Pretreatment with metformin prevents microcystin-LR-induced tau hyperphosphorylation via mTOR-dependent PP2A and GSK-3ß activation.

Microcystin-leucine-arginine (MC-LR) is a toxin secreted by freshwater cyanobacteria that is considered a potential environmental risk factor for Alzheimer's disease (AD). A previous study indicated that tau protein hyperphosphorylation via protein phosphatase 2A (PP2A) and GSK-3ß inhibition was the mechanism by which MC-LR induces neurotoxicity; however, how MC-LR-induced neurotoxicity can be effectively prevented remains unclear. In this study, the reversal effect of metformin on MC-LR-induced neurotoxicity was investigated. The results showed that metformin effectively prevented tau hyperphosphorylation at Ser202 caused by MC-LR through PP2A and GSK-3b activity. The effect of metformin on PP2A activity was dependent on the inhibition of mTOR in MC-LR-treated SH-SY5Y cells. Metformin prevented spatial memory deficits in rats caused by intrahippocampal MC-LR administration. In sum, the results suggested that metformin can ameliorate the MC-LR-induced AD-like phenotype by preventing tau phosphorylation at Ser202, which was mainly mediated by mTOR-dependent PP2A and GSK-3ß activation.

ncRNAs associated with drug resistance and the therapy of digestive system neoplasms.

Digestive system cancer remains a common cancer and the main cause of cancer-related death worldwide. Drug resistance is a major challenge in the therapy of digestive system cancer, and represents a primary obstacle in the treatment of cancer by restricting the efficiency of both traditional chemotherapy and biological therapies. Existing studies indicate that noncoding RNAs play an important role in the evolution and progression of drug resistance in digestive system cancer, mainly by modulating drug transporter-related proteins, DNA damage repair, cell-cycle-related proteins, cell apoptosis-related proteins, drug target-related proteins, and the tumor microenvironment. In this review, we address the potential mechanisms of ncRNAs underlying drug resistance in digestive system tumors and discuss the possible application of ncRNAs against drug resistance in digestive system tumors.

Emerging roles of noncoding RNAs in multiple myeloma: A review.

Multiple myeloma (MM) is a hematologic malignancy characterized by unrestricted secretion of monoclonal immunoglobulin and uncontrolled plasma cell proliferation. Extra-medullary infiltration and drug resistance are two major obstacles in the treatment of MM. To solve these problems, it is necessary to elucidate the underlying pathological mechanisms and find new therapeutic targets. Noncoding RNAs (ncRNAs), which were once considered "transcriptional noise," have been recognized as crucial regulators in the process of tumorigenesis including MM. Increasing evidence has shown that ncRNAs participate in MM pathogenesis via a series of complex cellular or extracellular processes. This review article summarizes examples of ncRNAs involved in myelosis and discusses their potential as biomarkers and therapeutic targets in the diagnosis and treatment of myelosis.

Heterogeneity of circulating CXCR5-PD-1hiTph cells in patients of type 2 and type 1 diabetes in Chinese population.

AIMS: Circulating peripheral helper T (Tph) cells are shown to promote the progression of autoimmune diseases. However, the role of Tph cells in inflammatory diseases such as type 2 diabetes mellitus (T2DM) and the differences between T2DM and autoimmune diabetes remain unclear. METHODS: We recruited 92 T2DM patients, 106 type 1 diabetes mellitus (T1DM) patients and 84 healthy control individuals. Peripheral blood mononucleated cells were isolated and examined by multicolor flow cytometry. We further evaluated the correlations between circulating Tph cells and clinical biochemical parameters, islet function, disease progression and islet autoantibodies. RESULTS: Circulating Tph cells were significantly higher in both T2DM and T1DM patients than in healthy control individuals. A significant positive correlation was observed between Tph cells and B cells in T1DM patients and overweight T2DM patients. Furthermore, Tph cells were negatively correlated with the area under the C-peptide curve (C-PAUC), and Tph cells were significantly positively correlated with fasting glucose and glycated hemoglobin levels in T2DM patients. However, no correlation was found between Tph cells and the above clinical indicators in T1DM patients. The frequency of Tph cells positively correlated with the titer of GAD autoantibodies and duration of disease in T1DM patients. In addition, we demonstrated that the frequency of Tph cells was decreased after rituximab therapy in T1DM patients. CONCLUSIONS: Circulating Tph cells are associated with blood glucose levels and islet function in T2DM patients. In T1DM patients, circulating Tph cells are associated with B cells and islet autoantibodies. This may suggest that Tph cells have different pathogenic mechanisms in the two types of diabetes. CLINICAL TRIAL INFORMATION: http://ClinicalTrials.gov NCT01280682 (registered July, 2010).

