Transcription factor Nrf2 binds to circRNAPIBF1 to regulate SOD2 in lung adenocarcinoma progression.

Emerging evidence indicates that circular RNAs (circRNAs) play important roles in disease development, especially in cancers. Analysis of circRNA expression microarrays from the Gene Expression Omnibus database revealed that circPIBF1 was highly upregulated in lung adenocarcinoma (LUAD). The main aim of this study was to probe the function of circPIBF1 in pyroptosis of LUAD cells and the signal transduction pathways involved. CircPIBF1 was significantly overexpressed in LUAD and was related to the dismal prognosis of patients with LUAD. CircPIBF1 could bind to nuclear factor erythroid 2-related factor 2 (Nrf2), which further promoted the expression of superoxide dismutase 2 (SOD2). In addition, Nrf2 was also observed to recruit histone acetyltransferase E1A binding protein p300 (EP300) to enhance H3K27ac modification of SOD2, thus modulating the Nrf2-Keap1 signaling pathway. Moreover, we found that knockdown of circPIBF1 significantly suppressed the expression of SOD2 in cells and LUAD cell growth, while enhanced the expression of pyroptosis-related factors, which were further reversed by overexpression of SOD2 or EP300. Collectively, our findings suggest a direct involvement of circPIBF1 in pyroptosis-related LUAD carcinogenesis and implicate a role of Nrf2/EP300/SOD2 signaling in this process.

CircFBXW7 Inhibits Proliferation, Migration, and Invasion of Nonsmall Cell Lung Cancer Cells by Regulating miR-492.

Background: CircFBXW7 has been determined to be involved in various cancers; however, its role in nonsmall cell lung cancer (NSCLC) remains unclear. This study examined the function and potential mechanism of circFBXW7 in NSCLC. Methods: The structure of circFBXW7 was verified via RT-PCR and Sanger sequencing. The expression of circFBXW7 in NSCLC was determined by qRT-PCR. The effect of circFBXW7 overexpression on the proliferation, migration, and invasion of NSCLC cells was examined by CCK-8 and Transwell assays. Furthermore, a circFBXW7-miRNA network was established to explore their interaction. Predicted miRNA was determined by qRT-PCR. Moreover, the miRNA mimics were synthesized, wherein its effect on proliferation, migration, and invasion of NSCLC cells overexpressed circFBXW7 was assessed. Results: The circularity of circFBXW7 was verified. The expression of circFBXW7 was found to be downregulated in NSCLC cells compared with that in normal human lung epithelial BEAS-2B cells. Overexpression of circFBXW7 reduced cell proliferation, migration, and invasion. Furthermore, according to the circFBXW7-miRNA network prediction and qRT-PCR validation, miR-492 was identified to be the target of circFBXW7. The inhibitory effect of circFBXW7 overexpression on cell proliferation, migration, and invasion was reversed by miR-492 mimics. Conclusion: CircFBXW7 is downregulated in NSCLC. CircFBXW7 inhibits NSCLC cells proliferation, migration, and invasion by regulating miR-492.

miR-181a-5p restrains non-small cell lung cancer cell invasion and migration by regulating the GTSE1/p53/NF-κB axis.

microRNAs (miRNAs) are relevant to metastasis and invasion of non-small cell lung cancer (NSCLC). This study investigated the role of miR-181a-5p in lung cancer. Expression patterns of miR-181a-5p and GTSE1 in the human NSCLC cell line A549 and normal lung epithelial cell line BASE-2B were detected. miR-181a-5p mimic was delivered into A549 cells utilizing Lipofectamine 2000 to overexpress miR-181a-5p, followed by analysis of cell viability, proliferation, apoptosis, invasion, and migration. GTSE1 (G2 and S phase-expressed-1) was predicted as the downstream target gene of miR-181a-5p using bioinformatics analysis software. Targeting relationship between miR-181a-5p and GTSE1 was validated via dual-luciferase assay, RIP assay, and RNA pull-down. Activation of the p53/NF-κB pathway was determined. miR-181a-5p was weakly-expressed in NSCLC cells relative to normal lung epithelial cells. miR-181a-5p overexpression prevented NSCLC cell proliferation, migration, and invasion. Mechanically, miR-181a-5p targeted GTSE1. GTSE1 overexpression partly annulled repression of miR-181a-5p overexpression on NSCLC cell malignant behavior. miR-181a-5p activated the p53 pathway and inhibited the NF-κB pathway by targeting GTSE1. Overall, this study for the first time validated that miR-181a-5p impeded NSCLC cell invasion and migration through activation of the p53 pathway and inhibition of the NF-κB pathway by targeting GTSE1, which may provide a potential novel insight into NSCLC treatment.

