Using integrated analysis from multicentre studies to identify RNA methylation-related lncRNA risk stratification systems for glioma

BACKGROUND

N6-methyladenosine (m6A), 5-methylcytosine (m5C) and N1-methyladenosine (m1A) are the main RNA methylation modifications involved in the progression of cancer. However, it is still unclear whether RNA methylation-related long noncoding RNAs (lncRNAs) affect the prognosis of glioma.

METHODS

We summarized 32 m6A/m5C/m1A-related genes and downloaded RNA-seq data and clinical information from The Cancer Genome Atlas (TCGA) database. Differential expression analysis and weighted gene co-expression network analysis (WGCNA) were used to identify differentially expressed (DE-) RNA methylation-related lncRNAs in order to construct a prognostic signature of glioma and in order to determine their correlation with immune function, immune therapy and drug sensitivity. In vitro and in vivo assays were performed to elucidate the effects of RNA methylation-related lncRNAs on glioma.

RESULTS

A total of ten RNA methylation-related lncRNAs were used to construct a survival and prognosis signature, which had good independent prediction ability for patients. It was found that the high-risk group had worse overall survival (OS) than the low-risk group in all cohorts. In addition, the risk group informed the immune function, immunotherapy response and drug sensitivity of patients with glioma in different subgroups. Knockdown of RP11-98I9.4 and RP11-752G15.8 induced a more invasive phenotype, accelerated cell growth and apparent resistance to temozolomide (TMZ) both in vitro and in vivo. We observed significantly elevated global RNA m5C and m6A levels in glioma cells.

CONCLUSION

Our study determined the prognostic implication of RNA methylation-related lncRNAs in gliomas, established an RNA methylation-related lncRNA prognostic model, and elucidated that RP11-98I9.4 and RP11-752G15.8 could suppress glioma proliferation, migration and TMZ resistance. In the future, these RNA methylation-related lncRNAs may become a new choice for immunotherapy of glioma.

Zinc accumulation aggravates cerebral ischemia/reperfusion injury by promoting inflammation

Intracellular zinc accumulation has been shown to be associated with neuronal death after cerebral ischemia. However, the mechanism of zinc accumulation leading to neuronal death in ischemia/reperfusion (I/R) is still unclear. Intracellular zinc signals are required for the production of proinflammatory cytokines. The present study investigated whether intracellular accumulated zinc aggravates I/R injury through inflammatory response, and inflammation-mediated neuronal apoptosis. Male Sprague-Dawley rats were treated with vehicle or zinc chelator TPEN 15 mg/kg before a 90-min middle cerebral artery occlusion (MCAO). The expressions of proinflammatory cytokines TNF-α, IL-6, NF-κB p65, and NF-κB inhibitory protein IκB-α, as well as anti-inflammatory cytokine IL-10 were assessed at 6 or 24 h after reperfusion. Our results demonstrated that the expression of TNF-α, IL-6, and NF-κB p65 increased after reperfusion, while the expression of IκB-α and IL-10 decreased, suggesting that cerebral ischemia triggers inflammatory response. Furthermore, TNF-α, NF-κB p65, and IL-10 were all colocalized with the neuron-specific nuclear protein (NeuN), suggesting that the ischemia-induced inflammatory response occurs in neurons. Moreover, TNF-α was also colocalized with the zinc-specific dyes Newport Green (NG), suggesting that intracellular accumulated zinc might be associated with neuronal inflammation following cerebral I/R. Chelating zinc with TPEN reversed the expression of TNF-α, NF-κB p65, IκB-α, IL-6, and IL-10 in ischemic rats. Besides, IL-6-positive cells were colocalized with TUNEL-positive cells in the ischemic penumbra of MCAO rats at 24 h after reperfusion, indicating that zinc accumulation following I/R might induce inflammation and inflammation-associated neuronal apoptosis. Taken together, this study demonstrates that excessive zinc activates inflammation and that the brain injury caused by zinc accumulation is at least partially due to specific neuronal apoptosis induced by inflammation, which may provide an important mechanism of cerebral I/R injury.

RGD Peptide-Conjugated Selenium Nanocomposite Inhibits Human Glioma Growth by Triggering Mitochondrial Dysfunction and ROS-Dependent MAPKs Activation

Chemotherapy is still one of the most common ways to treat human glioblastoma in clinic. However, severe side effects limited its clinic application. Design of cancer-targeted drugs with high efficiency and low side effect is urgently needed. Herein, silver nanoparticles (Ag NPs) and nano-selenium (Se NPs) conjugated with RGD peptides (Ag@Se@RGD NPs) to target integrin high-expressed glioma were designed. The results found that Ag@Se@RGD NPs displayed stable particle size and morphology in physiological condition, and induced significant integrin-targeted intracellular uptake. Ag@Se@RGD NPs in vitro dose-dependently inhibited U251 human glioma cells growth by induction of cells apoptosis through triggering the loss of mitochondrial membrane potential, overproduction of reactive oxygen species (ROS), and MAPKs activation. However, ROS inhibition dramatically attenuated Ag@Se@RGD NPs-induced MAPKs activation, indicating the significant role of ROS as an early apoptotic event. Importantly, Ag@Se@RGD NPs administration in vivov effectively inhibited U251 tumor xenografts growth by induction of apoptosis through regulation MAPKs activation. Taken together, our findings validated the rational design that Ag-Se NPs conjugated with RGD peptides was a promising strategy to combat human glioma by induction of apoptosis through triggering mitochondrial dysfunction and ROS-dependent MAPKs activation.