Microcystin-LR Induces NLRP3 Inflammasome Activation via FOXO1 Phosphorylation, Resulting in Interleukin-1ß Secretion and Pyroptosis in Hepatocytes.

Microcystin-LR (MC-LR), the most common and toxic microcystin (MC) present in freshwater, poses a substantial threat to human health, especially hepatotoxicity. Recent evidence reveals that the NLRP3 inflammasome plays an important role in liver injury by activating caspase-1 to promote interleukin-1ß (IL-1ß) secretion. In this study, we investigated the possible role of NLRP3 inflammasome activation in MC-LR-induced mouse liver inflammatory injury. We found that MC-LR administered to mice by oral gavage mainly accumulated in liver and induced the activation of the NLRP3 inflammasome and production of mature IL-1ß. Additionally, we observed an increase in the levels of NLRP3 inflammasome-related proteins and the proportion of pyroptosis in MC-LR-treated AML-12 cells. We also found that inhibition of NLRP3 in mice attenuated MC-LR-induced IL-1ß production, indicating an essential role for NLRP3 in MC-LR-induced liver inflammatory injury. In addition, we found that inhibition of FOXO1 by AKT-mediated hyperphosphorylation, due to protein phosphatase 2A (PP2A) inhibition, is required for MC-LR-induced expression of NLRP3. Taken together, our in vivo and in vitro findings suggest a model in which the NLRP3 inflammasome activation, a result of AKT-mediated hyperphosphorylation of FOXO1 through inhibition of PP2A, plays a key role in MC-LR-induced liver inflammatory injury via IL-1ß secretion and pyroptotic cell death.

Reduced methylation of PP2Ac promotes ethanol-induced lipid accumulation through FOXO1 phosphorylation in vitro and in vivo.

Although disturbance of the methionine cycle and sequent decrease in hepatic methylation capacity are known to be important factors in the development of alcoholic liver injury, the underlying mechanisms are not fully understood. Here, we investigated the importance of the methylation of protein phosphatase 2A (PP2A) in alcoholic liver disease (ALD). We found that the severity of ethanol-induced liver injury and the extent of demethylation of PP2A catalytic C subunit (PP2Ac) were reduced after treatment with betaine, a methyl donor involved in the methionine-homocysteine cycle. These results suggest that PP2Ac methylation is decreased due to a broad decrease in hepatic methylation capacity after exposure to ethanol. Moreover, we found that the reduction in PP2Ac methylation led to increased degradation of the regulatory Bα subunit, thus promoting the phosphorylation and nuclear exclusion of Forkhead box O1 (FOXO1) and reducing FOXO1 transcriptional activity. Ultimately, the reduced activity of FOXO1 led to increased expression of TXNIP, which caused hepatic lipid accumulation. Our findings suggest that the reduction of PP2A methylation, a result of decrease hepatic methylation capacity, played an important role in ethanol-induced lipid accumulation via down-regulation of PP2A/Bα and FOXO1 phosphorylation.

Circulatinglong non-coding RNA FEZF1-AS1 and AFAP1-AS1 serve as potential diagnostic biomarkers for gastric cancer.

BACKGROUND: Growing evidence indicates that two long non-coding RNAs (lncRNAs), FEZ family zinc finger 1 antisense RNA 1 (FEZF1-AS1) and Actin filament associated protein 1 antisenseRNA1 (AFAP1-AS1), are highly expressed in different cancers, including gastric cancer (GC). However, the expression pattern and clinical utility of these two lncRNAs are still unknown. METHODS: Serum expression levels of FEZF1-AS1 andAFAP1-AS1 were measured by quantitative real-time polymerase chain reaction (qRT-PCR). CEA and CA19-9 were detected by ARCHITET I2000 SR. Analyses were all performed using SPSS software version 20.0 (SPSS Inc., Chicago, USA). P < 0.05 was considered statistically significant. RESULTS: Detection of serum FEZF1-AS1 and AFAP1-AS1 showed both of them were up-regulated in GC patients compared with the normal controls (p < 0.0001), and high serum expression levels were correlated with tumor size, tumor-node-metastasis (TNM) stage and lymph node metastasis. Besides, the area under the ROC curve (AUC) demonstrated the two lncRNAs had higher diagnostic utility than CEA and CA19-9. Furthermore, when combined the two lncRNAs as a model, it yielded an AUC of 0.866, and the combination of the model, CEA and CA19-9 could observably improve diagnostic sensitivity to 95.5 %. What's more, circulating FEZF1-AS1 and AFAP1-AS1 were significantly decreased after the GC patients underwent the operation (both p < 0.001). CONCLUSION: Our study indicated that serum FEZF1-AS1 and AFAP1-AS1 had better sensitivity and efficiency for the diagnosis of GC and the combination of the two lncRNAs might be used as a potential prognostic indicator in GC.

