Regulatory mechanism of the SNHG3/miR-302a-3p/E2F1 feedback loop in nerve repair post cerebral ischemic stroke

Objective: Cerebral ischemic stroke (CIS) remains a primary cause of death worldwide. The current knowledge has identified the implication of microRNAs (miRNAs) in the pathophysiology of CIS. This study investigated the mechanism of miR-302a-3p in nerve repair post-CIS. Methods: A middle cerebral artery occlusion (MCAO) model was established in mice to simulate CIS. miR-302a-3p expression in brain tissues of MCAO mice was up-regulated by injecting agomiR-302a-3p. The neurological deficit of MCAO mice was evaluated through neurological function score, forelimb placing test, and balance beam walking test. Neuronal damage was measured using Nissl staining. The concentrations of nerve injury-related factors (S100B and GFAP) and the contents of neuroinflammatory factors (TNF-α and IL-1β) in serum were examined using ELISA kits. miR-302a-3p, E2F1, and long non-coding RNA (lncRNA) SNHG3 expressions in brain tissues of MCAO mice were determined using RT-qPCR and Western blot. The binding relationships between miR-302a-3p and E2F1 and E2F1 and SNHG3 were validated using dual-luciferase and ChIP assays, respectively. Results: miR-302a-3p expression was reduced in brain tissues of MCAO mice. miR-302a-3p overexpression increased the number of neurons, decreased the concentrations of S100B and GFAP, reduced the contents of TNF-α and IL-1β, promoted nerve repair, and alleviated CIS-induced brain injury. miR-302a-3p targeted E2F1 expression, and E2F1 activated SNHG3 transcription. E2F1 overexpression or SNHG3 overexpression reversed the effect of miR-302a-3p overexpression on nerve repair in MCAO mice. Conclusion: miR-302a-3p overexpression repressed SNHG3 transcription by targeting E2F1 expression, thereby promoting nerve repair and alleviating CIS.

Long non-coding RNA SNHG16 regulates E2F1 expression by sponging miR-20a-5p and aggravating proliferative diabetic retinopathy

Long non-coding RNAs (lncRNAs) were reported that related to microvascular dysfunction in diabetic retinopathy (DR), but the potential mechanism remains unknown. This study was designed to elucidate the effects of lncRNA SNHG16 in proliferative DR progression. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to measure the levels of SNHG16 and miR-20a-5p from peripheral blood samples of different participants. Pearson’s correlation analysis on the plasma data was applied to detect correlations between SNHG16 and miR-20a-5p. Finally, the interactions of miR-20a-5p and SNHG16 or E2F1 were assessed by luciferase reporter assays. SNHG16 and E2F1 were increased and miR-20a-5p was decreased in proliferative DR both in vivo and in vitro, when compared with control or non-proliferative DR. E2F1 was identified as the target of miR-20a-5p. MiR-20a-5p interacted with SNHG16 and E2F1, and was controlled by SNHG16. The regulation of SNHG16 on E2F1 was mediated by miR-20a-5p. Cells transfected with SNHG16 OE plasmid markedly increased cell apoptosis and vessel-like formation, whereas the miR-20a-5p mimic partially reversed these effects. Transfection with si-E2F1 plasmid rescued SNHG16 overexpression-aggravated proliferative DR. This study indicated that SNHG16 regulated E2F1 expression by sponging miR-20a-5p and aggravating proliferative DR.

E2F1 Maintains Gastric Cancer Stemness Properties by Regulating Stemness-Associated Genes

Purpose. To determine the regulatory role of E2F1 in maintaining gastric cancer stemness properties and the clinical significance of E2F1 in gastric cancer. Materials and Methods. We conducted a tumor spheroid formation assay to enrich gastric cancer stem-like cells. The protein and mRNA expression levels of genes were measured using Western Blot and qRT-PCR. Lentivirus-mediated overexpression and downregulation of E2F1 were performed to evaluate the effect of E2F1 on the stemness properties of gastric cancer cells. The effect of E2F1 on gastric cancer cell sensitivity of 5-Fu was evaluated using cell viability assay and TdT-mediated dUTP Nick-End Labeling staining. We also analyzed the association between E2F1 expression and clinical characteristics in gastric cancer patients. The KM plotter database was used to analyze the relationship between E2F1 and overall survival in GC patients. Results. We found that E2F1 expression was significantly higher in gastric cancer tissues than in the paired adjacent normal tissues ( p < 0.05 ) and was positively correlated with tumor size ( p < 0.05 ), T stage ( p < 0.05 ), and differentiation degree ( p < 0.05 ). KM plotter database demonstrated a close association between higher E2F1 expression level and worse overall survival of gastric cancer patients ( p < 0.05 ). In vitro assay illustrated that E2F1 could regulate the expression of stemness-associated genes, such as BMI1, OCT4, Nanog, and CD44, and maintain the tumor spheroid formation ability of gastric cancer cells. E2F1 enhanced 5-Fu resistance in gastric cancer cells, and the E2F1 expression level was correlated with the prognosis of gastric cancer patients receiving 5-Fu therapy. The expression levels of stemness-associated genes were also significantly higher in gastric cancer tissues than the paired adjacent normal tissues ( p < 0.05 ). A positive correlation was observed between E2F1 and BMI1 (r = 0.422, p < 0.05 ), CD44 (r = 0.634, p < 0.05 ), OCT4 (r = 0.456, p < 0.05 ), and Nanog (r = 0.337, p < 0.05 ) in gastric cancer tissues. The co-overexpression of E2F1 and stemness-associated genes was associated with worse overall survival. Conclusion. E2F1 plays a significant role in gastric cancer progression by maintaining gastric cancer stemness properties through the regulation of stemness-associated genes. The close association between E2F1 and poor prognosis of patients suggests that E2F1 could serve as a prognostic biomarker and a therapeutic target in gastric cancer patients.

Long noncoding RNA EMS connects c-Myc to cell cycle control and tumorigenesis

Deregulated expression of c-Myc is an important molecular hallmark of cancer. The oncogenic function of c-Myc has been largely attributed to its intrinsic nature as a master transcription factor. Here, we report the long noncoding RNA (lncRNA) E2F1 messenger RNA (mRNA) stabilizing factor (EMS) as a direct c-Myc transcriptional target. EMS functions as an oncogenic molecule by promoting G1/S cell cycle progression. Mechanistically, EMS cooperates with the RNA binding protein RALY to stabilize E2F1 mRNA, and thereby increases E2F1 expression. Furthermore, EMS is able to connect c-Myc to cell cycle control and tumorigenesis via modulating E2F1 mRNA stability. Together, these findings reveal a previously unappreciated mechanism through which c-Myc induces E2F1 expression and also implicate EMS as an important player in the regulation of c-Myc function.