Role of METTL3 in Aerobic Glycolysis of Glioma by Regulating m6A/miR-27b-3p/PDK1.

Methyltransferase like 3 (METTL3) has been reported to be dysregulated in glioma. However, its role in aerobic glycolysis of glioma remains unknown. This study was conducted to explore the molecular mechanism by which METTL3 regulates aerobic glycolysis of glioma and provide novel targets for the treatment of glioma. The expression levels of METTL3, microRNA (miR)-27b-3p, and pyruvate dehydrogenase kinase 1 (PDK1) were determined in glioma cell lines and normal human astrocytes. Cell proliferation and aerobic glycolysis were evaluated by cell counting kit-8 and colony formation assays and measurements of glucose uptake, lactate production, adenosine triphosphate, Hexokinase activity, oxygen consumption rate, and extracellular acidification rate. After m6A quantification analysis, methylated RNA immunoprecipitation, and the dual-luciferase assay, the rescue experiments were performed using miR-27b-3p inhibitor or pcDNA3.1-PDK1 with pcDNA3.1-METTL3. METTL3 was lower in glioma cells and METTL3 overexpression reduced aerobic glycolysis. METTL3 increased m6A modification to promote the processing of pri-miR-27b by DGCR8 and the expression of mature miR-27b-3p, and miR-27b-3p targeted and inhibited PDK1 expression. miR-27b-3p inhibition or PDK1 overexpression both neutralized the inhibitory role of METTL3 overexpression in aerobic glycolysis. Overall, METTL3 overexpression increased the expression of mature miR-27b-3p via m6A modification and inhibited PDK1 expression, thus suppressing aerobic glycolysis of glioma.

Netrin-1 upregulates GPX4 and prevents ferroptosis after traumatic brain injury via the UNC5B/Nrf2 signaling pathway.

AIM: We aimed to investigate the regulatory role of Netrin-1 (NTN1) in ferroptosis after traumatic brain injury (TBI) in mice. METHODS: We assessed the expression pattern of NTN1 by RT-PCR, western blot, and immunofluorescence after establishing the TBI model in mice. After treatment with NTN1 shRNA or recombinant NTN1, we determined the biochemical and morphological changes associated with ferroptosis and netrin-1-related pathways. We used Nissl staining to assess lesion volume and Morris water maze and beam-walking test to evaluate ethological manifestation. RESULTS: The mRNA and protein levels of NTN1 were upregulated after TBI. The application of NTN1 shRNA increased the number of FJB positive cells, malondialdehyde (MDA), and reactive oxygen species (ROSs) levels. However, the application of NTN1 recombinant had the opposite effect. Furthermore, knockdown or inhibition of GPX4, Nrf2, and UNC5B counteracted the effects of NTN1 recombinant. Intravenous injection of NTN1 recombinant reduced neuronal loss after CCI and improved motor and cognitive function. CONCLUSION: NTN1 had a neuroprotective effect after TBI and inhibited ferroptosis via activating the UNC5B/Nrf2 pathway. These findings may provide potential therapeutic strategies for TBI.

The Prognostic Value of Deleted in Colorectal Cancer (DCC) Receptor and Serum Netrin-1 in Severe Traumatic Brain Injury.

Traumatic brain injury (TBI) is a common neurological disease. Netrin-1 and deleted in colorectal cancer (DCC) receptor are potential biomarkers associated with nerve regeneration and immune regulation. We aimed to investigate the ability of the DCC receptor and Netrin-1 to predict a high ICP level after operation in severe traumatic brain injury and their prognostic significance. This study is a prospective observational study. We selected 23 patients with traumatic brain injury who had undergone surgical operations as subjects. Immunohistochemical staining was performed on the contusion tissue that was removed by the operation to determine the expression of DCC receptor. At the same time, enzyme-linked immunosorbent assay (ELISA) kits were used to detect the serum Netrin-1 content. Determination of intracranial pressure (ICP) value was measured by intraventricular catheter. The Glasgow Outcome Scale (GOS) score at six months after trauma was defined as the main study endpoint. The results showed that serum Netrin-1 concentrations of patients in the critical TBI group (GCS 3-5 points) was significantly lower than that in the severe TBI group (GCS 6-8 points). The ICP peak and average mannitol consumption in the high Netrin-1 group were significantly lower than those in the low Netrin-1 group. DCC receptor-positive patients had a significantly lower ICP peak. There was no significant difference in six month-GOS scores between patients in the high and low Netrin-1 groups, while DCC receptor concentrations below 3.82 ng/mL predicted poor prognosis (GOS 1-3 points). In conclusion, the expression level of the DCC receptor can better evaluate the postoperative high ICP level and prognosis than the level of serum Netrin-1 in severe traumatic brain injury.

Mutation and Copy Number Alterations Analysis of KIF23 in Glioma.

In glioma, kinesin family member 23 (KIF23) is up-regulated and plays a vital role in oncogenesis. However, the mechanism underlying KIF23 overexpression in malignant glioma remains to be elucidated. This study aims to find potential causes of KIF23 high expression at genome level. To clarify this issue, we obtained point mutation and copy number alterations (CNAs) of KIF23 in 319 gliomas using whole-exome sequencing. Only two glioma samples with missense mutations in KIF23 coding region were identified, while 7 patients were detected with amplification of KIF23. Additional analysis showed that KIF23 amplification was significantly associated with higher expression of KIF23. Gene ontology analysis indicated that higher copy number of KIF23 was associated TNF-α signaling pathway and mitotic cell circle checkpoint, which probably caused by subsequent upregulated expression of KIF23. Moreover, pan-cancer analysis showed that gaining of copy number was significantly associated with higher expression of KIF23, consolidating our findings in glioma. Thus, it was deduced that elevated KIF23 expression in glioma tended to be caused by DNA copy number amplification, instead of mutation.

Role of Dissolved Organic Matter in Sorption of Perfluorooctanoic Acid to Metal Oxides.

Perfluorooctanoic acid (PFOA) is an important perfluorinated chemical of significant environmental concern. It has been widely found at high concentrations in the environment. We have exposed sediment constituent minerals SiO2, Fe2O3, and Al2O3 to PFOA and humic acid (HA) and studied the adsorption of PFOA by introducing the adsorbates in different orders. The results suggest concurrent sorption of PFOA and HA to the mineral surface or enhanced PFOA sorption when both are introduced to the aqueous phase. However, when PFOA is introduced to the mineral surface that has already been exposed to and extensively coated with HA, little PFOA adsorption occurs, which implies that PFOA released to rivers rich in dissolved organic matter (DOM, i.e. HA) may be immune to sorptive retention by the sediment and be transported downstream unabated. DOM thus can play a significant role in the transport and fate of PFOA in the natural water system.