Low expression of miR-27b in serum exosomes of non-small cell lung cancer facilitates its progression by affecting EGFR.

Non-small cell lung cancer (NSCLC) is a malignant tumor. Serum exosomal miR-27b is related to tumor diagnosis. We explored the roles of serum exosomal miR-27b in NSCLC. NSCLC patients were assigned to NSCLC-early/terminal groups, with healthy subjects as controls. miR-27b expression was assessed using reverse transcription-quantitative polymerase chain reaction, and its diagnostic efficiency was analyzed using the receiver operating characteristic curve. The correlation between serum exosomal miR-27b expression and tumor markers carcinoembryonic antigen 125 (CA125), carcinoembryonic antigen (CEA), and cytokeratin 19-soluble fragment (CYFRA21-1) was analyzed using the Pearson analysis. The downstream target genes were predicted. Epidermal growth factor receptor (EGFR) level was assessed using enzyme-linked immunosorbent assay. Correlations of miR-27b expression with serum EGFR level and CA125, CEA, and CYFRA21-1 levels were analyzed using the Pearson analysis. Serum exosomal miR-27b was diminished in NSCLC and was further decreased in the NSCLS-terminal group. The sensitivity of miR-27b < 0.8150 for NSCLC diagnosis was 76.64%, and the specificity was 83.33%. Serum exosomal miR-27b was negatively correlated with CA125, CEA, and CYFRA21-1. miR-27b targeted EGFR. Serum EGFR was raised in NSCLC and was further elevated in the NSCLS-terminal group. miR-27b expression was negatively correlated with EGFR level. EGFR level was positively correlated with CA125, CEA, and CYFRA21-1 levels. Collectively, low expression of miR-27b assisted NSCLC diagnosis, and miR-27b exerted effects on NSCLC through EGFR.

TLR4/PKCα/occludin signaling pathway may be related to blood­brain barrier damage.

Abnormal blood-brain barrier (BBB) is a common pathological feature in brain damage. In the present study, a brain microvascular endothelial cell (BMEC) model was established to determine the role of the toll­like receptor 4 (TLR4)/protein kinase Cα (PKCα)/occludin signaling pathway in BBB dysfunction. Three small interfering (si)RNAs directed against PKCα were designed to investigate the molecular mechanisms of PKCα underlying BBB damage. BMECs were divided into 4 groups: Control group, TAK­242 (a TLR4 inhibitor) group, PKCα­siRNA group and TAK­242+PKCα­siRNA group. The results indicated that siRNA­3 was the most effective at silencing PKCα gene expression. Reverse transcription­quantitative polymerase chain reaction (RT­qPCR) analysis indicated no significant difference of TLR4 mRNA expression levels between three different treated groups and the Control group. However, PKCα mRNA expression in the PKCα­siRNA and TAK­242+PKCα­siRNA groups were significantly decreased compared with that in Control and TAK­242 groups. In addition, occludin mRNA expression in PKCα­siRNA and TAK­242+PKCα­siRNA groups were significantly higher compared with the Control group. Meanwhile, occluding expressions in three treated groups were also significantly higher compared with the Control group. Furthermore, TAK­242 treatment, PKCα­siRNA treatment, and TAK­242+PKCα­siRNA treatment could promote occludin junctional labeling compared with the Control group. The permeability of PKCα­siRNA and TAK­242+PKCα­siRNA groups was significantly promoted compared with the control group. The TLR4/PKCα/occludin signaling pathway was closely related to BBB damage. The present study will lead to an improved molecular understanding of BBB damage in the future.