Circular RNA hsa_circ_0001368 suppresses the progression of gastric cancer by regulating miR-6506-5p/FOXO3 axis.

Gastric cancer (GC) is still a major aggressive malignancy worldwide. While the importance of circular RNAs (circRNAs) involved in carcinogenesis has gradually been acknowledged, their role in human cancers is not largely understood, including in GC. Here, we focused on hsa_circ_0001368 in GC, a novel circRNA that has not been previously reported. In the current study, we found a broad downregulation of hsa_circ_0001368 in GC tissues and cells, which correlates with a worse prognosis in GC patients. Functional experiments suggested that the knockdown of hsa_circ_0001368 promoted cell viability and motility by cell proliferation and invasion assays. In addition, the knockdown of hsa_circ_0001368 led to accelerated tumor growth in vivo. Mechanically, we demonstrated that hsa_circ_0001368 served as a competing endogenous RNA (ceRNA) to sponge miR-6506-5p. Subsequently, FOXO3 may act as the functional target of miR-6506-5p, and the knockdown of hsa_circ_0001368 decreased the expression of the tumor-suppressive gene FOXO3. Taken together, our study revealed that hsa_circ_0001368 plays a tumor-suppression role in GC via the miR-6506-5p/FOXO3 axis and may serve as a potential target for GC therapy.

Hsa_circ_0000467 promotes cancer progression and serves as a diagnostic and prognostic biomarker for gastric cancer.

BACKGROUND: Emerging evidence indicates that dysregulation of circular RNAs (circRNAs) is implicated in the development of malignancies. However, the diagnostic value and functional role of circRNAs in gastric cancer (GC) remain largely elusive. METHODS: Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was performed to detect the expression of hsa_circ_0000467 in tissues, cell lines, and plasma. A receiver operating characteristic (ROC) curve was constructed to estimate the diagnostic value of hsa_circ_0000467. The association between the expression level of hsa_circ_0000467 and the clinicopathological features was analyzed. Moreover, cell functional assays were performed. RESULTS: Hsa_circ_0000467 was significantly upregulated in GC tissue compared to adjacent nontumor tissue (n = 51, P < 0.05). Similar results were detected in the HGC-27, MGC-803, AGS, NUGC-3, GES-1 cell lines (n = 15, P < 0.001), and in the plasma samples from GC patients (n = 20, P < 0.05). The area under the ROC curve of hsa_circ_0000467 was 0.790, which is superior to commonly used biomarkers including CEA and CA-724. We found that the expression levels of hsa_circ_0000467 in the same patient were significantly lower after surgery (n = 20, P < 0.05). Moreover, the hsa_circ_0000467 expression level is closely associated with TNM stage. Additionally, Cox multivariate analysis showed that hsa_circ_0000467 is a novel independent prognostic factor. Furthermore, in vitro experiments demonstrated that knockdown of hsa_circ_0000467 markedly inhibited the proliferation, migration, and invasion of GC cells. Moreover, hsa_circ_0000467 silencing increased tumor apoptosis in vitro. CONCLUSION: Hsa_circ_0000467 can act as a novel noninvasive biomarker for the diagnosis and prognosis of GC and may be a potential therapeutic target for GC.

General Carbon-Supporting Strategy to Boost the Oxygen Reduction Activity of Zeolitic-Imidazolate-Framework-Derived Fe/N/Carbon Catalysts in Proton Exchange Membrane Fuel Cells.

The oxygen reduction reaction (ORR) activity of the Fe/N/Carbon catalysts derived from the pyrolysis of zeolitic-imidazolate-framework-8 (ZIF-8) has been still lower than that of commercial Pt-based catalysts utilized in the proton exchange membrane fuel cells (PEMFCs) due to low density of accessible active sites. In this study, an efficient carbon-supporting strategy is developed to enhance the ORR efficiency of the ZIF-derived Fe/N/Carbon catalysts by increasing the accessible active site density. The enhancement lies in (i) improving the accessibility of active sites via converting dodecahedral particles to graphene-like layered materials and (ii) enhancing the density of FeNx active sites via suppressing the formation of nanoparticles as well as providing extra spaces to host active sites. The optimized and efficient Fe/N/Carbon catalyst shows a half-wave potential (E1/2) of 0.834 V versus reversible hydrogen electrode in acidic media and produces a peak power density of 0.66 W cm-2 in an air-fed PEMFC at 2 bar backpressure, outperforming most previously reported Pt-free ORR catalysts. Finally, the general applicability of the carbon-supporting strategy is confirmed using five different commercial carbon blacks. This work provides an effective route to derive Fe/N/Carbon catalysts exhibiting a higher power density in PEMFCs.

