Identification of a 4-miRNA signature as a potential prognostic biomarker for pancreatic adenocarcinoma.

An microRNA (miRNA) signature to predict the clinical outcome of pancreatic adenocarcinoma (PAAD) is still lacking. In the current study, we aimed at identifying and evaluating a prognostic miRNA signature for patients with PAAD. The miRNA expression profile and the clinical information regarding patients with PAAD were recruited from The Cancer Genome Atlas database. Differentially expressed miRNAs were identified between normal and tumor samples. By means of survival analysis, a 4-miRNA signature for predicting patients' with PAAD overall survival (OS) was constructed. Receiver operating characteristic (ROC) analysis was applied to determine the efficiency of survival prediction. Furthermore, the biological function of the predicted miRNAs was evaluated using a bioinformatics approach. Four (hsa-mir-126, hsa-mir-3613, hsa-mir-424, and hsa-mir-4772) out of 17 differentially expressed miRNAs were associated to the OS of patients with PAAD. Moreover, the area under the curve (AUC) of the constructed 4-miRNA signature associated to patients' with PAAD 2-year survival was 0.789. The multivariate Cox's proportional hazards regression model suggested that this 4-miRNA signature was an independent prognostic factor of other clinical parameters in patients with PAAD. Further pathway enrichment analyses revealed that the miRNAs in the 4-miRNA signature might regulate genes that affect focal adhesion, Wnt signaling pathway, and PI3K-Akt signaling pathway. Thus, these findings indicated that the 4-miRNA signature might be an effective independent prognostic biomarker in the prediction of PAAD patients' survival.

[Wogonoside reverses cisplatin resistance in SGC7901/cDDP cells through inhibition of PI3K/Akt/Nrf2/ARE signaling pathway].

The aim of this study was to investigate the effect of wogonoside (WGS) on the cisplatin (cDDP) resistance in human gastric carcinoma SGC7901/cDDP cells and its possible mechanism. The drug-resistant SGC7901/cDDP cells were established by stepwise exposure to cDDP. CCK-8 assay was employed to detect the cytotoxic effect of WGS and cDDP on SGC7901/cDDP cells, and the combined effect of WGS and cDDP was analyzed by Chou-Talalay method. Flow cytometry was used to determine the apoptosis and reactive oxygen species (ROS). Nuclear factor erythroid-2 related factor 2 (Nrf2) gene was knocked down by using the short hairpin RNA (shRNA) approach. The protein levels of Nrf2, NAD(P)H:quinone oxidoreductase 1 (NQO1), glutathione S transferase-π (GST-π), multidrug resistance-associated protein 1 (MRP1), cleaved Capase-3, p-Akt and Akt were detected by Western blotting. The result showed that after various concentrations of WGS and/or cDDP treatment for 48 h, the cell viability was remarkably reduced in a dose-dependent manner (P < 0.05). When the inhibition rate exceeded 16%, the combination of WGS and cDDP produced a synergistic effect. The protein levels of p-Akt, Nrf2 and MRP1 in SGC7901/cDDP cells were higher than those in SGC7901 cells (P < 0.05). WGS and LY294002 (PI3K inhibitor) both remarkably decreased the phosphorylation level of Akt (P < 0.05), down-regulated the protein level of Nrf2 (P < 0.05), increased the content of ROS (P < 0.05), up-regulated the protein level of cleaved Caspase-3 (P < 0.05), and induced apoptosis (P < 0.05). Meanwhile, N-acetyl-L-cysteine (NAC) decreased apoptosis and oxidative stress reaction induced by WGS (P < 0.05). WGS and Nrf2 gene silencing both down-regulated the protein levels of NQO1, GST-π and MRP1 (P < 0.05). These results suggest that WGS may reverse cDDP resistance in SGC7901/cDDP cells through blocking the PI3K/Akt/Nrf2/ARE signaling pathway, thus enhancing the cytotoxicity of cDDP and inducing oxidative stress reaction and apoptosis.

[Alcohol-induced proliferation of neurons in mouse hippocampal dentate gyrus: a possible role of ceramide].

To investigate the role and mechanism of ceramide (Cer) regulation in alcohol-induced neuronal proliferation and the newborn neurons formation, we used sphingomyelin synthase 2 (predominant enzyme of Cer metabolism) knockout (SMS2(-/-)) and wild type (WT) female mice to establish the model of prenatal alcohol exposure. In 24 h after being given birth (postnatal day 0, P0), the offspring of model mice received blood sphingomyelin (SM) measurement with enzymatic method. On P0, P7, P14 and P30, the proliferation of granule cells in the dentate gyrus and newborn neurons were investigated with immunofluorescent labeling. The expression of protein kinase Cα (PKCα) in the hippocampus was tested with Western blot analysis. The results showed that the SM level of blood in SMS2(-/-) pups was significantly lower than that in WT pups. No matter in SMS2(-/-) or WT mice, the prenatal alcohol exposure down-regulated the SM levels in pups with dose-dependency. In both SMS2(-/-) and WT pups, the number of proliferative neurons and newborn neurons in the dentate gyrus gradually decreased with the growing age. Compared with the WT pups, SMS2(-/-) pups showed significantly more proliferative neurons and newborn neurons in the dentate gyrus. Notably, prenatal alcohol exposure dose-dependently increased proliferative neurons and newborn neurons in the dentate gyrus in both WT and SMS2(-/-) pups. The hippocampal expression of PKCα protein in SMS2(-/-) mice was lower than that in WT mice, and prenatal alcohol exposure could up-regulate the PKCα protein expression in both WT and SMS2(-/-) mice with dose dependency. These results suggest that alcohol exposure during pregnancy can induce the compensatory neural cell proliferation and the production of newborn neurons in offspring, and the Cer-ceramide-1-phosphate (C1P) pathway is involved in alcohol-induced neural cell proliferation. The activation of PKCα may be a key step to start the Cer-C1P pathway and up-regulate the alcohol-induced neural cell proliferation and the newborn neurons formation.

The synaptic remodeling between regenerated perforant pathway and granule cells in slice culture.

In order to understand the synaptic remodeling in the course of axonal regeneration, the synaptic remodeling of the perforant path in hippocampus was investigated in the present study with entorhino-hippocampal coculture, DiI DiOlistic assay and transmission electron microscopy. The results showed that the regeneration of the perforant pathway occurred in entorhino-hippocampal slice coculture, and putative synaptic contacts formed between the regenerated fibers and dendritic spines of granule cells. Ultrastructural analysis confirmed the formation of new synaptic contacts. In conclusion, the synaptic formation implicated in the neuroregeneration could integrate into the network in CNS.