through glycosylation and antigen processing and presentation.

Conclusion: We showed that TXNDC12 is significantly highly expressed in gliomas. This high expression predicts the poor prognosis of glioma patients and is related to the gliomas’ local immune microenvironment. As a tumor-related gene, TXNDC12 may be used as a new prognostic judgment molecule.

Abnormal Expression and Prognosis Value of COG Complex Members in Kidney Renal Clear Cell Carcinoma (KIRC)

Kidney renal clear cell carcinoma (KIRC) is the most aggressive subtype of kidney tumours with poor prognosis as well as the increasing incidence rate in worldwide. The conserved oligomeric Golgi (COG) complex is an eight-subunit (Cog1-8) peripheral Golgi protein that controls membrane trafficking and protein glycosylation and plays vital roles in human disease including cancers. Therefore, to uncover the prognostic value of COG complex in KIRC, a series of databases, including UALCAN database, GEPIA database, and Kaplan-Meier plotter, were used to analyse the mRNA expression of COG complex subunits and their prognostic values in patients with KIRC in this study. Compared with normal counterparts, mRNA expression of six COG complex subunits was significantly downregulated in KIRC tissue in UALCAN database, while COG4 mRNA expression was significantly upregulated in KIRC tissue. Moreover, the survival analysis indicated that all members of COG complex subunits were closely related with the prognosis of KIRC patients, while COG1 and COG4 were significantly associated with unfavourable overall survival (OS), the rest of COG complex subunits were importantly correlated with favourable OS. Simultaneously, higher mRNA expression of COG3, COG6, and COG8 exhibits better progression-free survival (PFS) and disease-free survival (DFS) in KIRC patients. These results identified that COG complex subunits, especially COG3, COG6, and COG8, are potential prognostic biomarkers of KIRC patients and may offer effective and new strategies for more accurately diagnosing the patients with KIRC in advance.

Circular RNA ZNF609 enhances proliferation and glycolysis during glioma progression by miR-378b/SLC2A1 axis

Glioma is a prevalent brain malignancy with aggressive progression and with grave prognosis in adults. Circular RNAs have been reported to regulate glioma development and function as the diagnostic, prognostic, and therapeutic biomarkers. In this study, we were interested the function of circular RNA ZNF609 in modulating glioma. Remarkably, knockdown of ZNF609 by siRNA in glioma cells reduced cell viabilities and Edu-positive. The silencing of ZNF609 stimulated the apoptosis of glioma cells. Meanwhile, the ZNF609 depletion inhibited the invasion and migration of glioma cells. In glioma cells, the mRNA and protein expression of E-cadherin was enhanced, while Vimentin was reduced by the inhibition of ZNF609. The glucose uptake, lactate product, and ATP production in glioma cells were suppressed by ZNF609 knockdown. Mechanically, miR-378b was sponged by ZNF609 and targeted SLC2A1 in glioma cells. ZNF609 enhanced SLC2A1 expression by inhibiting miR-378b. The inhibition of miR-378b or the enhancement of SLC2A1 reversed ZNF609 depletion-regulated glioma cell proliferation in vitro. The depletion of ZNF609 suppressed glioma cell growth in the nude mice. Therefore, we concluded that ZNF609 contributed to cell survival and glycolysis of glioma by targeting miR-378b/SLC2A1 axis. ZNF609 and miR-378b may function as potential treatment targets in glioma.