Novel abdominal negative pressure lavage-drainage system for anastomotic leakage after R0 resection for gastric cancer.

BACKGROUND: Anastomotic leakage (AL) is a severe complication associated with high morbidity and mortality after radical gastrectomy (RG) for gastric cancer (GC). We hypothesized that a novel abdominal negative pressure lavage-drainage system (ANPLDS) can effectively reduce the failure-to-rescue (FTR) and the risk of reoperation, and it is a feasible management for AL. AIM: To report our institution's experience with a novel ANPLDS for AL after RG for GC. METHODS: The study enrolled 4173 patients who underwent R0 resection for GC at our institution between June 2009 and December 2016. ANPLDS was routinely used for patients with AL after January 2014. Characterization of patients who underwent R0 resection was compared between different study periods. AL rates and postoperative outcome among patients with AL were compared before and after the ANPLDS therapy. We used multivariate analyses to evaluate clinicopathological and perioperative factors for associations with AL and FTR after AL. RESULTS: AL occurred in 83 (83/4173, 2%) patients, leading to 7 deaths. The mean time of occurrence of AL was 5.6 days. The AL rate was similar before (2009-2013, period 1) and after (2014-2016, period 2) the implementation of the ANPLDS therapy (1.7% vs 2.3%, P = 0.121). Age and malnourishment were independently associated with AL. The FTR rate and abdominal bleeding rate after AL occurred were respectively 8.4% and 9.6% for the entire period; however, compared with period 1, this significantly decreased during period 2 (16.2% vs 2.2%, P = 0.041; 18.9% vs 2.2%, P = 0.020, respectively). Moreover, the reoperation rate was also reduced in period 2, although this result was not statistically significant (13.5% vs 2.2%, P = 0.084). Additionally, only ANPLDS therapy was an independent protective factor for FTR after AL (P = 0.04). CONCLUSION: Our experience demonstrates that ANPLDS is a feasible management for AL after RG for GC.

Circular RNA hsa_circ_0006848 Related to Ribosomal Protein L6 Acts as a Novel Biomarker for Early Gastric Cancer.

OBJECTIVE: Circular RNAs (circRNAs) have been reported to be widely involved in pathological processes of various cancers. However, little is known about their diagnostic values in early gastric cancer (EGC). This study is aimed at exploring whether circulating circRNAs in plasma could act as biomarkers for EGC diagnosis. MATERIALS AND METHODS: Mass spectrometry (MS) was performed to identify the proteins that at significantly aberrantly levels in gastric cancer (GC) tissues. The target circRNA was identified by bioinformatics analysis. A receiver operating characteristic (ROC) curve was generated to evaluate the diagnostic utility. RESULTS: MS revealed that the ribosomal protein L6 (RPL6) expression was significantly downregulated only in EGC tissues vs. nontumorous tissues; this was validated by western blotting (n = 30, p = 0.0094). Bioinformatics analysis predicted that there is a hsa_circ_0006848/hsa_miR-329-5p/RPL6 axis in GC progression. The hsa_circ_0006848 expression was significantly downregulated in EGC tissues (vs. nontumorous tissues, n = 30, p = 0.0073) and plasma samples from EGC patients (vs. paired healthy volunteers, n = 30, p = 0.0089). In addition, the hsa_circ_0006848 plasma level in postoperative patients was significantly higher than that of preoperative patients (n = 30, p = 0.047). Furthermore, the decreased hsa_circ_0006848 expression in plasma was negatively correlated with poor differentiation (p = 0.037) and tumor size (p = 0.046). The area under the ROC curve (AUC) of hsa_circ_0006848 in plasma was 0.733, suggesting a good diagnostic value. The plasma hsa_circ_0006848 level combined with the carcinoembryonic antigen (CEA), carbohydrate-associated antigen 19-9 (CA19-9), and carbohydrate-associated antigen 72-4 (CA72-4) level increased the AUC to 0.825. CONCLUSION: Our results indicated that plasma hsa_circ_0006848 may be a novel noninvasive biomarker in EGC diagnosis.

CDK5 suppresses the metastasis of gastric cancer cells by interacting with and regulating PP2A.