MiR-19b and miR-20a suppress apoptosis, promote proliferation and induce tumorigenicity of multiple myeloma cells by targeting PTEN.

Multiple myeloma (MM) is a common hematological malignancy that is often associated with osteolytic lesions, anemia and renal impairment. Deregulation of miRNA has been implicated in the pathogenesis of MM. It was found in our study that miR-19b and miR-20a as members of crucial oncogene miR-17-92 cluster were differentially expressed between patients with MM and normal controls by genechip microarray, and this result was further confirmed in sera of patients with MM by qRT-PCR. The functional effect of miR-19b/20a was analyzed and results showed that miR-19b/20a promoted cell proliferation and migration, inhibited cell apoptosis and altered cell cycle in MM cells. PTEN protein expression was reduced after transfection of miR-19b/20a, suggesting that PTEN was a direct target of miR-19b/20a. In addition, over-expression of miR-19b/20a reversed the anti-proliferation and pro-apoptosis effect of PTEN in MM cells. Finally, our in vivo experiment demonstrated that lentivirus-mediated delivery of miR-20a promoted tumor growth in murine xenograft model of MM, which provide evidence that miR-20a inhibitor exerts therapeutic activity in preclinical models and supports a framework for the development of miR-19b/20a-based treatment strategies for MM patients.

Circular RNAs are abundantly expressed and upregulated during repair of the damaged endometrium by Wharton's jelly-derived mesenchymal stem cells.

BACKGROUND: Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs) exhibit strong and powerful potential in repairing different diseases. The expression profile of circular RNA (circRNA) provides valuable insight for regulation of the repair process and exploration of reparative effect mechanisms. METHODS: Human endometrial stromal cells (ESCs) were cultured with mifepristone to obtain damaged ESCs, which were then cocultured with or without WJ-MSCs (cocultured group versus non-cocultured group) to observe the reparative effect upon damaged ESCs by WJ-MSCs. CircRNA microarray was performed between the two groups. Based on the transcriptomics data, the differential gene expression profiles of the two groups were analyzed by Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and network analysis methods. Screening of a circRNA database was performed, and the results were confirmed by quantitative polymerase chain reaction (qPCR). RESULTS: WJ-MSCs exerted a reparative effect upon damaged ESCs in the cocultured group such as improved cell morphology, higher proliferative ability, and lower apoptosis rate. CircRNA array showed that 7757 circRNAs were differentially expressed in ESCs from the cocultured group. Mitotic cell cycle, cell cycle process, and nuclear division ranked top in the GO upregulated list of the two groups, while DNA replication and cell cycle ranked top in the KEGG pathway analysis upregulated list of the two groups. The nine most aberrantly expressed circRNAs were selected for further verification in the same cohort of samples by microarray analysis. Seven of the nine most aberrantly circRNAs were confirmed to be significantly upregulated in the cocultured group. And four of the seven circRNAs (hsa_circ_0015825, hsa-circRNA4049-38, hsa-circRNA5028-15, and hsa_circ_0111659) expression both in ESCs and WJ-MSCs tended to decrease with time by qPCR. The levels of the remaining three circRNAs (hsa-circRNA8881-21, hsa_circ_0020492 and hsa_circ_ 0026141) did not change significantly over time in either ESCs or WJ-MSCs. Moreover, we focused on hsa_circRNA_0111659 and predicted its miRNAs and targeted mRNA. The association of circRNA-miRNA-mRNA is likely to be involved in regulating the repair of endometrial damage. CONCLUSIONS: Our results presented the abundant and upregulated circRNAs profile during repair of the damaged endometrium by WJ-MSCs and provided a novel perspective for circRNAs in the regulation of WJ-MSCs for endometrial repair.