Several previous studies have demonstrated that cyclin­dependent kinase (CDK)­5 expression serves an important role in promoting the development of malignant tumours. We have previously reported that CDK5 suppresses gastric tumourigenesis. The aim of the present study was to investigate the mechanistic basis of CDK5. The results of immunoprecipitation and western blot analysis demonstrated that CDK5 could interact with serine/threonine­protein phosphatase 2A (PP2A). The use of an inhibitor of PP2A in CDK5­overexpressing gastric cancer (GC) cell lines antagonized CDK5­mediated suppression in GC cells. Further analysis revealed that PP2A expression was downregulated in GC and patients with low levels of PP2A had worse survival outcomes than those with high levels of PP2A (P=0.035). Therefore, the present study provided a novel mechanism for CDK5­mediated tumour suppression, suggesting that CDK5 may be an attractive target for future therapeutic strategies for treating GC. In addition, low levels of PP2A may indicate a tendency for poor prognosis in patients with GC.

Promoting Ethylene Selectivity from CO2 Electroreduction on CuO Supported onto CO2 Capture Materials.

Cu is a unique catalyst for CO2 electroreduction, since it can catalyze CO2 reduction to a series of hydrocarbons, alcohols, and carboxylic acids. Nevertheless, such Cu catalysts suffer from poor selectivity. High pressure of CO2 is considered to facilitate the activity and selectivity of CO2 reduction. Herein, a new strategy is presented for CO2 reduction with improved C2 H4 selectivity on a Cu catalyst by using CO2 capture materials as the support at ambient pressure. N-doped carbon (Nx C) was synthesized through high-temperature carbonization of melamine and l-lysine. We observed that the CO2 uptake capacity of Nx C depends on both the microporous area and the content of pyridinic N species, which can be controlled by the carbonization temperature (600-800 °C). The as-prepared CuO/Nx C catalysts exhibit a considerably higher C2 H4 faradaic efficiency (36 %) than CuO supported on XC-72 carbon black (19 %), or unsupported CuO (20 %). Moreover, there is a good linear relationship between the C2 H4 faradaic efficiency and CO2 uptake capacity of the supports for CuO. The local high CO2 concentration near Cu catalysts, created by CO2 capture materials, was proposed to increase the coverage of CO intermediate, which is favorable for the coupling of two CO units in the formation of C2 H4 . This study demonstrates that pairing Cu catalysts with CO2 capture supports is a promising approach for designing highly effective CO2 reduction electrocatalysts.

CDK5RAP3 suppresses Wnt/ß-catenin signaling by inhibiting AKT phosphorylation in gastric cancer.

BACKGROUND: CDK5RAP3 was initially isolated as a binding protein of the CDK5 activator p35. Although CDK5RAP3 has been shown to negatively regulate the Wnt/ß-catenin signaling pathway in gastric cancer by repressing GSK-3ß phosphorylation, its in-depth mechanism has not been determined. METHODS: Following CDK5RAP3 overexpression or knock down, CDK5RAP3 signaling pathways were investigated in gastric cancer cells by Western Blotting. Cell growth, invasion and migration were also evaluated in gastric cancer cell lines. We analyzed CDK5RAP3, AKT, p-AKT (Ser473), GSK-3ß and p-GSK-3ß (Ser9) expression in gastric tumor samples and adjacent non-tumor tissues from 295 patients using immunohistochemistry and Western Blotting. The prognostic significance of CDK5RAP3 and p-AKT (Ser473) was confirmed by a Log-rank test. RESULTS: Our study demonstrated that the expression of p-AKT (Ser473) and p-GSK-3ß (Ser9) was negatively correlated with CDK5RAP3 in stable gastric cancer cell lines. CDK5RAP3 repressed AKT phosphorylation, which promoted GSK-3ß phosphorylation, thereby suppressing ß-catenin protein expression and, consequently, gastric cancer. The protein level of CDK5RAP3 was markedly decreased in most gastric tumor tissues compared with adjacent non-tumor tissues, and the levels of p-AKT (Ser473) and p-GSK-3ß (Ser9) were also negatively correlated with those of CDK5RAP3. The prognostic value of CDK5RAP3 for overall survival was found to be dependent on AKT phosphorylation. CONCLUSION: Our results demonstrated that CDK5RAP3 negatively regulates the Wnt/ß-catenin signaling pathway by repressing AKT phosphorylation, which leads to better survival of patients with gastric cancer.